public inbox for gcc-cvs@sourceware.org
help / color / mirror / Atom feed
* [gcc r11-6922] varpool: Restore GENERIC TREE_READONLY automatic var optimization [PR7260]
@ 2021-01-27 9:10 Jakub Jelinek
0 siblings, 0 replies; only message in thread
From: Jakub Jelinek @ 2021-01-27 9:10 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:efc9ccbfd0ca4da6bf0aba913df6f77f56044dc2
commit r11-6922-gefc9ccbfd0ca4da6bf0aba913df6f77f56044dc2
Author: Jakub Jelinek <jakub@redhat.com>
Date: Wed Jan 27 10:08:46 2021 +0100
varpool: Restore GENERIC TREE_READONLY automatic var optimization [PR7260]
In 4.8 and earlier we used to fold the following to 0 during GENERIC folding,
but we don't do that anymore because ctor_for_folding etc. has been turned into a
GIMPLE centric API, but as the testcase shows, it is invoked even during
GENERIC folding and there the automatic vars still should have meaningful
initializers. I've verified that the C++ FE drops TREE_READONLY on
automatic vars with const qualified types if they require non-constant
(runtime) initialization.
2021-01-27 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/97260
* varpool.c: Include tree-pass.h.
(ctor_for_folding): In GENERIC return DECL_INITIAL for TREE_READONLY
non-TREE_SIDE_EFFECTS automatic variables.
* gcc.dg/tree-ssa/pr97260.c: New test.
Diff:
---
gcc/testsuite/gcc.dg/tree-ssa/pr97260.c | 11 +++++++++++
gcc/varpool.c | 8 ++++++++
2 files changed, 19 insertions(+)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr97260.c b/gcc/testsuite/gcc.dg/tree-ssa/pr97260.c
new file mode 100644
index 00000000000..9b3723b7834
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr97260.c
@@ -0,0 +1,11 @@
+/* PR tree-optimization/97260 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump "return 0;" "optimized" } } */
+
+int
+foo (void)
+{
+ const char a[] = "1234";
+ return __builtin_memcmp (a, "1234", 4);
+}
diff --git a/gcc/varpool.c b/gcc/varpool.c
index e0488ed5a12..86f16052984 100644
--- a/gcc/varpool.c
+++ b/gcc/varpool.c
@@ -35,6 +35,7 @@ along with GCC; see the file COPYING3. If not see
#include "context.h"
#include "stringpool.h"
#include "attribs.h"
+#include "tree-pass.h"
const char * const tls_model_names[]={"none", "emulated",
"global-dynamic", "local-dynamic",
@@ -412,6 +413,13 @@ ctor_for_folding (tree decl)
if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
{
gcc_assert (!TREE_PUBLIC (decl));
+ /* Unless this is called during FE folding. */
+ if (cfun
+ && (cfun->curr_properties & (PROP_trees | PROP_rtl)) == 0
+ && TREE_READONLY (decl)
+ && !TREE_SIDE_EFFECTS (decl)
+ && DECL_INITIAL (decl))
+ return DECL_INITIAL (decl);
return error_mark_node;
}
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2021-01-27 9:10 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-27 9:10 [gcc r11-6922] varpool: Restore GENERIC TREE_READONLY automatic var optimization [PR7260] Jakub Jelinek
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).