/* Generic SSA value propagation engine.
- Copyright (C) 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
- Free Software Foundation; either version 2, or (at your option) any
+ Free Software Foundation; either version 3, or (at your option) any
later version.
GCC is distributed in the hope that it will be useful, but WITHOUT
for more details.
You should have received a copy of the GNU General Public License
- along with GCC; see the file COPYING. If not, write to the Free
- Software Foundation, 59 Temple Place - Suite 330, Boston, MA
- 02111-1307, USA. */
+ along with GCC; see the file COPYING3. If not see
+ <http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "ggc.h"
#include "basic-block.h"
#include "output.h"
-#include "errors.h"
#include "expr.h"
#include "function.h"
#include "diagnostic.h"
#include "tree-pass.h"
#include "tree-ssa-propagate.h"
#include "langhooks.h"
-
+#include "varray.h"
+#include "vec.h"
/* This file implements a generic value propagation engine based on
the same propagation used by the SSA-CCP algorithm [1].
SSA_PROP_INTERESTING: S produces a value that can be computed
at compile time. Its result can be propagated into the
- statements that feed from S. Furhtermore, if S is a
+ statements that feed from S. Furthermore, if S is a
conditional jump, only the edge known to be taken is added
to the work list. Edges that are known not to execute are
never simulated.
static sbitmap executable_blocks;
/* Array of control flow edges on the worklist. */
-static GTY(()) varray_type cfg_blocks = NULL;
+static VEC(basic_block,heap) *cfg_blocks;
static unsigned int cfg_blocks_num = 0;
static int cfg_blocks_tail;
definition has changed. SSA edges are def-use edges in the SSA
web. For each D-U edge, we store the target statement or PHI node
U. */
-static GTY(()) varray_type interesting_ssa_edges;
+static GTY(()) VEC(tree,gc) *interesting_ssa_edges;
/* Identical to INTERESTING_SSA_EDGES. For performance reasons, the
list of SSA edges is split into two. One contains all SSA edges
don't use a separate worklist for VARYING edges, we end up with
situations where lattice values move from
UNDEFINED->INTERESTING->VARYING instead of UNDEFINED->VARYING. */
-static GTY(()) varray_type varying_ssa_edges;
+static GTY(()) VEC(tree,gc) *varying_ssa_edges;
/* Return true if the block worklist empty. */
}
-/* Add a basic block to the worklist. */
+/* Add a basic block to the worklist. The block must not be already
+ in the worklist, and it must not be the ENTRY or EXIT block. */
static void
cfg_blocks_add (basic_block bb)
{
- if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR)
- return;
+ bool head = false;
- if (TEST_BIT (bb_in_list, bb->index))
- return;
+ gcc_assert (bb != ENTRY_BLOCK_PTR && bb != EXIT_BLOCK_PTR);
+ gcc_assert (!TEST_BIT (bb_in_list, bb->index));
if (cfg_blocks_empty_p ())
{
else
{
cfg_blocks_num++;
- if (cfg_blocks_num > VARRAY_SIZE (cfg_blocks))
+ if (cfg_blocks_num > VEC_length (basic_block, cfg_blocks))
{
- /* We have to grow the array now. Adjust to queue to occupy the
- full space of the original array. */
- cfg_blocks_tail = VARRAY_SIZE (cfg_blocks);
+ /* We have to grow the array now. Adjust to queue to occupy
+ the full space of the original array. We do not need to
+ initialize the newly allocated portion of the array
+ because we keep track of CFG_BLOCKS_HEAD and
+ CFG_BLOCKS_HEAD. */
+ cfg_blocks_tail = VEC_length (basic_block, cfg_blocks);
cfg_blocks_head = 0;
- VARRAY_GROW (cfg_blocks, 2 * VARRAY_SIZE (cfg_blocks));
+ VEC_safe_grow (basic_block, heap, cfg_blocks, 2 * cfg_blocks_tail);
}
+ /* Minor optimization: we prefer to see blocks with more
+ predecessors later, because there is more of a chance that
+ the incoming edges will be executable. */
+ else if (EDGE_COUNT (bb->preds)
+ >= EDGE_COUNT (VEC_index (basic_block, cfg_blocks,
+ cfg_blocks_head)->preds))
+ cfg_blocks_tail = ((cfg_blocks_tail + 1)
+ % VEC_length (basic_block, cfg_blocks));
else
- cfg_blocks_tail = (cfg_blocks_tail + 1) % VARRAY_SIZE (cfg_blocks);
+ {
+ if (cfg_blocks_head == 0)
+ cfg_blocks_head = VEC_length (basic_block, cfg_blocks);
+ --cfg_blocks_head;
+ head = true;
+ }
}
- VARRAY_BB (cfg_blocks, cfg_blocks_tail) = bb;
+ VEC_replace (basic_block, cfg_blocks,
+ head ? cfg_blocks_head : cfg_blocks_tail,
+ bb);
SET_BIT (bb_in_list, bb->index);
}
{
basic_block bb;
- bb = VARRAY_BB (cfg_blocks, cfg_blocks_head);
+ bb = VEC_index (basic_block, cfg_blocks, cfg_blocks_head);
-#ifdef ENABLE_CHECKING
- if (cfg_blocks_empty_p () || !bb)
- abort ();
-#endif
+ gcc_assert (!cfg_blocks_empty_p ());
+ gcc_assert (bb);
- cfg_blocks_head = (cfg_blocks_head + 1) % VARRAY_SIZE (cfg_blocks);
+ cfg_blocks_head = ((cfg_blocks_head + 1)
+ % VEC_length (basic_block, cfg_blocks));
--cfg_blocks_num;
RESET_BIT (bb_in_list, bb->index);
static void
add_ssa_edge (tree var, bool is_varying)
{
- tree stmt = SSA_NAME_DEF_STMT (var);
- dataflow_t df = get_immediate_uses (stmt);
- int num_uses = num_immediate_uses (df);
- int i;
+ imm_use_iterator iter;
+ use_operand_p use_p;
- for (i = 0; i < num_uses; i++)
+ FOR_EACH_IMM_USE_FAST (use_p, iter, var)
{
- tree use_stmt = immediate_use (df, i);
+ tree use_stmt = USE_STMT (use_p);
if (!DONT_SIMULATE_AGAIN (use_stmt)
&& !STMT_IN_SSA_EDGE_WORKLIST (use_stmt))
{
STMT_IN_SSA_EDGE_WORKLIST (use_stmt) = 1;
if (is_varying)
- VARRAY_PUSH_TREE (varying_ssa_edges, use_stmt);
+ VEC_safe_push (tree, gc, varying_ssa_edges, use_stmt);
else
- VARRAY_PUSH_TREE (interesting_ssa_edges, use_stmt);
+ VEC_safe_push (tree, gc, interesting_ssa_edges, use_stmt);
}
}
}
if (stmt_ends_bb_p (stmt))
{
edge e;
+ edge_iterator ei;
basic_block bb = bb_for_stmt (stmt);
- for (e = bb->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
add_control_edge (e);
}
}
/* Process an SSA edge worklist. WORKLIST is the SSA edge worklist to
drain. This pops statements off the given WORKLIST and processes
- them until there are no more statements on WORKLIST. */
+ them until there are no more statements on WORKLIST.
+ We take a pointer to WORKLIST because it may be reallocated when an
+ SSA edge is added to it in simulate_stmt. */
static void
-process_ssa_edge_worklist (varray_type *worklist)
+process_ssa_edge_worklist (VEC(tree,gc) **worklist)
{
/* Drain the entire worklist. */
- while (VARRAY_ACTIVE_SIZE (*worklist) > 0)
+ while (VEC_length (tree, *worklist) > 0)
{
basic_block bb;
/* Pull the statement to simulate off the worklist. */
- tree stmt = VARRAY_TOP_TREE (*worklist);
- VARRAY_POP (*worklist);
+ tree stmt = VEC_pop (tree, *worklist);
/* If this statement was already visited by simulate_block, then
we don't need to visit it again here. */
block_stmt_iterator j;
unsigned int normal_edge_count;
edge e, normal_edge;
+ edge_iterator ei;
/* Note that we have simulated this block. */
SET_BIT (executable_blocks, block->index);
worklist. */
normal_edge_count = 0;
normal_edge = NULL;
- for (e = block->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, block->succs)
{
if (e->flags & EDGE_ABNORMAL)
add_control_edge (e);
ssa_prop_init (void)
{
edge e;
+ edge_iterator ei;
basic_block bb;
+ size_t i;
/* Worklists of SSA edges. */
- VARRAY_TREE_INIT (interesting_ssa_edges, 20, "interesting_ssa_edges");
- VARRAY_TREE_INIT (varying_ssa_edges, 20, "varying_ssa_edges");
+ interesting_ssa_edges = VEC_alloc (tree, gc, 20);
+ varying_ssa_edges = VEC_alloc (tree, gc, 20);
executable_blocks = sbitmap_alloc (last_basic_block);
sbitmap_zero (executable_blocks);
if (dump_file && (dump_flags & TDF_DETAILS))
dump_immediate_uses (dump_file);
- VARRAY_BB_INIT (cfg_blocks, 20, "cfg_blocks");
+ cfg_blocks = VEC_alloc (basic_block, heap, 20);
+ VEC_safe_grow (basic_block, heap, cfg_blocks, 20);
- /* Initially assume that every edge in the CFG is not executable. */
- FOR_EACH_BB (bb)
+ /* Initialize the values for every SSA_NAME. */
+ for (i = 1; i < num_ssa_names; i++)
+ if (ssa_name (i))
+ SSA_NAME_VALUE (ssa_name (i)) = NULL_TREE;
+
+ /* Initially assume that every edge in the CFG is not executable.
+ (including the edges coming out of ENTRY_BLOCK_PTR). */
+ FOR_ALL_BB (bb)
{
block_stmt_iterator si;
for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
STMT_IN_SSA_EDGE_WORKLIST (bsi_stmt (si)) = 0;
- for (e = bb->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
e->flags &= ~EDGE_EXECUTABLE;
}
/* Seed the algorithm by adding the successors of the entry block to the
edge worklist. */
- for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
- {
- if (e->dest != EXIT_BLOCK_PTR)
- {
- e->flags |= EDGE_EXECUTABLE;
- cfg_blocks_add (e->dest);
- }
- }
+ FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
+ add_control_edge (e);
}
static void
ssa_prop_fini (void)
{
- interesting_ssa_edges = NULL;
- varying_ssa_edges = NULL;
+ VEC_free (tree, gc, interesting_ssa_edges);
+ VEC_free (tree, gc, varying_ssa_edges);
+ VEC_free (basic_block, heap, cfg_blocks);
cfg_blocks = NULL;
sbitmap_free (bb_in_list);
sbitmap_free (executable_blocks);
- free_df ();
}
{
case RETURN_EXPR:
stmt = TREE_OPERAND (stmt, 0);
- if (!stmt || TREE_CODE (stmt) != MODIFY_EXPR)
+ if (!stmt || TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
return stmt;
/* FALLTHRU */
- case MODIFY_EXPR:
- stmt = TREE_OPERAND (stmt, 1);
+ case GIMPLE_MODIFY_STMT:
+ stmt = GENERIC_TREE_OPERAND (stmt, 1);
if (TREE_CODE (stmt) == WITH_SIZE_EXPR)
return TREE_OPERAND (stmt, 0);
else
}
-/* Set the main expression of *STMT_P to EXPR. If EXPR is not a valid
- GIMPLE expression no changes are done and the function returns
- false. */
+/* Return true if EXPR is a valid GIMPLE expression. */
bool
-set_rhs (tree *stmt_p, tree expr)
+valid_gimple_expression_p (tree expr)
{
- tree stmt = *stmt_p, op;
enum tree_code code = TREE_CODE (expr);
- stmt_ann_t ann;
- tree var;
- ssa_op_iter iter;
- /* Verify the constant folded result is valid gimple. */
- if (TREE_CODE_CLASS (code) == '2')
+ switch (TREE_CODE_CLASS (code))
{
+ case tcc_declaration:
+ if (!is_gimple_variable (expr))
+ return false;
+ break;
+
+ case tcc_constant:
+ break;
+
+ case tcc_binary:
+ case tcc_comparison:
if (!is_gimple_val (TREE_OPERAND (expr, 0))
|| !is_gimple_val (TREE_OPERAND (expr, 1)))
return false;
- }
- else if (TREE_CODE_CLASS (code) == '1')
- {
+ break;
+
+ case tcc_unary:
if (!is_gimple_val (TREE_OPERAND (expr, 0)))
return false;
+ break;
+
+ case tcc_expression:
+ switch (code)
+ {
+ case ADDR_EXPR:
+ {
+ tree t = TREE_OPERAND (expr, 0);
+ while (handled_component_p (t))
+ {
+ /* ??? More checks needed, see the GIMPLE verifier. */
+ if ((TREE_CODE (t) == ARRAY_REF
+ || TREE_CODE (t) == ARRAY_RANGE_REF)
+ && !is_gimple_val (TREE_OPERAND (t, 1)))
+ return false;
+ t = TREE_OPERAND (t, 0);
+ }
+ if (!is_gimple_id (t))
+ return false;
+ break;
+ }
+
+ case TRUTH_NOT_EXPR:
+ if (!is_gimple_val (TREE_OPERAND (expr, 0)))
+ return false;
+ break;
+
+ case TRUTH_AND_EXPR:
+ case TRUTH_XOR_EXPR:
+ case TRUTH_OR_EXPR:
+ if (!is_gimple_val (TREE_OPERAND (expr, 0))
+ || !is_gimple_val (TREE_OPERAND (expr, 1)))
+ return false;
+ break;
+
+ case EXC_PTR_EXPR:
+ case FILTER_EXPR:
+ break;
+
+ default:
+ return false;
+ }
+ break;
+
+ case tcc_vl_exp:
+ switch (code)
+ {
+ case CALL_EXPR:
+ break;
+ default:
+ return false;
+ }
+ break;
+
+ case tcc_exceptional:
+ switch (code)
+ {
+ case SSA_NAME:
+ break;
+
+ default:
+ return false;
+ }
+ break;
+
+ default:
+ return false;
}
+ return true;
+}
+
+
+/* Set the main expression of *STMT_P to EXPR. If EXPR is not a valid
+ GIMPLE expression no changes are done and the function returns
+ false. */
+
+bool
+set_rhs (tree *stmt_p, tree expr)
+{
+ tree stmt = *stmt_p, op;
+ stmt_ann_t ann;
+ tree var;
+ ssa_op_iter iter;
+
+ if (!valid_gimple_expression_p (expr))
+ return false;
+
+ if (EXPR_HAS_LOCATION (stmt)
+ && (EXPR_P (expr)
+ || GIMPLE_STMT_P (expr))
+ && ! EXPR_HAS_LOCATION (expr)
+ && TREE_SIDE_EFFECTS (expr)
+ && TREE_CODE (expr) != LABEL_EXPR)
+ SET_EXPR_LOCATION (expr, EXPR_LOCATION (stmt));
+
switch (TREE_CODE (stmt))
{
case RETURN_EXPR:
op = TREE_OPERAND (stmt, 0);
- if (TREE_CODE (op) != MODIFY_EXPR)
+ if (TREE_CODE (op) != GIMPLE_MODIFY_STMT)
{
- TREE_OPERAND (stmt, 0) = expr;
+ GIMPLE_STMT_OPERAND (stmt, 0) = expr;
break;
}
stmt = op;
/* FALLTHRU */
- case MODIFY_EXPR:
- op = TREE_OPERAND (stmt, 1);
+ case GIMPLE_MODIFY_STMT:
+ op = GIMPLE_STMT_OPERAND (stmt, 1);
if (TREE_CODE (op) == WITH_SIZE_EXPR)
- stmt = op;
- TREE_OPERAND (stmt, 1) = expr;
+ {
+ stmt = op;
+ TREE_OPERAND (stmt, 1) = expr;
+ }
+ else
+ GIMPLE_STMT_OPERAND (stmt, 1) = expr;
break;
case COND_EXPR:
+ if (!is_gimple_condexpr (expr))
+ return false;
COND_EXPR_COND (stmt) = expr;
break;
case SWITCH_EXPR:
effects, then replace *STMT_P with an empty statement. */
ann = stmt_ann (stmt);
*stmt_p = TREE_SIDE_EFFECTS (expr) ? expr : build_empty_stmt ();
- (*stmt_p)->common.ann = (tree_ann_t) ann;
+ (*stmt_p)->base.ann = (tree_ann_t) ann;
- if (TREE_SIDE_EFFECTS (expr))
+ if (gimple_in_ssa_p (cfun)
+ && TREE_SIDE_EFFECTS (expr))
{
/* Fix all the SSA_NAMEs created by *STMT_P to point to its new
replacement. */
SSA_NAME_DEF_STMT (var) = *stmt_p;
}
}
+ stmt->base.ann = NULL;
break;
}
/* Iterate until the worklists are empty. */
while (!cfg_blocks_empty_p ()
- || VARRAY_ACTIVE_SIZE (interesting_ssa_edges) > 0
- || VARRAY_ACTIVE_SIZE (varying_ssa_edges) > 0)
+ || VEC_length (tree, interesting_ssa_edges) > 0
+ || VEC_length (tree, varying_ssa_edges) > 0)
{
if (!cfg_blocks_empty_p ())
{
ssa_prop_fini ();
}
+
+/* Return the first VDEF operand for STMT. */
+
+tree
+first_vdef (tree stmt)
+{
+ ssa_op_iter iter;
+ tree op;
+
+ /* Simply return the first operand we arrive at. */
+ FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_VIRTUAL_DEFS)
+ return (op);
+
+ gcc_unreachable ();
+}
+
+
+/* Return true if STMT is of the form 'LHS = mem_ref', where 'mem_ref'
+ is a non-volatile pointer dereference, a structure reference or a
+ reference to a single _DECL. Ignore volatile memory references
+ because they are not interesting for the optimizers. */
+
+bool
+stmt_makes_single_load (tree stmt)
+{
+ tree rhs;
+
+ if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
+ return false;
+
+ if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF|SSA_OP_VUSE))
+ return false;
+
+ rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+ STRIP_NOPS (rhs);
+
+ return (!TREE_THIS_VOLATILE (rhs)
+ && (DECL_P (rhs)
+ || REFERENCE_CLASS_P (rhs)));
+}
+
+
+/* Return true if STMT is of the form 'mem_ref = RHS', where 'mem_ref'
+ is a non-volatile pointer dereference, a structure reference or a
+ reference to a single _DECL. Ignore volatile memory references
+ because they are not interesting for the optimizers. */
+
+bool
+stmt_makes_single_store (tree stmt)
+{
+ tree lhs;
+
+ if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
+ return false;
+
+ if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF))
+ return false;
+
+ lhs = GIMPLE_STMT_OPERAND (stmt, 0);
+ STRIP_NOPS (lhs);
+
+ return (!TREE_THIS_VOLATILE (lhs)
+ && (DECL_P (lhs)
+ || REFERENCE_CLASS_P (lhs)));
+}
+
+
+/* If STMT makes a single memory load and all the virtual use operands
+ have the same value in array VALUES, return it. Otherwise, return
+ NULL. */
+
+prop_value_t *
+get_value_loaded_by (tree stmt, prop_value_t *values)
+{
+ ssa_op_iter i;
+ tree vuse;
+ prop_value_t *prev_val = NULL;
+ prop_value_t *val = NULL;
+
+ FOR_EACH_SSA_TREE_OPERAND (vuse, stmt, i, SSA_OP_VIRTUAL_USES)
+ {
+ val = &values[SSA_NAME_VERSION (vuse)];
+ if (prev_val && prev_val->value != val->value)
+ return NULL;
+ prev_val = val;
+ }
+
+ return val;
+}
+
+
+/* Propagation statistics. */
+struct prop_stats_d
+{
+ long num_const_prop;
+ long num_copy_prop;
+ long num_pred_folded;
+};
+
+static struct prop_stats_d prop_stats;
+
+/* Replace USE references in statement STMT with the values stored in
+ PROP_VALUE. Return true if at least one reference was replaced. If
+ REPLACED_ADDRESSES_P is given, it will be set to true if an address
+ constant was replaced. */
+
+bool
+replace_uses_in (tree stmt, bool *replaced_addresses_p,
+ prop_value_t *prop_value)
+{
+ bool replaced = false;
+ use_operand_p use;
+ ssa_op_iter iter;
+
+ FOR_EACH_SSA_USE_OPERAND (use, stmt, iter, SSA_OP_USE)
+ {
+ tree tuse = USE_FROM_PTR (use);
+ tree val = prop_value[SSA_NAME_VERSION (tuse)].value;
+
+ if (val == tuse || val == NULL_TREE)
+ continue;
+
+ if (TREE_CODE (stmt) == ASM_EXPR
+ && !may_propagate_copy_into_asm (tuse))
+ continue;
+
+ if (!may_propagate_copy (tuse, val))
+ continue;
+
+ if (TREE_CODE (val) != SSA_NAME)
+ prop_stats.num_const_prop++;
+ else
+ prop_stats.num_copy_prop++;
+
+ propagate_value (use, val);
+
+ replaced = true;
+ if (POINTER_TYPE_P (TREE_TYPE (tuse)) && replaced_addresses_p)
+ *replaced_addresses_p = true;
+ }
+
+ return replaced;
+}
+
+
+/* Replace the VUSE references in statement STMT with the values
+ stored in PROP_VALUE. Return true if a reference was replaced. If
+ REPLACED_ADDRESSES_P is given, it will be set to true if an address
+ constant was replaced.
+
+ Replacing VUSE operands is slightly more complex than replacing
+ regular USEs. We are only interested in two types of replacements
+ here:
+
+ 1- If the value to be replaced is a constant or an SSA name for a
+ GIMPLE register, then we are making a copy/constant propagation
+ from a memory store. For instance,
+
+ # a_3 = VDEF <a_2>
+ a.b = x_1;
+ ...
+ # VUSE <a_3>
+ y_4 = a.b;
+
+ This replacement is only possible iff STMT is an assignment
+ whose RHS is identical to the LHS of the statement that created
+ the VUSE(s) that we are replacing. Otherwise, we may do the
+ wrong replacement:
+
+ # a_3 = VDEF <a_2>
+ # b_5 = VDEF <b_4>
+ *p = 10;
+ ...
+ # VUSE <b_5>
+ x_8 = b;
+
+ Even though 'b_5' acquires the value '10' during propagation,
+ there is no way for the propagator to tell whether the
+ replacement is correct in every reached use, because values are
+ computed at definition sites. Therefore, when doing final
+ substitution of propagated values, we have to check each use
+ site. Since the RHS of STMT ('b') is different from the LHS of
+ the originating statement ('*p'), we cannot replace 'b' with
+ '10'.
+
+ Similarly, when merging values from PHI node arguments,
+ propagators need to take care not to merge the same values
+ stored in different locations:
+
+ if (...)
+ # a_3 = VDEF <a_2>
+ a.b = 3;
+ else
+ # a_4 = VDEF <a_2>
+ a.c = 3;
+ # a_5 = PHI <a_3, a_4>
+
+ It would be wrong to propagate '3' into 'a_5' because that
+ operation merges two stores to different memory locations.
+
+
+ 2- If the value to be replaced is an SSA name for a virtual
+ register, then we simply replace each VUSE operand with its
+ value from PROP_VALUE. This is the same replacement done by
+ replace_uses_in. */
+
+static bool
+replace_vuses_in (tree stmt, bool *replaced_addresses_p,
+ prop_value_t *prop_value)
+{
+ bool replaced = false;
+ ssa_op_iter iter;
+ use_operand_p vuse;
+
+ if (stmt_makes_single_load (stmt))
+ {
+ /* If STMT is an assignment whose RHS is a single memory load,
+ see if we are trying to propagate a constant or a GIMPLE
+ register (case #1 above). */
+ prop_value_t *val = get_value_loaded_by (stmt, prop_value);
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+
+ if (val
+ && val->value
+ && (is_gimple_reg (val->value)
+ || is_gimple_min_invariant (val->value))
+ && simple_cst_equal (rhs, val->mem_ref) == 1)
+
+ {
+ /* If we are replacing a constant address, inform our
+ caller. */
+ if (TREE_CODE (val->value) != SSA_NAME
+ && POINTER_TYPE_P (TREE_TYPE (GIMPLE_STMT_OPERAND (stmt, 1)))
+ && replaced_addresses_p)
+ *replaced_addresses_p = true;
+
+ /* We can only perform the substitution if the load is done
+ from the same memory location as the original store.
+ Since we already know that there are no intervening
+ stores between DEF_STMT and STMT, we only need to check
+ that the RHS of STMT is the same as the memory reference
+ propagated together with the value. */
+ GIMPLE_STMT_OPERAND (stmt, 1) = val->value;
+
+ if (TREE_CODE (val->value) != SSA_NAME)
+ prop_stats.num_const_prop++;
+ else
+ prop_stats.num_copy_prop++;
+
+ /* Since we have replaced the whole RHS of STMT, there
+ is no point in checking the other VUSEs, as they will
+ all have the same value. */
+ return true;
+ }
+ }
+
+ /* Otherwise, the values for every VUSE operand must be other
+ SSA_NAMEs that can be propagated into STMT. */
+ FOR_EACH_SSA_USE_OPERAND (vuse, stmt, iter, SSA_OP_VIRTUAL_USES)
+ {
+ tree var = USE_FROM_PTR (vuse);
+ tree val = prop_value[SSA_NAME_VERSION (var)].value;
+
+ if (val == NULL_TREE || var == val)
+ continue;
+
+ /* Constants and copies propagated between real and virtual
+ operands are only possible in the cases handled above. They
+ should be ignored in any other context. */
+ if (is_gimple_min_invariant (val) || is_gimple_reg (val))
+ continue;
+
+ propagate_value (vuse, val);
+ prop_stats.num_copy_prop++;
+ replaced = true;
+ }
+
+ return replaced;
+}
+
+
+/* Replace propagated values into all the arguments for PHI using the
+ values from PROP_VALUE. */
+
+static void
+replace_phi_args_in (tree phi, prop_value_t *prop_value)
+{
+ int i;
+ bool replaced = false;
+ tree prev_phi = NULL;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ prev_phi = unshare_expr (phi);
+
+ for (i = 0; i < PHI_NUM_ARGS (phi); i++)
+ {
+ tree arg = PHI_ARG_DEF (phi, i);
+
+ if (TREE_CODE (arg) == SSA_NAME)
+ {
+ tree val = prop_value[SSA_NAME_VERSION (arg)].value;
+
+ if (val && val != arg && may_propagate_copy (arg, val))
+ {
+ if (TREE_CODE (val) != SSA_NAME)
+ prop_stats.num_const_prop++;
+ else
+ prop_stats.num_copy_prop++;
+
+ propagate_value (PHI_ARG_DEF_PTR (phi, i), val);
+ replaced = true;
+
+ /* If we propagated a copy and this argument flows
+ through an abnormal edge, update the replacement
+ accordingly. */
+ if (TREE_CODE (val) == SSA_NAME
+ && PHI_ARG_EDGE (phi, i)->flags & EDGE_ABNORMAL)
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1;
+ }
+ }
+ }
+
+ if (replaced && dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Folded PHI node: ");
+ print_generic_stmt (dump_file, prev_phi, TDF_SLIM);
+ fprintf (dump_file, " into: ");
+ print_generic_stmt (dump_file, phi, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
+}
+
+
+/* If STMT has a predicate whose value can be computed using the value
+ range information computed by VRP, compute its value and return true.
+ Otherwise, return false. */
+
+static bool
+fold_predicate_in (tree stmt)
+{
+ tree *pred_p = NULL;
+ bool modify_stmt_p = false;
+ tree val;
+
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && COMPARISON_CLASS_P (GIMPLE_STMT_OPERAND (stmt, 1)))
+ {
+ modify_stmt_p = true;
+ pred_p = &GIMPLE_STMT_OPERAND (stmt, 1);
+ }
+ else if (TREE_CODE (stmt) == COND_EXPR)
+ pred_p = &COND_EXPR_COND (stmt);
+ else
+ return false;
+
+ val = vrp_evaluate_conditional (*pred_p, stmt);
+ if (val)
+ {
+ if (modify_stmt_p)
+ val = fold_convert (TREE_TYPE (*pred_p), val);
+
+ if (dump_file)
+ {
+ fprintf (dump_file, "Folding predicate ");
+ print_generic_expr (dump_file, *pred_p, 0);
+ fprintf (dump_file, " to ");
+ print_generic_expr (dump_file, val, 0);
+ fprintf (dump_file, "\n");
+ }
+
+ prop_stats.num_pred_folded++;
+ *pred_p = val;
+ return true;
+ }
+
+ return false;
+}
+
+
+/* Perform final substitution and folding of propagated values.
+
+ PROP_VALUE[I] contains the single value that should be substituted
+ at every use of SSA name N_I. If PROP_VALUE is NULL, no values are
+ substituted.
+
+ If USE_RANGES_P is true, statements that contain predicate
+ expressions are evaluated with a call to vrp_evaluate_conditional.
+ This will only give meaningful results when called from tree-vrp.c
+ (the information used by vrp_evaluate_conditional is built by the
+ VRP pass).
+
+ Return TRUE when something changed. */
+
+bool
+substitute_and_fold (prop_value_t *prop_value, bool use_ranges_p)
+{
+ basic_block bb;
+ bool something_changed = false;
+
+ if (prop_value == NULL && !use_ranges_p)
+ return false;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "\nSubstituing values and folding statements\n\n");
+
+ memset (&prop_stats, 0, sizeof (prop_stats));
+
+ /* Substitute values in every statement of every basic block. */
+ FOR_EACH_BB (bb)
+ {
+ block_stmt_iterator i;
+ tree phi;
+
+ /* Propagate known values into PHI nodes. */
+ if (prop_value)
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ replace_phi_args_in (phi, prop_value);
+
+ for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
+ {
+ bool replaced_address, did_replace;
+ tree prev_stmt = NULL;
+ tree stmt = bsi_stmt (i);
+
+ /* Ignore ASSERT_EXPRs. They are used by VRP to generate
+ range information for names and they are discarded
+ afterwards. */
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
+ continue;
+
+ /* Record the state of the statement before replacements. */
+ push_stmt_changes (bsi_stmt_ptr (i));
+
+ /* Replace the statement with its folded version and mark it
+ folded. */
+ did_replace = false;
+ replaced_address = false;
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ prev_stmt = unshare_expr (stmt);
+
+ /* If we have range information, see if we can fold
+ predicate expressions. */
+ if (use_ranges_p)
+ did_replace = fold_predicate_in (stmt);
+
+ if (prop_value)
+ {
+ /* Only replace real uses if we couldn't fold the
+ statement using value range information (value range
+ information is not collected on virtuals, so we only
+ need to check this for real uses). */
+ if (!did_replace)
+ did_replace |= replace_uses_in (stmt, &replaced_address,
+ prop_value);
+
+ did_replace |= replace_vuses_in (stmt, &replaced_address,
+ prop_value);
+ }
+
+ /* If we made a replacement, fold and cleanup the statement. */
+ if (did_replace)
+ {
+ tree old_stmt = stmt;
+ tree rhs;
+
+ fold_stmt (bsi_stmt_ptr (i));
+ stmt = bsi_stmt (i);
+
+ /* If we cleaned up EH information from the statement,
+ remove EH edges. */
+ if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
+ tree_purge_dead_eh_edges (bb);
+
+ rhs = get_rhs (stmt);
+ if (TREE_CODE (rhs) == ADDR_EXPR)
+ recompute_tree_invariant_for_addr_expr (rhs);
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Folded statement: ");
+ print_generic_stmt (dump_file, prev_stmt, TDF_SLIM);
+ fprintf (dump_file, " into: ");
+ print_generic_stmt (dump_file, stmt, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
+
+ /* Determine what needs to be done to update the SSA form. */
+ pop_stmt_changes (bsi_stmt_ptr (i));
+ something_changed = true;
+ }
+ else
+ {
+ /* The statement was not modified, discard the change buffer. */
+ discard_stmt_changes (bsi_stmt_ptr (i));
+ }
+
+ /* Some statements may be simplified using ranges. For
+ example, division may be replaced by shifts, modulo
+ replaced with bitwise and, etc. Do this after
+ substituting constants, folding, etc so that we're
+ presented with a fully propagated, canonicalized
+ statement. */
+ if (use_ranges_p)
+ simplify_stmt_using_ranges (stmt);
+ }
+ }
+
+ if (dump_file && (dump_flags & TDF_STATS))
+ {
+ fprintf (dump_file, "Constants propagated: %6ld\n",
+ prop_stats.num_const_prop);
+ fprintf (dump_file, "Copies propagated: %6ld\n",
+ prop_stats.num_copy_prop);
+ fprintf (dump_file, "Predicates folded: %6ld\n",
+ prop_stats.num_pred_folded);
+ }
+ return something_changed;
+}
+
#include "gt-tree-ssa-propagate.h"