/* Predicate aware uninitialized variable warning.
- Copyright (C) 2001-2015 Free Software Foundation, Inc.
+ Copyright (C) 2001-2020 Free Software Foundation, Inc.
Contributed by Xinliang David Li <davidxl@google.com>
This file is part of GCC.
#include "config.h"
#include "system.h"
#include "coretypes.h"
-#include "tm.h"
-#include "hash-set.h"
-#include "machmode.h"
-#include "vec.h"
-#include "double-int.h"
-#include "input.h"
-#include "alias.h"
-#include "symtab.h"
-#include "wide-int.h"
-#include "inchash.h"
+#include "backend.h"
#include "tree.h"
-#include "fold-const.h"
-#include "flags.h"
-#include "tm_p.h"
-#include "predict.h"
-#include "hard-reg-set.h"
-#include "input.h"
-#include "function.h"
-#include "dominance.h"
-#include "cfg.h"
-#include "basic-block.h"
-#include "gimple-pretty-print.h"
-#include "bitmap.h"
-#include "tree-ssa-alias.h"
-#include "internal-fn.h"
-#include "gimple-expr.h"
-#include "is-a.h"
#include "gimple.h"
-#include "gimple-iterator.h"
-#include "gimple-ssa.h"
-#include "tree-phinodes.h"
-#include "ssa-iterators.h"
-#include "tree-ssa.h"
-#include "tree-inline.h"
#include "tree-pass.h"
+#include "ssa.h"
+#include "gimple-pretty-print.h"
#include "diagnostic-core.h"
-#include "params.h"
+#include "fold-const.h"
+#include "gimple-iterator.h"
+#include "tree-ssa.h"
+#include "tree-cfg.h"
+#include "cfghooks.h"
/* This implements the pass that does predicate aware warning on uses of
- possibly uninitialized variables. The pass first collects the set of
- possibly uninitialized SSA names. For each such name, it walks through
- all its immediate uses. For each immediate use, it rebuilds the condition
- expression (the predicate) that guards the use. The predicate is then
+ possibly uninitialized variables. The pass first collects the set of
+ possibly uninitialized SSA names. For each such name, it walks through
+ all its immediate uses. For each immediate use, it rebuilds the condition
+ expression (the predicate) that guards the use. The predicate is then
examined to see if the variable is always defined under that same condition.
This is done either by pruning the unrealizable paths that lead to the
default definitions or by checking if the predicate set that guards the
defining paths is a superset of the use predicate. */
+/* Max PHI args we can handle in pass. */
+const unsigned max_phi_args = 32;
/* Pointer set of potentially undefined ssa names, i.e.,
ssa names that are defined by phi with operands that
#define MASK_EMPTY(mask) (mask == 0)
/* Returns the first bit position (starting from LSB)
- in mask that is non zero. Returns -1 if the mask is empty. */
+ in mask that is non zero. Returns -1 if the mask is empty. */
static int
get_mask_first_set_bit (unsigned mask)
{
has_undefined_value_p (tree t)
{
return (ssa_undefined_value_p (t)
- || (possibly_undefined_names
- && possibly_undefined_names->contains (t)));
+ || (possibly_undefined_names
+ && possibly_undefined_names->contains (t)));
}
-
-
/* Like has_undefined_value_p, but don't return true if TREE_NO_WARNING
is set on SSA_NAME_VAR. */
static inline bool
-uninit_undefined_value_p (tree t) {
+uninit_undefined_value_p (tree t)
+{
if (!has_undefined_value_p (t))
return false;
if (SSA_NAME_VAR (t) && TREE_NO_WARNING (SSA_NAME_VAR (t)))
/* Emit a warning for EXPR based on variable VAR at the point in the
program T, an SSA_NAME, is used being uninitialized. The exact
warning text is in MSGID and DATA is the gimple stmt with info about
- the location in source code. When DATA is a GIMPLE_PHI, PHIARG_IDX
+ the location in source code. When DATA is a GIMPLE_PHI, PHIARG_IDX
gives which argument of the phi node to take the location from. WC
is the warning code. */
warn_uninit (enum opt_code wc, tree t, tree expr, tree var,
const char *gmsgid, void *data, location_t phiarg_loc)
{
- gimple context = (gimple) data;
+ gimple *context = (gimple *) data;
location_t location, cfun_loc;
expanded_location xloc, floc;
if (!has_undefined_value_p (t))
return;
+ /* Anonymous SSA_NAMEs shouldn't be uninitialized, but ssa_undefined_value_p
+ can return true if the def stmt of anonymous SSA_NAME is COMPLEX_EXPR
+ created for conversion from scalar to complex. Use the underlying var of
+ the COMPLEX_EXPRs real part in that case. See PR71581. */
+ if (expr == NULL_TREE
+ && var == NULL_TREE
+ && SSA_NAME_VAR (t) == NULL_TREE
+ && is_gimple_assign (SSA_NAME_DEF_STMT (t))
+ && gimple_assign_rhs_code (SSA_NAME_DEF_STMT (t)) == COMPLEX_EXPR)
+ {
+ tree v = gimple_assign_rhs1 (SSA_NAME_DEF_STMT (t));
+ if (TREE_CODE (v) == SSA_NAME
+ && has_undefined_value_p (v)
+ && zerop (gimple_assign_rhs2 (SSA_NAME_DEF_STMT (t))))
+ {
+ expr = SSA_NAME_VAR (v);
+ var = expr;
+ }
+ }
+
+ if (expr == NULL_TREE)
+ return;
+
/* TREE_NO_WARNING either means we already warned, or the front end
wishes to suppress the warning. */
if ((context
else
location = DECL_SOURCE_LOCATION (var);
location = linemap_resolve_location (line_table, location,
- LRK_SPELLING_LOCATION,
- NULL);
+ LRK_SPELLING_LOCATION, NULL);
cfun_loc = DECL_SOURCE_LOCATION (cfun->decl);
xloc = expand_location (location);
floc = expand_location (cfun_loc);
+ auto_diagnostic_group d;
if (warning_at (location, wc, gmsgid, expr))
{
TREE_NO_WARNING (expr) = 1;
if (location == DECL_SOURCE_LOCATION (var))
return;
if (xloc.file != floc.file
- || linemap_location_before_p (line_table,
- location, cfun_loc)
- || linemap_location_before_p (line_table,
- cfun->function_end_locus,
+ || linemap_location_before_p (line_table, location, cfun_loc)
+ || linemap_location_before_p (line_table, cfun->function_end_locus,
location))
inform (DECL_SOURCE_LOCATION (var), "%qD was declared here", var);
}
}
+struct check_defs_data
+{
+ /* If we found any may-defs besides must-def clobbers. */
+ bool found_may_defs;
+};
+
+/* Callback for walk_aliased_vdefs. */
+
+static bool
+check_defs (ao_ref *ref, tree vdef, void *data_)
+{
+ check_defs_data *data = (check_defs_data *)data_;
+ gimple *def_stmt = SSA_NAME_DEF_STMT (vdef);
+ /* If this is a clobber then if it is not a kill walk past it. */
+ if (gimple_clobber_p (def_stmt))
+ {
+ if (stmt_kills_ref_p (def_stmt, ref))
+ return true;
+ return false;
+ }
+ /* Found a may-def on this path. */
+ data->found_may_defs = true;
+ return true;
+}
+
static unsigned int
warn_uninitialized_vars (bool warn_possibly_uninitialized)
{
gimple_stmt_iterator gsi;
basic_block bb;
+ unsigned int vdef_cnt = 0;
+ unsigned int oracle_cnt = 0;
+ unsigned limit = 0;
FOR_EACH_BB_FN (bb, cfun)
{
- bool always_executed = dominated_by_p (CDI_POST_DOMINATORS,
- single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)), bb);
+ basic_block succ = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+ bool always_executed = dominated_by_p (CDI_POST_DOMINATORS, succ, bb);
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
- gimple stmt = gsi_stmt (gsi);
+ gimple *stmt = gsi_stmt (gsi);
use_operand_p use_p;
ssa_op_iter op_iter;
tree use;
can warn about. */
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, op_iter, SSA_OP_USE)
{
+ /* BIT_INSERT_EXPR first operand should not be considered
+ a use for the purpose of uninit warnings. */
+ if (gassign *ass = dyn_cast <gassign *> (stmt))
+ {
+ if (gimple_assign_rhs_code (ass) == BIT_INSERT_EXPR
+ && use_p->use == gimple_assign_rhs1_ptr (ass))
+ continue;
+ }
use = USE_FROM_PTR (use_p);
if (always_executed)
- warn_uninit (OPT_Wuninitialized, use,
- SSA_NAME_VAR (use), SSA_NAME_VAR (use),
- "%qD is used uninitialized in this function",
- stmt, UNKNOWN_LOCATION);
+ warn_uninit (OPT_Wuninitialized, use, SSA_NAME_VAR (use),
+ SSA_NAME_VAR (use),
+ "%qD is used uninitialized in this function", stmt,
+ UNKNOWN_LOCATION);
else if (warn_possibly_uninitialized)
- warn_uninit (OPT_Wmaybe_uninitialized, use,
- SSA_NAME_VAR (use), SSA_NAME_VAR (use),
+ warn_uninit (OPT_Wmaybe_uninitialized, use, SSA_NAME_VAR (use),
+ SSA_NAME_VAR (use),
"%qD may be used uninitialized in this function",
stmt, UNKNOWN_LOCATION);
}
- /* For memory the only cheap thing we can do is see if we
- have a use of the default def of the virtual operand.
- ??? Not so cheap would be to use the alias oracle via
- walk_aliased_vdefs, if we don't find any aliasing vdef
- warn as is-used-uninitialized, if we don't find an aliasing
- vdef that kills our use (stmt_kills_ref_p), warn as
- may-be-used-uninitialized. But this walk is quadratic and
- so must be limited which means we would miss warning
- opportunities. */
- use = gimple_vuse (stmt);
- if (use
- && gimple_assign_single_p (stmt)
- && !gimple_vdef (stmt)
- && SSA_NAME_IS_DEFAULT_DEF (use))
+ /* For limiting the alias walk below we count all
+ vdefs in the function. */
+ if (gimple_vdef (stmt))
+ vdef_cnt++;
+
+ if (gimple_assign_load_p (stmt)
+ && gimple_has_location (stmt))
{
tree rhs = gimple_assign_rhs1 (stmt);
- tree base = get_base_address (rhs);
+ tree lhs = gimple_assign_lhs (stmt);
+ bool has_bit_insert = false;
+ use_operand_p luse_p;
+ imm_use_iterator liter;
+
+ if (TREE_NO_WARNING (rhs))
+ continue;
+
+ ao_ref ref;
+ ao_ref_init (&ref, rhs);
+
+ /* Do not warn if the base was marked so or this is a
+ hard register var. */
+ tree base = ao_ref_base (&ref);
+ if ((VAR_P (base)
+ && DECL_HARD_REGISTER (base))
+ || TREE_NO_WARNING (base))
+ continue;
+
+ /* Do not warn if the access is fully outside of the
+ variable. */
+ poly_int64 decl_size;
+ if (DECL_P (base)
+ && known_size_p (ref.size)
+ && ((known_eq (ref.max_size, ref.size)
+ && known_le (ref.offset + ref.size, 0))
+ || (known_ge (ref.offset, 0)
+ && DECL_SIZE (base)
+ && poly_int_tree_p (DECL_SIZE (base), &decl_size)
+ && known_le (decl_size, ref.offset))))
+ continue;
+
+ /* Do not warn if the access is then used for a BIT_INSERT_EXPR. */
+ if (TREE_CODE (lhs) == SSA_NAME)
+ FOR_EACH_IMM_USE_FAST (luse_p, liter, lhs)
+ {
+ gimple *use_stmt = USE_STMT (luse_p);
+ /* BIT_INSERT_EXPR first operand should not be considered
+ a use for the purpose of uninit warnings. */
+ if (gassign *ass = dyn_cast <gassign *> (use_stmt))
+ {
+ if (gimple_assign_rhs_code (ass) == BIT_INSERT_EXPR
+ && luse_p->use == gimple_assign_rhs1_ptr (ass))
+ {
+ has_bit_insert = true;
+ break;
+ }
+ }
+ }
+ if (has_bit_insert)
+ continue;
- /* Do not warn if it can be initialized outside this function. */
- if (TREE_CODE (base) != VAR_DECL
- || DECL_HARD_REGISTER (base)
- || is_global_var (base))
+ /* Limit the walking to a constant number of stmts after
+ we overcommit quadratic behavior for small functions
+ and O(n) behavior. */
+ if (oracle_cnt > 128 * 128
+ && oracle_cnt > vdef_cnt * 2)
+ limit = 32;
+ check_defs_data data;
+ bool fentry_reached = false;
+ data.found_may_defs = false;
+ use = gimple_vuse (stmt);
+ int res = walk_aliased_vdefs (&ref, use,
+ check_defs, &data, NULL,
+ &fentry_reached, limit);
+ if (res == -1)
+ {
+ oracle_cnt += limit;
+ continue;
+ }
+ oracle_cnt += res;
+ if (data.found_may_defs)
+ continue;
+ /* Do not warn if it can be initialized outside this function.
+ If we did not reach function entry then we found killing
+ clobbers on all paths to entry. */
+ if (fentry_reached
+ /* ??? We'd like to use ref_may_alias_global_p but that
+ excludes global readonly memory and thus we get bougs
+ warnings from p = cond ? "a" : "b" for example. */
+ && (!VAR_P (base)
+ || is_global_var (base)))
continue;
+ /* We didn't find any may-defs so on all paths either
+ reached function entry or a killing clobber. */
+ location_t location
+ = linemap_resolve_location (line_table, gimple_location (stmt),
+ LRK_SPELLING_LOCATION, NULL);
if (always_executed)
- warn_uninit (OPT_Wuninitialized, use,
- gimple_assign_rhs1 (stmt), base,
- "%qE is used uninitialized in this function",
- stmt, UNKNOWN_LOCATION);
+ {
+ if (warning_at (location, OPT_Wuninitialized,
+ "%qE is used uninitialized in this function",
+ rhs))
+ /* ??? This is only effective for decls as in
+ gcc.dg/uninit-B-O0.c. Avoid doing this for
+ maybe-uninit uses as it may hide important
+ locations. */
+ TREE_NO_WARNING (rhs) = 1;
+ }
else if (warn_possibly_uninitialized)
- warn_uninit (OPT_Wmaybe_uninitialized, use,
- gimple_assign_rhs1 (stmt), base,
- "%qE may be used uninitialized in this function",
- stmt, UNKNOWN_LOCATION);
+ warning_at (location, OPT_Wmaybe_uninitialized,
+ "%qE may be used uninitialized in this function",
+ rhs);
}
}
}
/* Checks if the operand OPND of PHI is defined by
another phi with one operand defined by this PHI,
- but the rest operands are all defined. If yes,
- returns true to skip this this operand as being
- redundant. Can be enhanced to be more general. */
+ but the rest operands are all defined. If yes,
+ returns true to skip this operand as being
+ redundant. Can be enhanced to be more general. */
static bool
-can_skip_redundant_opnd (tree opnd, gimple phi)
+can_skip_redundant_opnd (tree opnd, gimple *phi)
{
- gimple op_def;
+ gimple *op_def;
tree phi_def;
int i, n;
{
tree op = gimple_phi_arg_def (op_def, i);
if (TREE_CODE (op) != SSA_NAME)
- continue;
+ continue;
if (op != phi_def && uninit_undefined_value_p (op))
- return false;
+ return false;
}
return true;
n = gimple_phi_num_args (phi);
/* Bail out for phi with too many args. */
- if (n > 32)
+ if (n > max_phi_args)
return 0;
for (i = 0; i < n; ++i)
{
tree op = gimple_phi_arg_def (phi, i);
if (TREE_CODE (op) == SSA_NAME
- && uninit_undefined_value_p (op)
- && !can_skip_redundant_opnd (op, phi))
+ && uninit_undefined_value_p (op)
+ && !can_skip_redundant_opnd (op, phi))
{
- if (cfun->has_nonlocal_label || cfun->calls_setjmp)
+ if (cfun->has_nonlocal_label || cfun->calls_setjmp)
{
/* Ignore SSA_NAMEs that appear on abnormal edges
somewhere. */
static inline basic_block
find_pdom (basic_block block)
{
- if (block == EXIT_BLOCK_PTR_FOR_FN (cfun))
- return EXIT_BLOCK_PTR_FOR_FN (cfun);
- else
- {
- basic_block bb
- = get_immediate_dominator (CDI_POST_DOMINATORS, block);
- if (! bb)
- return EXIT_BLOCK_PTR_FOR_FN (cfun);
- return bb;
- }
+ if (block == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ return EXIT_BLOCK_PTR_FOR_FN (cfun);
+ else
+ {
+ basic_block bb = get_immediate_dominator (CDI_POST_DOMINATORS, block);
+ if (!bb)
+ return EXIT_BLOCK_PTR_FOR_FN (cfun);
+ return bb;
+ }
}
-/* Find the immediate DOM of the specified
- basic block BLOCK. */
+/* Find the immediate DOM of the specified basic block BLOCK. */
static inline basic_block
find_dom (basic_block block)
{
- if (block == ENTRY_BLOCK_PTR_FOR_FN (cfun))
- return ENTRY_BLOCK_PTR_FOR_FN (cfun);
- else
- {
- basic_block bb = get_immediate_dominator (CDI_DOMINATORS, block);
- if (! bb)
- return ENTRY_BLOCK_PTR_FOR_FN (cfun);
- return bb;
- }
+ if (block == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ return ENTRY_BLOCK_PTR_FOR_FN (cfun);
+ else
+ {
+ basic_block bb = get_immediate_dominator (CDI_DOMINATORS, block);
+ if (!bb)
+ return ENTRY_BLOCK_PTR_FOR_FN (cfun);
+ return bb;
+ }
}
/* Returns true if BB1 is postdominating BB2 and BB1 is
- not a loop exit bb. The loop exit bb check is simple and does
+ not a loop exit bb. The loop exit bb check is simple and does
not cover all cases. */
static bool
/* Find the closest postdominator of a specified BB, which is control
equivalent to BB. */
-static inline basic_block
+static inline basic_block
find_control_equiv_block (basic_block bb)
{
basic_block pdom;
#define MAX_NUM_CHAINS 8
#define MAX_CHAIN_LEN 5
#define MAX_POSTDOM_CHECK 8
+#define MAX_SWITCH_CASES 40
/* Computes the control dependence chains (paths of edges)
for DEP_BB up to the dominating basic block BB (the head node of a
static bool
compute_control_dep_chain (basic_block bb, basic_block dep_bb,
- vec<edge> *cd_chains,
- size_t *num_chains,
+ vec<edge> *cd_chains,
+ size_t *num_chains,
vec<edge> *cur_cd_chain,
int *num_calls)
{
bool found_cd_chain = false;
size_t cur_chain_len = 0;
- if (EDGE_COUNT (bb->succs) < 2)
- return false;
-
- if (*num_calls > PARAM_VALUE (PARAM_UNINIT_CONTROL_DEP_ATTEMPTS))
+ if (*num_calls > param_uninit_control_dep_attempts)
return false;
++*num_calls;
for (i = 0; i < cur_chain_len; i++)
{
edge e = (*cur_cd_chain)[i];
- /* Cycle detected. */
+ /* Cycle detected. */
if (e->src == bb)
- return false;
+ return false;
}
FOR_EACH_EDGE (e, ei, bb->succs)
basic_block cd_bb;
int post_dom_check = 0;
if (e->flags & (EDGE_FAKE | EDGE_ABNORMAL))
- continue;
+ continue;
cd_bb = e->dest;
cur_cd_chain->safe_push (e);
while (!is_non_loop_exit_postdominating (cd_bb, bb))
- {
- if (cd_bb == dep_bb)
- {
- /* Found a direct control dependence. */
- if (*num_chains < MAX_NUM_CHAINS)
- {
- cd_chains[*num_chains] = cur_cd_chain->copy ();
- (*num_chains)++;
- }
- found_cd_chain = true;
- /* Check path from next edge. */
- break;
- }
-
- /* Now check if DEP_BB is indirectly control dependent on BB. */
- if (compute_control_dep_chain (cd_bb, dep_bb, cd_chains,
- num_chains, cur_cd_chain, num_calls))
- {
- found_cd_chain = true;
- break;
- }
-
- cd_bb = find_pdom (cd_bb);
- post_dom_check++;
- if (cd_bb == EXIT_BLOCK_PTR_FOR_FN (cfun) || post_dom_check >
- MAX_POSTDOM_CHECK)
- break;
- }
+ {
+ if (cd_bb == dep_bb)
+ {
+ /* Found a direct control dependence. */
+ if (*num_chains < MAX_NUM_CHAINS)
+ {
+ cd_chains[*num_chains] = cur_cd_chain->copy ();
+ (*num_chains)++;
+ }
+ found_cd_chain = true;
+ /* Check path from next edge. */
+ break;
+ }
+
+ /* Now check if DEP_BB is indirectly control dependent on BB. */
+ if (compute_control_dep_chain (cd_bb, dep_bb, cd_chains, num_chains,
+ cur_cd_chain, num_calls))
+ {
+ found_cd_chain = true;
+ break;
+ }
+
+ cd_bb = find_pdom (cd_bb);
+ post_dom_check++;
+ if (cd_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)
+ || post_dom_check > MAX_POSTDOM_CHECK)
+ break;
+ }
cur_cd_chain->pop ();
gcc_assert (cur_cd_chain->length () == cur_chain_len);
}
return found_cd_chain;
}
-/* The type to represent a simple predicate */
+/* The type to represent a simple predicate. */
-typedef struct use_def_pred_info
+struct pred_info
{
tree pred_lhs;
tree pred_rhs;
enum tree_code cond_code;
bool invert;
-} pred_info;
+};
/* The type to represent a sequence of predicates grouped
with .AND. operation. */
typedef vec<pred_chain, va_heap, vl_ptr> pred_chain_union;
/* Converts the chains of control dependence edges into a set of
- predicates. A control dependence chain is represented by a vector
- edges. DEP_CHAINS points to an array of dependence chains.
- NUM_CHAINS is the size of the chain array. One edge in a dependence
+ predicates. A control dependence chain is represented by a vector
+ edges. DEP_CHAINS points to an array of dependence chains.
+ NUM_CHAINS is the size of the chain array. One edge in a dependence
chain is mapped to predicate expression represented by pred_info
- type. One dependence chain is converted to a composite predicate that
+ type. One dependence chain is converted to a composite predicate that
is the result of AND operation of pred_info mapped to each edge.
- A composite predicate is presented by a vector of pred_info. On
+ A composite predicate is presented by a vector of pred_info. On
return, *PREDS points to the resulting array of composite predicates.
*NUM_PREDS is the number of composite predictes. */
static bool
convert_control_dep_chain_into_preds (vec<edge> *dep_chains,
- size_t num_chains,
- pred_chain_union *preds)
+ size_t num_chains,
+ pred_chain_union *preds)
{
bool has_valid_pred = false;
size_t i, j;
has_valid_pred = false;
pred_chain t_chain = vNULL;
for (j = 0; j < one_cd_chain.length (); j++)
- {
- gimple cond_stmt;
- gimple_stmt_iterator gsi;
- basic_block guard_bb;
- pred_info one_pred;
- edge e;
-
- e = one_cd_chain[j];
- guard_bb = e->src;
- gsi = gsi_last_bb (guard_bb);
- if (gsi_end_p (gsi))
- {
- has_valid_pred = false;
- break;
- }
- cond_stmt = gsi_stmt (gsi);
- if (is_gimple_call (cond_stmt)
- && EDGE_COUNT (e->src->succs) >= 2)
- {
- /* Ignore EH edge. Can add assertion
- on the other edge's flag. */
- continue;
- }
- /* Skip if there is essentially one succesor. */
- if (EDGE_COUNT (e->src->succs) == 2)
- {
- edge e1;
- edge_iterator ei1;
- bool skip = false;
-
- FOR_EACH_EDGE (e1, ei1, e->src->succs)
- {
- if (EDGE_COUNT (e1->dest->succs) == 0)
- {
- skip = true;
- break;
- }
- }
- if (skip)
- continue;
- }
- if (gimple_code (cond_stmt) != GIMPLE_COND)
- {
- has_valid_pred = false;
- break;
- }
- one_pred.pred_lhs = gimple_cond_lhs (cond_stmt);
- one_pred.pred_rhs = gimple_cond_rhs (cond_stmt);
- one_pred.cond_code = gimple_cond_code (cond_stmt);
- one_pred.invert = !!(e->flags & EDGE_FALSE_VALUE);
- t_chain.safe_push (one_pred);
- has_valid_pred = true;
- }
+ {
+ gimple *cond_stmt;
+ gimple_stmt_iterator gsi;
+ basic_block guard_bb;
+ pred_info one_pred;
+ edge e;
+
+ e = one_cd_chain[j];
+ guard_bb = e->src;
+ gsi = gsi_last_bb (guard_bb);
+ /* Ignore empty forwarder blocks. */
+ if (empty_block_p (guard_bb) && single_succ_p (guard_bb))
+ continue;
+ /* An empty basic block here is likely a PHI, and is not one
+ of the cases we handle below. */
+ if (gsi_end_p (gsi))
+ {
+ has_valid_pred = false;
+ break;
+ }
+ cond_stmt = gsi_stmt (gsi);
+ if (is_gimple_call (cond_stmt) && EDGE_COUNT (e->src->succs) >= 2)
+ /* Ignore EH edge. Can add assertion on the other edge's flag. */
+ continue;
+ /* Skip if there is essentially one succesor. */
+ if (EDGE_COUNT (e->src->succs) == 2)
+ {
+ edge e1;
+ edge_iterator ei1;
+ bool skip = false;
+
+ FOR_EACH_EDGE (e1, ei1, e->src->succs)
+ {
+ if (EDGE_COUNT (e1->dest->succs) == 0)
+ {
+ skip = true;
+ break;
+ }
+ }
+ if (skip)
+ continue;
+ }
+ if (gimple_code (cond_stmt) == GIMPLE_COND)
+ {
+ one_pred.pred_lhs = gimple_cond_lhs (cond_stmt);
+ one_pred.pred_rhs = gimple_cond_rhs (cond_stmt);
+ one_pred.cond_code = gimple_cond_code (cond_stmt);
+ one_pred.invert = !!(e->flags & EDGE_FALSE_VALUE);
+ t_chain.safe_push (one_pred);
+ has_valid_pred = true;
+ }
+ else if (gswitch *gs = dyn_cast<gswitch *> (cond_stmt))
+ {
+ /* Avoid quadratic behavior. */
+ if (gimple_switch_num_labels (gs) > MAX_SWITCH_CASES)
+ {
+ has_valid_pred = false;
+ break;
+ }
+ /* Find the case label. */
+ tree l = NULL_TREE;
+ unsigned idx;
+ for (idx = 0; idx < gimple_switch_num_labels (gs); ++idx)
+ {
+ tree tl = gimple_switch_label (gs, idx);
+ if (e->dest == label_to_block (cfun, CASE_LABEL (tl)))
+ {
+ if (!l)
+ l = tl;
+ else
+ {
+ l = NULL_TREE;
+ break;
+ }
+ }
+ }
+ /* If more than one label reaches this block or the case
+ label doesn't have a single value (like the default one)
+ fail. */
+ if (!l
+ || !CASE_LOW (l)
+ || (CASE_HIGH (l)
+ && !operand_equal_p (CASE_LOW (l), CASE_HIGH (l), 0)))
+ {
+ has_valid_pred = false;
+ break;
+ }
+ one_pred.pred_lhs = gimple_switch_index (gs);
+ one_pred.pred_rhs = CASE_LOW (l);
+ one_pred.cond_code = EQ_EXPR;
+ one_pred.invert = false;
+ t_chain.safe_push (one_pred);
+ has_valid_pred = true;
+ }
+ else
+ {
+ has_valid_pred = false;
+ break;
+ }
+ }
if (!has_valid_pred)
- break;
+ break;
else
- preds->safe_push (t_chain);
+ preds->safe_push (t_chain);
}
return has_valid_pred;
}
-/* Computes all control dependence chains for USE_BB. The control
+/* Computes all control dependence chains for USE_BB. The control
dependence chains are then converted to an array of composite
predicates pointed to by PREDS. PHI_BB is the basic block of
the phi whose result is used in USE_BB. */
static bool
find_predicates (pred_chain_union *preds,
- basic_block phi_bb,
- basic_block use_bb)
+ basic_block phi_bb,
+ basic_block use_bb)
{
size_t num_chains = 0, i;
int num_calls = 0;
{
basic_block ctrl_eq_bb = find_control_equiv_block (cd_root);
if (ctrl_eq_bb && dominated_by_p (CDI_DOMINATORS, use_bb, ctrl_eq_bb))
- cd_root = ctrl_eq_bb;
+ cd_root = ctrl_eq_bb;
else
- break;
+ break;
}
compute_control_dep_chain (cd_root, use_bb, dep_chains, &num_chains,
/* Computes the set of incoming edges of PHI that have non empty
definitions of a phi chain. The collection will be done
- recursively on operands that are defined by phis. CD_ROOT
- is the control dependence root. *EDGES holds the result, and
+ recursively on operands that are defined by phis. CD_ROOT
+ is the control dependence root. *EDGES holds the result, and
VISITED_PHIS is a pointer set for detecting cycles. */
static void
collect_phi_def_edges (gphi *phi, basic_block cd_root,
- vec<edge> *edges,
- hash_set<gimple> *visited_phis)
+ auto_vec<edge> *edges,
+ hash_set<gimple *> *visited_phis)
{
size_t i, n;
edge opnd_edge;
opnd = gimple_phi_arg_def (phi, i);
if (TREE_CODE (opnd) != SSA_NAME)
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "\n[CHECK] Found def edge %d in ", (int)i);
- print_gimple_stmt (dump_file, phi, 0, 0);
- }
- edges->safe_push (opnd_edge);
- }
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "\n[CHECK] Found def edge %d in ", (int) i);
+ print_gimple_stmt (dump_file, phi, 0);
+ }
+ edges->safe_push (opnd_edge);
+ }
else
- {
- gimple def = SSA_NAME_DEF_STMT (opnd);
-
- if (gimple_code (def) == GIMPLE_PHI
- && dominated_by_p (CDI_DOMINATORS,
- gimple_bb (def), cd_root))
- collect_phi_def_edges (as_a <gphi *> (def), cd_root, edges,
- visited_phis);
- else if (!uninit_undefined_value_p (opnd))
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "\n[CHECK] Found def edge %d in ", (int)i);
- print_gimple_stmt (dump_file, phi, 0, 0);
- }
- edges->safe_push (opnd_edge);
- }
- }
+ {
+ gimple *def = SSA_NAME_DEF_STMT (opnd);
+
+ if (gimple_code (def) == GIMPLE_PHI
+ && dominated_by_p (CDI_DOMINATORS, gimple_bb (def), cd_root))
+ collect_phi_def_edges (as_a<gphi *> (def), cd_root, edges,
+ visited_phis);
+ else if (!uninit_undefined_value_p (opnd))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "\n[CHECK] Found def edge %d in ",
+ (int) i);
+ print_gimple_stmt (dump_file, phi, 0);
+ }
+ edges->safe_push (opnd_edge);
+ }
+ }
}
}
size_t num_chains = 0, i, n;
vec<edge> dep_chains[MAX_NUM_CHAINS];
auto_vec<edge, MAX_CHAIN_LEN + 1> cur_chain;
- vec<edge> def_edges = vNULL;
+ auto_vec<edge> def_edges;
bool has_valid_pred = false;
basic_block phi_bb, cd_root = 0;
phi_bb = gimple_bb (phi);
/* First find the closest dominating bb to be
- the control dependence root */
+ the control dependence root. */
cd_root = find_dom (phi_bb);
if (!cd_root)
return false;
- hash_set<gimple> visited_phis;
+ hash_set<gimple *> visited_phis;
collect_phi_def_edges (phi, cd_root, &def_edges, &visited_phis);
n = def_edges.length ();
&num_chains, &cur_chain, &num_calls);
/* Now update the newly added chains with
- the phi operand edge: */
+ the phi operand edge: */
if (EDGE_COUNT (opnd_edge->src->succs) > 1)
- {
+ {
if (prev_nc == num_chains && num_chains < MAX_NUM_CHAINS)
dep_chains[num_chains++] = vNULL;
- for (j = prev_nc; j < num_chains; j++)
+ for (j = prev_nc; j < num_chains; j++)
dep_chains[j].safe_push (opnd_edge);
- }
+ }
}
has_valid_pred
return has_valid_pred;
}
+/* Dump a pred_info. */
+
+static void
+dump_pred_info (pred_info one_pred)
+{
+ if (one_pred.invert)
+ fprintf (dump_file, " (.NOT.) ");
+ print_generic_expr (dump_file, one_pred.pred_lhs);
+ fprintf (dump_file, " %s ", op_symbol_code (one_pred.cond_code));
+ print_generic_expr (dump_file, one_pred.pred_rhs);
+}
+
+/* Dump a pred_chain. */
+
+static void
+dump_pred_chain (pred_chain one_pred_chain)
+{
+ size_t np = one_pred_chain.length ();
+ for (size_t j = 0; j < np; j++)
+ {
+ dump_pred_info (one_pred_chain[j]);
+ if (j < np - 1)
+ fprintf (dump_file, " (.AND.) ");
+ else
+ fprintf (dump_file, "\n");
+ }
+}
+
/* Dumps the predicates (PREDS) for USESTMT. */
static void
-dump_predicates (gimple usestmt, pred_chain_union preds,
- const char* msg)
+dump_predicates (gimple *usestmt, pred_chain_union preds, const char *msg)
{
- size_t i, j;
- pred_chain one_pred_chain = vNULL;
- fprintf (dump_file, msg);
- print_gimple_stmt (dump_file, usestmt, 0, 0);
- fprintf (dump_file, "is guarded by :\n\n");
+ fprintf (dump_file, "%s", msg);
+ if (usestmt)
+ {
+ print_gimple_stmt (dump_file, usestmt, 0);
+ fprintf (dump_file, "is guarded by :\n\n");
+ }
size_t num_preds = preds.length ();
- /* Do some dumping here: */
- for (i = 0; i < num_preds; i++)
+ for (size_t i = 0; i < num_preds; i++)
{
- size_t np;
-
- one_pred_chain = preds[i];
- np = one_pred_chain.length ();
-
- for (j = 0; j < np; j++)
- {
- pred_info one_pred = one_pred_chain[j];
- if (one_pred.invert)
- fprintf (dump_file, " (.NOT.) ");
- print_generic_expr (dump_file, one_pred.pred_lhs, 0);
- fprintf (dump_file, " %s ", op_symbol_code (one_pred.cond_code));
- print_generic_expr (dump_file, one_pred.pred_rhs, 0);
- if (j < np - 1)
- fprintf (dump_file, " (.AND.) ");
- else
- fprintf (dump_file, "\n");
- }
+ dump_pred_chain (preds[i]);
if (i < num_preds - 1)
- fprintf (dump_file, "(.OR.)\n");
+ fprintf (dump_file, "(.OR.)\n");
else
- fprintf (dump_file, "\n\n");
+ fprintf (dump_file, "\n\n");
}
}
/* Destroys the predicate set *PREDS. */
static void
-destroy_predicate_vecs (pred_chain_union preds)
+destroy_predicate_vecs (pred_chain_union *preds)
{
size_t i;
- size_t n = preds.length ();
+ size_t n = preds->length ();
for (i = 0; i < n; i++)
- preds[i].release ();
- preds.release ();
+ (*preds)[i].release ();
+ preds->release ();
}
-
/* Computes the 'normalized' conditional code with operand
swapping and condition inversion. */
static enum tree_code
-get_cmp_code (enum tree_code orig_cmp_code,
- bool swap_cond, bool invert)
+get_cmp_code (enum tree_code orig_cmp_code, bool swap_cond, bool invert)
{
enum tree_code tc = orig_cmp_code;
return tc;
}
-/* Returns true if VAL falls in the range defined by BOUNDARY and CMPC, i.e.
- all values in the range satisfies (x CMPC BOUNDARY) == true. */
+/* Returns whether VAL CMPC BOUNDARY is true. */
static bool
is_value_included_in (tree val, tree boundary, enum tree_code cmpc)
{
bool inverted = false;
- bool is_unsigned;
bool result;
/* Only handle integer constant here. */
- if (TREE_CODE (val) != INTEGER_CST
- || TREE_CODE (boundary) != INTEGER_CST)
+ if (TREE_CODE (val) != INTEGER_CST || TREE_CODE (boundary) != INTEGER_CST)
return true;
- is_unsigned = TYPE_UNSIGNED (TREE_TYPE (val));
-
- if (cmpc == GE_EXPR || cmpc == GT_EXPR
- || cmpc == NE_EXPR)
+ if (cmpc == GE_EXPR || cmpc == GT_EXPR || cmpc == NE_EXPR)
{
cmpc = invert_tree_comparison (cmpc, false);
inverted = true;
}
- if (is_unsigned)
- {
- if (cmpc == EQ_EXPR)
- result = tree_int_cst_equal (val, boundary);
- else if (cmpc == LT_EXPR)
- result = tree_int_cst_lt (val, boundary);
- else
- {
- gcc_assert (cmpc == LE_EXPR);
- result = tree_int_cst_le (val, boundary);
- }
- }
+ if (cmpc == EQ_EXPR)
+ result = tree_int_cst_equal (val, boundary);
+ else if (cmpc == LT_EXPR)
+ result = tree_int_cst_lt (val, boundary);
else
{
- if (cmpc == EQ_EXPR)
- result = tree_int_cst_equal (val, boundary);
- else if (cmpc == LT_EXPR)
- result = tree_int_cst_lt (val, boundary);
- else
- {
- gcc_assert (cmpc == LE_EXPR);
- result = (tree_int_cst_equal (val, boundary)
- || tree_int_cst_lt (val, boundary));
- }
+ gcc_assert (cmpc == LE_EXPR);
+ result = tree_int_cst_le (val, boundary);
}
if (inverted)
return result;
}
+/* Returns whether VAL satisfies (x CMPC BOUNDARY) predicate. CMPC can be
+ either one of the range comparison codes ({GE,LT,EQ,NE}_EXPR and the like),
+ or BIT_AND_EXPR. EXACT_P is only meaningful for the latter. It modifies the
+ question from whether VAL & BOUNDARY != 0 to whether VAL & BOUNDARY == VAL.
+ For other values of CMPC, EXACT_P is ignored. */
+
+static bool
+value_sat_pred_p (tree val, tree boundary, enum tree_code cmpc,
+ bool exact_p = false)
+{
+ if (cmpc != BIT_AND_EXPR)
+ return is_value_included_in (val, boundary, cmpc);
+
+ wide_int andw = wi::to_wide (val) & wi::to_wide (boundary);
+ if (exact_p)
+ return andw == wi::to_wide (val);
+ else
+ return andw.to_uhwi ();
+}
+
/* Returns true if PRED is common among all the predicate
chains (PREDS) (and therefore can be factored out).
NUM_PRED_CHAIN is the size of array PREDS. */
static bool
find_matching_predicate_in_rest_chains (pred_info pred,
- pred_chain_union preds,
- size_t num_pred_chains)
+ pred_chain_union preds,
+ size_t num_pred_chains)
{
size_t i, j, n;
pred_chain one_chain = preds[i];
n = one_chain.length ();
for (j = 0; j < n; j++)
- {
- pred_info pred2 = one_chain[j];
- /* Can relax the condition comparison to not
- use address comparison. However, the most common
- case is that multiple control dependent paths share
- a common path prefix, so address comparison should
- be ok. */
-
- if (operand_equal_p (pred2.pred_lhs, pred.pred_lhs, 0)
- && operand_equal_p (pred2.pred_rhs, pred.pred_rhs, 0)
- && pred2.invert == pred.invert)
- {
- found = true;
- break;
- }
- }
+ {
+ pred_info pred2 = one_chain[j];
+ /* Can relax the condition comparison to not
+ use address comparison. However, the most common
+ case is that multiple control dependent paths share
+ a common path prefix, so address comparison should
+ be ok. */
+
+ if (operand_equal_p (pred2.pred_lhs, pred.pred_lhs, 0)
+ && operand_equal_p (pred2.pred_rhs, pred.pred_rhs, 0)
+ && pred2.invert == pred.invert)
+ {
+ found = true;
+ break;
+ }
+ }
if (!found)
- return false;
+ return false;
}
return true;
}
/* Forward declaration. */
-static bool
-is_use_properly_guarded (gimple use_stmt,
- basic_block use_bb,
- gphi *phi,
- unsigned uninit_opnds,
- hash_set<gphi *> *visited_phis);
-
-/* Returns true if all uninitialized opnds are pruned. Returns false
- otherwise. PHI is the phi node with uninitialized operands,
+static bool is_use_properly_guarded (gimple *use_stmt,
+ basic_block use_bb,
+ gphi *phi,
+ unsigned uninit_opnds,
+ pred_chain_union *def_preds,
+ hash_set<gphi *> *visited_phis);
+
+/* Returns true if all uninitialized opnds are pruned. Returns false
+ otherwise. PHI is the phi node with uninitialized operands,
UNINIT_OPNDS is the bitmap of the uninitialize operand positions,
FLAG_DEF is the statement defining the flag guarding the use of the
PHI output, BOUNDARY_CST is the const value used in the predicate
Example scenario:
BB1:
- flag_1 = phi <0, 1> // (1)
+ flag_1 = phi <0, 1> // (1)
var_1 = phi <undef, some_val>
goto BB3;
BB3:
- use of var_2 // (3)
+ use of var_2 // (3)
Because some flag arg in (1) is not constant, if we do not look into the
flag phis recursively, it is conservatively treated as unknown and var_1
- is thought to be flowed into use at (3). Since var_1 is potentially uninitialized
- a false warning will be emitted. Checking recursively into (1), the compiler can
- find out that only some_val (which is defined) can flow into (3) which is OK.
-
-*/
+ is thought to be flowed into use at (3). Since var_1 is potentially
+ uninitialized a false warning will be emitted.
+ Checking recursively into (1), the compiler can find out that only some_val
+ (which is defined) can flow into (3) which is OK. */
static bool
-prune_uninit_phi_opnds_in_unrealizable_paths (gphi *phi,
- unsigned uninit_opnds,
- gphi *flag_def,
- tree boundary_cst,
- enum tree_code cmp_code,
- hash_set<gphi *> *visited_phis,
- bitmap *visited_flag_phis)
+prune_uninit_phi_opnds (gphi *phi, unsigned uninit_opnds, gphi *flag_def,
+ tree boundary_cst, enum tree_code cmp_code,
+ hash_set<gphi *> *visited_phis,
+ bitmap *visited_flag_phis)
{
unsigned i;
- for (i = 0; i < MIN (32, gimple_phi_num_args (flag_def)); i++)
+ for (i = 0; i < MIN (max_phi_args, gimple_phi_num_args (flag_def)); i++)
{
tree flag_arg;
if (!MASK_TEST_BIT (uninit_opnds, i))
- continue;
+ continue;
flag_arg = gimple_phi_arg_def (flag_def, i);
if (!is_gimple_constant (flag_arg))
- {
- gphi *flag_arg_def, *phi_arg_def;
- tree phi_arg;
- unsigned uninit_opnds_arg_phi;
-
- if (TREE_CODE (flag_arg) != SSA_NAME)
- return false;
- flag_arg_def = dyn_cast <gphi *> (SSA_NAME_DEF_STMT (flag_arg));
+ {
+ gphi *flag_arg_def, *phi_arg_def;
+ tree phi_arg;
+ unsigned uninit_opnds_arg_phi;
+
+ if (TREE_CODE (flag_arg) != SSA_NAME)
+ return false;
+ flag_arg_def = dyn_cast<gphi *> (SSA_NAME_DEF_STMT (flag_arg));
if (!flag_arg_def)
- return false;
+ return false;
- phi_arg = gimple_phi_arg_def (phi, i);
- if (TREE_CODE (phi_arg) != SSA_NAME)
- return false;
+ phi_arg = gimple_phi_arg_def (phi, i);
+ if (TREE_CODE (phi_arg) != SSA_NAME)
+ return false;
- phi_arg_def = dyn_cast <gphi *> (SSA_NAME_DEF_STMT (phi_arg));
+ phi_arg_def = dyn_cast<gphi *> (SSA_NAME_DEF_STMT (phi_arg));
if (!phi_arg_def)
- return false;
+ return false;
- if (gimple_bb (phi_arg_def) != gimple_bb (flag_arg_def))
- return false;
+ if (gimple_bb (phi_arg_def) != gimple_bb (flag_arg_def))
+ return false;
- if (!*visited_flag_phis)
- *visited_flag_phis = BITMAP_ALLOC (NULL);
+ if (!*visited_flag_phis)
+ *visited_flag_phis = BITMAP_ALLOC (NULL);
- if (bitmap_bit_p (*visited_flag_phis,
- SSA_NAME_VERSION (gimple_phi_result (flag_arg_def))))
- return false;
+ tree phi_result = gimple_phi_result (flag_arg_def);
+ if (bitmap_bit_p (*visited_flag_phis, SSA_NAME_VERSION (phi_result)))
+ return false;
- bitmap_set_bit (*visited_flag_phis,
- SSA_NAME_VERSION (gimple_phi_result (flag_arg_def)));
+ bitmap_set_bit (*visited_flag_phis,
+ SSA_NAME_VERSION (gimple_phi_result (flag_arg_def)));
- /* Now recursively prune the uninitialized phi args. */
- uninit_opnds_arg_phi = compute_uninit_opnds_pos (phi_arg_def);
- if (!prune_uninit_phi_opnds_in_unrealizable_paths
- (phi_arg_def, uninit_opnds_arg_phi, flag_arg_def,
- boundary_cst, cmp_code, visited_phis, visited_flag_phis))
- return false;
+ /* Now recursively prune the uninitialized phi args. */
+ uninit_opnds_arg_phi = compute_uninit_opnds_pos (phi_arg_def);
+ if (!prune_uninit_phi_opnds
+ (phi_arg_def, uninit_opnds_arg_phi, flag_arg_def, boundary_cst,
+ cmp_code, visited_phis, visited_flag_phis))
+ return false;
- bitmap_clear_bit (*visited_flag_phis,
- SSA_NAME_VERSION (gimple_phi_result (flag_arg_def)));
- continue;
- }
+ phi_result = gimple_phi_result (flag_arg_def);
+ bitmap_clear_bit (*visited_flag_phis, SSA_NAME_VERSION (phi_result));
+ continue;
+ }
/* Now check if the constant is in the guarded range. */
if (is_value_included_in (flag_arg, boundary_cst, cmp_code))
- {
- tree opnd;
- gimple opnd_def;
-
- /* Now that we know that this undefined edge is not
- pruned. If the operand is defined by another phi,
- we can further prune the incoming edges of that
- phi by checking the predicates of this operands. */
-
- opnd = gimple_phi_arg_def (phi, i);
- opnd_def = SSA_NAME_DEF_STMT (opnd);
- if (gphi *opnd_def_phi = dyn_cast <gphi *> (opnd_def))
- {
- edge opnd_edge;
- unsigned uninit_opnds2
- = compute_uninit_opnds_pos (opnd_def_phi);
- gcc_assert (!MASK_EMPTY (uninit_opnds2));
- opnd_edge = gimple_phi_arg_edge (phi, i);
- if (!is_use_properly_guarded (phi,
- opnd_edge->src,
- opnd_def_phi,
- uninit_opnds2,
- visited_phis))
- return false;
- }
- else
- return false;
- }
+ {
+ tree opnd;
+ gimple *opnd_def;
+
+ /* Now that we know that this undefined edge is not
+ pruned. If the operand is defined by another phi,
+ we can further prune the incoming edges of that
+ phi by checking the predicates of this operands. */
+
+ opnd = gimple_phi_arg_def (phi, i);
+ opnd_def = SSA_NAME_DEF_STMT (opnd);
+ if (gphi *opnd_def_phi = dyn_cast <gphi *> (opnd_def))
+ {
+ edge opnd_edge;
+ unsigned uninit_opnds2 = compute_uninit_opnds_pos (opnd_def_phi);
+ if (!MASK_EMPTY (uninit_opnds2))
+ {
+ pred_chain_union def_preds = vNULL;
+ bool ok;
+ opnd_edge = gimple_phi_arg_edge (phi, i);
+ ok = is_use_properly_guarded (phi,
+ opnd_edge->src,
+ opnd_def_phi,
+ uninit_opnds2,
+ &def_preds,
+ visited_phis);
+ destroy_predicate_vecs (&def_preds);
+ if (!ok)
+ return false;
+ }
+ }
+ else
+ return false;
+ }
}
return true;
of the use is not overlapping with that of the uninit paths.
The most common senario of guarded use is in Example 1:
Example 1:
- if (some_cond)
- {
- x = ...;
- flag = true;
- }
+ if (some_cond)
+ {
+ x = ...;
+ flag = true;
+ }
- ... some code ...
+ ... some code ...
- if (flag)
- use (x);
+ if (flag)
+ use (x);
The real world examples are usually more complicated, but similar
and usually result from inlining:
- bool init_func (int * x)
- {
- if (some_cond)
- return false;
- *x = ..
- return true;
- }
+ bool init_func (int * x)
+ {
+ if (some_cond)
+ return false;
+ *x = ..
+ return true;
+ }
- void foo(..)
- {
- int x;
+ void foo (..)
+ {
+ int x;
- if (!init_func(&x))
- return;
+ if (!init_func (&x))
+ return;
- .. some_code ...
- use (x);
- }
+ .. some_code ...
+ use (x);
+ }
Another possible use scenario is in the following trivial example:
Example 2:
- if (n > 0)
- x = 1;
- ...
- if (n > 0)
- {
- if (m < 2)
- .. = x;
- }
+ if (n > 0)
+ x = 1;
+ ...
+ if (n > 0)
+ {
+ if (m < 2)
+ .. = x;
+ }
Predicate analysis needs to compute the composite predicate:
bb and is dominating the operand def.)
and check overlapping:
- (n > 0) .AND. (m < 2) .AND. (.NOT. (n > 0))
- <==> false
+ (n > 0) .AND. (m < 2) .AND. (.NOT. (n > 0))
+ <==> false
This implementation provides framework that can handle
- scenarios. (Note that many simple cases are handled properly
+ scenarios. (Note that many simple cases are handled properly
without the predicate analysis -- this is due to jump threading
transformation which eliminates the merge point thus makes
path sensitive analysis unnecessary.)
- NUM_PREDS is the number is the number predicate chains, PREDS is
- the array of chains, PHI is the phi node whose incoming (undefined)
- paths need to be pruned, and UNINIT_OPNDS is the bitmap holding
- uninit operand positions. VISITED_PHIS is the pointer set of phi
- stmts being checked. */
-
+ PHI is the phi node whose incoming (undefined) paths need to be
+ pruned, and UNINIT_OPNDS is the bitmap holding uninit operand
+ positions. VISITED_PHIS is the pointer set of phi stmts being
+ checked. */
static bool
use_pred_not_overlap_with_undef_path_pred (pred_chain_union preds,
- gphi *phi, unsigned uninit_opnds,
+ gphi *phi, unsigned uninit_opnds,
hash_set<gphi *> *visited_phis)
{
unsigned int i, n;
- gimple flag_def = 0;
- tree boundary_cst = 0;
+ gimple *flag_def = 0;
+ tree boundary_cst = 0;
enum tree_code cmp_code;
bool swap_cond = false;
bool invert = false;
cmp_code = the_pred.cond_code;
if (cond_lhs != NULL_TREE && TREE_CODE (cond_lhs) == SSA_NAME
- && cond_rhs != NULL_TREE && is_gimple_constant (cond_rhs))
- {
- boundary_cst = cond_rhs;
- flag = cond_lhs;
- }
+ && cond_rhs != NULL_TREE && is_gimple_constant (cond_rhs))
+ {
+ boundary_cst = cond_rhs;
+ flag = cond_lhs;
+ }
else if (cond_rhs != NULL_TREE && TREE_CODE (cond_rhs) == SSA_NAME
- && cond_lhs != NULL_TREE && is_gimple_constant (cond_lhs))
- {
- boundary_cst = cond_lhs;
- flag = cond_rhs;
- swap_cond = true;
- }
+ && cond_lhs != NULL_TREE && is_gimple_constant (cond_lhs))
+ {
+ boundary_cst = cond_lhs;
+ flag = cond_rhs;
+ swap_cond = true;
+ }
if (!flag)
- continue;
+ continue;
flag_def = SSA_NAME_DEF_STMT (flag);
if (!flag_def)
- continue;
+ continue;
if ((gimple_code (flag_def) == GIMPLE_PHI)
- && (gimple_bb (flag_def) == gimple_bb (phi))
- && find_matching_predicate_in_rest_chains (the_pred, preds,
+ && (gimple_bb (flag_def) == gimple_bb (phi))
+ && find_matching_predicate_in_rest_chains (the_pred, preds,
num_preds))
- break;
+ break;
flag_def = 0;
}
if (cmp_code == ERROR_MARK)
return false;
- all_pruned = prune_uninit_phi_opnds_in_unrealizable_paths (phi,
- uninit_opnds,
- as_a <gphi *> (flag_def),
- boundary_cst,
- cmp_code,
- visited_phis,
- &visited_flag_phis);
+ all_pruned = prune_uninit_phi_opnds
+ (phi, uninit_opnds, as_a<gphi *> (flag_def), boundary_cst, cmp_code,
+ visited_phis, &visited_flag_phis);
if (visited_flag_phis)
BITMAP_FREE (visited_flag_phis);
}
/* The helper function returns true if two predicates X1 and X2
- are equivalent. It assumes the expressions have already
+ are equivalent. It assumes the expressions have already
properly re-associated. */
static inline bool
return false;
c1 = x1.cond_code;
- if (x1.invert != x2.invert)
+ if (x1.invert != x2.invert
+ && TREE_CODE_CLASS (x2.cond_code) == tcc_comparison)
c2 = invert_tree_comparison (x2.cond_code, false);
else
c2 = x2.cond_code;
is_neq_relop_p (pred_info pred)
{
- return (pred.cond_code == NE_EXPR && !pred.invert)
- || (pred.cond_code == EQ_EXPR && pred.invert);
+ return ((pred.cond_code == NE_EXPR && !pred.invert)
+ || (pred.cond_code == EQ_EXPR && pred.invert));
}
/* Returns true if pred is of the form X != 0. */
-static inline bool
+static inline bool
is_neq_zero_form_p (pred_info pred)
{
if (!is_neq_relop_p (pred) || !integer_zerop (pred.pred_rhs)
}
/* Returns true of the domain of single predicate expression
- EXPR1 is a subset of that of EXPR2. Returns false if it
- can not be proved. */
+ EXPR1 is a subset of that of EXPR2. Returns false if it
+ cannot be proved. */
static bool
is_pred_expr_subset_of (pred_info expr1, pred_info expr2)
if (expr2.invert)
code2 = invert_tree_comparison (code2, false);
- if (code1 != code2 && code2 != NE_EXPR)
+ if (code2 == NE_EXPR && code1 == NE_EXPR)
return false;
- if (is_value_included_in (expr1.pred_rhs, expr2.pred_rhs, code2))
- return true;
+ if (code2 == NE_EXPR)
+ return !value_sat_pred_p (expr2.pred_rhs, expr1.pred_rhs, code1);
+
+ if (code1 == EQ_EXPR)
+ return value_sat_pred_p (expr1.pred_rhs, expr2.pred_rhs, code2);
+
+ if (code1 == code2)
+ return value_sat_pred_p (expr1.pred_rhs, expr2.pred_rhs, code2,
+ code1 == BIT_AND_EXPR);
return false;
}
/* Returns true if the domain of PRED1 is a subset
- of that of PRED2. Returns false if it can not be proved so. */
+ of that of PRED2. Returns false if it cannot be proved so. */
static bool
-is_pred_chain_subset_of (pred_chain pred1,
- pred_chain pred2)
+is_pred_chain_subset_of (pred_chain pred1, pred_chain pred2)
{
size_t np1, np2, i1, i2;
bool found = false;
pred_info info2 = pred2[i2];
for (i1 = 0; i1 < np1; i1++)
- {
- pred_info info1 = pred1[i1];
- if (is_pred_expr_subset_of (info1, info2))
- {
- found = true;
- break;
- }
- }
+ {
+ pred_info info1 = pred1[i1];
+ if (is_pred_expr_subset_of (info1, info2))
+ {
+ found = true;
+ break;
+ }
+ }
if (!found)
- return false;
+ return false;
}
return true;
}
/* Returns true if the domain defined by
one pred chain ONE_PRED is a subset of the domain
- of *PREDS. It returns false if ONE_PRED's domain is
+ of *PREDS. It returns false if ONE_PRED's domain is
not a subset of any of the sub-domains of PREDS
(corresponding to each individual chains in it), even
though it may be still be a subset of whole domain
for (i = 0; i < n; i++)
{
if (is_pred_chain_subset_of (one_pred, preds[i]))
- return true;
+ return true;
}
return false;
/* Compares two predicate sets PREDS1 and PREDS2 and returns
true if the domain defined by PREDS1 is a superset
- of PREDS2's domain. N1 and N2 are array sizes of PREDS1 and
- PREDS2 respectively. The implementation chooses not to build
+ of PREDS2's domain. N1 and N2 are array sizes of PREDS1 and
+ PREDS2 respectively. The implementation chooses not to build
generic trees (and relying on the folding capability of the
compiler), but instead performs brute force comparison of
individual predicate chains (won't be a compile time problem
- as the chains are pretty short). When the function returns
+ as the chains are pretty short). When the function returns
false, it does not necessarily mean *PREDS1 is not a superset
- of *PREDS2, but mean it may not be so since the analysis can
- not prove it. In such cases, false warnings may still be
+ of *PREDS2, but mean it may not be so since the analysis cannot
+ prove it. In such cases, false warnings may still be
emitted. */
static bool
{
one_pred_chain = preds2[i];
if (!is_included_in (one_pred_chain, preds1))
- return false;
+ return false;
}
return true;
}
-/* Returns true if TC is AND or OR. */
-
-static inline bool
-is_and_or_or_p (enum tree_code tc, tree type)
-{
- return (tc == BIT_IOR_EXPR
- || (tc == BIT_AND_EXPR
- && (type == 0 || TREE_CODE (type) == BOOLEAN_TYPE)));
-}
-
/* Returns true if X1 is the negate of X2. */
static inline bool
if (!operand_equal_p (x1.pred_lhs, x2.pred_lhs, 0)
|| !operand_equal_p (x1.pred_rhs, x2.pred_rhs, 0))
return false;
-
+
c1 = x1.cond_code;
if (x1.invert == x2.invert)
c2 = invert_tree_comparison (x2.cond_code, false);
4) ((x IAND y) != 0) || (x != 0 AND y != 0)) is equivalent to
(x != 0 AND y != 0)
5) (X AND Y) OR (!X AND Z) OR (!Y AND Z) is equivalent to
- (X AND Y) OR Z
+ (X AND Y) OR Z
PREDS is the predicate chains, and N is the number of chains. */
pred_info *a_pred = &(*one_chain)[i];
if (!a_pred->pred_lhs)
- continue;
+ continue;
if (!is_neq_zero_form_p (*a_pred))
- continue;
+ continue;
- gimple def_stmt = SSA_NAME_DEF_STMT (a_pred->pred_lhs);
+ gimple *def_stmt = SSA_NAME_DEF_STMT (a_pred->pred_lhs);
if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
- continue;
+ continue;
if (gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR)
- {
- for (j = 0; j < n; j++)
- {
- pred_info *b_pred = &(*one_chain)[j];
-
- if (!b_pred->pred_lhs)
- continue;
- if (!is_neq_zero_form_p (*b_pred))
- continue;
-
- if (pred_expr_equal_p (*b_pred, gimple_assign_rhs1 (def_stmt))
- || pred_expr_equal_p (*b_pred, gimple_assign_rhs2 (def_stmt)))
- {
- /* Mark a_pred for removal. */
- a_pred->pred_lhs = NULL;
- a_pred->pred_rhs = NULL;
- simplified = true;
- break;
- }
- }
- }
+ {
+ for (j = 0; j < n; j++)
+ {
+ pred_info *b_pred = &(*one_chain)[j];
+
+ if (!b_pred->pred_lhs)
+ continue;
+ if (!is_neq_zero_form_p (*b_pred))
+ continue;
+
+ if (pred_expr_equal_p (*b_pred, gimple_assign_rhs1 (def_stmt))
+ || pred_expr_equal_p (*b_pred, gimple_assign_rhs2 (def_stmt)))
+ {
+ /* Mark a_pred for removal. */
+ a_pred->pred_lhs = NULL;
+ a_pred->pred_rhs = NULL;
+ simplified = true;
+ break;
+ }
+ }
+ }
}
if (!simplified)
- return;
+ return;
for (i = 0; i < n; i++)
{
pred_info *a_pred = &(*one_chain)[i];
if (!a_pred->pred_lhs)
- continue;
+ continue;
s_chain.safe_push (*a_pred);
}
- one_chain->release ();
- *one_chain = s_chain;
+ one_chain->release ();
+ *one_chain = s_chain;
}
/* The helper function implements the rule 2 for the
bool simplified = false;
pred_chain_union s_preds = vNULL;
- /* (X AND Y) OR (!X AND Y) is equivalent to Y.
+ /* (X AND Y) OR (!X AND Y) is equivalent to Y.
(X AND Y) OR (X AND !Y) is equivalent to X. */
n = preds->length ();
pred_chain *a_chain = &(*preds)[i];
if (a_chain->length () != 2)
- continue;
+ continue;
x = (*a_chain)[0];
y = (*a_chain)[1];
for (j = 0; j < n; j++)
- {
- pred_chain *b_chain;
- pred_info x2, y2;
-
- if (j == i)
- continue;
-
- b_chain = &(*preds)[j];
- if (b_chain->length () != 2)
- continue;
-
- x2 = (*b_chain)[0];
- y2 = (*b_chain)[1];
-
- if (pred_equal_p (x, x2) && pred_neg_p (y, y2))
- {
- /* Kill a_chain. */
- a_chain->release ();
- b_chain->release ();
- b_chain->safe_push (x);
- simplified = true;
- break;
- }
- if (pred_neg_p (x, x2) && pred_equal_p (y, y2))
- {
- /* Kill a_chain. */
- a_chain->release ();
- b_chain->release ();
- b_chain->safe_push (y);
- simplified = true;
- break;
- }
- }
+ {
+ pred_chain *b_chain;
+ pred_info x2, y2;
+
+ if (j == i)
+ continue;
+
+ b_chain = &(*preds)[j];
+ if (b_chain->length () != 2)
+ continue;
+
+ x2 = (*b_chain)[0];
+ y2 = (*b_chain)[1];
+
+ if (pred_equal_p (x, x2) && pred_neg_p (y, y2))
+ {
+ /* Kill a_chain. */
+ a_chain->release ();
+ b_chain->release ();
+ b_chain->safe_push (x);
+ simplified = true;
+ break;
+ }
+ if (pred_neg_p (x, x2) && pred_equal_p (y, y2))
+ {
+ /* Kill a_chain. */
+ a_chain->release ();
+ b_chain->release ();
+ b_chain->safe_push (y);
+ simplified = true;
+ break;
+ }
+ }
}
/* Now clean up the chain. */
if (simplified)
{
for (i = 0; i < n; i++)
- {
- if ((*preds)[i].is_empty ())
- continue;
- s_preds.safe_push ((*preds)[i]);
- }
+ {
+ if ((*preds)[i].is_empty ())
+ continue;
+ s_preds.safe_push ((*preds)[i]);
+ }
preds->release ();
(*preds) = s_preds;
s_preds = vNULL;
pred_chain *a_chain = &(*preds)[i];
if (a_chain->length () != 1)
- continue;
+ continue;
x = (*a_chain)[0];
for (j = 0; j < n; j++)
- {
- pred_chain *b_chain;
- pred_info x2;
- size_t k;
-
- if (j == i)
- continue;
-
- b_chain = &(*preds)[j];
- if (b_chain->length () < 2)
- continue;
-
- for (k = 0; k < b_chain->length (); k++)
- {
- x2 = (*b_chain)[k];
- if (pred_neg_p (x, x2))
- {
- b_chain->unordered_remove (k);
- simplified = true;
- break;
- }
- }
- }
+ {
+ pred_chain *b_chain;
+ pred_info x2;
+ size_t k;
+
+ if (j == i)
+ continue;
+
+ b_chain = &(*preds)[j];
+ if (b_chain->length () < 2)
+ continue;
+
+ for (k = 0; k < b_chain->length (); k++)
+ {
+ x2 = (*b_chain)[k];
+ if (pred_neg_p (x, x2))
+ {
+ b_chain->unordered_remove (k);
+ simplified = true;
+ break;
+ }
+ }
+ }
}
return simplified;
}
size_t i, j, n;
bool simplified = false;
pred_chain_union s_preds = vNULL;
- gimple def_stmt;
+ gimple *def_stmt;
n = preds->length ();
for (i = 0; i < n; i++)
pred_chain *a_chain = &(*preds)[i];
if (a_chain->length () != 1)
- continue;
+ continue;
z = (*a_chain)[0];
if (!is_neq_zero_form_p (z))
- continue;
+ continue;
def_stmt = SSA_NAME_DEF_STMT (z.pred_lhs);
if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
- continue;
+ continue;
if (gimple_assign_rhs_code (def_stmt) != BIT_AND_EXPR)
- continue;
+ continue;
for (j = 0; j < n; j++)
- {
- pred_chain *b_chain;
- pred_info x2, y2;
-
- if (j == i)
- continue;
-
- b_chain = &(*preds)[j];
- if (b_chain->length () != 2)
- continue;
-
- x2 = (*b_chain)[0];
- y2 = (*b_chain)[1];
- if (!is_neq_zero_form_p (x2)
- || !is_neq_zero_form_p (y2))
- continue;
-
- if ((pred_expr_equal_p (x2, gimple_assign_rhs1 (def_stmt))
- && pred_expr_equal_p (y2, gimple_assign_rhs2 (def_stmt)))
- || (pred_expr_equal_p (x2, gimple_assign_rhs2 (def_stmt))
- && pred_expr_equal_p (y2, gimple_assign_rhs1 (def_stmt))))
- {
- /* Kill a_chain. */
- a_chain->release ();
- simplified = true;
- break;
- }
- }
+ {
+ pred_chain *b_chain;
+ pred_info x2, y2;
+
+ if (j == i)
+ continue;
+
+ b_chain = &(*preds)[j];
+ if (b_chain->length () != 2)
+ continue;
+
+ x2 = (*b_chain)[0];
+ y2 = (*b_chain)[1];
+ if (!is_neq_zero_form_p (x2) || !is_neq_zero_form_p (y2))
+ continue;
+
+ if ((pred_expr_equal_p (x2, gimple_assign_rhs1 (def_stmt))
+ && pred_expr_equal_p (y2, gimple_assign_rhs2 (def_stmt)))
+ || (pred_expr_equal_p (x2, gimple_assign_rhs2 (def_stmt))
+ && pred_expr_equal_p (y2, gimple_assign_rhs1 (def_stmt))))
+ {
+ /* Kill a_chain. */
+ a_chain->release ();
+ simplified = true;
+ break;
+ }
+ }
}
/* Now clean up the chain. */
if (simplified)
{
for (i = 0; i < n; i++)
- {
- if ((*preds)[i].is_empty ())
- continue;
- s_preds.safe_push ((*preds)[i]);
- }
+ {
+ if ((*preds)[i].is_empty ())
+ continue;
+ s_preds.safe_push ((*preds)[i]);
+ }
+
preds->release ();
(*preds) = s_preds;
s_preds = vNULL;
return simplified;
}
-
/* This function simplifies predicates in PREDS. */
static void
-simplify_preds (pred_chain_union *preds, gimple use_or_def, bool is_use)
+simplify_preds (pred_chain_union *preds, gimple *use_or_def, bool is_use)
{
size_t i, n;
bool changed = false;
{
changed = false;
if (simplify_preds_2 (preds))
- changed = true;
+ changed = true;
/* Now iteratively simplify X OR (!X AND Z ..)
into X OR (Z ...). */
if (simplify_preds_3 (preds))
- changed = true;
+ changed = true;
if (simplify_preds_4 (preds))
- changed = true;
-
- } while (changed);
+ changed = true;
+ }
+ while (changed);
return;
}
/* This is a helper function which attempts to normalize predicate chains
- by following UD chains. It basically builds up a big tree of either IOR
- operations or AND operations, and convert the IOR tree into a
+ by following UD chains. It basically builds up a big tree of either IOR
+ operations or AND operations, and convert the IOR tree into a
pred_chain_union or BIT_AND tree into a pred_chain.
Example:
then _t != 0 will be normalized into a pred_chain:
(_2 RELOP1 _1) AND (_5 RELOP2 _4) AND (_8 RELOP3 _7) AND (_0 != 0)
-
+
*/
/* This is a helper function that stores a PRED into NORM_PREDS. */
inline static void
push_to_worklist (tree op, vec<pred_info, va_heap, vl_ptr> *work_list,
- hash_set<tree> *mark_set)
+ hash_set<tree> *mark_set)
{
if (mark_set->contains (op))
return;
CMP_ASSIGN with comparison rhs. */
static pred_info
-get_pred_info_from_cmp (gimple cmp_assign)
+get_pred_info_from_cmp (gimple *cmp_assign)
{
pred_info n_pred;
n_pred.pred_lhs = gimple_assign_rhs1 (cmp_assign);
}
/* Returns true if the PHI is a degenerated phi with
- all args with the same value (relop). In that case, *PRED
+ all args with the same value (relop). In that case, *PRED
will be updated to that value. */
static bool
-is_degenerated_phi (gimple phi, pred_info *pred_p)
+is_degenerated_phi (gimple *phi, pred_info *pred_p)
{
int i, n;
tree op0;
- gimple def0;
+ gimple *def0;
pred_info pred0;
n = gimple_phi_num_args (phi);
def0 = SSA_NAME_DEF_STMT (op0);
if (gimple_code (def0) != GIMPLE_ASSIGN)
return false;
- if (TREE_CODE_CLASS (gimple_assign_rhs_code (def0))
- != tcc_comparison)
+ if (TREE_CODE_CLASS (gimple_assign_rhs_code (def0)) != tcc_comparison)
return false;
pred0 = get_pred_info_from_cmp (def0);
for (i = 1; i < n; ++i)
{
- gimple def;
+ gimple *def;
pred_info pred;
tree op = gimple_phi_arg_def (phi, i);
if (TREE_CODE (op) != SSA_NAME)
- return false;
+ return false;
def = SSA_NAME_DEF_STMT (op);
if (gimple_code (def) != GIMPLE_ASSIGN)
- return false;
- if (TREE_CODE_CLASS (gimple_assign_rhs_code (def))
- != tcc_comparison)
- return false;
+ return false;
+ if (TREE_CODE_CLASS (gimple_assign_rhs_code (def)) != tcc_comparison)
+ return false;
pred = get_pred_info_from_cmp (def);
if (!pred_equal_p (pred, pred0))
- return false;
+ return false;
}
*pred_p = pred0;
return true;
}
-/* Normalize one predicate PRED
+/* Normalize one predicate PRED
1) if PRED can no longer be normlized, put it into NORM_PREDS.
2) otherwise if PRED is of the form x != 0, follow x's definition
and put normalized predicates into WORK_LIST. */
-
+
static void
-normalize_one_pred_1 (pred_chain_union *norm_preds,
- pred_chain *norm_chain,
- pred_info pred,
- enum tree_code and_or_code,
-
vec<pred_info, va_heap, vl_ptr> *work_list,
+normalize_one_pred_1 (pred_chain_union *norm_preds,
+ pred_chain *norm_chain,
+ pred_info pred,
+ enum tree_code and_or_code,
+ vec<pred_info, va_heap, vl_ptr> *work_list,
hash_set<tree> *mark_set)
{
if (!is_neq_zero_form_p (pred))
{
if (and_or_code == BIT_IOR_EXPR)
- push_pred (norm_preds, pred);
+ push_pred (norm_preds, pred);
else
- norm_chain->safe_push (pred);
+ norm_chain->safe_push (pred);
return;
}
- gimple def_stmt = SSA_NAME_DEF_STMT (pred.pred_lhs);
-
+ gimple *def_stmt = SSA_NAME_DEF_STMT (pred.pred_lhs);
+
if (gimple_code (def_stmt) == GIMPLE_PHI
&& is_degenerated_phi (def_stmt, &pred))
work_list->safe_push (pred);
- else if (gimple_code (def_stmt) == GIMPLE_PHI
- && and_or_code == BIT_IOR_EXPR)
+ else if (gimple_code (def_stmt) == GIMPLE_PHI && and_or_code == BIT_IOR_EXPR)
{
int i, n;
n = gimple_phi_num_args (def_stmt);
- /* If we see non zero constant, we should punt. The predicate
+ /* If we see non zero constant, we should punt. The predicate
* should be one guarding the phi edge. */
for (i = 0; i < n; ++i)
- {
- tree op = gimple_phi_arg_def (def_stmt, i);
- if (TREE_CODE (op) == INTEGER_CST && !integer_zerop (op))
- {
- push_pred (norm_preds, pred);
- return;
- }
- }
+ {
+ tree op = gimple_phi_arg_def (def_stmt, i);
+ if (TREE_CODE (op) == INTEGER_CST && !integer_zerop (op))
+ {
+ push_pred (norm_preds, pred);
+ return;
+ }
+ }
for (i = 0; i < n; ++i)
- {
- tree op = gimple_phi_arg_def (def_stmt, i);
- if (integer_zerop (op))
- continue;
+ {
+ tree op = gimple_phi_arg_def (def_stmt, i);
+ if (integer_zerop (op))
+ continue;
- push_to_worklist (op, work_list, mark_set);
- }
+ push_to_worklist (op, work_list, mark_set);
+ }
}
else if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
{
}
else if (gimple_assign_rhs_code (def_stmt) == and_or_code)
{
- push_to_worklist (gimple_assign_rhs1 (def_stmt), work_list, mark_set);
- push_to_worklist (gimple_assign_rhs2 (def_stmt), work_list, mark_set);
+ /* Avoid splitting up bit manipulations like x & 3 or y | 1. */
+ if (is_gimple_min_invariant (gimple_assign_rhs2 (def_stmt)))
+ {
+ /* But treat x & 3 as condition. */
+ if (and_or_code == BIT_AND_EXPR)
+ {
+ pred_info n_pred;
+ n_pred.pred_lhs = gimple_assign_rhs1 (def_stmt);
+ n_pred.pred_rhs = gimple_assign_rhs2 (def_stmt);
+ n_pred.cond_code = and_or_code;
+ n_pred.invert = false;
+ norm_chain->safe_push (n_pred);
+ }
+ }
+ else
+ {
+ push_to_worklist (gimple_assign_rhs1 (def_stmt), work_list, mark_set);
+ push_to_worklist (gimple_assign_rhs2 (def_stmt), work_list, mark_set);
+ }
}
else if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt))
== tcc_comparison)
/* Normalize PRED and store the normalized predicates into NORM_PREDS. */
static void
-normalize_one_pred (pred_chain_union *norm_preds,
- pred_info pred)
+normalize_one_pred (pred_chain_union *norm_preds, pred_info pred)
{
vec<pred_info, va_heap, vl_ptr> work_list = vNULL;
enum tree_code and_or_code = ERROR_MARK;
return;
}
- gimple def_stmt = SSA_NAME_DEF_STMT (pred.pred_lhs);
+ gimple *def_stmt = SSA_NAME_DEF_STMT (pred.pred_lhs);
if (gimple_code (def_stmt) == GIMPLE_ASSIGN)
and_or_code = gimple_assign_rhs_code (def_stmt);
- if (and_or_code != BIT_IOR_EXPR
- && and_or_code != BIT_AND_EXPR)
+ if (and_or_code != BIT_IOR_EXPR && and_or_code != BIT_AND_EXPR)
{
- if (TREE_CODE_CLASS (and_or_code)
- == tcc_comparison)
- {
- pred_info n_pred = get_pred_info_from_cmp (def_stmt);
- push_pred (norm_preds, n_pred);
- }
- else
- push_pred (norm_preds, pred);
+ if (TREE_CODE_CLASS (and_or_code) == tcc_comparison)
+ {
+ pred_info n_pred = get_pred_info_from_cmp (def_stmt);
+ push_pred (norm_preds, n_pred);
+ }
+ else
+ push_pred (norm_preds, pred);
return;
}
while (!work_list.is_empty ())
{
pred_info a_pred = work_list.pop ();
- normalize_one_pred_1 (norm_preds, &norm_chain, a_pred,
- and_or_code, &work_list, &mark_set);
+ normalize_one_pred_1 (norm_preds, &norm_chain, a_pred, and_or_code,
+ &work_list, &mark_set);
}
if (and_or_code == BIT_AND_EXPR)
norm_preds->safe_push (norm_chain);
}
static void
-normalize_one_pred_chain (pred_chain_union *norm_preds,
- pred_chain one_chain)
+normalize_one_pred_chain (pred_chain_union *norm_preds, pred_chain one_chain)
{
vec<pred_info, va_heap, vl_ptr> work_list = vNULL;
hash_set<tree> mark_set;
while (!work_list.is_empty ())
{
pred_info a_pred = work_list.pop ();
- normalize_one_pred_1 (0, &norm_chain, a_pred,
- BIT_AND_EXPR, &work_list, &mark_set);
+ normalize_one_pred_1 (0, &norm_chain, a_pred, BIT_AND_EXPR, &work_list,
+ &mark_set);
}
norm_preds->safe_push (norm_chain);
/* Normalize predicate chains PREDS and returns the normalized one. */
static pred_chain_union
-normalize_preds (pred_chain_union preds, gimple use_or_def, bool is_use)
+normalize_preds (pred_chain_union preds, gimple *use_or_def, bool is_use)
{
pred_chain_union norm_preds = vNULL;
size_t n = preds.length ();
for (i = 0; i < n; i++)
{
if (preds[i].length () != 1)
- normalize_one_pred_chain (&norm_preds, preds[i]);
+ normalize_one_pred_chain (&norm_preds, preds[i]);
else
- {
- normalize_one_pred (&norm_preds, preds[i][0]);
- preds[i].release ();
- }
+ {
+ normalize_one_pred (&norm_preds, preds[i][0]);
+ preds[i].release ();
+ }
}
if (dump_file)
{
fprintf (dump_file, "[AFTER NORMALIZATION -- ");
- dump_predicates (use_or_def, norm_preds, is_use ? "[USE]:\n" : "[DEF]:\n");
+ dump_predicates (use_or_def, norm_preds,
+ is_use ? "[USE]:\n" : "[DEF]:\n");
}
- preds.release ();
+ destroy_predicate_vecs (&preds);
return norm_preds;
}
+/* Return TRUE if PREDICATE can be invalidated by any individual
+ predicate in USE_GUARD. */
+
+static bool
+can_one_predicate_be_invalidated_p (pred_info predicate,
+ pred_chain use_guard)
+{
+ if (dump_file && dump_flags & TDF_DETAILS)
+ {
+ fprintf (dump_file, "Testing if this predicate: ");
+ dump_pred_info (predicate);
+ fprintf (dump_file, "\n...can be invalidated by a USE guard of: ");
+ dump_pred_chain (use_guard);
+ }
+ for (size_t i = 0; i < use_guard.length (); ++i)
+ {
+ /* NOTE: This is a very simple check, and only understands an
+ exact opposite. So, [i == 0] is currently only invalidated
+ by [.NOT. i == 0] or [i != 0]. Ideally we should also
+ invalidate with say [i > 5] or [i == 8]. There is certainly
+ room for improvement here. */
+ if (pred_neg_p (predicate, use_guard[i]))
+ {
+ if (dump_file && dump_flags & TDF_DETAILS)
+ {
+ fprintf (dump_file, " Predicate was invalidated by: ");
+ dump_pred_info (use_guard[i]);
+ fputc ('\n', dump_file);
+ }
+ return true;
+ }
+ }
+ return false;
+}
+
+/* Return TRUE if all predicates in UNINIT_PRED are invalidated by
+ USE_GUARD being true. */
+
+static bool
+can_chain_union_be_invalidated_p (pred_chain_union uninit_pred,
+ pred_chain use_guard)
+{
+ if (uninit_pred.is_empty ())
+ return false;
+ if (dump_file && dump_flags & TDF_DETAILS)
+ dump_predicates (NULL, uninit_pred,
+ "Testing if anything here can be invalidated: ");
+ for (size_t i = 0; i < uninit_pred.length (); ++i)
+ {
+ pred_chain c = uninit_pred[i];
+ size_t j;
+ for (j = 0; j < c.length (); ++j)
+ if (can_one_predicate_be_invalidated_p (c[j], use_guard))
+ break;
+
+ /* If we were unable to invalidate any predicate in C, then there
+ is a viable path from entry to the PHI where the PHI takes
+ an uninitialized value and continues to a use of the PHI. */
+ if (j == c.length ())
+ return false;
+ }
+ return true;
+}
+
+/* Return TRUE if none of the uninitialized operands in UNINT_OPNDS
+ can actually happen if we arrived at a use for PHI.
+
+ PHI_USE_GUARDS are the guard conditions for the use of the PHI. */
+
+static bool
+uninit_uses_cannot_happen (gphi *phi, unsigned uninit_opnds,
+ pred_chain_union phi_use_guards)
+{
+ unsigned phi_args = gimple_phi_num_args (phi);
+ if (phi_args > max_phi_args)
+ return false;
+
+ /* PHI_USE_GUARDS are OR'ed together. If we have more than one
+ possible guard, there's no way of knowing which guard was true.
+ Since we need to be absolutely sure that the uninitialized
+ operands will be invalidated, bail. */
+ if (phi_use_guards.length () != 1)
+ return false;
+
+ /* Look for the control dependencies of all the uninitialized
+ operands and build guard predicates describing them. */
+ pred_chain_union uninit_preds;
+ bool ret = true;
+ for (unsigned i = 0; i < phi_args; ++i)
+ {
+ if (!MASK_TEST_BIT (uninit_opnds, i))
+ continue;
+
+ edge e = gimple_phi_arg_edge (phi, i);
+ vec<edge> dep_chains[MAX_NUM_CHAINS];
+ auto_vec<edge, MAX_CHAIN_LEN + 1> cur_chain;
+ size_t num_chains = 0;
+ int num_calls = 0;
+
+ /* Build the control dependency chain for uninit operand `i'... */
+ uninit_preds = vNULL;
+ if (!compute_control_dep_chain (ENTRY_BLOCK_PTR_FOR_FN (cfun),
+ e->src, dep_chains, &num_chains,
+ &cur_chain, &num_calls))
+ {
+ ret = false;
+ break;
+ }
+ /* ...and convert it into a set of predicates. */
+ bool has_valid_preds
+ = convert_control_dep_chain_into_preds (dep_chains, num_chains,
+ &uninit_preds);
+ for (size_t j = 0; j < num_chains; ++j)
+ dep_chains[j].release ();
+ if (!has_valid_preds)
+ {
+ ret = false;
+ break;
+ }
+ simplify_preds (&uninit_preds, NULL, false);
+ uninit_preds = normalize_preds (uninit_preds, NULL, false);
+
+ /* Can the guard for this uninitialized operand be invalidated
+ by the PHI use? */
+ if (!can_chain_union_be_invalidated_p (uninit_preds, phi_use_guards[0]))
+ {
+ ret = false;
+ break;
+ }
+ }
+ destroy_predicate_vecs (&uninit_preds);
+ return ret;
+}
/* Computes the predicates that guard the use and checks
if the incoming paths that have empty (or possibly
- empty) definition can be pruned/filtered. The function returns
+ empty) definition can be pruned/filtered. The function returns
true if it can be determined that the use of PHI's def in
USE_STMT is guarded with a predicate set not overlapping with
predicate sets of all runtime paths that do not have a definition.
- Returns false if it is not or it can not be determined. USE_BB is
+
+ Returns false if it is not or it cannot be determined. USE_BB is
the bb of the use (for phi operand use, the bb is not the bb of
- the phi stmt, but the src bb of the operand edge). UNINIT_OPNDS
- is a bit vector. If an operand of PHI is uninitialized, the
- corresponding bit in the vector is 1. VISIED_PHIS is a pointer
- set of phis being visted. */
+ the phi stmt, but the src bb of the operand edge).
+
+ UNINIT_OPNDS is a bit vector. If an operand of PHI is uninitialized, the
+ corresponding bit in the vector is 1. VISITED_PHIS is a pointer
+ set of phis being visited.
+
+ *DEF_PREDS contains the (memoized) defining predicate chains of PHI.
+ If *DEF_PREDS is the empty vector, the defining predicate chains of
+ PHI will be computed and stored into *DEF_PREDS as needed.
+
+ VISITED_PHIS is a pointer set of phis being visited. */
static bool
-is_use_properly_guarded (gimple use_stmt,
- basic_block use_bb,
- gphi *phi,
- unsigned uninit_opnds,
- hash_set<gphi *> *visited_phis)
+is_use_properly_guarded (gimple *use_stmt,
+ basic_block use_bb,
+ gphi *phi,
+ unsigned uninit_opnds,
+ pred_chain_union *def_preds,
+ hash_set<gphi *> *visited_phis)
{
basic_block phi_bb;
pred_chain_union preds = vNULL;
- pred_chain_union def_preds = vNULL;
bool has_valid_preds = false;
bool is_properly_guarded = false;
if (!has_valid_preds)
{
- destroy_predicate_vecs (preds);
+ destroy_predicate_vecs (&preds);
return false;
}
- /* Try to prune the dead incoming phi edges. */
+ /* Try to prune the dead incoming phi edges. */
is_properly_guarded
= use_pred_not_overlap_with_undef_path_pred (preds, phi, uninit_opnds,
visited_phis);
+ /* We might be able to prove that if the control dependencies
+ for UNINIT_OPNDS are true, that the control dependencies for
+ USE_STMT can never be true. */
+ if (!is_properly_guarded)
+ is_properly_guarded |= uninit_uses_cannot_happen (phi, uninit_opnds,
+ preds);
+
if (is_properly_guarded)
{
- destroy_predicate_vecs (preds);
+ destroy_predicate_vecs (&preds);
return true;
}
- has_valid_preds = find_def_preds (&def_preds, phi);
-
- if (!has_valid_preds)
+ if (def_preds->is_empty ())
{
- destroy_predicate_vecs (preds);
- destroy_predicate_vecs (def_preds);
- return false;
+ has_valid_preds = find_def_preds (def_preds, phi);
+
+ if (!has_valid_preds)
+ {
+ destroy_predicate_vecs (&preds);
+ return false;
+ }
+
+ simplify_preds (def_preds, phi, false);
+ *def_preds = normalize_preds (*def_preds, phi, false);
}
simplify_preds (&preds, use_stmt, true);
preds = normalize_preds (preds, use_stmt, true);
- simplify_preds (&def_preds, phi, false);
- def_preds = normalize_preds (def_preds, phi, false);
+ is_properly_guarded = is_superset_of (*def_preds, preds);
- is_properly_guarded = is_superset_of (def_preds, preds);
-
- destroy_predicate_vecs (preds);
- destroy_predicate_vecs (def_preds);
+ destroy_predicate_vecs (&preds);
return is_properly_guarded;
}
/* Searches through all uses of a potentially
uninitialized variable defined by PHI and returns a use
- statement if the use is not properly guarded. It returns
- NULL if all uses are guarded. UNINIT_OPNDS is a bitvector
- holding the position(s) of uninit PHI operands. WORKLIST
+ statement if the use is not properly guarded. It returns
+ NULL if all uses are guarded. UNINIT_OPNDS is a bitvector
+ holding the position(s) of uninit PHI operands. WORKLIST
is the vector of candidate phis that may be updated by this
- function. ADDED_TO_WORKLIST is the pointer set tracking
+ function. ADDED_TO_WORKLIST is the pointer set tracking
if the new phi is already in the worklist. */
-static gimple
+static gimple *
find_uninit_use (gphi *phi, unsigned uninit_opnds,
- vec<gphi *> *worklist,
+ vec<gphi *> *worklist,
hash_set<gphi *> *added_to_worklist)
{
tree phi_result;
use_operand_p use_p;
- gimple use_stmt;
+ gimple *use_stmt;
imm_use_iterator iter;
+ pred_chain_union def_preds = vNULL;
+ gimple *ret = NULL;
phi_result = gimple_phi_result (phi);
if (is_gimple_debug (use_stmt))
continue;
- if (gphi *use_phi = dyn_cast <gphi *> (use_stmt))
+ if (gphi *use_phi = dyn_cast<gphi *> (use_stmt))
use_bb = gimple_phi_arg_edge (use_phi,
PHI_ARG_INDEX_FROM_USE (use_p))->src;
else
hash_set<gphi *> visited_phis;
if (is_use_properly_guarded (use_stmt, use_bb, phi, uninit_opnds,
- &visited_phis))
+ &def_preds, &visited_phis))
continue;
if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "[CHECK]: Found unguarded use: ");
- print_gimple_stmt (dump_file, use_stmt, 0, 0);
- }
+ {
+ fprintf (dump_file, "[CHECK]: Found unguarded use: ");
+ print_gimple_stmt (dump_file, use_stmt, 0);
+ }
/* Found one real use, return. */
if (gimple_code (use_stmt) != GIMPLE_PHI)
- return use_stmt;
+ {
+ ret = use_stmt;
+ break;
+ }
/* Found a phi use that is not guarded,
- add the phi to the worklist. */
- if (!added_to_worklist->add (as_a <gphi *> (use_stmt)))
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "[WORKLIST]: Update worklist with phi: ");
- print_gimple_stmt (dump_file, use_stmt, 0, 0);
- }
-
- worklist->safe_push (as_a <gphi *> (use_stmt));
- possibly_undefined_names->add (phi_result);
- }
+ add the phi to the worklist. */
+ if (!added_to_worklist->add (as_a<gphi *> (use_stmt)))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "[WORKLIST]: Update worklist with phi: ");
+ print_gimple_stmt (dump_file, use_stmt, 0);
+ }
+
+ worklist->safe_push (as_a<gphi *> (use_stmt));
+ possibly_undefined_names->add (phi_result);
+ }
}
- return NULL;
+ destroy_predicate_vecs (&def_preds);
+ return ret;
}
/* Look for inputs to PHI that are SSA_NAMEs that have empty definitions
and gives warning if there exists a runtime path from the entry to a
- use of the PHI def that does not contain a definition. In other words,
- the warning is on the real use. The more dead paths that can be pruned
- by the compiler, the fewer false positives the warning is. WORKLIST
- is a vector of candidate phis to be examined. ADDED_TO_WORKLIST is
+ use of the PHI def that does not contain a definition. In other words,
+ the warning is on the real use. The more dead paths that can be pruned
+ by the compiler, the fewer false positives the warning is. WORKLIST
+ is a vector of candidate phis to be examined. ADDED_TO_WORKLIST is
a pointer set tracking if the new phi is added to the worklist or not. */
static void
warn_uninitialized_phi (gphi *phi, vec<gphi *> *worklist,
- hash_set<gphi *> *added_to_worklist)
+ hash_set<gphi *> *added_to_worklist)
{
unsigned uninit_opnds;
- gimple uninit_use_stmt = 0;
+ gimple *uninit_use_stmt = 0;
tree uninit_op;
int phiarg_index;
location_t loc;
uninit_opnds = compute_uninit_opnds_pos (phi);
- if (MASK_EMPTY (uninit_opnds))
+ if (MASK_EMPTY (uninit_opnds))
return;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "[CHECK]: examining phi: ");
- print_gimple_stmt (dump_file, phi, 0, 0);
+ print_gimple_stmt (dump_file, phi, 0);
}
/* Now check if we have any use of the value without proper guard. */
uninit_use_stmt = find_uninit_use (phi, uninit_opnds,
- worklist, added_to_worklist);
+ worklist, added_to_worklist);
/* All uses are properly guarded. */
if (!uninit_use_stmt)
loc = UNKNOWN_LOCATION;
warn_uninit (OPT_Wmaybe_uninitialized, uninit_op, SSA_NAME_VAR (uninit_op),
SSA_NAME_VAR (uninit_op),
- "%qD may be used uninitialized in this function",
- uninit_use_stmt, loc);
-
+ "%qD may be used uninitialized in this function",
+ uninit_use_stmt, loc);
}
static bool
{}
/* opt_pass methods: */
- opt_pass * clone () { return new pass_late_warn_uninitialized (m_ctxt); }
+ opt_pass *clone () { return new pass_late_warn_uninitialized (m_ctxt); }
virtual bool gate (function *) { return gate_warn_uninitialized (); }
virtual unsigned int execute (function *);
for (i = 0; i < n; ++i)
{
tree op = gimple_phi_arg_def (phi, i);
- if (TREE_CODE (op) == SSA_NAME
- && uninit_undefined_value_p (op))
+ if (TREE_CODE (op) == SSA_NAME && uninit_undefined_value_p (op))
{
worklist.safe_push (phi);
added_to_worklist.add (phi);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "[WORKLIST]: add to initial list: ");
- print_gimple_stmt (dump_file, phi, 0, 0);
+ print_gimple_stmt (dump_file, phi, 0);
}
break;
}
return new pass_late_warn_uninitialized (ctxt);
}
-
static unsigned int
execute_early_warn_uninitialized (void)
{
/* Currently, this pass runs always but
- execute_late_warn_uninitialized only runs with optimization. With
+ execute_late_warn_uninitialized only runs with optimization. With
optimization we want to warn about possible uninitialized as late
as possible, thus don't do it here. However, without
optimization we need to warn here about "may be uninitialized". */
warn_uninitialized_vars (/*warn_possibly_uninitialized=*/!optimize);
- /* Post-dominator information can not be reliably updated. Free it
+ /* Post-dominator information cannot be reliably updated. Free it
after the use. */
free_dominance_info (CDI_POST_DOMINATORS);
return 0;
}
-
namespace {
const pass_data pass_data_early_warn_uninitialized =
/* opt_pass methods: */
virtual bool gate (function *) { return gate_warn_uninitialized (); }
virtual unsigned int execute (function *)
- {
- return execute_early_warn_uninitialized ();
- }
+ {
+ return execute_early_warn_uninitialized ();
+ }
}; // class pass_early_warn_uninitialized
projects / thirdparty / gcc.git / blobdiff