/* Generic SSA value propagation engine.
- Copyright (C) 2004, 2005, 2006 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, 51 Franklin Street, Fifth Floor, Boston, MA
- 02110-1301, USA. */
+ along with GCC; see the file COPYING3. If not see
+ <http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
static void
cfg_blocks_add (basic_block bb)
{
+ bool head = false;
+
gcc_assert (bb != ENTRY_BLOCK_PTR && bb != EXIT_BLOCK_PTR);
gcc_assert (!TEST_BIT (bb_in_list, bb->index));
cfg_blocks_head = 0;
VEC_safe_grow (basic_block, heap, cfg_blocks, 2 * cfg_blocks_tail);
}
- else
+ /* 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
+ {
+ if (cfg_blocks_head == 0)
+ cfg_blocks_head = VEC_length (basic_block, cfg_blocks);
+ --cfg_blocks_head;
+ head = true;
+ }
}
- VEC_replace (basic_block, 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);
}
{
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. */
switch (TREE_CODE_CLASS (code))
{
case tcc_declaration:
- if (!is_gimple_variable(expr))
+ if (!is_gimple_variable (expr))
return false;
break;
switch (code)
{
case ADDR_EXPR:
- if (TREE_CODE (TREE_OPERAND (expr, 0)) == ARRAY_REF
- && !is_gimple_val (TREE_OPERAND (TREE_OPERAND (expr, 0), 1)))
- return false;
- break;
+ {
+ 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 CALL_EXPR:
case EXC_PTR_EXPR:
case FILTER_EXPR:
break;
}
break;
+ case tcc_vl_exp:
+ switch (code)
+ {
+ case CALL_EXPR:
+ break;
+ default:
+ return false;
+ }
+ break;
+
case tcc_exceptional:
switch (code)
{
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)
+ && (EXPR_P (expr)
+ || GIMPLE_STMT_P (expr))
&& ! EXPR_HAS_LOCATION (expr)
&& TREE_SIDE_EFFECTS (expr)
&& TREE_CODE (expr) != LABEL_EXPR)
{
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;
+ TREE_OPERAND (op, 0) = expr;
+ else
+ GIMPLE_STMT_OPERAND (stmt, 1) = expr;
break;
case COND_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 (in_ssa_p
+ if (gimple_in_ssa_p (cfun)
&& TREE_SIDE_EFFECTS (expr))
{
/* Fix all the SSA_NAMEs created by *STMT_P to point to its new
SSA_NAME_DEF_STMT (var) = *stmt_p;
}
}
+ stmt->base.ann = NULL;
break;
}
}
-/* Return the first V_MAY_DEF or V_MUST_DEF operand for STMT. */
+/* Return the first VDEF operand for STMT. */
tree
first_vdef (tree stmt)
{
tree rhs;
- if (TREE_CODE (stmt) != MODIFY_EXPR)
+ if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
return false;
- if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF|SSA_OP_VUSE))
+ if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF|SSA_OP_VUSE))
return false;
- rhs = TREE_OPERAND (stmt, 1);
+ rhs = GIMPLE_STMT_OPERAND (stmt, 1);
STRIP_NOPS (rhs);
return (!TREE_THIS_VOLATILE (rhs)
{
tree lhs;
- if (TREE_CODE (stmt) != MODIFY_EXPR)
+ if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
return false;
- if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF|SSA_OP_VMUSTDEF))
+ if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF))
return false;
- lhs = TREE_OPERAND (stmt, 0);
+ lhs = GIMPLE_STMT_OPERAND (stmt, 0);
STRIP_NOPS (lhs);
return (!TREE_THIS_VOLATILE (lhs)
GIMPLE register, then we are making a copy/constant propagation
from a memory store. For instance,
- # a_3 = V
_MAY_DEF <a_2>
+ # a_3 = VDEF <a_2>
a.b = x_1;
...
# VUSE <a_3>
the VUSE(s) that we are replacing. Otherwise, we may do the
wrong replacement:
- # a_3 = V
_MAY_DEF <a_2>
- # b_5 = V_MAY_DEF <b_4>
+ # a_3 = VDEF <a_2>
+ # b_5 = VDEF <b_4>
*p = 10;
...
# VUSE <b_5>
stored in different locations:
if (...)
- # a_3 = V
_MAY_DEF <a_2>
+ # a_3 = VDEF <a_2>
a.b = 3;
else
- # a_4 = V
_MAY_DEF <a_2>
+ # a_4 = VDEF <a_2>
a.c = 3;
# a_5 = PHI <a_3, a_4>
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 = TREE_OPERAND (stmt, 1);
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
if (val
&& val->value
/* If we are replacing a constant address, inform our
caller. */
if (TREE_CODE (val->value) != SSA_NAME
- && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (stmt, 1)))
+ && POINTER_TYPE_P (TREE_TYPE (GIMPLE_STMT_OPERAND (stmt, 1)))
&& replaced_addresses_p)
*replaced_addresses_p = true;
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. */
- TREE_OPERAND (stmt, 1) = val->value;
+ GIMPLE_STMT_OPERAND (stmt, 1) = val->value;
if (TREE_CODE (val->value) != SSA_NAME)
prop_stats.num_const_prop++;
fold_predicate_in (tree stmt)
{
tree *pred_p = NULL;
- bool modify_expr_p = false;
+ bool modify_stmt_p = false;
tree val;
- if (TREE_CODE (stmt) == MODIFY_EXPR
- && COMPARISON_CLASS_P (TREE_OPERAND (stmt, 1)))
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && COMPARISON_CLASS_P (GIMPLE_STMT_OPERAND (stmt, 1)))
{
- modify_expr_p = true;
- pred_p = &TREE_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, true);
+ val = vrp_evaluate_conditional (*pred_p, stmt);
if (val)
{
- if (modify_expr_p)
+ if (modify_stmt_p)
val = fold_convert (TREE_TYPE (*pred_p), val);
if (dump_file)
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). */
+ VRP pass).
-void
+ 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;
+ return false;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "\nSubstituing values and folding statements\n\n");
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))
+ /* Propagate known values into stmts. Do a backward walk to expose
+ more trivially deletable stmts. */
+ for (i = bsi_last (bb); !bsi_end_p (i);)
{
bool replaced_address, did_replace;
- tree prev_stmt = NULL;
+ tree call, 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) == MODIFY_EXPR
- && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
- continue;
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
+ {
+ bsi_prev (&i);
+ continue;
+ }
+
+ /* No point propagating into a stmt whose result is not used,
+ but instead we might be able to remove a trivially dead stmt. */
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) == SSA_NAME
+ && !stmt_ann (stmt)->has_volatile_ops
+ && has_zero_uses (GIMPLE_STMT_OPERAND (stmt, 0))
+ && !tree_could_throw_p (stmt)
+ && (!(call = get_call_expr_in (stmt))
+ || !TREE_SIDE_EFFECTS (call)))
+ {
+ if (dump_file && dump_flags & TDF_DETAILS)
+ {
+ fprintf (dump_file, "Removing dead stmt ");
+ print_generic_expr (dump_file, stmt, 0);
+ fprintf (dump_file, "\n");
+ }
+ bsi_remove (&i, true);
+ release_defs (stmt);
+ if (!bsi_end_p (i))
+ bsi_prev (&i);
+ 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. */
fold_stmt (bsi_stmt_ptr (i));
stmt = bsi_stmt (i);
- /* If we folded a builtin function, we'll likely
- need to rename VDEFs. */
- mark_new_vars_to_rename (stmt);
-
/* If we cleaned up EH information from the statement,
remove EH edges. */
if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
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
if (use_ranges_p)
simplify_stmt_using_ranges (stmt);
+ bsi_prev (&i);
}
}
fprintf (dump_file, "Predicates folded: %6ld\n",
prop_stats.num_pred_folded);
}
+ return something_changed;
}
#include "gt-tree-ssa-propagate.h"
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