/* SSA Dominator optimizations for trees
- Copyright (C) 2001-2015 Free Software Foundation, Inc.
+ Copyright (C) 2001-2021 Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
#include "system.h"
#include "coretypes.h"
#include "backend.h"
-#include "cfghooks.h"
#include "tree.h"
#include "gimple.h"
-#include "hard-reg-set.h"
+#include "tree-pass.h"
#include "ssa.h"
-#include "alias.h"
+#include "gimple-pretty-print.h"
#include "fold-const.h"
-#include "stor-layout.h"
-#include "flags.h"
-#include "tm_p.h"
#include "cfganal.h"
#include "cfgloop.h"
-#include "gimple-pretty-print.h"
-#include "internal-fn.h"
#include "gimple-fold.h"
#include "tree-eh.h"
+#include "tree-inline.h"
#include "gimple-iterator.h"
#include "tree-cfg.h"
#include "tree-into-ssa.h"
#include "domwalk.h"
-#include "tree-pass.h"
#include "tree-ssa-propagate.h"
#include "tree-ssa-threadupdate.h"
-#include "langhooks.h"
-#include "params.h"
#include "tree-ssa-scopedtables.h"
#include "tree-ssa-threadedge.h"
#include "tree-ssa-dom.h"
#include "gimplify.h"
#include "tree-cfgcleanup.h"
+#include "dbgcnt.h"
+#include "alloc-pool.h"
+#include "tree-vrp.h"
+#include "vr-values.h"
+#include "gimple-ssa-evrp-analyze.h"
+#include "alias.h"
/* This file implements optimizations on the dominator tree. */
-/* Representation of a "naked" right-hand-side expression, to be used
- in recording available expressions in the expression hash table. */
-
-enum expr_kind
-{
- EXPR_SINGLE,
- EXPR_UNARY,
- EXPR_BINARY,
- EXPR_TERNARY,
- EXPR_CALL,
- EXPR_PHI
-};
-
-struct hashable_expr
-{
- tree type;
- enum expr_kind kind;
- union {
- struct { tree rhs; } single;
- struct { enum tree_code op; tree opnd; } unary;
- struct { enum tree_code op; tree opnd0, opnd1; } binary;
- struct { enum tree_code op; tree opnd0, opnd1, opnd2; } ternary;
- struct { gcall *fn_from; bool pure; size_t nargs; tree *args; } call;
- struct { size_t nargs; tree *args; } phi;
- } ops;
-};
-
-/* Structure for recording known values of a conditional expression
- at the exits from its block. */
-
-typedef struct cond_equivalence_s
-{
- struct hashable_expr cond;
- tree value;
-} cond_equivalence;
-
-
-/* Structure for recording edge equivalences as well as any pending
- edge redirections during the dominator optimizer.
+/* Structure for recording edge equivalences.
Computing and storing the edge equivalences instead of creating
them on-demand can save significant amounts of time, particularly
These structures live for a single iteration of the dominator
optimizer in the edge's AUX field. At the end of an iteration we
- free each of these structures and update the AUX field to point
- to any requested redirection target (the code for updating the
- CFG and SSA graph for edge redirection expects redirection edge
- targets to be in the AUX field for each edge. */
-
-struct edge_info
+ free each of these structures. */
+class edge_info
{
- /* If this edge creates a simple equivalence, the LHS and RHS of
- the equivalence will be stored here. */
- tree lhs;
- tree rhs;
+ public:
+ typedef std::pair <tree, tree> equiv_pair;
+ edge_info (edge);
+ ~edge_info ();
+
+ /* Record a simple LHS = RHS equivalence. This may trigger
+ calls to derive_equivalences. */
+ void record_simple_equiv (tree, tree);
+
+ /* If traversing this edge creates simple equivalences, we store
+ them as LHS/RHS pairs within this vector. */
+ vec<equiv_pair> simple_equivalences;
/* Traversing an edge may also indicate one or more particular conditions
are true or false. */
vec<cond_equivalence> cond_equivalences;
-};
-
-/* Stack of available expressions in AVAIL_EXPRs. Each block pushes any
- expressions it enters into the hash table along with a marker entry
- (null). When we finish processing the block, we pop off entries and
- remove the expressions from the global hash table until we hit the
- marker. */
-typedef struct expr_hash_elt * expr_hash_elt_t;
-
-static vec<std::pair<expr_hash_elt_t, expr_hash_elt_t> > avail_exprs_stack;
-
-/* Structure for entries in the expression hash table. */
-
-struct expr_hash_elt
-{
- /* The value (lhs) of this expression. */
- tree lhs;
-
- /* The expression (rhs) we want to record. */
- struct hashable_expr expr;
-
- /* The virtual operand associated with the nearest dominating stmt
- loading from or storing to expr. */
- tree vop;
-
- /* The hash value for RHS. */
- hashval_t hash;
-
- /* A unique stamp, typically the address of the hash
- element itself, used in removing entries from the table. */
- struct expr_hash_elt *stamp;
-};
-
-/* Hashtable helpers. */
-static bool hashable_expr_equal_p (const struct hashable_expr *,
- const struct hashable_expr *);
-static void free_expr_hash_elt (void *);
-
-struct expr_elt_hasher : pointer_hash <expr_hash_elt>
-{
- static inline hashval_t hash (const value_type &);
- static inline bool equal (const value_type &, const compare_type &);
- static inline void remove (value_type &);
+ private:
+ /* Derive equivalences by walking the use-def chains. */
+ void derive_equivalences (tree, tree, int);
};
-inline hashval_t
-expr_elt_hasher::hash (const value_type &p)
-{
- return p->hash;
-}
-
-inline bool
-expr_elt_hasher::equal (const value_type &p1, const compare_type &p2)
-{
- const struct hashable_expr *expr1 = &p1->expr;
- const struct expr_hash_elt *stamp1 = p1->stamp;
- const struct hashable_expr *expr2 = &p2->expr;
- const struct expr_hash_elt *stamp2 = p2->stamp;
-
- /* This case should apply only when removing entries from the table. */
- if (stamp1 == stamp2)
- return true;
-
- if (p1->hash != p2->hash)
- return false;
-
- /* In case of a collision, both RHS have to be identical and have the
- same VUSE operands. */
- if (hashable_expr_equal_p (expr1, expr2)
- && types_compatible_p (expr1->type, expr2->type))
- return true;
-
- return false;
-}
-
-/* Delete an expr_hash_elt and reclaim its storage. */
-
-inline void
-expr_elt_hasher::remove (value_type &element)
-{
- free_expr_hash_elt (element);
-}
-
-/* Hash table with expressions made available during the renaming process.
- When an assignment of the form X_i = EXPR is found, the statement is
- stored in this table. If the same expression EXPR is later found on the
- RHS of another statement, it is replaced with X_i (thus performing
- global redundancy elimination). Similarly as we pass through conditionals
- we record the conditional itself as having either a true or false value
- in this table. */
-static hash_table<expr_elt_hasher> *avail_exprs;
-
-/* Unwindable const/copy equivalences. */
-static const_and_copies *const_and_copies;
-
/* Track whether or not we have changed the control flow graph. */
static bool cfg_altered;
/* Bitmap of blocks that have had EH statements cleaned. We should
remove their dead edges eventually. */
static bitmap need_eh_cleanup;
-static vec<gimple> need_noreturn_fixup;
+static vec<gimple *> need_noreturn_fixup;
/* Statistics for dominator optimizations. */
struct opt_stats_d
static struct opt_stats_d opt_stats;
/* Local functions. */
-static void optimize_stmt (basic_block, gimple_stmt_iterator);
-static tree lookup_avail_expr (gimple, bool);
-static hashval_t avail_expr_hash (const void *);
-static void htab_statistics (FILE *,
- const hash_table<expr_elt_hasher> &);
-static void record_cond (cond_equivalence *);
-static void record_equality (tree, tree);
+static void record_equality (tree, tree, class const_and_copies *);
static void record_equivalences_from_phis (basic_block);
-static void record_equivalences_from_incoming_edge (basic_block);
-static void eliminate_redundant_computations (gimple_stmt_iterator *);
-static void record_equivalences_from_stmt (gimple, int);
-static void remove_local_expressions_from_table (void);
-static edge single_incoming_edge_ignoring_loop_edges (basic_block);
-
-
-/* Given a statement STMT, initialize the hash table element pointed to
- by ELEMENT. */
-
-static void
-initialize_hash_element (gimple stmt, tree lhs,
- struct expr_hash_elt *element)
-{
- enum gimple_code code = gimple_code (stmt);
- struct hashable_expr *expr = &element->expr;
-
- if (code == GIMPLE_ASSIGN)
- {
- enum tree_code subcode = gimple_assign_rhs_code (stmt);
-
- switch (get_gimple_rhs_class (subcode))
- {
- case GIMPLE_SINGLE_RHS:
- expr->kind = EXPR_SINGLE;
- expr->type = TREE_TYPE (gimple_assign_rhs1 (stmt));
- expr->ops.single.rhs = gimple_assign_rhs1 (stmt);
- break;
- case GIMPLE_UNARY_RHS:
- expr->kind = EXPR_UNARY;
- expr->type = TREE_TYPE (gimple_assign_lhs (stmt));
- if (CONVERT_EXPR_CODE_P (subcode))
- subcode = NOP_EXPR;
- expr->ops.unary.op = subcode;
- expr->ops.unary.opnd = gimple_assign_rhs1 (stmt);
- break;
- case GIMPLE_BINARY_RHS:
- expr->kind = EXPR_BINARY;
- expr->type = TREE_TYPE (gimple_assign_lhs (stmt));
- expr->ops.binary.op = subcode;
- expr->ops.binary.opnd0 = gimple_assign_rhs1 (stmt);
- expr->ops.binary.opnd1 = gimple_assign_rhs2 (stmt);
- break;
- case GIMPLE_TERNARY_RHS:
- expr->kind = EXPR_TERNARY;
- expr->type = TREE_TYPE (gimple_assign_lhs (stmt));
- expr->ops.ternary.op = subcode;
- expr->ops.ternary.opnd0 = gimple_assign_rhs1 (stmt);
- expr->ops.ternary.opnd1 = gimple_assign_rhs2 (stmt);
- expr->ops.ternary.opnd2 = gimple_assign_rhs3 (stmt);
- break;
- default:
- gcc_unreachable ();
- }
- }
- else if (code == GIMPLE_COND)
- {
- expr->type = boolean_type_node;
- expr->kind = EXPR_BINARY;
- expr->ops.binary.op = gimple_cond_code (stmt);
- expr->ops.binary.opnd0 = gimple_cond_lhs (stmt);
- expr->ops.binary.opnd1 = gimple_cond_rhs (stmt);
- }
- else if (gcall *call_stmt = dyn_cast <gcall *> (stmt))
- {
- size_t nargs = gimple_call_num_args (call_stmt);
- size_t i;
-
- gcc_assert (gimple_call_lhs (call_stmt));
-
- expr->type = TREE_TYPE (gimple_call_lhs (call_stmt));
- expr->kind = EXPR_CALL;
- expr->ops.call.fn_from = call_stmt;
-
- if (gimple_call_flags (call_stmt) & (ECF_CONST | ECF_PURE))
- expr->ops.call.pure = true;
- else
- expr->ops.call.pure = false;
-
- expr->ops.call.nargs = nargs;
- expr->ops.call.args = XCNEWVEC (tree, nargs);
- for (i = 0; i < nargs; i++)
- expr->ops.call.args[i] = gimple_call_arg (call_stmt, i);
- }
- else if (gswitch *swtch_stmt = dyn_cast <gswitch *> (stmt))
- {
- expr->type = TREE_TYPE (gimple_switch_index (swtch_stmt));
- expr->kind = EXPR_SINGLE;
- expr->ops.single.rhs = gimple_switch_index (swtch_stmt);
- }
- else if (code == GIMPLE_GOTO)
- {
- expr->type = TREE_TYPE (gimple_goto_dest (stmt));
- expr->kind = EXPR_SINGLE;
- expr->ops.single.rhs = gimple_goto_dest (stmt);
- }
- else if (code == GIMPLE_PHI)
- {
- size_t nargs = gimple_phi_num_args (stmt);
- size_t i;
-
- expr->type = TREE_TYPE (gimple_phi_result (stmt));
- expr->kind = EXPR_PHI;
- expr->ops.phi.nargs = nargs;
- expr->ops.phi.args = XCNEWVEC (tree, nargs);
-
- for (i = 0; i < nargs; i++)
- expr->ops.phi.args[i] = gimple_phi_arg_def (stmt, i);
- }
- else
- gcc_unreachable ();
-
- element->lhs = lhs;
- element->vop = gimple_vuse (stmt);
- element->hash = avail_expr_hash (element);
- element->stamp = element;
+static void record_equivalences_from_incoming_edge (basic_block,
+ class const_and_copies *,
+ class avail_exprs_stack *);
+static void eliminate_redundant_computations (gimple_stmt_iterator *,
+ class const_and_copies *,
+ class avail_exprs_stack *);
+static void record_equivalences_from_stmt (gimple *, int,
+ class avail_exprs_stack *);
+static void dump_dominator_optimization_stats (FILE *file,
+ hash_table<expr_elt_hasher> *);
+
+/* Constructor for EDGE_INFO. An EDGE_INFO instance is always
+ associated with an edge E. */
+
+edge_info::edge_info (edge e)
+{
+ /* Free the old one associated with E, if it exists and
+ associate our new object with E. */
+ free_dom_edge_info (e);
+ e->aux = this;
+
+ /* And initialize the embedded vectors. */
+ simple_equivalences = vNULL;
+ cond_equivalences = vNULL;
}
-/* Given a conditional expression COND as a tree, initialize
- a hashable_expr expression EXPR. The conditional must be a
- comparison or logical negation. A constant or a variable is
- not permitted. */
+/* Destructor just needs to release the vectors. */
-static void
-initialize_expr_from_cond (tree cond, struct hashable_expr *expr)
+edge_info::~edge_info (void)
{
- expr->type = boolean_type_node;
-
- if (COMPARISON_CLASS_P (cond))
- {
- expr->kind = EXPR_BINARY;
- expr->ops.binary.op = TREE_CODE (cond);
- expr->ops.binary.opnd0 = TREE_OPERAND (cond, 0);
- expr->ops.binary.opnd1 = TREE_OPERAND (cond, 1);
- }
- else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
- {
- expr->kind = EXPR_UNARY;
- expr->ops.unary.op = TRUTH_NOT_EXPR;
- expr->ops.unary.opnd = TREE_OPERAND (cond, 0);
- }
- else
- gcc_unreachable ();
+ this->cond_equivalences.release ();
+ this->simple_equivalences.release ();
}
-/* Given a hashable_expr expression EXPR and an LHS,
- initialize the hash table element pointed to by ELEMENT. */
+/* NAME is known to have the value VALUE, which must be a constant.
-static void
-initialize_hash_element_from_expr (struct hashable_expr *expr,
- tree lhs,
- struct expr_hash_elt *element)
-{
- element->expr = *expr;
- element->lhs = lhs;
- element->vop = NULL_TREE;
- element->hash = avail_expr_hash (element);
- element->stamp = element;
-}
+ Walk through its use-def chain to see if there are other equivalences
+ we might be able to derive.
-/* Compare two hashable_expr structures for equivalence. They are
- considered equivalent when the expressions they denote must
- necessarily be equal. The logic is intended to follow that of
- operand_equal_p in fold-const.c */
+ RECURSION_LIMIT controls how far back we recurse through the use-def
+ chains. */
-static bool
-hashable_expr_equal_p (const struct hashable_expr *expr0,
- const struct hashable_expr *expr1)
+void
+edge_info::derive_equivalences (tree name, tree value, int recursion_limit)
{
- tree type0 = expr0->type;
- tree type1 = expr1->type;
-
- /* If either type is NULL, there is nothing to check. */
- if ((type0 == NULL_TREE) ^ (type1 == NULL_TREE))
- return false;
+ if (TREE_CODE (name) != SSA_NAME || TREE_CODE (value) != INTEGER_CST)
+ return;
- /* If both types don't have the same signedness, precision, and mode,
- then we can't consider them equal. */
- if (type0 != type1
- && (TREE_CODE (type0) == ERROR_MARK
- || TREE_CODE (type1) == ERROR_MARK
- || TYPE_UNSIGNED (type0) != TYPE_UNSIGNED (type1)
- || TYPE_PRECISION (type0) != TYPE_PRECISION (type1)
- || TYPE_MODE (type0) != TYPE_MODE (type1)))
- return false;
+ /* This records the equivalence for the toplevel object. Do
+ this before checking the recursion limit. */
+ simple_equivalences.safe_push (equiv_pair (name, value));
- if (expr0->kind != expr1->kind)
- return false;
+ /* Limit how far up the use-def chains we are willing to walk. */
+ if (recursion_limit == 0)
+ return;
- switch (expr0->kind)
+ /* We can walk up the use-def chains to potentially find more
+ equivalences. */
+ gimple *def_stmt = SSA_NAME_DEF_STMT (name);
+ if (is_gimple_assign (def_stmt))
{
- case EXPR_SINGLE:
- return operand_equal_p (expr0->ops.single.rhs,
- expr1->ops.single.rhs, 0);
-
- case EXPR_UNARY:
- if (expr0->ops.unary.op != expr1->ops.unary.op)
- return false;
-
- if ((CONVERT_EXPR_CODE_P (expr0->ops.unary.op)
- || expr0->ops.unary.op == NON_LVALUE_EXPR)
- && TYPE_UNSIGNED (expr0->type) != TYPE_UNSIGNED (expr1->type))
- return false;
-
- return operand_equal_p (expr0->ops.unary.opnd,
- expr1->ops.unary.opnd, 0);
-
- case EXPR_BINARY:
- if (expr0->ops.binary.op != expr1->ops.binary.op)
- return false;
-
- if (operand_equal_p (expr0->ops.binary.opnd0,
- expr1->ops.binary.opnd0, 0)
- && operand_equal_p (expr0->ops.binary.opnd1,
- expr1->ops.binary.opnd1, 0))
- return true;
-
- /* For commutative ops, allow the other order. */
- return (commutative_tree_code (expr0->ops.binary.op)
- && operand_equal_p (expr0->ops.binary.opnd0,
- expr1->ops.binary.opnd1, 0)
- && operand_equal_p (expr0->ops.binary.opnd1,
- expr1->ops.binary.opnd0, 0));
-
- case EXPR_TERNARY:
- if (expr0->ops.ternary.op != expr1->ops.ternary.op
- || !operand_equal_p (expr0->ops.ternary.opnd2,
- expr1->ops.ternary.opnd2, 0))
- return false;
-
- if (operand_equal_p (expr0->ops.ternary.opnd0,
- expr1->ops.ternary.opnd0, 0)
- && operand_equal_p (expr0->ops.ternary.opnd1,
- expr1->ops.ternary.opnd1, 0))
- return true;
-
- /* For commutative ops, allow the other order. */
- return (commutative_ternary_tree_code (expr0->ops.ternary.op)
- && operand_equal_p (expr0->ops.ternary.opnd0,
- expr1->ops.ternary.opnd1, 0)
- && operand_equal_p (expr0->ops.ternary.opnd1,
- expr1->ops.ternary.opnd0, 0));
-
- case EXPR_CALL:
- {
- size_t i;
-
- /* If the calls are to different functions, then they
- clearly cannot be equal. */
- if (!gimple_call_same_target_p (expr0->ops.call.fn_from,
- expr1->ops.call.fn_from))
- return false;
-
- if (! expr0->ops.call.pure)
- return false;
+ enum tree_code code = gimple_assign_rhs_code (def_stmt);
+ switch (code)
+ {
+ /* If the result of an OR is zero, then its operands are, too. */
+ case BIT_IOR_EXPR:
+ if (integer_zerop (value))
+ {
+ tree rhs1 = gimple_assign_rhs1 (def_stmt);
+ tree rhs2 = gimple_assign_rhs2 (def_stmt);
- if (expr0->ops.call.nargs != expr1->ops.call.nargs)
- return false;
+ value = build_zero_cst (TREE_TYPE (rhs1));
+ derive_equivalences (rhs1, value, recursion_limit - 1);
+ value = build_zero_cst (TREE_TYPE (rhs2));
+ derive_equivalences (rhs2, value, recursion_limit - 1);
+ }
+ break;
- for (i = 0; i < expr0->ops.call.nargs; i++)
- if (! operand_equal_p (expr0->ops.call.args[i],
- expr1->ops.call.args[i], 0))
- return false;
+ /* If the result of an AND is nonzero, then its operands are, too. */
+ case BIT_AND_EXPR:
+ if (!integer_zerop (value))
+ {
+ tree rhs1 = gimple_assign_rhs1 (def_stmt);
+ tree rhs2 = gimple_assign_rhs2 (def_stmt);
+
+ /* If either operand has a boolean range, then we
+ know its value must be one, otherwise we just know it
+ is nonzero. The former is clearly useful, I haven't
+ seen cases where the latter is helpful yet. */
+ if (TREE_CODE (rhs1) == SSA_NAME)
+ {
+ if (ssa_name_has_boolean_range (rhs1))
+ {
+ value = build_one_cst (TREE_TYPE (rhs1));
+ derive_equivalences (rhs1, value, recursion_limit - 1);
+ }
+ }
+ if (TREE_CODE (rhs2) == SSA_NAME)
+ {
+ if (ssa_name_has_boolean_range (rhs2))
+ {
+ value = build_one_cst (TREE_TYPE (rhs2));
+ derive_equivalences (rhs2, value, recursion_limit - 1);
+ }
+ }
+ }
+ break;
- if (stmt_could_throw_p (expr0->ops.call.fn_from))
+ /* If LHS is an SSA_NAME and RHS is a constant integer and LHS was
+ set via a widening type conversion, then we may be able to record
+ additional equivalences. */
+ case NOP_EXPR:
+ case CONVERT_EXPR:
{
- int lp0 = lookup_stmt_eh_lp (expr0->ops.call.fn_from);
- int lp1 = lookup_stmt_eh_lp (expr1->ops.call.fn_from);
- if ((lp0 > 0 || lp1 > 0) && lp0 != lp1)
- return false;
+ tree rhs = gimple_assign_rhs1 (def_stmt);
+ tree rhs_type = TREE_TYPE (rhs);
+ if (INTEGRAL_TYPE_P (rhs_type)
+ && (TYPE_PRECISION (TREE_TYPE (name))
+ >= TYPE_PRECISION (rhs_type))
+ && int_fits_type_p (value, rhs_type))
+ derive_equivalences (rhs,
+ fold_convert (rhs_type, value),
+ recursion_limit - 1);
+ break;
}
- return true;
- }
-
- case EXPR_PHI:
- {
- size_t i;
-
- if (expr0->ops.phi.nargs != expr1->ops.phi.nargs)
- return false;
-
- for (i = 0; i < expr0->ops.phi.nargs; i++)
- if (! operand_equal_p (expr0->ops.phi.args[i],
- expr1->ops.phi.args[i], 0))
- return false;
-
- return true;
- }
-
- default:
- gcc_unreachable ();
- }
-}
-
-/* Generate a hash value for a pair of expressions. This can be used
- iteratively by passing a previous result in HSTATE.
-
- The same hash value is always returned for a given pair of expressions,
- regardless of the order in which they are presented. This is useful in
- hashing the operands of commutative functions. */
-
-namespace inchash
-{
-
-static void
-add_expr_commutative (const_tree t1, const_tree t2, hash &hstate)
-{
- hash one, two;
-
- inchash::add_expr (t1, one);
- inchash::add_expr (t2, two);
- hstate.add_commutative (one, two);
-}
-
-/* Compute a hash value for a hashable_expr value EXPR and a
- previously accumulated hash value VAL. If two hashable_expr
- values compare equal with hashable_expr_equal_p, they must
- hash to the same value, given an identical value of VAL.
- The logic is intended to follow inchash::add_expr in tree.c. */
-
-static void
-add_hashable_expr (const struct hashable_expr *expr, hash &hstate)
-{
- switch (expr->kind)
- {
- case EXPR_SINGLE:
- inchash::add_expr (expr->ops.single.rhs, hstate);
- break;
-
- case EXPR_UNARY:
- hstate.add_object (expr->ops.unary.op);
-
- /* Make sure to include signedness in the hash computation.
- Don't hash the type, that can lead to having nodes which
- compare equal according to operand_equal_p, but which
- have different hash codes. */
- if (CONVERT_EXPR_CODE_P (expr->ops.unary.op)
- || expr->ops.unary.op == NON_LVALUE_EXPR)
- hstate.add_int (TYPE_UNSIGNED (expr->type));
-
- inchash::add_expr (expr->ops.unary.opnd, hstate);
- break;
-
- case EXPR_BINARY:
- hstate.add_object (expr->ops.binary.op);
- if (commutative_tree_code (expr->ops.binary.op))
- inchash::add_expr_commutative (expr->ops.binary.opnd0,
- expr->ops.binary.opnd1, hstate);
- else
- {
- inchash::add_expr (expr->ops.binary.opnd0, hstate);
- inchash::add_expr (expr->ops.binary.opnd1, hstate);
- }
- break;
-
- case EXPR_TERNARY:
- hstate.add_object (expr->ops.ternary.op);
- if (commutative_ternary_tree_code (expr->ops.ternary.op))
- inchash::add_expr_commutative (expr->ops.ternary.opnd0,
- expr->ops.ternary.opnd1, hstate);
- else
- {
- inchash::add_expr (expr->ops.ternary.opnd0, hstate);
- inchash::add_expr (expr->ops.ternary.opnd1, hstate);
- }
- inchash::add_expr (expr->ops.ternary.opnd2, hstate);
- break;
-
- case EXPR_CALL:
- {
- size_t i;
- enum tree_code code = CALL_EXPR;
- gcall *fn_from;
-
- hstate.add_object (code);
- fn_from = expr->ops.call.fn_from;
- if (gimple_call_internal_p (fn_from))
- hstate.merge_hash ((hashval_t) gimple_call_internal_fn (fn_from));
- else
- inchash::add_expr (gimple_call_fn (fn_from), hstate);
- for (i = 0; i < expr->ops.call.nargs; i++)
- inchash::add_expr (expr->ops.call.args[i], hstate);
- }
- break;
-
- case EXPR_PHI:
- {
- size_t i;
-
- for (i = 0; i < expr->ops.phi.nargs; i++)
- inchash::add_expr (expr->ops.phi.args[i], hstate);
- }
- break;
-
- default:
- gcc_unreachable ();
- }
-}
-
-}
-
-/* Print a diagnostic dump of an expression hash table entry. */
-
-static void
-print_expr_hash_elt (FILE * stream, const struct expr_hash_elt *element)
-{
- fprintf (stream, "STMT ");
-
- if (element->lhs)
- {
- print_generic_expr (stream, element->lhs, 0);
- fprintf (stream, " = ");
- }
+ /* We can invert the operation of these codes trivially if
+ one of the RHS operands is a constant to produce a known
+ value for the other RHS operand. */
+ case POINTER_PLUS_EXPR:
+ case PLUS_EXPR:
+ {
+ tree rhs1 = gimple_assign_rhs1 (def_stmt);
+ tree rhs2 = gimple_assign_rhs2 (def_stmt);
+
+ /* If either argument is a constant, then we can compute
+ a constant value for the nonconstant argument. */
+ if (TREE_CODE (rhs1) == INTEGER_CST
+ && TREE_CODE (rhs2) == SSA_NAME)
+ derive_equivalences (rhs2,
+ fold_binary (MINUS_EXPR, TREE_TYPE (rhs1),
+ value, rhs1),
+ recursion_limit - 1);
+ else if (TREE_CODE (rhs2) == INTEGER_CST
+ && TREE_CODE (rhs1) == SSA_NAME)
+ derive_equivalences (rhs1,
+ fold_binary (MINUS_EXPR, TREE_TYPE (rhs1),
+ value, rhs2),
+ recursion_limit - 1);
+ break;
+ }
- switch (element->expr.kind)
- {
- case EXPR_SINGLE:
- print_generic_expr (stream, element->expr.ops.single.rhs, 0);
- break;
-
- case EXPR_UNARY:
- fprintf (stream, "%s ", get_tree_code_name (element->expr.ops.unary.op));
- print_generic_expr (stream, element->expr.ops.unary.opnd, 0);
- break;
-
- case EXPR_BINARY:
- print_generic_expr (stream, element->expr.ops.binary.opnd0, 0);
- fprintf (stream, " %s ", get_tree_code_name (element->expr.ops.binary.op));
- print_generic_expr (stream, element->expr.ops.binary.opnd1, 0);
- break;
-
- case EXPR_TERNARY:
- fprintf (stream, " %s <", get_tree_code_name (element->expr.ops.ternary.op));
- print_generic_expr (stream, element->expr.ops.ternary.opnd0, 0);
- fputs (", ", stream);
- print_generic_expr (stream, element->expr.ops.ternary.opnd1, 0);
- fputs (", ", stream);
- print_generic_expr (stream, element->expr.ops.ternary.opnd2, 0);
- fputs (">", stream);
- break;
-
- case EXPR_CALL:
- {
- size_t i;
- size_t nargs = element->expr.ops.call.nargs;
- gcall *fn_from;
-
- fn_from = element->expr.ops.call.fn_from;
- if (gimple_call_internal_p (fn_from))
- fputs (internal_fn_name (gimple_call_internal_fn (fn_from)),
- stream);
- else
- print_generic_expr (stream, gimple_call_fn (fn_from), 0);
- fprintf (stream, " (");
- for (i = 0; i < nargs; i++)
- {
- print_generic_expr (stream, element->expr.ops.call.args[i], 0);
- if (i + 1 < nargs)
- fprintf (stream, ", ");
- }
- fprintf (stream, ")");
- }
- break;
+ /* If one of the operands is a constant, then we can compute
+ the value of the other operand. If both operands are
+ SSA_NAMEs, then they must be equal if the result is zero. */
+ case MINUS_EXPR:
+ {
+ tree rhs1 = gimple_assign_rhs1 (def_stmt);
+ tree rhs2 = gimple_assign_rhs2 (def_stmt);
+
+ /* If either argument is a constant, then we can compute
+ a constant value for the nonconstant argument. */
+ if (TREE_CODE (rhs1) == INTEGER_CST
+ && TREE_CODE (rhs2) == SSA_NAME)
+ derive_equivalences (rhs2,
+ fold_binary (MINUS_EXPR, TREE_TYPE (rhs1),
+ rhs1, value),
+ recursion_limit - 1);
+ else if (TREE_CODE (rhs2) == INTEGER_CST
+ && TREE_CODE (rhs1) == SSA_NAME)
+ derive_equivalences (rhs1,
+ fold_binary (PLUS_EXPR, TREE_TYPE (rhs1),
+ value, rhs2),
+ recursion_limit - 1);
+ else if (integer_zerop (value))
+ {
+ tree cond = build2 (EQ_EXPR, boolean_type_node,
+ gimple_assign_rhs1 (def_stmt),
+ gimple_assign_rhs2 (def_stmt));
+ tree inverted = invert_truthvalue (cond);
+ record_conditions (&this->cond_equivalences, cond, inverted);
+ }
+ break;
+ }
- case EXPR_PHI:
- {
- size_t i;
- size_t nargs = element->expr.ops.phi.nargs;
+ case EQ_EXPR:
+ case NE_EXPR:
+ {
+ if ((code == EQ_EXPR && integer_onep (value))
+ || (code == NE_EXPR && integer_zerop (value)))
+ {
+ tree rhs1 = gimple_assign_rhs1 (def_stmt);
+ tree rhs2 = gimple_assign_rhs2 (def_stmt);
+
+ /* If either argument is a constant, then record the
+ other argument as being the same as that constant.
+
+ If neither operand is a constant, then we have a
+ conditional name == name equivalence. */
+ if (TREE_CODE (rhs1) == INTEGER_CST)
+ derive_equivalences (rhs2, rhs1, recursion_limit - 1);
+ else if (TREE_CODE (rhs2) == INTEGER_CST)
+ derive_equivalences (rhs1, rhs2, recursion_limit - 1);
+ }
+ else
+ {
+ tree cond = build2 (code, boolean_type_node,
+ gimple_assign_rhs1 (def_stmt),
+ gimple_assign_rhs2 (def_stmt));
+ tree inverted = invert_truthvalue (cond);
+ if (integer_zerop (value))
+ std::swap (cond, inverted);
+ record_conditions (&this->cond_equivalences, cond, inverted);
+ }
+ break;
+ }
- fprintf (stream, "PHI <");
- for (i = 0; i < nargs; i++)
- {
- print_generic_expr (stream, element->expr.ops.phi.args[i], 0);
- if (i + 1 < nargs)
- fprintf (stream, ", ");
- }
- fprintf (stream, ">");
- }
- break;
- }
+ /* For BIT_NOT and NEGATE, we can just apply the operation to the
+ VALUE to get the new equivalence. It will always be a constant
+ so we can recurse. */
+ case BIT_NOT_EXPR:
+ case NEGATE_EXPR:
+ {
+ tree rhs = gimple_assign_rhs1 (def_stmt);
+ tree res;
+ /* If this is a NOT and the operand has a boolean range, then we
+ know its value must be zero or one. We are not supposed to
+ have a BIT_NOT_EXPR for boolean types with precision > 1 in
+ the general case, see e.g. the handling of TRUTH_NOT_EXPR in
+ the gimplifier, but it can be generated by match.pd out of
+ a BIT_XOR_EXPR wrapped in a BIT_AND_EXPR. Now the handling
+ of BIT_AND_EXPR above already forces a specific semantics for
+ boolean types with precision > 1 so we must do the same here,
+ otherwise we could change the semantics of TRUTH_NOT_EXPR for
+ boolean types with precision > 1. */
+ if (code == BIT_NOT_EXPR
+ && TREE_CODE (rhs) == SSA_NAME
+ && ssa_name_has_boolean_range (rhs))
+ {
+ if ((TREE_INT_CST_LOW (value) & 1) == 0)
+ res = build_one_cst (TREE_TYPE (rhs));
+ else
+ res = build_zero_cst (TREE_TYPE (rhs));
+ }
+ else
+ res = fold_build1 (code, TREE_TYPE (rhs), value);
+ derive_equivalences (rhs, res, recursion_limit - 1);
+ break;
+ }
- if (element->vop)
- {
- fprintf (stream, " with ");
- print_generic_expr (stream, element->vop, 0);
+ default:
+ {
+ if (TREE_CODE_CLASS (code) == tcc_comparison)
+ {
+ tree cond = build2 (code, boolean_type_node,
+ gimple_assign_rhs1 (def_stmt),
+ gimple_assign_rhs2 (def_stmt));
+ tree inverted = invert_truthvalue (cond);
+ if (integer_zerop (value))
+ std::swap (cond, inverted);
+ record_conditions (&this->cond_equivalences, cond, inverted);
+ break;
+ }
+ break;
+ }
+ }
}
-
- fprintf (stream, "\n");
-}
-
-/* Delete variable sized pieces of the expr_hash_elt ELEMENT. */
-
-static void
-free_expr_hash_elt_contents (struct expr_hash_elt *element)
-{
- if (element->expr.kind == EXPR_CALL)
- free (element->expr.ops.call.args);
- else if (element->expr.kind == EXPR_PHI)
- free (element->expr.ops.phi.args);
}
-/* Delete an expr_hash_elt and reclaim its storage. */
-
-static void
-free_expr_hash_elt (void *elt)
+void
+edge_info::record_simple_equiv (tree lhs, tree rhs)
{
- struct expr_hash_elt *element = ((struct expr_hash_elt *)elt);
- free_expr_hash_elt_contents (element);
- free (element);
+ /* If the RHS is a constant, then we may be able to derive
+ further equivalences. Else just record the name = name
+ equivalence. */
+ if (TREE_CODE (rhs) == INTEGER_CST)
+ derive_equivalences (lhs, rhs, 4);
+ else
+ simple_equivalences.safe_push (equiv_pair (lhs, rhs));
}
-/* Allocate an EDGE_INFO for edge E and attach it to E.
- Return the new EDGE_INFO structure. */
+/* Free the edge_info data attached to E, if it exists. */
-static struct edge_info *
-allocate_edge_info (edge e)
+void
+free_dom_edge_info (edge e)
{
- struct edge_info *edge_info;
-
- edge_info = XCNEW (struct edge_info);
+ class edge_info *edge_info = (class edge_info *)e->aux;
- e->aux = edge_info;
- return edge_info;
+ if (edge_info)
+ delete edge_info;
}
/* Free all EDGE_INFO structures associated with edges in the CFG.
{
FOR_EACH_EDGE (e, ei, bb->preds)
{
- struct edge_info *edge_info = (struct edge_info *) e->aux;
-
- if (edge_info)
- {
- edge_info->cond_equivalences.release ();
- free (edge_info);
- e->aux = NULL;
- }
+ free_dom_edge_info (e);
+ e->aux = NULL;
}
}
}
-/* Build a cond_equivalence record indicating that the comparison
- CODE holds between operands OP0 and OP1 and push it to **P. */
-
-static void
-build_and_record_new_cond (enum tree_code code,
- tree op0, tree op1,
- vec<cond_equivalence> *p,
- bool val = true)
-{
- cond_equivalence c;
- struct hashable_expr *cond = &c.cond;
-
- gcc_assert (TREE_CODE_CLASS (code) == tcc_comparison);
-
- cond->type = boolean_type_node;
- cond->kind = EXPR_BINARY;
- cond->ops.binary.op = code;
- cond->ops.binary.opnd0 = op0;
- cond->ops.binary.opnd1 = op1;
-
- c.value = val ? boolean_true_node : boolean_false_node;
- p->safe_push (c);
-}
-
-/* Record that COND is true and INVERTED is false into the edge information
- structure. Also record that any conditions dominated by COND are true
- as well.
-
- For example, if a < b is true, then a <= b must also be true. */
+/* We have finished optimizing BB, record any information implied by
+ taking a specific outgoing edge from BB. */
static void
-record_conditions (struct edge_info *edge_info, tree cond, tree inverted)
+record_edge_info (basic_block bb)
{
- tree op0, op1;
- cond_equivalence c;
-
- if (!COMPARISON_CLASS_P (cond))
- return;
-
- op0 = TREE_OPERAND (cond, 0);
- op1 = TREE_OPERAND (cond, 1);
+ gimple_stmt_iterator gsi = gsi_last_bb (bb);
+ class edge_info *edge_info;
- switch (TREE_CODE (cond))
+ if (! gsi_end_p (gsi))
{
- case LT_EXPR:
- case GT_EXPR:
- if (FLOAT_TYPE_P (TREE_TYPE (op0)))
- {
- build_and_record_new_cond (ORDERED_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (LTGT_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- }
+ gimple *stmt = gsi_stmt (gsi);
+ location_t loc = gimple_location (stmt);
- build_and_record_new_cond ((TREE_CODE (cond) == LT_EXPR
- ? LE_EXPR : GE_EXPR),
- op0, op1, &edge_info->cond_equivalences);
- build_and_record_new_cond (NE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (EQ_EXPR, op0, op1,
- &edge_info->cond_equivalences, false);
- break;
-
- case GE_EXPR:
- case LE_EXPR:
- if (FLOAT_TYPE_P (TREE_TYPE (op0)))
+ if (gimple_code (stmt) == GIMPLE_SWITCH)
{
- build_and_record_new_cond (ORDERED_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- }
- break;
-
- case EQ_EXPR:
- if (FLOAT_TYPE_P (TREE_TYPE (op0)))
- {
- build_and_record_new_cond (ORDERED_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- }
- build_and_record_new_cond (LE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (GE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- break;
-
- case UNORDERED_EXPR:
- build_and_record_new_cond (NE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (UNLE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (UNGE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (UNEQ_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (UNLT_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (UNGT_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- break;
-
- case UNLT_EXPR:
- case UNGT_EXPR:
- build_and_record_new_cond ((TREE_CODE (cond) == UNLT_EXPR
- ? UNLE_EXPR : UNGE_EXPR),
- op0, op1, &edge_info->cond_equivalences);
- build_and_record_new_cond (NE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- break;
-
- case UNEQ_EXPR:
- build_and_record_new_cond (UNLE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (UNGE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- break;
-
- case LTGT_EXPR:
- build_and_record_new_cond (NE_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- build_and_record_new_cond (ORDERED_EXPR, op0, op1,
- &edge_info->cond_equivalences);
- break;
-
- default:
- break;
- }
-
- /* Now store the original true and false conditions into the first
- two slots. */
- initialize_expr_from_cond (cond, &c.cond);
- c.value = boolean_true_node;
- edge_info->cond_equivalences.safe_push (c);
-
- /* It is possible for INVERTED to be the negation of a comparison,
- and not a valid RHS or GIMPLE_COND condition. This happens because
- invert_truthvalue may return such an expression when asked to invert
- a floating-point comparison. These comparisons are not assumed to
- obey the trichotomy law. */
- initialize_expr_from_cond (inverted, &c.cond);
- c.value = boolean_false_node;
- edge_info->cond_equivalences.safe_push (c);
-}
-
-/* We have finished optimizing BB, record any information implied by
- taking a specific outgoing edge from BB. */
-
-static void
-record_edge_info (basic_block bb)
-{
- gimple_stmt_iterator gsi = gsi_last_bb (bb);
- struct edge_info *edge_info;
-
- if (! gsi_end_p (gsi))
- {
- gimple stmt = gsi_stmt (gsi);
- location_t loc = gimple_location (stmt);
-
- if (gimple_code (stmt) == GIMPLE_SWITCH)
- {
- gswitch *switch_stmt = as_a <gswitch *> (stmt);
- tree index = gimple_switch_index (switch_stmt);
+ gswitch *switch_stmt = as_a <gswitch *> (stmt);
+ tree index = gimple_switch_index (switch_stmt);
if (TREE_CODE (index) == SSA_NAME)
{
for (i = 0; i < n_labels; i++)
{
tree label = gimple_switch_label (switch_stmt, i);
- basic_block target_bb = label_to_block (CASE_LABEL (label));
+ basic_block target_bb
+ = label_to_block (cfun, CASE_LABEL (label));
if (CASE_HIGH (label)
|| !CASE_LOW (label)
|| info[target_bb->index])
{
tree x = fold_convert_loc (loc, TREE_TYPE (index),
CASE_LOW (label));
- edge_info = allocate_edge_info (e);
- edge_info->lhs = index;
- edge_info->rhs = x;
+ edge_info = new class edge_info (e);
+ edge_info->record_simple_equiv (index, x);
}
}
free (info);
/* Special case comparing booleans against a constant as we
know the value of OP0 on both arms of the branch. i.e., we
- can record an equivalence for OP0 rather than COND. */
- if ((code == EQ_EXPR || code == NE_EXPR)
- && TREE_CODE (op0) == SSA_NAME
- && TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE
- && is_gimple_min_invariant (op1))
+ can record an equivalence for OP0 rather than COND.
+
+ However, don't do this if the constant isn't zero or one.
+ Such conditionals will get optimized more thoroughly during
+ the domwalk. */
+ if ((code == EQ_EXPR || code == NE_EXPR)
+ && TREE_CODE (op0) == SSA_NAME
+ && ssa_name_has_boolean_range (op0)
+ && is_gimple_min_invariant (op1)
+ && (integer_zerop (op1) || integer_onep (op1)))
{
+ tree true_val = constant_boolean_node (true, TREE_TYPE (op0));
+ tree false_val = constant_boolean_node (false, TREE_TYPE (op0));
+
if (code == EQ_EXPR)
{
- edge_info = allocate_edge_info (true_edge);
- edge_info->lhs = op0;
- edge_info->rhs = (integer_zerop (op1)
- ? boolean_false_node
- : boolean_true_node);
-
- edge_info = allocate_edge_info (false_edge);
- edge_info->lhs = op0;
- edge_info->rhs = (integer_zerop (op1)
- ? boolean_true_node
- : boolean_false_node);
+ edge_info = new class edge_info (true_edge);
+ edge_info->record_simple_equiv (op0,
+ (integer_zerop (op1)
+ ? false_val : true_val));
+ edge_info = new class edge_info (false_edge);
+ edge_info->record_simple_equiv (op0,
+ (integer_zerop (op1)
+ ? true_val : false_val));
}
else
{
- edge_info = allocate_edge_info (true_edge);
- edge_info->lhs = op0;
- edge_info->rhs = (integer_zerop (op1)
- ? boolean_true_node
- : boolean_false_node);
-
- edge_info = allocate_edge_info (false_edge);
- edge_info->lhs = op0;
- edge_info->rhs = (integer_zerop (op1)
- ? boolean_false_node
- : boolean_true_node);
+ edge_info = new class edge_info (true_edge);
+ edge_info->record_simple_equiv (op0,
+ (integer_zerop (op1)
+ ? true_val : false_val));
+ edge_info = new class edge_info (false_edge);
+ edge_info->record_simple_equiv (op0,
+ (integer_zerop (op1)
+ ? false_val : true_val));
}
}
+ /* This can show up in the IL as a result of copy propagation
+ it will eventually be canonicalized, but we have to cope
+ with this case within the pass. */
else if (is_gimple_min_invariant (op0)
- && (TREE_CODE (op1) == SSA_NAME
- || is_gimple_min_invariant (op1)))
+ && TREE_CODE (op1) == SSA_NAME)
{
tree cond = build2 (code, boolean_type_node, op0, op1);
tree inverted = invert_truthvalue_loc (loc, cond);
bool can_infer_simple_equiv
= !(HONOR_SIGNED_ZEROS (op0)
&& real_zerop (op0));
- struct edge_info *edge_info;
+ class edge_info *edge_info;
- edge_info = allocate_edge_info (true_edge);
- record_conditions (edge_info, cond, inverted);
+ edge_info = new class edge_info (true_edge);
+ record_conditions (&edge_info->cond_equivalences, cond, inverted);
if (can_infer_simple_equiv && code == EQ_EXPR)
- {
- edge_info->lhs = op1;
- edge_info->rhs = op0;
- }
+ edge_info->record_simple_equiv (op1, op0);
- edge_info = allocate_edge_info (false_edge);
- record_conditions (edge_info, inverted, cond);
+ edge_info = new class edge_info (false_edge);
+ record_conditions (&edge_info->cond_equivalences, inverted, cond);
if (can_infer_simple_equiv && TREE_CODE (inverted) == EQ_EXPR)
- {
- edge_info->lhs = op1;
- edge_info->rhs = op0;
- }
+ edge_info->record_simple_equiv (op1, op0);
}
else if (TREE_CODE (op0) == SSA_NAME
bool can_infer_simple_equiv
= !(HONOR_SIGNED_ZEROS (op1)
&& (TREE_CODE (op1) == SSA_NAME || real_zerop (op1)));
- struct edge_info *edge_info;
+ class edge_info *edge_info;
- edge_info = allocate_edge_info (true_edge);
- record_conditions (edge_info, cond, inverted);
+ edge_info = new class edge_info (true_edge);
+ record_conditions (&edge_info->cond_equivalences, cond, inverted);
if (can_infer_simple_equiv && code == EQ_EXPR)
- {
- edge_info->lhs = op0;
- edge_info->rhs = op1;
- }
+ edge_info->record_simple_equiv (op0, op1);
- edge_info = allocate_edge_info (false_edge);
- record_conditions (edge_info, inverted, cond);
+ edge_info = new class edge_info (false_edge);
+ record_conditions (&edge_info->cond_equivalences, inverted, cond);
if (can_infer_simple_equiv && TREE_CODE (inverted) == EQ_EXPR)
- {
- edge_info->lhs = op0;
- edge_info->rhs = op1;
- }
+ edge_info->record_simple_equiv (op0, op1);
}
}
-
- /* ??? TRUTH_NOT_EXPR can create an equivalence too. */
}
}
+class dom_jump_threader_simplifier : public jump_threader_simplifier
+{
+public:
+ dom_jump_threader_simplifier (vr_values *v,
+ avail_exprs_stack *avails)
+ : jump_threader_simplifier (v), m_avail_exprs_stack (avails) { }
+
+private:
+ tree simplify (gimple *, gimple *, basic_block, jt_state *) override;
+ avail_exprs_stack *m_avail_exprs_stack;
+};
+
+tree
+dom_jump_threader_simplifier::simplify (gimple *stmt,
+ gimple *within_stmt,
+ basic_block bb,
+ jt_state *state)
+{
+ /* First see if the conditional is in the hash table. */
+ tree cached_lhs = m_avail_exprs_stack->lookup_avail_expr (stmt,
+ false, true);
+ if (cached_lhs)
+ return cached_lhs;
+
+ return jump_threader_simplifier::simplify (stmt, within_stmt, bb, state);
+}
class dom_opt_dom_walker : public dom_walker
{
public:
- dom_opt_dom_walker (cdi_direction direction)
- : dom_walker (direction), m_dummy_cond (NULL) {}
+ dom_opt_dom_walker (cdi_direction direction,
+ jump_threader *threader,
+ jt_state *state,
+ evrp_range_analyzer *analyzer,
+ const_and_copies *const_and_copies,
+ avail_exprs_stack *avail_exprs_stack)
+ : dom_walker (direction, REACHABLE_BLOCKS)
+ {
+ m_evrp_range_analyzer = analyzer;
+ m_state = state;
+ m_dummy_cond = gimple_build_cond (NE_EXPR, integer_zero_node,
+ integer_zero_node, NULL, NULL);
+ m_const_and_copies = const_and_copies;
+ m_avail_exprs_stack = avail_exprs_stack;
+ m_threader = threader;
+ }
- virtual void before_dom_children (basic_block);
+ virtual edge before_dom_children (basic_block);
virtual void after_dom_children (basic_block);
private:
- void thread_across_edge (edge);
+ /* Unwindable equivalences, both const/copy and expression varieties. */
+ class const_and_copies *m_const_and_copies;
+ class avail_exprs_stack *m_avail_exprs_stack;
+
+ /* Dummy condition to avoid creating lots of throw away statements. */
gcond *m_dummy_cond;
+
+ /* Optimize a single statement within a basic block using the
+ various tables mantained by DOM. Returns the taken edge if
+ the statement is a conditional with a statically determined
+ value. */
+ edge optimize_stmt (basic_block, gimple_stmt_iterator *, bool *);
+
+
+ void test_for_singularity (gimple *, avail_exprs_stack *);
+
+ jump_threader *m_threader;
+ evrp_range_analyzer *m_evrp_range_analyzer;
+ jt_state *m_state;
};
/* Jump threading, redundancy elimination and const/copy propagation.
{
public:
pass_dominator (gcc::context *ctxt)
- : gimple_opt_pass (pass_data_dominator, ctxt)
+ : gimple_opt_pass (pass_data_dominator, ctxt),
+ may_peel_loop_headers_p (false)
{}
/* opt_pass methods: */
opt_pass * clone () { return new pass_dominator (m_ctxt); }
+ void set_pass_param (unsigned int n, bool param)
+ {
+ gcc_assert (n == 0);
+ may_peel_loop_headers_p = param;
+ }
virtual bool gate (function *) { return flag_tree_dom != 0; }
virtual unsigned int execute (function *);
+ private:
+ /* This flag is used to prevent loops from being peeled repeatedly in jump
+ threading; it will be removed once we preserve loop structures throughout
+ the compilation -- we will be able to mark the affected loops directly in
+ jump threading, and avoid peeling them next time. */
+ bool may_peel_loop_headers_p;
}; // class pass_dominator
unsigned int
memset (&opt_stats, 0, sizeof (opt_stats));
/* Create our hash tables. */
- avail_exprs = new hash_table<expr_elt_hasher> (1024);
- avail_exprs_stack.create (20);
- const_and_copies = new class const_and_copies (dump_file, dump_flags);
+ hash_table<expr_elt_hasher> *avail_exprs
+ = new hash_table<expr_elt_hasher> (1024);
+ class avail_exprs_stack *avail_exprs_stack
+ = new class avail_exprs_stack (avail_exprs);
+ class const_and_copies *const_and_copies = new class const_and_copies ();
need_eh_cleanup = BITMAP_ALLOC (NULL);
need_noreturn_fixup.create (0);
gcc.dg/tree-ssa/pr21417.c can't be threaded if loop preheader is
missing. We should improve jump threading in future then
LOOPS_HAVE_PREHEADERS won't be needed here. */
- loop_optimizer_init (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES);
-
- /* Initialize the value-handle array. */
- threadedge_initialize_values ();
+ loop_optimizer_init (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES
+ | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS);
/* We need accurate information regarding back edges in the CFG
for jump threading; this may include back edges that are not part of
a single loop. */
mark_dfs_back_edges ();
+ /* We want to create the edge info structures before the dominator walk
+ so that they'll be in place for the jump threader, particularly when
+ threading through a join block.
+
+ The conditions will be lazily updated with global equivalences as
+ we reach them during the dominator walk. */
+ basic_block bb;
+ FOR_EACH_BB_FN (bb, fun)
+ record_edge_info (bb);
+
/* Recursively walk the dominator tree optimizing statements. */
- dom_opt_dom_walker (CDI_DOMINATORS).walk (fun->cfg->x_entry_block_ptr);
+ evrp_range_analyzer analyzer (true);
+ dom_jump_threader_simplifier simplifier (&analyzer, avail_exprs_stack);
+ jt_state state (const_and_copies, avail_exprs_stack, &analyzer);
+ jump_threader threader (&simplifier, &state);
+ dom_opt_dom_walker walker (CDI_DOMINATORS,
+ &threader,
+ &state,
+ &analyzer,
+ const_and_copies,
+ avail_exprs_stack);
+ walker.walk (fun->cfg->x_entry_block_ptr);
+
+ /* Look for blocks where we cleared EDGE_EXECUTABLE on an outgoing
+ edge. When found, remove jump threads which contain any outgoing
+ edge from the affected block. */
+ if (cfg_altered)
+ {
+ FOR_EACH_BB_FN (bb, fun)
+ {
+ edge_iterator ei;
+ edge e;
+
+ /* First see if there are any edges without EDGE_EXECUTABLE
+ set. */
+ bool found = false;
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ if ((e->flags & EDGE_EXECUTABLE) == 0)
+ {
+ found = true;
+ break;
+ }
+ }
+
+ /* If there were any such edges found, then remove jump threads
+ containing any edge leaving BB. */
+ if (found)
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ threader.remove_jump_threads_including (e);
+ }
+ }
{
gimple_stmt_iterator gsi;
free_all_edge_infos ();
/* Thread jumps, creating duplicate blocks as needed. */
- cfg_altered |= thread_through_all_blocks (first_pass_instance);
+ cfg_altered |= threader.thread_through_all_blocks (may_peel_loop_headers_p);
if (cfg_altered)
free_dominance_info (CDI_DOMINATORS);
if (bb == NULL)
continue;
while (single_succ_p (bb)
- && (single_succ_edge (bb)->flags & EDGE_EH) == 0)
+ && (single_succ_edge (bb)->flags
+ & (EDGE_EH|EDGE_DFS_BACK)) == 0)
bb = single_succ (bb);
if (bb == EXIT_BLOCK_PTR_FOR_FN (fun))
continue;
now noreturn call first. */
while (!need_noreturn_fixup.is_empty ())
{
- gimple stmt = need_noreturn_fixup.pop ();
+ gimple *stmt = need_noreturn_fixup.pop ();
if (dump_file && dump_flags & TDF_DETAILS)
{
fprintf (dump_file, "Fixing up noreturn call ");
- print_gimple_stmt (dump_file, stmt, 0, 0);
+ print_gimple_stmt (dump_file, stmt, 0);
fprintf (dump_file, "\n");
}
fixup_noreturn_call (stmt);
/* Debugging dumps. */
if (dump_file && (dump_flags & TDF_STATS))
- dump_dominator_optimization_stats (dump_file);
+ dump_dominator_optimization_stats (dump_file, avail_exprs);
loop_optimizer_finalize ();
/* Free asserted bitmaps and stacks. */
BITMAP_FREE (need_eh_cleanup);
need_noreturn_fixup.release ();
- avail_exprs_stack.release ();
+ delete avail_exprs_stack;
delete const_and_copies;
- /* Free the value-handle array. */
- threadedge_finalize_values ();
-
return 0;
}
return new pass_dominator (ctxt);
}
+/* Valueize hook for gimple_fold_stmt_to_constant_1. */
-/* Given a conditional statement CONDSTMT, convert the
- condition to a canonical form. */
-
-static void
-canonicalize_comparison (gcond *condstmt)
+static tree
+dom_valueize (tree t)
{
- tree op0;
- tree op1;
- enum tree_code code;
-
- gcc_assert (gimple_code (condstmt) == GIMPLE_COND);
-
- op0 = gimple_cond_lhs (condstmt);
- op1 = gimple_cond_rhs (condstmt);
-
- code = gimple_cond_code (condstmt);
-
- /* If it would be profitable to swap the operands, then do so to
- canonicalize the statement, enabling better optimization.
-
- By placing canonicalization of such expressions here we
- transparently keep statements in canonical form, even
- when the statement is modified. */
- if (tree_swap_operands_p (op0, op1, false))
+ if (TREE_CODE (t) == SSA_NAME)
{
- /* For relationals we need to swap the operands
- and change the code. */
- if (code == LT_EXPR
- || code == GT_EXPR
- || code == LE_EXPR
- || code == GE_EXPR)
- {
- code = swap_tree_comparison (code);
-
- gimple_cond_set_code (condstmt, code);
- gimple_cond_set_lhs (condstmt, op1);
- gimple_cond_set_rhs (condstmt, op0);
-
- update_stmt (condstmt);
- }
+ tree tem = SSA_NAME_VALUE (t);
+ if (tem)
+ return tem;
}
+ return t;
}
-/* Initialize local stacks for this optimizer and record equivalences
- upon entry to BB. Equivalences can come from the edge traversed to
- reach BB or they may come from PHI nodes at the start of BB. */
-
-/* Remove all the expressions in LOCALS from TABLE, stopping when there are
- LIMIT entries left in LOCALs. */
-
+/* We have just found an equivalence for LHS on an edge E.
+ Look backwards to other uses of LHS and see if we can derive
+ additional equivalences that are valid on edge E. */
static void
-remove_local_expressions_from_table (void)
+back_propagate_equivalences (tree lhs, edge e,
+ class const_and_copies *const_and_copies)
{
- /* Remove all the expressions made available in this block. */
- while (avail_exprs_stack.length () > 0)
+ use_operand_p use_p;
+ imm_use_iterator iter;
+ bitmap domby = NULL;
+ basic_block dest = e->dest;
+
+ /* Iterate over the uses of LHS to see if any dominate E->dest.
+ If so, they may create useful equivalences too.
+
+ ??? If the code gets re-organized to a worklist to catch more
+ indirect opportunities and it is made to handle PHIs then this
+ should only consider use_stmts in basic-blocks we have already visited. */
+ FOR_EACH_IMM_USE_FAST (use_p, iter, lhs)
{
- std::pair<expr_hash_elt_t, expr_hash_elt_t> victim
- = avail_exprs_stack.pop ();
- expr_hash_elt **slot;
+ gimple *use_stmt = USE_STMT (use_p);
- if (victim.first == NULL)
- break;
+ /* Often the use is in DEST, which we trivially know we can't use.
+ This is cheaper than the dominator set tests below. */
+ if (dest == gimple_bb (use_stmt))
+ continue;
- /* This must precede the actual removal from the hash table,
- as ELEMENT and the table entry may share a call argument
- vector which will be freed during removal. */
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "<<<< ");
- print_expr_hash_elt (dump_file, victim.first);
- }
+ /* Filter out statements that can never produce a useful
+ equivalence. */
+ tree lhs2 = gimple_get_lhs (use_stmt);
+ if (!lhs2 || TREE_CODE (lhs2) != SSA_NAME)
+ continue;
- slot = avail_exprs->find_slot (victim.first, NO_INSERT);
- gcc_assert (slot && *slot == victim.first);
- if (victim.second != NULL)
+ /* Profiling has shown the domination tests here can be fairly
+ expensive. We get significant improvements by building the
+ set of blocks that dominate BB. We can then just test
+ for set membership below.
+
+ We also initialize the set lazily since often the only uses
+ are going to be in the same block as DEST. */
+ if (!domby)
{
- free_expr_hash_elt (*slot);
- *slot = victim.second;
+ domby = BITMAP_ALLOC (NULL);
+ basic_block bb = get_immediate_dominator (CDI_DOMINATORS, dest);
+ while (bb)
+ {
+ bitmap_set_bit (domby, bb->index);
+ bb = get_immediate_dominator (CDI_DOMINATORS, bb);
+ }
}
- else
- avail_exprs->clear_slot (slot);
- }
-}
-/* A trivial wrapper so that we can present the generic jump
- threading code with a simple API for simplifying statements. */
-static tree
-simplify_stmt_for_jump_threading (gimple stmt,
- gimple within_stmt ATTRIBUTE_UNUSED)
-{
- return lookup_avail_expr (stmt, false);
-}
-
-/* Valueize hook for gimple_fold_stmt_to_constant_1. */
+ /* This tests if USE_STMT does not dominate DEST. */
+ if (!bitmap_bit_p (domby, gimple_bb (use_stmt)->index))
+ continue;
-static tree
-dom_valueize (tree t)
-{
- if (TREE_CODE (t) == SSA_NAME)
- {
- tree tem = SSA_NAME_VALUE (t);
- if (tem)
- return tem;
+ /* At this point USE_STMT dominates DEST and may result in a
+ useful equivalence. Try to simplify its RHS to a constant
+ or SSA_NAME. */
+ tree res = gimple_fold_stmt_to_constant_1 (use_stmt, dom_valueize,
+ no_follow_ssa_edges);
+ if (res && (TREE_CODE (res) == SSA_NAME || is_gimple_min_invariant (res)))
+ record_equality (lhs2, res, const_and_copies);
}
- return t;
+
+ if (domby)
+ BITMAP_FREE (domby);
}
-/* Record into the equivalence tables any equivalences implied by
- traversing edge E (which are cached in E->aux).
+/* Record into CONST_AND_COPIES and AVAIL_EXPRS_STACK any equivalences implied
+ by traversing edge E (which are cached in E->aux).
Callers are responsible for managing the unwinding markers. */
-static void
-record_temporary_equivalences (edge e)
+void
+record_temporary_equivalences (edge e,
+ class const_and_copies *const_and_copies,
+ class avail_exprs_stack *avail_exprs_stack)
{
int i;
- struct edge_info *edge_info = (struct edge_info *) e->aux;
+ class edge_info *edge_info = (class edge_info *) e->aux;
/* If we have info associated with this edge, record it into
our equivalence tables. */
if (edge_info)
{
cond_equivalence *eq;
- tree lhs = edge_info->lhs;
- tree rhs = edge_info->rhs;
-
- /* If we have a simple NAME = VALUE equivalence, record it. */
- if (lhs)
- record_equality (lhs, rhs);
-
- /* If LHS is an SSA_NAME and RHS is a constant integer and LHS was
- set via a widening type conversion, then we may be able to record
- additional equivalences. */
- if (lhs
- && TREE_CODE (lhs) == SSA_NAME
- && TREE_CODE (rhs) == INTEGER_CST)
+ /* If we have 0 = COND or 1 = COND equivalences, record them
+ into our expression hash tables. */
+ for (i = 0; edge_info->cond_equivalences.iterate (i, &eq); ++i)
+ avail_exprs_stack->record_cond (eq);
+
+ edge_info::equiv_pair *seq;
+ for (i = 0; edge_info->simple_equivalences.iterate (i, &seq); ++i)
{
- gimple defstmt = SSA_NAME_DEF_STMT (lhs);
+ tree lhs = seq->first;
+ if (!lhs || TREE_CODE (lhs) != SSA_NAME)
+ continue;
- if (defstmt
- && is_gimple_assign (defstmt)
- && CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (defstmt)))
- {
- tree old_rhs = gimple_assign_rhs1 (defstmt);
-
- /* If the conversion widens the original value and
- the constant is in the range of the type of OLD_RHS,
- then convert the constant and record the equivalence.
-
- Note that int_fits_type_p does not check the precision
- if the upper and lower bounds are OK. */
- if (INTEGRAL_TYPE_P (TREE_TYPE (old_rhs))
- && (TYPE_PRECISION (TREE_TYPE (lhs))
- > TYPE_PRECISION (TREE_TYPE (old_rhs)))
- && int_fits_type_p (rhs, TREE_TYPE (old_rhs)))
- {
- tree newval = fold_convert (TREE_TYPE (old_rhs), rhs);
- record_equality (old_rhs, newval);
- }
- }
- }
+ /* Record the simple NAME = VALUE equivalence. */
+ tree rhs = seq->second;
- /* If LHS is an SSA_NAME with a new equivalency then try if
- stmts with uses of that LHS that dominate the edge destination
- simplify and allow further equivalences to be recorded. */
- if (lhs && TREE_CODE (lhs) == SSA_NAME)
- {
- use_operand_p use_p;
- imm_use_iterator iter;
- FOR_EACH_IMM_USE_FAST (use_p, iter, lhs)
+ /* If this is a SSA_NAME = SSA_NAME equivalence and one operand is
+ cheaper to compute than the other, then set up the equivalence
+ such that we replace the expensive one with the cheap one.
+
+ If they are the same cost to compute, then do not record
+ anything. */
+ if (TREE_CODE (lhs) == SSA_NAME && TREE_CODE (rhs) == SSA_NAME)
{
- gimple use_stmt = USE_STMT (use_p);
-
- /* Only bother to record more equivalences for lhs that
- can be directly used by e->dest.
- ??? If the code gets re-organized to a worklist to
- catch more indirect opportunities and it is made to
- handle PHIs then this should only consider use_stmts
- in basic-blocks we have already visited. */
- if (e->dest == gimple_bb (use_stmt)
- || !dominated_by_p (CDI_DOMINATORS,
- e->dest, gimple_bb (use_stmt)))
- continue;
- tree lhs2 = gimple_get_lhs (use_stmt);
- if (lhs2 && TREE_CODE (lhs2) == SSA_NAME)
- {
- tree res
- = gimple_fold_stmt_to_constant_1 (use_stmt, dom_valueize,
- no_follow_ssa_edges);
- if (res
- && (TREE_CODE (res) == SSA_NAME
- || is_gimple_min_invariant (res)))
- record_equality (lhs2, res);
- }
- }
- }
+ gimple *rhs_def = SSA_NAME_DEF_STMT (rhs);
+ int rhs_cost = estimate_num_insns (rhs_def, &eni_size_weights);
- /* If we have 0 = COND or 1 = COND equivalences, record them
- into our expression hash tables. */
- for (i = 0; edge_info->cond_equivalences.iterate (i, &eq); ++i)
- record_cond (eq);
- }
-}
+ gimple *lhs_def = SSA_NAME_DEF_STMT (lhs);
+ int lhs_cost = estimate_num_insns (lhs_def, &eni_size_weights);
+
+ if (rhs_cost > lhs_cost)
+ record_equality (rhs, lhs, const_and_copies);
+ else if (rhs_cost < lhs_cost)
+ record_equality (lhs, rhs, const_and_copies);
+ }
+ else
+ record_equality (lhs, rhs, const_and_copies);
-/* Wrapper for common code to attempt to thread an edge. For example,
- it handles lazily building the dummy condition and the bookkeeping
- when jump threading is successful. */
-void
-dom_opt_dom_walker::thread_across_edge (edge e)
-{
- if (! m_dummy_cond)
- m_dummy_cond =
- gimple_build_cond (NE_EXPR,
- integer_zero_node, integer_zero_node,
- NULL, NULL);
-
- /* Push a marker on both stacks so we can unwind the tables back to their
- current state. */
- avail_exprs_stack.safe_push
- (std::pair<expr_hash_elt_t, expr_hash_elt_t> (NULL, NULL));
- const_and_copies->push_marker ();
-
- /* Traversing E may result in equivalences we can utilize. */
- record_temporary_equivalences (e);
-
- /* With all the edge equivalences in the tables, go ahead and attempt
- to thread through E->dest. */
- ::thread_across_edge (m_dummy_cond, e, false,
- const_and_copies,
- simplify_stmt_for_jump_threading);
-
- /* And restore the various tables to their state before
- we threaded this edge.
-
- XXX The code in tree-ssa-threadedge.c will restore the state of
- the const_and_copies table. We we just have to restore the expression
- table. */
- remove_local_expressions_from_table ();
+ /* Any equivalence found for LHS may result in additional
+ equivalences for other uses of LHS that we have already
+ processed. */
+ back_propagate_equivalences (lhs, e, const_and_copies);
+ }
+ }
}
/* PHI nodes can create equivalences too.
{
gphi_iterator gsi;
- for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); )
{
gphi *phi = gsi.phi ();
+ /* We might eliminate the PHI, so advance GSI now. */
+ gsi_next (&gsi);
+
tree lhs = gimple_phi_result (phi);
tree rhs = NULL;
size_t i;
if (lhs == t)
continue;
- /* Valueize t. */
- if (TREE_CODE (t) == SSA_NAME)
- {
- tree tmp = SSA_NAME_VALUE (t);
- t = tmp ? tmp : t;
- }
+ /* If the associated edge is not marked as executable, then it
+ can be ignored. */
+ if ((gimple_phi_arg_edge (phi, i)->flags & EDGE_EXECUTABLE) == 0)
+ continue;
+
+ t = dom_valueize (t);
+
+ /* If T is an SSA_NAME and its associated edge is a backedge,
+ then quit as we cannot utilize this equivalence. */
+ if (TREE_CODE (t) == SSA_NAME
+ && (gimple_phi_arg_edge (phi, i)->flags & EDGE_DFS_BACK))
+ break;
/* If we have not processed an alternative yet, then set
RHS to this alternative. */
this, since this is a true assignment and not an equivalence
inferred from a comparison. All uses of this ssa name are dominated
by this assignment, so unwinding just costs time and space. */
- if (i == gimple_phi_num_args (phi)
- && may_propagate_copy (lhs, rhs))
- set_ssa_name_value (lhs, rhs);
- }
-}
-
-/* Ignoring loop backedges, if BB has precisely one incoming edge then
- return that edge. Otherwise return NULL. */
-static edge
-single_incoming_edge_ignoring_loop_edges (basic_block bb)
-{
- edge retval = NULL;
- edge e;
- edge_iterator ei;
-
- FOR_EACH_EDGE (e, ei, bb->preds)
- {
- /* A loop back edge can be identified by the destination of
- the edge dominating the source of the edge. */
- if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
- continue;
-
- /* If we have already seen a non-loop edge, then we must have
- multiple incoming non-loop edges and thus we return NULL. */
- if (retval)
- return NULL;
-
- /* This is the first non-loop incoming edge we have found. Record
- it. */
- retval = e;
+ if (i == gimple_phi_num_args (phi))
+ {
+ if (may_propagate_copy (lhs, rhs))
+ set_ssa_name_value (lhs, rhs);
+ else if (virtual_operand_p (lhs))
+ {
+ gimple *use_stmt;
+ imm_use_iterator iter;
+ use_operand_p use_p;
+ /* For virtual operands we have to propagate into all uses as
+ otherwise we will create overlapping life-ranges. */
+ FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
+ FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
+ SET_USE (use_p, rhs);
+ if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1;
+ gimple_stmt_iterator tmp_gsi = gsi_for_stmt (phi);
+ remove_phi_node (&tmp_gsi, true);
+ }
+ }
}
-
- return retval;
}
-/* Record any equivalences created by the incoming edge to BB. If BB
- has more than one incoming edge, then no equivalence is created. */
+/* Record any equivalences created by the incoming edge to BB into
+ CONST_AND_COPIES and AVAIL_EXPRS_STACK. If BB has more than one
+ incoming edge, then no equivalence is created. */
static void
-record_equivalences_from_incoming_edge (basic_block bb)
+record_equivalences_from_incoming_edge (basic_block bb,
+ class const_and_copies *const_and_copies,
+ class avail_exprs_stack *avail_exprs_stack)
{
edge e;
basic_block parent;
the parent was followed. */
parent = get_immediate_dominator (CDI_DOMINATORS, bb);
- e = single_incoming_edge_ignoring_loop_edges (bb);
+ e = single_pred_edge_ignoring_loop_edges (bb, true);
/* If we had a single incoming edge from our parent block, then enter
any data associated with the edge into our tables. */
if (e && e->src == parent)
- record_temporary_equivalences (e);
-}
-
-/* Dump SSA statistics on FILE. */
-
-void
-dump_dominator_optimization_stats (FILE *file)
-{
- fprintf (file, "Total number of statements: %6ld\n\n",
- opt_stats.num_stmts);
- fprintf (file, "Exprs considered for dominator optimizations: %6ld\n",
- opt_stats.num_exprs_considered);
-
- fprintf (file, "\nHash table statistics:\n");
-
- fprintf (file, " avail_exprs: ");
- htab_statistics (file, *avail_exprs);
-}
-
-
-/* Dump SSA statistics on stderr. */
-
-DEBUG_FUNCTION void
-debug_dominator_optimization_stats (void)
-{
- dump_dominator_optimization_stats (stderr);
+ record_temporary_equivalences (e, const_and_copies, avail_exprs_stack);
}
-
/* Dump statistics for the hash table HTAB. */
static void
htab.collisions ());
}
-
-/* Enter condition equivalence into the expression hash table.
- This indicates that a conditional expression has a known
- boolean value. */
+/* Dump SSA statistics on FILE. */
static void
-record_cond (cond_equivalence *p)
+dump_dominator_optimization_stats (FILE *file,
+ hash_table<expr_elt_hasher> *avail_exprs)
{
- struct expr_hash_elt *element = XCNEW (struct expr_hash_elt);
- expr_hash_elt **slot;
-
- initialize_hash_element_from_expr (&p->cond, p->value, element);
-
- slot = avail_exprs->find_slot_with_hash (element, element->hash, INSERT);
- if (*slot == NULL)
- {
- *slot = element;
+ fprintf (file, "Total number of statements: %6ld\n\n",
+ opt_stats.num_stmts);
+ fprintf (file, "Exprs considered for dominator optimizations: %6ld\n",
+ opt_stats.num_exprs_considered);
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "1>>> ");
- print_expr_hash_elt (dump_file, element);
- }
+ fprintf (file, "\nHash table statistics:\n");
- avail_exprs_stack.safe_push
- (std::pair<expr_hash_elt_t, expr_hash_elt_t> (element, NULL));
- }
- else
- free_expr_hash_elt (element);
+ fprintf (file, " avail_exprs: ");
+ htab_statistics (file, *avail_exprs);
}
-/* Return the loop depth of the basic block of the defining statement of X.
- This number should not be treated as absolutely correct because the loop
- information may not be completely up-to-date when dom runs. However, it
- will be relatively correct, and as more passes are taught to keep loop info
- up to date, the result will become more and more accurate. */
-
-static int
-loop_depth_of_name (tree x)
-{
- gimple defstmt;
- basic_block defbb;
-
- /* If it's not an SSA_NAME, we have no clue where the definition is. */
- if (TREE_CODE (x) != SSA_NAME)
- return 0;
-
- /* Otherwise return the loop depth of the defining statement's bb.
- Note that there may not actually be a bb for this statement, if the
- ssa_name is live on entry. */
- defstmt = SSA_NAME_DEF_STMT (x);
- defbb = gimple_bb (defstmt);
- if (!defbb)
- return 0;
-
- return bb_loop_depth (defbb);
-}
/* Similarly, but assume that X and Y are the two operands of an EQ_EXPR.
This constrains the cases in which we may treat this as assignment. */
static void
-record_equality (tree x, tree y)
+record_equality (tree x, tree y, class const_and_copies *const_and_copies)
{
tree prev_x = NULL, prev_y = NULL;
- if (tree_swap_operands_p (x, y, false))
+ if (tree_swap_operands_p (x, y))
std::swap (x, y);
/* Most of the time tree_swap_operands_p does what we want. But there
long as we canonicalize on one value. */
if (is_gimple_min_invariant (y))
;
- else if (is_gimple_min_invariant (x)
- /* ??? When threading over backedges the following is important
- for correctness. See PR61757. */
- || (loop_depth_of_name (x) < loop_depth_of_name (y)))
+ else if (is_gimple_min_invariant (x))
prev_x = x, x = y, y = prev_x, prev_x = prev_y;
else if (prev_x && is_gimple_min_invariant (prev_x))
x = y, y = prev_x, prev_x = prev_y;
nonzero. */
if (HONOR_SIGNED_ZEROS (x)
&& (TREE_CODE (y) != REAL_CST
- || REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (y))))
+ || real_equal (&dconst0, &TREE_REAL_CST (y))))
return;
const_and_copies->record_const_or_copy (x, y, prev_x);
/* Returns true when STMT is a simple iv increment. It detects the
following situation:
- i_1 = phi (..., i_2)
- i_2 = i_1 +/- ... */
+ i_1 = phi (..., i_k)
+ [...]
+ i_j = i_{j-1} for each j : 2 <= j <= k-1
+ [...]
+ i_k = i_{k-1} +/- ... */
bool
-simple_iv_increment_p (gimple stmt)
+simple_iv_increment_p (gimple *stmt)
{
enum tree_code code;
tree lhs, preinc;
- gimple phi;
+ gimple *phi;
size_t i;
if (gimple_code (stmt) != GIMPLE_ASSIGN)
return false;
phi = SSA_NAME_DEF_STMT (preinc);
- if (gimple_code (phi) != GIMPLE_PHI)
- return false;
+ while (gimple_code (phi) != GIMPLE_PHI)
+ {
+ /* Follow trivial copies, but not the DEF used in a back edge,
+ so that we don't prevent coalescing. */
+ if (!gimple_assign_ssa_name_copy_p (phi))
+ return false;
+ preinc = gimple_assign_rhs1 (phi);
+ phi = SSA_NAME_DEF_STMT (preinc);
+ }
for (i = 0; i < gimple_phi_num_args (phi); i++)
if (gimple_phi_arg_def (phi, i) == lhs)
return false;
}
-/* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
- known value for that SSA_NAME (or NULL if no value is known).
-
- Propagate values from CONST_AND_COPIES into the PHI nodes of the
+/* Propagate know values from SSA_NAME_VALUE into the PHI nodes of the
successors of BB. */
static void
-cprop_into_successor_phis (basic_block bb)
+cprop_into_successor_phis (basic_block bb,
+ class const_and_copies *const_and_copies)
{
edge e;
edge_iterator ei;
continue;
/* We may have an equivalence associated with this edge. While
- we can not propagate it into non-dominated blocks, we can
+ we cannot propagate it into non-dominated blocks, we can
propagate them into PHIs in non-dominated blocks. */
/* Push the unwind marker so we can reset the const and copies
Don't bother with [01] = COND equivalences, they're not useful
here. */
- struct edge_info *edge_info = (struct edge_info *) e->aux;
+ class edge_info *edge_info = (class edge_info *) e->aux;
+
if (edge_info)
{
- tree lhs = edge_info->lhs;
- tree rhs = edge_info->rhs;
+ edge_info::equiv_pair *seq;
+ for (int i = 0; edge_info->simple_equivalences.iterate (i, &seq); ++i)
+ {
+ tree lhs = seq->first;
+ tree rhs = seq->second;
+
+ if (lhs && TREE_CODE (lhs) == SSA_NAME)
+ const_and_copies->record_const_or_copy (lhs, rhs);
+ }
- if (lhs && TREE_CODE (lhs) == SSA_NAME)
- const_and_copies->record_const_or_copy (lhs, rhs);
}
indx = e->dest_idx;
new_val = SSA_NAME_VALUE (orig_val);
if (new_val
&& new_val != orig_val
- && (TREE_CODE (new_val) == SSA_NAME
- || is_gimple_min_invariant (new_val))
&& may_propagate_copy (orig_val, new_val))
propagate_value (orig_p, new_val);
}
}
}
-void
+edge
dom_opt_dom_walker::before_dom_children (basic_block bb)
{
gimple_stmt_iterator gsi;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "\n\nOptimizing block #%d\n\n", bb->index);
+ m_evrp_range_analyzer->enter (bb);
+
/* Push a marker on the stacks of local information so that we know how
far to unwind when we finalize this block. */
- avail_exprs_stack.safe_push
- (std::pair<expr_hash_elt_t, expr_hash_elt_t> (NULL, NULL));
- const_and_copies->push_marker ();
+ m_avail_exprs_stack->push_marker ();
+ m_const_and_copies->push_marker ();
- record_equivalences_from_incoming_edge (bb);
+ record_equivalences_from_incoming_edge (bb, m_const_and_copies,
+ m_avail_exprs_stack);
/* PHI nodes can create equivalences too. */
record_equivalences_from_phis (bb);
/* Create equivalences from redundant PHIs. PHIs are only truly
redundant when they exist in the same block, so push another
marker and unwind right afterwards. */
- avail_exprs_stack.safe_push
- (std::pair<expr_hash_elt_t, expr_hash_elt_t> (NULL, NULL));
+ m_avail_exprs_stack->push_marker ();
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
- eliminate_redundant_computations (&gsi);
- remove_local_expressions_from_table ();
+ eliminate_redundant_computations (&gsi, m_const_and_copies,
+ m_avail_exprs_stack);
+ m_avail_exprs_stack->pop_to_marker ();
+ edge taken_edge = NULL;
+ /* Initialize visited flag ahead of us, it has undefined state on
+ pass entry. */
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
- optimize_stmt (bb, gsi);
+ gimple_set_visited (gsi_stmt (gsi), false);
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
+ {
+ /* Do not optimize a stmt twice, substitution might end up with
+ _3 = _3 which is not valid. */
+ if (gimple_visited_p (gsi_stmt (gsi)))
+ {
+ gsi_next (&gsi);
+ continue;
+ }
+
+ m_state->record_ranges_from_stmt (gsi_stmt (gsi), false);
+ bool removed_p = false;
+ taken_edge = this->optimize_stmt (bb, &gsi, &removed_p);
+ if (!removed_p)
+ gimple_set_visited (gsi_stmt (gsi), true);
+
+ /* Go back and visit stmts inserted by folding after substituting
+ into the stmt at gsi. */
+ if (gsi_end_p (gsi))
+ {
+ gcc_checking_assert (removed_p);
+ gsi = gsi_last_bb (bb);
+ while (!gsi_end_p (gsi) && !gimple_visited_p (gsi_stmt (gsi)))
+ gsi_prev (&gsi);
+ }
+ else
+ {
+ do
+ {
+ gsi_prev (&gsi);
+ }
+ while (!gsi_end_p (gsi) && !gimple_visited_p (gsi_stmt (gsi)));
+ }
+ if (gsi_end_p (gsi))
+ gsi = gsi_start_bb (bb);
+ else
+ gsi_next (&gsi);
+ }
/* Now prepare to process dominated blocks. */
record_edge_info (bb);
- cprop_into_successor_phis (bb);
+ cprop_into_successor_phis (bb, m_const_and_copies);
+ if (taken_edge && !dbg_cnt (dom_unreachable_edges))
+ return NULL;
+
+ return taken_edge;
}
/* We have finished processing the dominator children of BB, perform
void
dom_opt_dom_walker::after_dom_children (basic_block bb)
{
- gimple last;
-
- /* If we have an outgoing edge to a block with multiple incoming and
- outgoing edges, then we may be able to thread the edge, i.e., we
- may be able to statically determine which of the outgoing edges
- will be traversed when the incoming edge from BB is traversed. */
- if (single_succ_p (bb)
- && (single_succ_edge (bb)->flags & EDGE_ABNORMAL) == 0
- && potentially_threadable_block (single_succ (bb)))
- {
- thread_across_edge (single_succ_edge (bb));
- }
- else if ((last = last_stmt (bb))
- && gimple_code (last) == GIMPLE_COND
- && EDGE_COUNT (bb->succs) == 2
- && (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) == 0
- && (EDGE_SUCC (bb, 1)->flags & EDGE_ABNORMAL) == 0)
- {
- edge true_edge, false_edge;
-
- extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
-
- /* Only try to thread the edge if it reaches a target block with
- more than one predecessor and more than one successor. */
- if (potentially_threadable_block (true_edge->dest))
- thread_across_edge (true_edge);
-
- /* Similarly for the ELSE arm. */
- if (potentially_threadable_block (false_edge->dest))
- thread_across_edge (false_edge);
-
- }
-
- /* These remove expressions local to BB from the tables. */
- remove_local_expressions_from_table ();
- const_and_copies->pop_to_marker ();
-}
+ m_threader->thread_outgoing_edges (bb);
+ m_avail_exprs_stack->pop_to_marker ();
+ m_const_and_copies->pop_to_marker ();
+ m_evrp_range_analyzer->leave (bb);
+}
/* Search for redundant computations in STMT. If any are found, then
replace them with the variable holding the result of the computation.
- If safe, record this expression into the available expression hash
- table. */
+ If safe, record this expression into AVAIL_EXPRS_STACK and
+ CONST_AND_COPIES. */
static void
-eliminate_redundant_computations (gimple_stmt_iterator* gsi)
+eliminate_redundant_computations (gimple_stmt_iterator* gsi,
+ class const_and_copies *const_and_copies,
+ class avail_exprs_stack *avail_exprs_stack)
{
tree expr_type;
tree cached_lhs;
bool insert = true;
bool assigns_var_p = false;
- gimple stmt = gsi_stmt (*gsi);
+ gimple *stmt = gsi_stmt (*gsi);
if (gimple_code (stmt) == GIMPLE_PHI)
def = gimple_phi_result (stmt);
else
def = gimple_get_lhs (stmt);
- /* Certain expressions on the RHS can be optimized away, but can not
+ /* Certain expressions on the RHS can be optimized away, but cannot
themselves be entered into the hash tables. */
if (! def
|| TREE_CODE (def) != SSA_NAME
insert = false;
/* Check if the expression has been computed before. */
- cached_lhs = lookup_avail_expr (stmt, insert);
+ cached_lhs = avail_exprs_stack->lookup_avail_expr (stmt, insert, true);
opt_stats.num_exprs_considered++;
/* STMT, a GIMPLE_ASSIGN, may create certain equivalences, in either
the available expressions table or the const_and_copies table.
- Detect and record those equivalences. */
-/* We handle only very simple copy equivalences here. The heavy
+ Detect and record those equivalences into AVAIL_EXPRS_STACK.
+
+ We handle only very simple copy equivalences here. The heavy
lifing is done by eliminate_redundant_computations. */
static void
-record_equivalences_from_stmt (gimple stmt, int may_optimize_p)
+record_equivalences_from_stmt (gimple *stmt, int may_optimize_p,
+ class avail_exprs_stack *avail_exprs_stack)
{
tree lhs;
enum tree_code lhs_code;
&& (TREE_CODE (rhs) == SSA_NAME
|| is_gimple_min_invariant (rhs)))
{
- /* Valueize rhs. */
- if (TREE_CODE (rhs) == SSA_NAME)
- {
- tree tmp = SSA_NAME_VALUE (rhs);
- rhs = tmp ? tmp : rhs;
- }
+ rhs = dom_valueize (rhs);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "==== ASGN ");
- print_generic_expr (dump_file, lhs, 0);
+ print_generic_expr (dump_file, lhs);
fprintf (dump_file, " = ");
- print_generic_expr (dump_file, rhs, 0);
+ print_generic_expr (dump_file, rhs);
fprintf (dump_file, "\n");
}
tree op0 = gimple_assign_rhs1 (stmt);
tree op1 = gimple_assign_rhs2 (stmt);
tree new_rhs
- = build_fold_addr_expr (fold_build2 (MEM_REF,
- TREE_TYPE (TREE_TYPE (op0)),
- unshare_expr (op0),
- fold_convert (ptr_type_node,
- op1)));
+ = build1 (ADDR_EXPR, TREE_TYPE (op0),
+ fold_build2 (MEM_REF, TREE_TYPE (TREE_TYPE (op0)),
+ unshare_expr (op0), fold_convert (ptr_type_node,
+ op1)));
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "==== ASGN ");
- print_generic_expr (dump_file, lhs, 0);
+ print_generic_expr (dump_file, lhs);
fprintf (dump_file, " = ");
- print_generic_expr (dump_file, new_rhs, 0);
+ print_generic_expr (dump_file, new_rhs);
fprintf (dump_file, "\n");
}
generate here may in fact be ill-formed, but it is simply
used as an internal device in this pass, and never becomes
part of the CFG. */
- gimple defstmt = SSA_NAME_DEF_STMT (rhs);
+ gimple *defstmt = SSA_NAME_DEF_STMT (rhs);
new_stmt = gimple_build_assign (rhs, lhs);
SSA_NAME_DEF_STMT (rhs) = defstmt;
}
/* Finally enter the statement into the available expression
table. */
- lookup_avail_expr (new_stmt, true);
+ avail_exprs_stack->lookup_avail_expr (new_stmt, true, true);
}
}
CONST_AND_COPIES. */
static void
-cprop_operand (gimple stmt, use_operand_p op_p)
+cprop_operand (gimple *stmt, use_operand_p op_p, vr_values *vr_values)
{
tree val;
tree op = USE_FROM_PTR (op_p);
copy of some other variable, use the value or copy stored in
CONST_AND_COPIES. */
val = SSA_NAME_VALUE (op);
+ if (!val)
+ val = vr_values->op_with_constant_singleton_value_range (op);
+
if (val && val != op)
{
/* Do not replace hard register operands in asm statements. */
number of iteration analysis. */
if (TREE_CODE (val) != INTEGER_CST)
{
- gimple def = SSA_NAME_DEF_STMT (op);
+ gimple *def = SSA_NAME_DEF_STMT (op);
if (gimple_code (def) == GIMPLE_PHI
&& gimple_bb (def)->loop_father->header == gimple_bb (def))
return;
vdef_ops of STMT. */
static void
-cprop_into_stmt (gimple stmt)
+cprop_into_stmt (gimple *stmt, vr_values *vr_values)
{
use_operand_p op_p;
ssa_op_iter iter;
+ tree last_copy_propagated_op = NULL;
FOR_EACH_SSA_USE_OPERAND (op_p, stmt, iter, SSA_OP_USE)
- cprop_operand (stmt, op_p);
+ {
+ tree old_op = USE_FROM_PTR (op_p);
+
+ /* If we have A = B and B = A in the copy propagation tables
+ (due to an equality comparison), avoid substituting B for A
+ then A for B in the trivially discovered cases. This allows
+ optimization of statements were A and B appear as input
+ operands. */
+ if (old_op != last_copy_propagated_op)
+ {
+ cprop_operand (stmt, op_p, vr_values);
+
+ tree new_op = USE_FROM_PTR (op_p);
+ if (new_op != old_op && TREE_CODE (new_op) == SSA_NAME)
+ last_copy_propagated_op = new_op;
+ }
+ }
+}
+
+/* If STMT contains a relational test, try to convert it into an
+ equality test if there is only a single value which can ever
+ make the test true.
+
+ For example, if the expression hash table contains:
+
+ TRUE = (i <= 1)
+
+ And we have a test within statement of i >= 1, then we can safely
+ rewrite the test as i == 1 since there only a single value where
+ the test is true.
+
+ This is similar to code in VRP. */
+
+void
+dom_opt_dom_walker::test_for_singularity (gimple *stmt,
+ avail_exprs_stack *avail_exprs_stack)
+{
+ /* We want to support gimple conditionals as well as assignments
+ where the RHS contains a conditional. */
+ if (is_gimple_assign (stmt) || gimple_code (stmt) == GIMPLE_COND)
+ {
+ enum tree_code code = ERROR_MARK;
+ tree lhs, rhs;
+
+ /* Extract the condition of interest from both forms we support. */
+ if (is_gimple_assign (stmt))
+ {
+ code = gimple_assign_rhs_code (stmt);
+ lhs = gimple_assign_rhs1 (stmt);
+ rhs = gimple_assign_rhs2 (stmt);
+ }
+ else if (gimple_code (stmt) == GIMPLE_COND)
+ {
+ code = gimple_cond_code (as_a <gcond *> (stmt));
+ lhs = gimple_cond_lhs (as_a <gcond *> (stmt));
+ rhs = gimple_cond_rhs (as_a <gcond *> (stmt));
+ }
+
+ /* We're looking for a relational test using LE/GE. Also note we can
+ canonicalize LT/GT tests against constants into LE/GT tests. */
+ if (code == LE_EXPR || code == GE_EXPR
+ || ((code == LT_EXPR || code == GT_EXPR)
+ && TREE_CODE (rhs) == INTEGER_CST))
+ {
+ /* For LT_EXPR and GT_EXPR, canonicalize to LE_EXPR and GE_EXPR. */
+ if (code == LT_EXPR)
+ rhs = fold_build2 (MINUS_EXPR, TREE_TYPE (rhs),
+ rhs, build_int_cst (TREE_TYPE (rhs), 1));
+
+ if (code == GT_EXPR)
+ rhs = fold_build2 (PLUS_EXPR, TREE_TYPE (rhs),
+ rhs, build_int_cst (TREE_TYPE (rhs), 1));
+
+ /* Determine the code we want to check for in the hash table. */
+ enum tree_code test_code;
+ if (code == GE_EXPR || code == GT_EXPR)
+ test_code = LE_EXPR;
+ else
+ test_code = GE_EXPR;
+
+ /* Update the dummy statement so we can query the hash tables. */
+ gimple_cond_set_code (m_dummy_cond, test_code);
+ gimple_cond_set_lhs (m_dummy_cond, lhs);
+ gimple_cond_set_rhs (m_dummy_cond, rhs);
+ tree cached_lhs
+ = avail_exprs_stack->lookup_avail_expr (m_dummy_cond,
+ false, false);
+
+ /* If the lookup returned 1 (true), then the expression we
+ queried was in the hash table. As a result there is only
+ one value that makes the original conditional true. Update
+ STMT accordingly. */
+ if (cached_lhs && integer_onep (cached_lhs))
+ {
+ if (is_gimple_assign (stmt))
+ {
+ gimple_assign_set_rhs_code (stmt, EQ_EXPR);
+ gimple_assign_set_rhs2 (stmt, rhs);
+ gimple_set_modified (stmt, true);
+ }
+ else
+ {
+ gimple_set_modified (stmt, true);
+ gimple_cond_set_code (as_a <gcond *> (stmt), EQ_EXPR);
+ gimple_cond_set_rhs (as_a <gcond *> (stmt), rhs);
+ gimple_set_modified (stmt, true);
+ }
+ }
+ }
+ }
+}
+
+/* If STMT is a comparison of two uniform vectors reduce it to a comparison
+ of scalar objects, otherwise leave STMT unchanged. */
+
+static void
+reduce_vector_comparison_to_scalar_comparison (gimple *stmt)
+{
+ if (gimple_code (stmt) == GIMPLE_COND)
+ {
+ tree lhs = gimple_cond_lhs (stmt);
+ tree rhs = gimple_cond_rhs (stmt);
+
+ /* We may have a vector comparison where both arms are uniform
+ vectors. If so, we can simplify the vector comparison down
+ to a scalar comparison. */
+ if (TREE_CODE (TREE_TYPE (lhs)) == VECTOR_TYPE
+ && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE)
+ {
+ /* If either operand is an SSA_NAME, then look back to its
+ defining statement to try and get at a suitable source. */
+ if (TREE_CODE (rhs) == SSA_NAME)
+ {
+ gimple *def_stmt = SSA_NAME_DEF_STMT (rhs);
+ if (gimple_assign_single_p (def_stmt))
+ rhs = gimple_assign_rhs1 (def_stmt);
+ }
+
+ if (TREE_CODE (lhs) == SSA_NAME)
+ {
+ gimple *def_stmt = SSA_NAME_DEF_STMT (lhs);
+ if (gimple_assign_single_p (def_stmt))
+ lhs = gimple_assign_rhs1 (def_stmt);
+ }
+
+ /* Now see if they are both uniform vectors and if so replace
+ the vector comparison with a scalar comparison. */
+ tree rhs_elem = rhs ? uniform_vector_p (rhs) : NULL_TREE;
+ tree lhs_elem = lhs ? uniform_vector_p (lhs) : NULL_TREE;
+ if (rhs_elem && lhs_elem)
+ {
+ if (dump_file && dump_flags & TDF_DETAILS)
+ {
+ fprintf (dump_file, "Reducing vector comparison: ");
+ print_gimple_stmt (dump_file, stmt, 0);
+ }
+
+ gimple_cond_set_rhs (as_a <gcond *>(stmt), rhs_elem);
+ gimple_cond_set_lhs (as_a <gcond *>(stmt), lhs_elem);
+ gimple_set_modified (stmt, true);
+
+ if (dump_file && dump_flags & TDF_DETAILS)
+ {
+ fprintf (dump_file, "To scalar equivalent: ");
+ print_gimple_stmt (dump_file, stmt, 0);
+ fprintf (dump_file, "\n");
+ }
+ }
+ }
+ }
}
-/* Optimize the statement pointed to by iterator SI.
+/* Optimize the statement in block BB pointed to by iterator SI.
We try to perform some simplistic global redundancy elimination and
constant propagation:
2- Constant values and copy assignments. This is used to do very
simplistic constant and copy propagation. When a constant or copy
assignment is found, we map the value on the RHS of the assignment to
- the variable in the LHS in the CONST_AND_COPIES table. */
+ the variable in the LHS in the CONST_AND_COPIES table.
-static void
-optimize_stmt (basic_block bb, gimple_stmt_iterator si)
+ 3- Very simple redundant store elimination is performed.
+
+ 4- We can simplify a condition to a constant or from a relational
+ condition to an equality condition. */
+
+edge
+dom_opt_dom_walker::optimize_stmt (basic_block bb, gimple_stmt_iterator *si,
+ bool *removed_p)
{
- gimple stmt, old_stmt;
+ gimple *stmt, *old_stmt;
bool may_optimize_p;
bool modified_p = false;
bool was_noreturn;
+ edge retval = NULL;
- old_stmt = stmt = gsi_stmt (si);
+ old_stmt = stmt = gsi_stmt (*si);
was_noreturn = is_gimple_call (stmt) && gimple_call_noreturn_p (stmt);
if (dump_file && (dump_flags & TDF_DETAILS))
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
}
- if (gimple_code (stmt) == GIMPLE_COND)
- canonicalize_comparison (as_a <gcond *> (stmt));
+ /* STMT may be a comparison of uniform vectors that we can simplify
+ down to a comparison of scalars. Do that transformation first
+ so that all the scalar optimizations from here onward apply. */
+ reduce_vector_comparison_to_scalar_comparison (stmt);
update_stmt_if_modified (stmt);
opt_stats.num_stmts++;
/* Const/copy propagate into USES, VUSES and the RHS of VDEFs. */
- cprop_into_stmt (stmt);
+ cprop_into_stmt (stmt, m_evrp_range_analyzer);
/* If the statement has been modified with constant replacements,
fold its RHS before checking for redundant computations. */
/* Try to fold the statement making sure that STMT is kept
up to date. */
- if (fold_stmt (&si))
+ if (fold_stmt (si))
{
- stmt = gsi_stmt (si);
+ stmt = gsi_stmt (*si);
gimple_set_modified (stmt, true);
if (dump_file && (dump_flags & TDF_DETAILS))
certain that the value simply isn't constant. */
tree callee = gimple_call_fndecl (stmt);
if (callee
- && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
- && DECL_FUNCTION_CODE (callee) == BUILT_IN_CONSTANT_P)
+ && fndecl_built_in_p (callee, BUILT_IN_CONSTANT_P))
+ {
+ propagate_tree_value_into_stmt (si, integer_zero_node);
+ stmt = gsi_stmt (*si);
+ }
+ }
+
+ if (gimple_code (stmt) == GIMPLE_COND)
+ {
+ tree lhs = gimple_cond_lhs (stmt);
+ tree rhs = gimple_cond_rhs (stmt);
+
+ /* If the LHS has a range [0..1] and the RHS has a range ~[0..1],
+ then this conditional is computable at compile time. We can just
+ shove either 0 or 1 into the LHS, mark the statement as modified
+ and all the right things will just happen below.
+
+ Note this would apply to any case where LHS has a range
+ narrower than its type implies and RHS is outside that
+ narrower range. Future work. */
+ if (TREE_CODE (lhs) == SSA_NAME
+ && ssa_name_has_boolean_range (lhs)
+ && TREE_CODE (rhs) == INTEGER_CST
+ && ! (integer_zerop (rhs) || integer_onep (rhs)))
+ {
+ gimple_cond_set_lhs (as_a <gcond *> (stmt),
+ fold_convert (TREE_TYPE (lhs),
+ integer_zero_node));
+ gimple_set_modified (stmt, true);
+ }
+ else if (TREE_CODE (lhs) == SSA_NAME)
{
- propagate_tree_value_into_stmt (&si, integer_zero_node);
- stmt = gsi_stmt (si);
+ /* Exploiting EVRP data is not yet fully integrated into DOM
+ but we need to do something for this case to avoid regressing
+ udr4.f90 and new1.C which have unexecutable blocks with
+ undefined behavior that get diagnosed if they're left in the
+ IL because we've attached range information to new
+ SSA_NAMES. */
+ update_stmt_if_modified (stmt);
+ edge taken_edge = NULL;
+ m_evrp_range_analyzer->vrp_visit_cond_stmt
+ (as_a <gcond *> (stmt), &taken_edge);
+ if (taken_edge)
+ {
+ if (taken_edge->flags & EDGE_TRUE_VALUE)
+ gimple_cond_make_true (as_a <gcond *> (stmt));
+ else if (taken_edge->flags & EDGE_FALSE_VALUE)
+ gimple_cond_make_false (as_a <gcond *> (stmt));
+ else
+ gcc_unreachable ();
+ gimple_set_modified (stmt, true);
+ update_stmt (stmt);
+ cfg_altered = true;
+ return taken_edge;
+ }
}
}
update_stmt_if_modified (stmt);
- eliminate_redundant_computations (&si);
- stmt = gsi_stmt (si);
+ eliminate_redundant_computations (si, m_const_and_copies,
+ m_avail_exprs_stack);
+ stmt = gsi_stmt (*si);
/* Perform simple redundant store elimination. */
if (gimple_assign_single_p (stmt)
tree rhs = gimple_assign_rhs1 (stmt);
tree cached_lhs;
gassign *new_stmt;
- if (TREE_CODE (rhs) == SSA_NAME)
- {
- tree tem = SSA_NAME_VALUE (rhs);
- if (tem)
- rhs = tem;
- }
+ rhs = dom_valueize (rhs);
/* Build a new statement with the RHS and LHS exchanged. */
if (TREE_CODE (rhs) == SSA_NAME)
{
- gimple defstmt = SSA_NAME_DEF_STMT (rhs);
+ gimple *defstmt = SSA_NAME_DEF_STMT (rhs);
new_stmt = gimple_build_assign (rhs, lhs);
SSA_NAME_DEF_STMT (rhs) = defstmt;
}
else
new_stmt = gimple_build_assign (rhs, lhs);
gimple_set_vuse (new_stmt, gimple_vuse (stmt));
- cached_lhs = lookup_avail_expr (new_stmt, false);
+ expr_hash_elt *elt = NULL;
+ cached_lhs = m_avail_exprs_stack->lookup_avail_expr (new_stmt, false,
+ false, &elt);
if (cached_lhs
- && rhs == cached_lhs)
+ && operand_equal_p (rhs, cached_lhs, 0)
+ && refs_same_for_tbaa_p (elt->expr ()->kind == EXPR_SINGLE
+ ? elt->expr ()->ops.single.rhs
+ : NULL_TREE, lhs))
{
basic_block bb = gimple_bb (stmt);
unlink_stmt_vdef (stmt);
- if (gsi_remove (&si, true))
+ if (gsi_remove (si, true))
{
bitmap_set_bit (need_eh_cleanup, bb->index);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " Flagged to clear EH edges.\n");
}
release_defs (stmt);
- return;
+ *removed_p = true;
+ return retval;
}
}
+
+ /* If this statement was not redundant, we may still be able to simplify
+ it, which may in turn allow other part of DOM or other passes to do
+ a better job. */
+ test_for_singularity (stmt, m_avail_exprs_stack);
}
/* Record any additional equivalences created by this statement. */
if (is_gimple_assign (stmt))
- record_equivalences_from_stmt (stmt, may_optimize_p);
-
- /* If STMT is a COND_EXPR and it was modified, then we may know
- where it goes. If that is the case, then mark the CFG as altered.
+ record_equivalences_from_stmt (stmt, may_optimize_p, m_avail_exprs_stack);
- This will cause us to later call remove_unreachable_blocks and
- cleanup_tree_cfg when it is safe to do so. It is not safe to
- clean things up here since removal of edges and such can trigger
- the removal of PHI nodes, which in turn can release SSA_NAMEs to
- the manager.
-
- That's all fine and good, except that once SSA_NAMEs are released
- to the manager, we must not call create_ssa_name until all references
- to released SSA_NAMEs have been eliminated.
-
- All references to the deleted SSA_NAMEs can not be eliminated until
- we remove unreachable blocks.
-
- We can not remove unreachable blocks until after we have completed
- any queued jump threading.
-
- We can not complete any queued jump threads until we have taken
- appropriate variables out of SSA form. Taking variables out of
- SSA form can call create_ssa_name and thus we lose.
-
- Ultimately I suspect we're going to need to change the interface
- into the SSA_NAME manager. */
+ /* If STMT is a COND_EXPR or SWITCH_EXPR and it was modified, then we may
+ know where it goes. */
if (gimple_modified_p (stmt) || modified_p)
{
tree val = NULL;
- update_stmt_if_modified (stmt);
-
if (gimple_code (stmt) == GIMPLE_COND)
val = fold_binary_loc (gimple_location (stmt),
- gimple_cond_code (stmt), boolean_type_node,
- gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
+ gimple_cond_code (stmt), boolean_type_node,
+ gimple_cond_lhs (stmt),
+ gimple_cond_rhs (stmt));
else if (gswitch *swtch_stmt = dyn_cast <gswitch *> (stmt))
val = gimple_switch_index (swtch_stmt);
- if (val && TREE_CODE (val) == INTEGER_CST && find_taken_edge (bb, val))
- cfg_altered = true;
-
- /* If we simplified a statement in such a way as to be shown that it
- cannot trap, update the eh information and the cfg to match. */
- if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
+ if (val && TREE_CODE (val) == INTEGER_CST)
{
- bitmap_set_bit (need_eh_cleanup, bb->index);
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, " Flagged to clear EH edges.\n");
- }
-
- if (!was_noreturn
- && is_gimple_call (stmt) && gimple_call_noreturn_p (stmt))
- need_noreturn_fixup.safe_push (stmt);
- }
-}
-
-/* Helper for walk_non_aliased_vuses. Determine if we arrived at
- the desired memory state. */
-
-static void *
-vuse_eq (ao_ref *, tree vuse1, unsigned int cnt, void *data)
-{
- tree vuse2 = (tree) data;
- if (vuse1 == vuse2)
- return data;
-
- /* This bounds the stmt walks we perform on reference lookups
- to O(1) instead of O(N) where N is the number of dominating
- stores leading to a candidate. We re-use the SCCVN param
- for this as it is basically the same complexity. */
- if (cnt > (unsigned) PARAM_VALUE (PARAM_SCCVN_MAX_ALIAS_QUERIES_PER_ACCESS))
- return (void *)-1;
-
- return NULL;
-}
-
-/* Search for an existing instance of STMT in the AVAIL_EXPRS table.
- If found, return its LHS. Otherwise insert STMT in the table and
- return NULL_TREE.
-
- Also, when an expression is first inserted in the table, it is also
- is also added to AVAIL_EXPRS_STACK, so that it can be removed when
- we finish processing this block and its children. */
-
-static tree
-lookup_avail_expr (gimple stmt, bool insert)
-{
- expr_hash_elt **slot;
- tree lhs;
- tree temp;
- struct expr_hash_elt element;
-
- /* Get LHS of phi, assignment, or call; else NULL_TREE. */
- if (gimple_code (stmt) == GIMPLE_PHI)
- lhs = gimple_phi_result (stmt);
- else
- lhs = gimple_get_lhs (stmt);
-
- initialize_hash_element (stmt, lhs, &element);
-
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "LKUP ");
- print_expr_hash_elt (dump_file, &element);
- }
-
- /* Don't bother remembering constant assignments and copy operations.
- Constants and copy operations are handled by the constant/copy propagator
- in optimize_stmt. */
- if (element.expr.kind == EXPR_SINGLE
- && (TREE_CODE (element.expr.ops.single.rhs) == SSA_NAME
- || is_gimple_min_invariant (element.expr.ops.single.rhs)))
- return NULL_TREE;
-
- /* Finally try to find the expression in the main expression hash table. */
- slot = avail_exprs->find_slot (&element, (insert ? INSERT : NO_INSERT));
- if (slot == NULL)
- {
- free_expr_hash_elt_contents (&element);
- return NULL_TREE;
- }
- else if (*slot == NULL)
- {
- struct expr_hash_elt *element2 = XNEW (struct expr_hash_elt);
- *element2 = element;
- element2->stamp = element2;
- *slot = element2;
-
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "2>>> ");
- print_expr_hash_elt (dump_file, element2);
- }
-
- avail_exprs_stack.safe_push
- (std::pair<expr_hash_elt_t, expr_hash_elt_t> (element2, NULL));
- return NULL_TREE;
- }
-
- /* If we found a redundant memory operation do an alias walk to
- check if we can re-use it. */
- if (gimple_vuse (stmt) != (*slot)->vop)
- {
- tree vuse1 = (*slot)->vop;
- tree vuse2 = gimple_vuse (stmt);
- /* If we have a load of a register and a candidate in the
- hash with vuse1 then try to reach its stmt by walking
- up the virtual use-def chain using walk_non_aliased_vuses.
- But don't do this when removing expressions from the hash. */
- ao_ref ref;
- if (!(vuse1 && vuse2
- && gimple_assign_single_p (stmt)
- && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
- && (ao_ref_init (&ref, gimple_assign_rhs1 (stmt)), true)
- && walk_non_aliased_vuses (&ref, vuse2,
- vuse_eq, NULL, NULL, vuse1) != NULL))
- {
- if (insert)
+ retval = find_taken_edge (bb, val);
+ if (retval)
{
- struct expr_hash_elt *element2 = XNEW (struct expr_hash_elt);
- *element2 = element;
- element2->stamp = element2;
-
- /* Insert the expr into the hash by replacing the current
- entry and recording the value to restore in the
- avail_exprs_stack. */
- avail_exprs_stack.safe_push (std::make_pair (element2, *slot));
- *slot = element2;
- if (dump_file && (dump_flags & TDF_DETAILS))
+ /* Fix the condition to be either true or false. */
+ if (gimple_code (stmt) == GIMPLE_COND)
{
- fprintf (dump_file, "2>>> ");
- print_expr_hash_elt (dump_file, *slot);
- }
- }
- return NULL_TREE;
- }
- }
-
- free_expr_hash_elt_contents (&element);
-
- /* Extract the LHS of the assignment so that it can be used as the current
- definition of another variable. */
- lhs = (*slot)->lhs;
-
- /* See if the LHS appears in the CONST_AND_COPIES table. If it does, then
- use the value from the const_and_copies table. */
- if (TREE_CODE (lhs) == SSA_NAME)
- {
- temp = SSA_NAME_VALUE (lhs);
- if (temp)
- lhs = temp;
- }
-
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "FIND: ");
- print_generic_expr (dump_file, lhs, 0);
- fprintf (dump_file, "\n");
- }
-
- return lhs;
-}
-
-/* Hashing and equality functions for AVAIL_EXPRS. We compute a value number
- for expressions using the code of the expression and the SSA numbers of
- its operands. */
-
-static hashval_t
-avail_expr_hash (const void *p)
-{
- const struct hashable_expr *expr = &((const struct expr_hash_elt *)p)->expr;
- inchash::hash hstate;
-
- inchash::add_hashable_expr (expr, hstate);
-
- return hstate.end ();
-}
-
-/* PHI-ONLY copy and constant propagation. This pass is meant to clean
- up degenerate PHIs created by or exposed by jump threading. */
-
-/* Given a statement STMT, which is either a PHI node or an assignment,
- remove it from the IL. */
-
-static void
-remove_stmt_or_phi (gimple stmt)
-{
- gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
-
- if (gimple_code (stmt) == GIMPLE_PHI)
- remove_phi_node (&gsi, true);
- else
- {
- gsi_remove (&gsi, true);
- release_defs (stmt);
- }
-}
-
-/* Given a statement STMT, which is either a PHI node or an assignment,
- return the "rhs" of the node, in the case of a non-degenerate
- phi, NULL is returned. */
-
-static tree
-get_rhs_or_phi_arg (gimple stmt)
-{
- if (gimple_code (stmt) == GIMPLE_PHI)
- return degenerate_phi_result (as_a <gphi *> (stmt));
- else if (gimple_assign_single_p (stmt))
- return gimple_assign_rhs1 (stmt);
- else
- gcc_unreachable ();
-}
-
-
-/* Given a statement STMT, which is either a PHI node or an assignment,
- return the "lhs" of the node. */
-
-static tree
-get_lhs_or_phi_result (gimple stmt)
-{
- if (gimple_code (stmt) == GIMPLE_PHI)
- return gimple_phi_result (stmt);
- else if (is_gimple_assign (stmt))
- return gimple_assign_lhs (stmt);
- else
- gcc_unreachable ();
-}
-
-/* Propagate RHS into all uses of LHS (when possible).
-
- RHS and LHS are derived from STMT, which is passed in solely so
- that we can remove it if propagation is successful.
-
- When propagating into a PHI node or into a statement which turns
- into a trivial copy or constant initialization, set the
- appropriate bit in INTERESTING_NAMEs so that we will visit those
- nodes as well in an effort to pick up secondary optimization
- opportunities. */
-
-static void
-propagate_rhs_into_lhs (gimple stmt, tree lhs, tree rhs, bitmap interesting_names)
-{
- /* First verify that propagation is valid. */
- if (may_propagate_copy (lhs, rhs))
- {
- use_operand_p use_p;
- imm_use_iterator iter;
- gimple use_stmt;
- bool all = true;
-
- /* Dump details. */
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, " Replacing '");
- print_generic_expr (dump_file, lhs, dump_flags);
- fprintf (dump_file, "' with %s '",
- (TREE_CODE (rhs) != SSA_NAME ? "constant" : "variable"));
- print_generic_expr (dump_file, rhs, dump_flags);
- fprintf (dump_file, "'\n");
- }
-
- /* Walk over every use of LHS and try to replace the use with RHS.
- At this point the only reason why such a propagation would not
- be successful would be if the use occurs in an ASM_EXPR. */
- FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
- {
- /* Leave debug stmts alone. If we succeed in propagating
- all non-debug uses, we'll drop the DEF, and propagation
- into debug stmts will occur then. */
- if (gimple_debug_bind_p (use_stmt))
- continue;
-
- /* It's not always safe to propagate into an ASM_EXPR. */
- if (gimple_code (use_stmt) == GIMPLE_ASM
- && ! may_propagate_copy_into_asm (lhs))
- {
- all = false;
- continue;
- }
-
- /* It's not ok to propagate into the definition stmt of RHS.
- <bb 9>:
- # prephitmp.12_36 = PHI <g_67.1_6(9)>
- g_67.1_6 = prephitmp.12_36;
- goto <bb 9>;
- While this is strictly all dead code we do not want to
- deal with this here. */
- if (TREE_CODE (rhs) == SSA_NAME
- && SSA_NAME_DEF_STMT (rhs) == use_stmt)
- {
- all = false;
- continue;
- }
-
- /* Dump details. */
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, " Original statement:");
- print_gimple_stmt (dump_file, use_stmt, 0, dump_flags);
- }
-
- /* Propagate the RHS into this use of the LHS. */
- FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
- propagate_value (use_p, rhs);
-
- /* Special cases to avoid useless calls into the folding
- routines, operand scanning, etc.
-
- Propagation into a PHI may cause the PHI to become
- a degenerate, so mark the PHI as interesting. No other
- actions are necessary. */
- if (gimple_code (use_stmt) == GIMPLE_PHI)
- {
- tree result;
+ if (integer_zerop (val))
+ gimple_cond_make_false (as_a <gcond *> (stmt));
+ else if (integer_onep (val))
+ gimple_cond_make_true (as_a <gcond *> (stmt));
+ else
+ gcc_unreachable ();
- /* Dump details. */
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, " Updated statement:");
- print_gimple_stmt (dump_file, use_stmt, 0, dump_flags);
+ gimple_set_modified (stmt, true);
}
- result = get_lhs_or_phi_result (use_stmt);
- bitmap_set_bit (interesting_names, SSA_NAME_VERSION (result));
- continue;
- }
-
- /* From this point onward we are propagating into a
- real statement. Folding may (or may not) be possible,
- we may expose new operands, expose dead EH edges,
- etc. */
- /* NOTE tuples. In the tuples world, fold_stmt_inplace
- cannot fold a call that simplifies to a constant,
- because the GIMPLE_CALL must be replaced by a
- GIMPLE_ASSIGN, and there is no way to effect such a
- transformation in-place. We might want to consider
- using the more general fold_stmt here. */
- {
- gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
- fold_stmt_inplace (&gsi);
- }
-
- /* Sometimes propagation can expose new operands to the
- renamer. */
- update_stmt (use_stmt);
-
- /* Dump details. */
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, " Updated statement:");
- print_gimple_stmt (dump_file, use_stmt, 0, dump_flags);
- }
-
- /* If we replaced a variable index with a constant, then
- we would need to update the invariant flag for ADDR_EXPRs. */
- if (gimple_assign_single_p (use_stmt)
- && TREE_CODE (gimple_assign_rhs1 (use_stmt)) == ADDR_EXPR)
- recompute_tree_invariant_for_addr_expr
- (gimple_assign_rhs1 (use_stmt));
-
- /* If we cleaned up EH information from the statement,
- mark its containing block as needing EH cleanups. */
- if (maybe_clean_or_replace_eh_stmt (use_stmt, use_stmt))
- {
- bitmap_set_bit (need_eh_cleanup, gimple_bb (use_stmt)->index);
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, " Flagged to clear EH edges.\n");
- }
-
- /* Propagation may expose new trivial copy/constant propagation
- opportunities. */
- if (gimple_assign_single_p (use_stmt)
- && TREE_CODE (gimple_assign_lhs (use_stmt)) == SSA_NAME
- && (TREE_CODE (gimple_assign_rhs1 (use_stmt)) == SSA_NAME
- || is_gimple_min_invariant (gimple_assign_rhs1 (use_stmt))))
- {
- tree result = get_lhs_or_phi_result (use_stmt);
- bitmap_set_bit (interesting_names, SSA_NAME_VERSION (result));
- }
-
- /* Propagation into these nodes may make certain edges in
- the CFG unexecutable. We want to identify them as PHI nodes
- at the destination of those unexecutable edges may become
- degenerates. */
- else if (gimple_code (use_stmt) == GIMPLE_COND
- || gimple_code (use_stmt) == GIMPLE_SWITCH
- || gimple_code (use_stmt) == GIMPLE_GOTO)
- {
- tree val;
-
- if (gimple_code (use_stmt) == GIMPLE_COND)
- val = fold_binary_loc (gimple_location (use_stmt),
- gimple_cond_code (use_stmt),
- boolean_type_node,
- gimple_cond_lhs (use_stmt),
- gimple_cond_rhs (use_stmt));
- else if (gimple_code (use_stmt) == GIMPLE_SWITCH)
- val = gimple_switch_index (as_a <gswitch *> (use_stmt));
- else
- val = gimple_goto_dest (use_stmt);
-
- if (val && is_gimple_min_invariant (val))
- {
- basic_block bb = gimple_bb (use_stmt);
- edge te = find_taken_edge (bb, val);
- if (!te)
- continue;
-
- edge_iterator ei;
- edge e;
- gimple_stmt_iterator gsi;
- gphi_iterator psi;
-
- /* Remove all outgoing edges except TE. */
- for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei));)
- {
- if (e != te)
- {
- /* Mark all the PHI nodes at the destination of
- the unexecutable edge as interesting. */
- for (psi = gsi_start_phis (e->dest);
- !gsi_end_p (psi);
- gsi_next (&psi))
- {
- gphi *phi = psi.phi ();
-
- tree result = gimple_phi_result (phi);
- int version = SSA_NAME_VERSION (result);
-
- bitmap_set_bit (interesting_names, version);
- }
-
- te->probability += e->probability;
-
- te->count += e->count;
- remove_edge (e);
- cfg_altered = true;
- }
- else
- ei_next (&ei);
- }
-
- gsi = gsi_last_bb (gimple_bb (use_stmt));
- gsi_remove (&gsi, true);
-
- /* And fixup the flags on the single remaining edge. */
- te->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
- te->flags &= ~EDGE_ABNORMAL;
- te->flags |= EDGE_FALLTHRU;
- if (te->probability > REG_BR_PROB_BASE)
- te->probability = REG_BR_PROB_BASE;
- }
+ /* Further simplifications may be possible. */
+ cfg_altered = true;
}
}
- /* Ensure there is nothing else to do. */
- gcc_assert (!all || has_zero_uses (lhs));
-
- /* If we were able to propagate away all uses of LHS, then
- we can remove STMT. */
- if (all)
- remove_stmt_or_phi (stmt);
- }
-}
-
-/* STMT is either a PHI node (potentially a degenerate PHI node) or
- a statement that is a trivial copy or constant initialization.
-
- Attempt to eliminate T by propagating its RHS into all uses of
- its LHS. This may in turn set new bits in INTERESTING_NAMES
- for nodes we want to revisit later.
-
- All exit paths should clear INTERESTING_NAMES for the result
- of STMT. */
-
-static void
-eliminate_const_or_copy (gimple stmt, bitmap interesting_names)
-{
- tree lhs = get_lhs_or_phi_result (stmt);
- tree rhs;
- int version = SSA_NAME_VERSION (lhs);
-
- /* If the LHS of this statement or PHI has no uses, then we can
- just eliminate it. This can occur if, for example, the PHI
- was created by block duplication due to threading and its only
- use was in the conditional at the end of the block which was
- deleted. */
- if (has_zero_uses (lhs))
- {
- bitmap_clear_bit (interesting_names, version);
- remove_stmt_or_phi (stmt);
- return;
- }
-
- /* Get the RHS of the assignment or PHI node if the PHI is a
- degenerate. */
- rhs = get_rhs_or_phi_arg (stmt);
- if (!rhs)
- {
- bitmap_clear_bit (interesting_names, version);
- return;
- }
-
- if (!virtual_operand_p (lhs))
- propagate_rhs_into_lhs (stmt, lhs, rhs, interesting_names);
- else
- {
- gimple use_stmt;
- imm_use_iterator iter;
- use_operand_p use_p;
- /* For virtual operands we have to propagate into all uses as
- otherwise we will create overlapping life-ranges. */
- FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
- FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
- SET_USE (use_p, rhs);
- if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
- SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1;
- remove_stmt_or_phi (stmt);
- }
-
- /* Note that STMT may well have been deleted by now, so do
- not access it, instead use the saved version # to clear
- T's entry in the worklist. */
- bitmap_clear_bit (interesting_names, version);
-}
-
-/* The first phase in degenerate PHI elimination.
-
- Eliminate the degenerate PHIs in BB, then recurse on the
- dominator children of BB. */
-
-static void
-eliminate_degenerate_phis_1 (basic_block bb, bitmap interesting_names)
-{
- gphi_iterator gsi;
- basic_block son;
-
- for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
- {
- gphi *phi = gsi.phi ();
-
- eliminate_const_or_copy (phi, interesting_names);
- }
-
- /* Recurse into the dominator children of BB. */
- for (son = first_dom_son (CDI_DOMINATORS, bb);
- son;
- son = next_dom_son (CDI_DOMINATORS, son))
- eliminate_degenerate_phis_1 (son, interesting_names);
-}
-
-
-/* A very simple pass to eliminate degenerate PHI nodes from the
- IL. This is meant to be fast enough to be able to be run several
- times in the optimization pipeline.
-
- Certain optimizations, particularly those which duplicate blocks
- or remove edges from the CFG can create or expose PHIs which are
- trivial copies or constant initializations.
-
- While we could pick up these optimizations in DOM or with the
- combination of copy-prop and CCP, those solutions are far too
- heavy-weight for our needs.
-
- This implementation has two phases so that we can efficiently
- eliminate the first order degenerate PHIs and second order
- degenerate PHIs.
-
- The first phase performs a dominator walk to identify and eliminate
- the vast majority of the degenerate PHIs. When a degenerate PHI
- is identified and eliminated any affected statements or PHIs
- are put on a worklist.
-
- The second phase eliminates degenerate PHIs and trivial copies
- or constant initializations using the worklist. This is how we
- pick up the secondary optimization opportunities with minimal
- cost. */
-
-namespace {
-
-const pass_data pass_data_phi_only_cprop =
-{
- GIMPLE_PASS, /* type */
- "phicprop", /* name */
- OPTGROUP_NONE, /* optinfo_flags */
- TV_TREE_PHI_CPROP, /* tv_id */
- ( PROP_cfg | PROP_ssa ), /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- ( TODO_cleanup_cfg | TODO_update_ssa ), /* todo_flags_finish */
-};
-
-class pass_phi_only_cprop : public gimple_opt_pass
-{
-public:
- pass_phi_only_cprop (gcc::context *ctxt)
- : gimple_opt_pass (pass_data_phi_only_cprop, ctxt)
- {}
-
- /* opt_pass methods: */
- opt_pass * clone () { return new pass_phi_only_cprop (m_ctxt); }
- virtual bool gate (function *) { return flag_tree_dom != 0; }
- virtual unsigned int execute (function *);
-
-}; // class pass_phi_only_cprop
-
-unsigned int
-pass_phi_only_cprop::execute (function *fun)
-{
- bitmap interesting_names;
- bitmap interesting_names1;
-
- /* Bitmap of blocks which need EH information updated. We can not
- update it on-the-fly as doing so invalidates the dominator tree. */
- need_eh_cleanup = BITMAP_ALLOC (NULL);
-
- /* INTERESTING_NAMES is effectively our worklist, indexed by
- SSA_NAME_VERSION.
-
- A set bit indicates that the statement or PHI node which
- defines the SSA_NAME should be (re)examined to determine if
- it has become a degenerate PHI or trivial const/copy propagation
- opportunity.
-
- Experiments have show we generally get better compilation
- time behavior with bitmaps rather than sbitmaps. */
- interesting_names = BITMAP_ALLOC (NULL);
- interesting_names1 = BITMAP_ALLOC (NULL);
-
- calculate_dominance_info (CDI_DOMINATORS);
- cfg_altered = false;
-
- /* First phase. Eliminate degenerate PHIs via a dominator
- walk of the CFG.
-
- Experiments have indicated that we generally get better
- compile-time behavior by visiting blocks in the first
- phase in dominator order. Presumably this is because walking
- in dominator order leaves fewer PHIs for later examination
- by the worklist phase. */
- eliminate_degenerate_phis_1 (ENTRY_BLOCK_PTR_FOR_FN (fun),
- interesting_names);
-
- /* Second phase. Eliminate second order degenerate PHIs as well
- as trivial copies or constant initializations identified by
- the first phase or this phase. Basically we keep iterating
- until our set of INTERESTING_NAMEs is empty. */
- while (!bitmap_empty_p (interesting_names))
- {
- unsigned int i;
- bitmap_iterator bi;
-
- /* EXECUTE_IF_SET_IN_BITMAP does not like its bitmap
- changed during the loop. Copy it to another bitmap and
- use that. */
- bitmap_copy (interesting_names1, interesting_names);
+ update_stmt_if_modified (stmt);
- EXECUTE_IF_SET_IN_BITMAP (interesting_names1, 0, i, bi)
+ /* If we simplified a statement in such a way as to be shown that it
+ cannot trap, update the eh information and the cfg to match. */
+ if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
{
- tree name = ssa_name (i);
-
- /* Ignore SSA_NAMEs that have been released because
- their defining statement was deleted (unreachable). */
- if (name)
- eliminate_const_or_copy (SSA_NAME_DEF_STMT (ssa_name (i)),
- interesting_names);
+ bitmap_set_bit (need_eh_cleanup, bb->index);
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, " Flagged to clear EH edges.\n");
}
- }
-
- if (cfg_altered)
- {
- free_dominance_info (CDI_DOMINATORS);
- /* If we changed the CFG schedule loops for fixup by cfgcleanup. */
- loops_state_set (LOOPS_NEED_FIXUP);
- }
- /* Propagation of const and copies may make some EH edges dead. Purge
- such edges from the CFG as needed. */
- if (!bitmap_empty_p (need_eh_cleanup))
- {
- gimple_purge_all_dead_eh_edges (need_eh_cleanup);
- BITMAP_FREE (need_eh_cleanup);
+ if (!was_noreturn
+ && is_gimple_call (stmt) && gimple_call_noreturn_p (stmt))
+ need_noreturn_fixup.safe_push (stmt);
}
-
- BITMAP_FREE (interesting_names);
- BITMAP_FREE (interesting_names1);
- return 0;
-}
-
-} // anon namespace
-
-gimple_opt_pass *
-make_pass_phi_only_cprop (gcc::context *ctxt)
-{
- return new pass_phi_only_cprop (ctxt);
+ return retval;
}
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