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* [Bug middle-end/48590] New: Alias analysis confused by builtin-stack-save/restore
@ 2011-04-13 11:02 rguenth at gcc dot gnu.org
2011-04-13 11:04 ` [Bug middle-end/48590] " rguenth at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-04-13 11:02 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48590
Summary: Alias analysis confused by builtin-stack-save/restore
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: middle-end
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: rguenth@gcc.gnu.org
Lame testcase for now:
float foo (int i, double *d)
{
float f;
double dd;
int j;
dd = *d;
for (j = 0; j<i; ++j)
{
float a[i];
f+=a[j] + *d + dd;
}
return f;
}
we fail to CSE *d because we think that __builtin_stack_save () clobbers it.
__builtin_stack_restore () has similar effects on DSE (it appears to use
all aliased memory).
We have to be careful when improving this to not allow sinking operations
on alloca'd memory over a __builtin_stack_restore ().
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/48590] Alias analysis confused by builtin-stack-save/restore
2011-04-13 11:02 [Bug middle-end/48590] New: Alias analysis confused by builtin-stack-save/restore rguenth at gcc dot gnu.org
@ 2011-04-13 11:04 ` rguenth at gcc dot gnu.org
2011-04-13 11:13 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-04-13 11:04 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48590
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2011.04.13 11:04:23
AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org
|gnu.org |
Ever Confirmed|0 |1
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-04-13 11:04:23 UTC ---
Mine anyway.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/48590] Alias analysis confused by builtin-stack-save/restore
2011-04-13 11:02 [Bug middle-end/48590] New: Alias analysis confused by builtin-stack-save/restore rguenth at gcc dot gnu.org
2011-04-13 11:04 ` [Bug middle-end/48590] " rguenth at gcc dot gnu.org
@ 2011-04-13 11:13 ` rguenth at gcc dot gnu.org
2011-04-14 12:19 ` rguenth at gcc dot gnu.org
2011-04-14 12:37 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-04-13 11:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48590
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-04-13 11:13:14 UTC ---
The following should be safe (but doesn't try to address the dead code
elimination issue).
Index: gcc/tree-ssa-alias.c
===================================================================
--- gcc/tree-ssa-alias.c (revision 170321)
+++ gcc/tree-ssa-alias.c (working copy)
@@ -1432,6 +1432,9 @@ call_may_clobber_ref_p_1 (gimple call, a
tree ptr = gimple_call_arg (call, 0);
return ptr_deref_may_alias_ref_p_1 (ptr, ref);
}
+ case BUILT_IN_STACK_SAVE:
+ case BUILT_IN_STACK_RESTORE:
+ return false;
case BUILT_IN_GAMMA_R:
case BUILT_IN_GAMMAF_R:
case BUILT_IN_GAMMAL_R:
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/48590] Alias analysis confused by builtin-stack-save/restore
2011-04-13 11:02 [Bug middle-end/48590] New: Alias analysis confused by builtin-stack-save/restore rguenth at gcc dot gnu.org
2011-04-13 11:04 ` [Bug middle-end/48590] " rguenth at gcc dot gnu.org
2011-04-13 11:13 ` rguenth at gcc dot gnu.org
@ 2011-04-14 12:19 ` rguenth at gcc dot gnu.org
2011-04-14 12:37 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-04-14 12:19 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48590
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-04-14 12:19:35 UTC ---
Author: rguenth
Date: Thu Apr 14 12:19:28 2011
New Revision: 172427
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=172427
Log:
2011-04-14 Richard Guenther <rguenther@suse.de>
PR tree-optimization/48590
* tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Handle
BUILT_IN_ALLOCA, BUILT_IN_STACK_SAVE and BUILT_IN_STACK_RESTORE.
(call_may_clobber_ref_p_1): Handle BUILT_IN_ALLOCA and
BUILT_IN_STACK_SAVE.
* tree-ssa-dce.c (propagate_necessity): Handle
BUILT_IN_ALLOCA, BUILT_IN_STACK_SAVE and BUILT_IN_STACK_RESTORE.
Modified:
trunk/gcc/ChangeLog
trunk/gcc/tree-ssa-alias.c
trunk/gcc/tree-ssa-dce.c
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/48590] Alias analysis confused by builtin-stack-save/restore
2011-04-13 11:02 [Bug middle-end/48590] New: Alias analysis confused by builtin-stack-save/restore rguenth at gcc dot gnu.org
` (2 preceding siblings ...)
2011-04-14 12:19 ` rguenth at gcc dot gnu.org
@ 2011-04-14 12:37 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-04-14 12:37 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48590
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-04-14 12:37:40 UTC ---
Fixed.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2011-04-13 11:02 [Bug middle-end/48590] New: Alias analysis confused by builtin-stack-save/restore rguenth at gcc dot gnu.org
2011-04-13 11:04 ` [Bug middle-end/48590] " rguenth at gcc dot gnu.org
2011-04-13 11:13 ` rguenth at gcc dot gnu.org
2011-04-14 12:19 ` rguenth at gcc dot gnu.org
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