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[RFC] Fix PR 43562
- From: Jie Zhang <jie at codesourcery dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 29 Mar 2010 12:03:29 +0800
- Subject: [RFC] Fix PR 43562
I asked a related question several days ago about this PR but no replies:
http://gcc.gnu.org/ml/gcc/2010-03/msg00367.html
So I encouraged myself to have a try. I take a further look at this PR.
It seems none of options 2, 3, 4, which were listed in the above email,
is feasible, because the comment above backend_init_target says:
/* This function can be called multiple times to reinitialize the compiler
back end when register classes or instruction sets have changed,
before each function. */
So we cannot add a flag to avoid multiple calls to init_caller_save.
This leaves us only option 1. This patch just makes backend_init_target
always call init_caller_save. Is it OK if no regressions found?
--
Jie Zhang
CodeSourcery
(650) 331-3385 x735
* toplev.c (backend_init_target): Always calls init_caller_save.
testsuite/
* gcc.dg/pr43562.c: New test.
Index: toplev.c
===================================================================
--- toplev.c (revision 157628)
+++ toplev.c (working copy)
@@ -2183,8 +2183,7 @@ backend_init_target (void)
/* We may need to recompute regno_save_code[] and regno_restore_code[]
after a mode change as well. */
- if (flag_caller_saves)
- init_caller_save ();
+ init_caller_save ();
expand_dummy_function_end ();
}
Index: testsuite/gcc.dg/pr43562.c
===================================================================
--- testsuite/gcc.dg/pr43562.c (revision 0)
+++ testsuite/gcc.dg/pr43562.c (revision 0)
@@ -0,0 +1,20 @@
+/* { dg-options "-O0" } */
+/* { dg-do compile } */
+
+extern unsigned foo (void);
+extern void bar (void);
+
+__attribute__ ((optimize ("O2")))
+void bak ()
+{
+ unsigned a;
+ while (1)
+ {
+ a = foo ();
+ while (a)
+ {
+ a &= 1;
+ bar ();
+ }
+ }
+}