/* Generic routines for manipulating PHIs
- Copyright (C) 2003, 2005, 2007, 2008 Free Software Foundation, Inc.
+ Copyright (C) 2003-2020 Free Software Foundation, Inc.
This file is part of GCC.
#include "config.h"
#include "system.h"
#include "coretypes.h"
-#include "tm.h"
+#include "backend.h"
#include "tree.h"
-#include "rtl.h" /* FIXME: Only for ceil_log2, of all things... */
-#include "ggc.h"
-#include "basic-block.h"
-#include "tree-flow.h"
-#include "toplev.h"
#include "gimple.h"
+#include "ssa.h"
+#include "fold-const.h"
+#include "gimple-iterator.h"
+#include "tree-ssa.h"
/* Rewriting a function into SSA form can create a huge number of PHIs
many of which may be thrown away shortly after their creation if jumps
garbage collector. Similar results have been seen on a wider variety
of tests (such as the compiler itself).
- Right now we maintain our free list on a per-function basis. It may
- or may not make sense to maintain the free list for the duration of
- a compilation unit.
-
- We could also use a zone allocator for these objects since they have
- a very well defined lifetime. If someone wants to experiment with that
- this is the place to try it.
-
PHI nodes have different sizes, so we can't have a single list of all
the PHI nodes as it would be too expensive to walk down that list to
find a PHI of a suitable size.
the -2 on all the calculations below. */
#define NUM_BUCKETS 10
-static GTY ((deletable (""))) VEC(gimple,gc) *free_phinodes[NUM_BUCKETS - 2];
+static GTY ((deletable (""))) vec<gimple *, va_gc> *free_phinodes[NUM_BUCKETS - 2];
static unsigned long free_phinode_count;
static int ideal_phi_node_len (int);
-#ifdef GATHER_STATISTICS
unsigned int phi_nodes_reused;
unsigned int phi_nodes_created;
-#endif
-
-/* Initialize management of PHIs. */
-
-void
-init_phinodes (void)
-{
- int i;
-
- for (i = 0; i < NUM_BUCKETS - 2; i++)
- free_phinodes[i] = NULL;
- free_phinode_count = 0;
-}
-
-/* Finalize management of PHIs. */
-
-void
-fini_phinodes (void)
-{
- int i;
-
- for (i = 0; i < NUM_BUCKETS - 2; i++)
- free_phinodes[i] = NULL;
- free_phinode_count = 0;
-}
/* Dump some simple statistics regarding the re-use of PHI nodes. */
-#ifdef GATHER_STATISTICS
void
phinodes_print_statistics (void)
{
- fprintf (stderr, "PHI nodes allocated: %u\n", phi_nodes_created);
- fprintf (stderr, "PHI nodes reused: %u\n", phi_nodes_reused);
+ fprintf (stderr, "%-32s" PRsa (11) "\n", "PHI nodes allocated:",
+ SIZE_AMOUNT (phi_nodes_created));
+ fprintf (stderr, "%-32s" PRsa (11) "\n", "PHI nodes reused:",
+ SIZE_AMOUNT (phi_nodes_reused));
}
-#endif
/* Allocate a PHI node with at least LEN arguments. If the free list
happens to contain a PHI node with LEN arguments or more, return
that one. */
-static inline gimple
+static inline gphi *
allocate_phi_node (size_t len)
{
- gimple phi;
+ gphi *phi;
size_t bucket = NUM_BUCKETS - 2;
- size_t size = sizeof (struct gimple_statement_phi)
+ size_t size = sizeof (struct gphi)
+ (len - 1) * sizeof (struct phi_arg_d);
if (free_phinode_count)
/* If our free list has an element, then use it. */
if (bucket < NUM_BUCKETS - 2
- && gimple_phi_capacity (VEC_index (gimple, free_phinodes[bucket], 0))
- >= len)
+ && gimple_phi_capacity ((*free_phinodes[bucket])[0]) >= len)
{
free_phinode_count--;
- phi = VEC_pop (gimple, free_phinodes[bucket]);
- if (VEC_empty (gimple, free_phinodes[bucket]))
- VEC_free (gimple, gc, free_phinodes[bucket]);
-#ifdef GATHER_STATISTICS
- phi_nodes_reused++;
-#endif
+ phi = as_a <gphi *> (free_phinodes[bucket]->pop ());
+ if (free_phinodes[bucket]->is_empty ())
+ vec_free (free_phinodes[bucket]);
+ if (GATHER_STATISTICS)
+ phi_nodes_reused++;
}
else
{
- phi = (gimple) ggc_alloc (size);
-#ifdef GATHER_STATISTICS
- phi_nodes_created++;
+ phi = static_cast <gphi *> (ggc_internal_alloc (size));
+ if (GATHER_STATISTICS)
{
enum gimple_alloc_kind kind = gimple_alloc_kind (GIMPLE_PHI);
- gimple_alloc_counts[(int) kind]++;
- gimple_alloc_sizes[(int) kind] += size;
+ phi_nodes_created++;
+ gimple_alloc_counts[(int) kind]++;
+ gimple_alloc_sizes[(int) kind] += size;
}
-#endif
}
return phi;
len = 2;
/* Compute the number of bytes of the original request. */
- size = sizeof (struct gimple_statement_phi)
+ size = sizeof (struct gphi)
+ (len - 1) * sizeof (struct phi_arg_d);
/* Round it up to the next power of two. */
/* Return a PHI node with LEN argument slots for variable VAR. */
-gimple
+static gphi *
make_phi_node (tree var, int len)
{
- gimple phi;
+ gphi *phi;
int capacity, i;
capacity = ideal_phi_node_len (len);
/* We need to clear the entire PHI node, including the argument
portion, because we represent a "missing PHI argument" by placing
NULL_TREE in PHI_ARG_DEF. */
- memset (phi, 0, (sizeof (struct gimple_statement_phi)
+ memset (phi, 0, (sizeof (struct gphi)
- sizeof (struct phi_arg_d)
+ sizeof (struct phi_arg_d) * len));
- phi->gsbase.code = GIMPLE_PHI;
- phi->gimple_phi.nargs = len;
- phi->gimple_phi.capacity = capacity;
- if (TREE_CODE (var) == SSA_NAME)
+ phi->code = GIMPLE_PHI;
+ gimple_init_singleton (phi);
+ phi->nargs = len;
+ phi->capacity = capacity;
+ if (!var)
+ ;
+ else if (TREE_CODE (var) == SSA_NAME)
gimple_phi_set_result (phi, var);
else
gimple_phi_set_result (phi, make_ssa_name (var, phi));
- for (i = 0; i < capacity; i++)
+ for (i = 0; i < len; i++)
{
use_operand_p imm;
/* We no longer need PHI, release it so that it may be reused. */
-void
-release_phi_node (gimple phi)
+static void
+release_phi_node (gimple *phi)
{
size_t bucket;
size_t len = gimple_phi_capacity (phi);
bucket = len > NUM_BUCKETS - 1 ? NUM_BUCKETS - 1 : len;
bucket -= 2;
- VEC_safe_push (gimple, gc, free_phinodes[bucket], phi);
+ vec_safe_push (free_phinodes[bucket], phi);
free_phinode_count++;
}
/* Resize an existing PHI node. The only way is up. Return the
possibly relocated phi. */
-static void
-resize_phi_node (gimple *phi, size_t len)
+static gphi *
+resize_phi_node (gphi *phi, size_t len)
{
size_t old_size, i;
- gimple new_phi;
+ gphi *new_phi;
- gcc_assert (len > gimple_phi_capacity (*phi));
+ gcc_assert (len > gimple_phi_capacity (phi));
/* The garbage collector will not look at the PHI node beyond the
first PHI_NUM_ARGS elements. Therefore, all we have to copy is a
portion of the PHI node currently in use. */
- old_size = sizeof (struct gimple_statement_phi)
- + (gimple_phi_num_args (*phi) - 1) * sizeof (struct phi_arg_d);
+ old_size = sizeof (struct gphi)
+ + (gimple_phi_num_args (phi) - 1) * sizeof (struct phi_arg_d);
new_phi = allocate_phi_node (len);
- memcpy (new_phi, *phi, old_size);
+ memcpy (new_phi, phi, old_size);
+ memset ((char *)new_phi + old_size, 0,
+ (sizeof (struct gphi)
+ - sizeof (struct phi_arg_d)
+ + sizeof (struct phi_arg_d) * len) - old_size);
for (i = 0; i < gimple_phi_num_args (new_phi); i++)
{
use_operand_p imm, old_imm;
imm = gimple_phi_arg_imm_use_ptr (new_phi, i);
- old_imm = gimple_phi_arg_imm_use_ptr (*phi, i);
+ old_imm = gimple_phi_arg_imm_use_ptr (phi, i);
imm->use = gimple_phi_arg_def_ptr (new_phi, i);
relink_imm_use_stmt (imm, old_imm, new_phi);
}
- new_phi->gimple_phi.capacity = len;
-
- for (i = gimple_phi_num_args (new_phi); i < len; i++)
- {
- use_operand_p imm;
-
- gimple_phi_arg_set_location (new_phi, i, UNKNOWN_LOCATION);
- imm = gimple_phi_arg_imm_use_ptr (new_phi, i);
- imm->use = gimple_phi_arg_def_ptr (new_phi, i);
- imm->prev = NULL;
- imm->next = NULL;
- imm->loc.stmt = new_phi;
- }
+ new_phi->capacity = len;
- *phi = new_phi;
+ return new_phi;
}
/* Reserve PHI arguments for a new edge to basic block BB. */
{
size_t len = EDGE_COUNT (bb->preds);
size_t cap = ideal_phi_node_len (len + 4);
- gimple_stmt_iterator gsi;
+ gphi_iterator gsi;
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
- gimple *loc = gsi_stmt_ptr (&gsi);
+ gphi *stmt = gsi.phi ();
- if (len > gimple_phi_capacity (*loc))
+ if (len > gimple_phi_capacity (stmt))
{
- gimple old_phi = *loc;
-
- resize_phi_node (loc, cap);
+ gphi *new_phi = resize_phi_node (stmt, cap);
/* The result of the PHI is defined by this PHI node. */
- SSA_NAME_DEF_STMT (gimple_phi_result (*loc)) = *loc;
+ SSA_NAME_DEF_STMT (gimple_phi_result (new_phi)) = new_phi;
+ gsi_set_stmt (&gsi, new_phi);
- release_phi_node (old_phi);
+ release_phi_node (stmt);
+ stmt = new_phi;
}
+ stmt->nargs++;
+
/* We represent a "missing PHI argument" by placing NULL_TREE in
the corresponding slot. If PHI arguments were added
immediately after an edge is created, this zeroing would not
example, the loop optimizer duplicates several basic blocks,
redirects edges, and then fixes up PHI arguments later in
batch. */
- SET_PHI_ARG_DEF (*loc, len - 1, NULL_TREE);
-
- (*loc)->gimple_phi.nargs++;
+ use_operand_p imm = gimple_phi_arg_imm_use_ptr (stmt, len - 1);
+ imm->use = gimple_phi_arg_def_ptr (stmt, len - 1);
+ imm->prev = NULL;
+ imm->next = NULL;
+ imm->loc.stmt = stmt;
+ SET_PHI_ARG_DEF (stmt, len - 1, NULL_TREE);
+ gimple_phi_arg_set_location (stmt, len - 1, UNKNOWN_LOCATION);
}
}
/* Adds PHI to BB. */
void
-add_phi_node_to_bb (gimple phi, basic_block bb)
+add_phi_node_to_bb (gphi *phi, basic_block bb)
{
- gimple_stmt_iterator gsi;
+ gimple_seq seq = phi_nodes (bb);
/* Add the new PHI node to the list of PHI nodes for block BB. */
- if (phi_nodes (bb) == NULL)
- set_phi_nodes (bb, gimple_seq_alloc ());
-
- gsi = gsi_last (phi_nodes (bb));
- gsi_insert_after (&gsi, phi, GSI_NEW_STMT);
+ if (seq == NULL)
+ set_phi_nodes (bb, gimple_seq_alloc_with_stmt (phi));
+ else
+ {
+ gimple_seq_add_stmt (&seq, phi);
+ gcc_assert (seq == phi_nodes (bb));
+ }
/* Associate BB to the PHI node. */
gimple_set_bb (phi, bb);
/* Create a new PHI node for variable VAR at basic block BB. */
-gimple
+gphi *
create_phi_node (tree var, basic_block bb)
{
- gimple phi = make_phi_node (var, EDGE_COUNT (bb->preds));
+ gphi *phi = make_phi_node (var, EDGE_COUNT (bb->preds));
add_phi_node_to_bb (phi, bb);
return phi;
PHI points to the reallocated phi node when we return. */
void
-add_phi_arg (gimple phi, tree def, edge e, source_location locus)
+add_phi_arg (gphi *phi, tree def, edge e, location_t locus)
{
basic_block bb = e->dest;
is consistent with how we remove an edge from the edge vector. */
static void
-remove_phi_arg_num (gimple phi, int i)
+remove_phi_arg_num (gphi *phi, int i)
{
int num_elem = gimple_phi_num_args (phi);
/* Shrink the vector and return. Note that we do not have to clear
PHI_ARG_DEF because the garbage collector will not look at those
elements beyond the first PHI_NUM_ARGS elements of the array. */
- phi->gimple_phi.nargs--;
+ phi->nargs--;
}
void
remove_phi_args (edge e)
{
- gimple_stmt_iterator gsi;
+ gphi_iterator gsi;
for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi))
- remove_phi_arg_num (gsi_stmt (gsi), e->dest_idx);
+ remove_phi_arg_num (gsi.phi (),
+ e->dest_idx);
}
void
remove_phi_node (gimple_stmt_iterator *gsi, bool release_lhs_p)
{
- gimple phi = gsi_stmt (*gsi);
+ gimple *phi = gsi_stmt (*gsi);
if (release_lhs_p)
insert_debug_temps_for_defs (gsi);
void
remove_phi_nodes (basic_block bb)
{
- gimple_stmt_iterator gsi;
+ gphi_iterator gsi;
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); )
remove_phi_node (&gsi, true);
set_phi_nodes (bb, NULL);
}
+/* Given PHI, return its RHS if the PHI is a degenerate, otherwise return
+ NULL. */
+
+tree
+degenerate_phi_result (gphi *phi)
+{
+ tree lhs = gimple_phi_result (phi);
+ tree val = NULL;
+ size_t i;
+
+ /* Ignoring arguments which are the same as LHS, if all the remaining
+ arguments are the same, then the PHI is a degenerate and has the
+ value of that common argument. */
+ for (i = 0; i < gimple_phi_num_args (phi); i++)
+ {
+ tree arg = gimple_phi_arg_def (phi, i);
+
+ if (arg == lhs)
+ continue;
+ else if (!arg)
+ break;
+ else if (!val)
+ val = arg;
+ else if (arg == val)
+ continue;
+ /* We bring in some of operand_equal_p not only to speed things
+ up, but also to avoid crashing when dereferencing the type of
+ a released SSA name. */
+ else if (TREE_CODE (val) != TREE_CODE (arg)
+ || TREE_CODE (val) == SSA_NAME
+ || !operand_equal_p (arg, val, 0))
+ break;
+ }
+ return (i == gimple_phi_num_args (phi) ? val : NULL);
+}
+
+/* Set PHI nodes of a basic block BB to SEQ. */
+
+void
+set_phi_nodes (basic_block bb, gimple_seq seq)
+{
+ gimple_stmt_iterator i;
+
+ gcc_checking_assert (!(bb->flags & BB_RTL));
+ bb->il.gimple.phi_nodes = seq;
+ if (seq)
+ for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i))
+ gimple_set_bb (gsi_stmt (i), bb);
+}
+
#include "gt-tree-phinodes.h"