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[PATCH] Improve handle_char_store in strlen pass (PR tree-optimization/57230)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Richard Biener <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 10 May 2013 16:49:50 +0200
- Subject: [PATCH] Improve handle_char_store in strlen pass (PR tree-optimization/57230)
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
Related to the previously posted patch, I've noticed that
on the attached testcase we don't optimize the strlen into
constant, even when we easily could.
Implemented thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk?
2013-05-10 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/57230
* tree-ssa-strlen.c (handle_char_store): Record length for
array store from STRING_CST.
* gcc.dg/strlenopt-24.c: New test.
--- gcc/tree-ssa-strlen.c.jj 2013-05-10 08:57:20.000000000 +0200
+++ gcc/tree-ssa-strlen.c 2013-05-10 10:22:03.166458997 +0200
@@ -1740,6 +1740,25 @@ handle_char_store (gimple_stmt_iterator
if (si != NULL)
si->writable = true;
}
+ else if (idx == 0
+ && TREE_CODE (gimple_assign_rhs1 (stmt)) == STRING_CST
+ && ssaname == NULL_TREE
+ && TREE_CODE (TREE_TYPE (lhs)) == ARRAY_TYPE)
+ {
+ size_t l = strlen (TREE_STRING_POINTER (gimple_assign_rhs1 (stmt)));
+ HOST_WIDE_INT a = int_size_in_bytes (TREE_TYPE (lhs));
+ if (a > 0 && (unsigned HOST_WIDE_INT) a > l)
+ {
+ int idx = new_addr_stridx (lhs);
+ if (idx != 0)
+ {
+ si = new_strinfo (build_fold_addr_expr (lhs), idx,
+ build_int_cst (size_type_node, l));
+ set_strinfo (idx, si);
+ si->dont_invalidate = true;
+ }
+ }
+ }
if (si != NULL && initializer_zerop (gimple_assign_rhs1 (stmt)))
{
--- gcc/testsuite/gcc.dg/strlenopt-24.c.jj 2013-05-10 10:30:01.343821849 +0200
+++ gcc/testsuite/gcc.dg/strlenopt-24.c 2013-05-10 10:30:37.736621582 +0200
@@ -0,0 +1,17 @@
+/* PR tree-optimization/57230 */
+/* { dg-do run } */
+/* { dg-options "-O2 -fdump-tree-strlen" } */
+
+#include "strlenopt.h"
+
+int
+main ()
+{
+ char p[] = "hello world";
+ if (strlen (p) != 11)
+ abort ();
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "strlen \\(" 0 "strlen" } } *
+/* { dg-final { cleanup-tree-dump "strlen" } } */
Jakub