This fixes the PR in another way as well, allowing as many capture
uses in the replacement expression as in the original one, avoiding
some spurious save_exprs that way (and not perform "CSE" within
the match-and-simplify framework).
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2015-12-01 Richard Biener <rguent...@suse.de>
PR middle-end/68590
* genmatch.c (struct capture_info): Add match_use_count.
(capture_info::walk_match): Increment match_use_count.
(dt_simplify::gen_1): For GENERIC, only wrap multi-use
replacements in a save_expr if they occur more often than
in the original expression.
Index: gcc/genmatch.c
===================================================================
--- gcc/genmatch.c (revision 231101)
+++ gcc/genmatch.c (working copy)
@@ -1851,7 +1850,8 @@ struct capture_info
bool force_single_use;
bool cond_expr_cond_p;
unsigned long toplevel_msk;
- int result_use_count;
+ unsigned match_use_count;
+ unsigned result_use_count;
unsigned same_as;
capture *c;
};
@@ -1901,6 +1901,7 @@ capture_info::walk_match (operand *o, un
if (capture *c = dyn_cast <capture *> (o))
{
unsigned where = c->where;
+ info[where].match_use_count++;
info[where].toplevel_msk |= 1 << toplevel_arg;
info[where].force_no_side_effects_p |= conditional_p;
info[where].cond_expr_cond_p |= cond_expr_cond_p;
@@ -3106,13 +3107,16 @@ dt_simplify::gen_1 (FILE *f, int indent,
else if (is_a <predicate_id *> (opr))
is_predicate = true;
/* Search for captures used multiple times in the result expression
- and dependent on TREE_SIDE_EFFECTS emit a SAVE_EXPR. */
+ and wrap them in a SAVE_EXPR. Allow as many uses as in the
+ original expression. */
if (!is_predicate)
for (int i = 0; i < s->capture_max + 1; ++i)
{
- if (cinfo.info[i].same_as != (unsigned)i)
+ if (cinfo.info[i].same_as != (unsigned)i
+ || cinfo.info[i].cse_p)
continue;
- if (cinfo.info[i].result_use_count > 1)
+ if (cinfo.info[i].result_use_count
+ > cinfo.info[i].match_use_count)
fprintf_indent (f, indent,
"captures[%d] = save_expr (captures[%d]);\n",
i, i);
