/* 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);
}
}
-/* 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;
}
+ 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))
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;
+ GIMPLE_STMT_OPERAND (stmt, 1) = expr;
break;
case COND_EXPR:
SSA_NAME_DEF_STMT (var) = *stmt_p;
}
}
+ stmt->base.ann = NULL;
break;
}
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
afterwards. */
if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
&& TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
- continue;
+ {
+ 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));
statement. */
if (use_ranges_p)
simplify_stmt_using_ranges (stmt);
+
+ bsi_prev (&i);
}
}
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