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* [Bug tree-optimization/47365] New: [4.5 Regression] wrong code with -O -ftree-pre
@ 2011-01-19 23:12 zsojka at seznam dot cz
2011-01-20 10:55 ` [Bug tree-optimization/47365] " rguenth at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: zsojka at seznam dot cz @ 2011-01-19 23:12 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47365
Summary: [4.5 Regression] wrong code with -O -ftree-pre
Product: gcc
Version: 4.5.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: zsojka@seznam.cz
Host: x86_64-pc-linux-gnu
Target: x86_64-pc-linux-gnu
Created attachment 23035
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23035
reduced testcase
Reported by Vegard Nossum at IRC.
Output:
$ gcc-4.5 -O -ftree-pre testcase.c
$ ./a.out
Aborted
In the testcase.c.092t.pre dump, there is:
...
<bb 2>:
D.2739_4 = b.a[0].i;
i.0_5 = i;
if (D.2739_4 != i.0_5)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
b.a[0] = b.a[1];
b.a[1].i = D.2739_4;
pretmp.3_6 = b.a[1].i;
goto <bb 6>;
<bb 4>:
...
<bb 9>:
<bb 6>:
# prephitmp.4_8 = PHI <D.2739_4(9), pretmp.3_6(3)>
D.2739_9 = prephitmp.4_8;
D.2739_9 = prephitmp.4_8;
if (D.2739_9 == 0)
goto <bb 7>;
...
Problematic line is
pretmp.3_6 = b.a[1].i;
which reads the new value of "b.a[1].i". It should either happen one line
earlier, or it should read "b.a[0].i".
It seems that the fact "b.a[0] = b.a[1]" overwrites "b.a[0].i" is ignored.
Of couse I can be wrong.
Tested revisions:
r169006 - OK
4.5 r168785 - fail
4.4 r168785 - OK
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/47365] [4.5 Regression] wrong code with -O -ftree-pre
2011-01-19 23:12 [Bug tree-optimization/47365] New: [4.5 Regression] wrong code with -O -ftree-pre zsojka at seznam dot cz
@ 2011-01-20 10:55 ` rguenth at gcc dot gnu.org
2011-01-20 12:21 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-01-20 10:55 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47365
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2011.01.20 10:50:43
AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org
|gnu.org |
Target Milestone|--- |4.5.3
Ever Confirmed|0 |1
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-20 10:50:43 UTC ---
Confirmed and mine.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/47365] [4.5 Regression] wrong code with -O -ftree-pre
2011-01-19 23:12 [Bug tree-optimization/47365] New: [4.5 Regression] wrong code with -O -ftree-pre zsojka at seznam dot cz
2011-01-20 10:55 ` [Bug tree-optimization/47365] " rguenth at gcc dot gnu.org
@ 2011-01-20 12:21 ` rguenth at gcc dot gnu.org
2011-01-21 4:17 ` [Bug tree-optimization/47365] [4.5/4.6 " zsojka at seznam dot cz
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-01-20 12:21 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47365
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-20 12:01:23 UTC ---
What happens is that when translating D.2739_9 = b.a[0].i; from bb6 to
bb3 value-numbering does look through the aggregate copy b.a[0] = b.a[1];
continuing to look for b.a[1].i and finding D.2737_7 = b.a[1].i; from bb4
(which is ok - the consumer has to check availability). Thus
b.a[1].i ends up in antic-out (not a problem) with a new value-number,
it doesn't end up in antic-in of bb3.
b.a[0].i is partially redundant in bb6, D.2739_4 is correctly found as
the available expression for it via bb6. But when we translate
b.a[0].i to bb3 again during insertion we again obtain b.a[1].i
(because it's also still in the phi-translation cache). It is
obviously not available here so we insert it. Oops.
We don't prune invalid translations during insertion - that's the
basic problem. We'd expect to find a leader as the translated
expression has a SCCVN value-number.
The problem is latent on trunk.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/47365] [4.5/4.6 Regression] wrong code with -O -ftree-pre
2011-01-19 23:12 [Bug tree-optimization/47365] New: [4.5 Regression] wrong code with -O -ftree-pre zsojka at seznam dot cz
2011-01-20 10:55 ` [Bug tree-optimization/47365] " rguenth at gcc dot gnu.org
2011-01-20 12:21 ` rguenth at gcc dot gnu.org
@ 2011-01-21 4:17 ` zsojka at seznam dot cz
2011-01-21 14:08 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: zsojka at seznam dot cz @ 2011-01-21 4:17 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47365
Zdenek Sojka <zsojka at seznam dot cz> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work|4.6.0 |
Summary|[4.5 Regression] wrong code |[4.5/4.6 Regression] wrong
|with -O -ftree-pre |code with -O -ftree-pre
Known to fail| |4.6.0
--- Comment #3 from Zdenek Sojka <zsojka at seznam dot cz> 2011-01-21 00:06:51 UTC ---
(In reply to comment #2)
> The problem is latent on trunk.
Updating the summary to show in the 4.6 regression list.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/47365] [4.5/4.6 Regression] wrong code with -O -ftree-pre
2011-01-19 23:12 [Bug tree-optimization/47365] New: [4.5 Regression] wrong code with -O -ftree-pre zsojka at seznam dot cz
` (2 preceding siblings ...)
2011-01-21 4:17 ` [Bug tree-optimization/47365] [4.5/4.6 " zsojka at seznam dot cz
@ 2011-01-21 14:08 ` rguenth at gcc dot gnu.org
2011-01-21 14:14 ` rguenth at gcc dot gnu.org
2011-01-21 14:22 ` rguenth at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-01-21 14:08 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47365
--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-21 14:02:45 UTC ---
Author: rguenth
Date: Fri Jan 21 14:02:41 2011
New Revision: 169089
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=169089
Log:
2011-01-21 Richard Guenther <rguenther@suse.de>
PR tree-optimization/47365
* tree-ssa-sccvn.h (vn_lookup_kind): Declare.
(vn_reference_lookup_pieces): Adjust.
(vn_reference_lookup): Likewise.
* tree-ssa-sccvn.c (vn_walk_kind): New static global.
(vn_reference_lookup_3): Only look through kills if in
VN_WALKREWRITE mode.
(vn_reference_lookup_pieces): Adjust.
(vn_reference_lookup): Likewise.
(visit_reference_op_load): Likewise.
(visit_reference_op_store): Likewise.
* tree-ssa-pre.c (phi_translate_1): Use VN_WALK mode.
(compute_avail): Likewise.
(eliminate): Likewise.
* gcc.dg/torture/pr47365.c: New testcase.
* gcc.dg/tree-ssa/pr47392.c: Likewise.
Added:
trunk/gcc/testsuite/gcc.dg/torture/pr47365.c
trunk/gcc/testsuite/gcc.dg/tree-ssa/pr47392.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-pre.c
trunk/gcc/tree-ssa-sccvn.c
trunk/gcc/tree-ssa-sccvn.h
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/47365] [4.5/4.6 Regression] wrong code with -O -ftree-pre
2011-01-19 23:12 [Bug tree-optimization/47365] New: [4.5 Regression] wrong code with -O -ftree-pre zsojka at seznam dot cz
` (3 preceding siblings ...)
2011-01-21 14:08 ` rguenth at gcc dot gnu.org
@ 2011-01-21 14:14 ` rguenth at gcc dot gnu.org
2011-01-21 14:22 ` rguenth at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-01-21 14:14 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47365
--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-21 14:05:03 UTC ---
Author: rguenth
Date: Fri Jan 21 14:05:00 2011
New Revision: 169090
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=169090
Log:
2011-01-21 Richard Guenther <rguenther@suse.de>
PR tree-optimization/47365
* tree-ssa-sccvn.h (vn_lookup_kind): Declare.
(vn_reference_lookup_pieces): Adjust.
(vn_reference_lookup): Likewise.
* tree-ssa-sccvn.c (vn_walk_kind): New static global.
(vn_reference_lookup_3): Only look through kills if in
VN_WALKREWRITE mode.
(vn_reference_lookup_pieces): Adjust.
(vn_reference_lookup): Likewise.
(visit_reference_op_load): Likewise.
(visit_reference_op_store): Likewise.
* tree-ssa-pre.c (phi_translate_1): Use VN_WALK mode.
(compute_avail): Likewise.
(eliminate): Likewise.
* gcc.dg/torture/pr47365.c: New testcase.
* gcc.dg/tree-ssa/pr47392.c: Likewise.
Added:
branches/gcc-4_5-branch/gcc/testsuite/gcc.dg/torture/pr47365.c
branches/gcc-4_5-branch/gcc/testsuite/gcc.dg/tree-ssa/pr47392.c
Modified:
branches/gcc-4_5-branch/gcc/ChangeLog
branches/gcc-4_5-branch/gcc/testsuite/ChangeLog
branches/gcc-4_5-branch/gcc/tree-ssa-pre.c
branches/gcc-4_5-branch/gcc/tree-ssa-sccvn.c
branches/gcc-4_5-branch/gcc/tree-ssa-sccvn.h
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/47365] [4.5/4.6 Regression] wrong code with -O -ftree-pre
2011-01-19 23:12 [Bug tree-optimization/47365] New: [4.5 Regression] wrong code with -O -ftree-pre zsojka at seznam dot cz
` (4 preceding siblings ...)
2011-01-21 14:14 ` rguenth at gcc dot gnu.org
@ 2011-01-21 14:22 ` rguenth at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-01-21 14:22 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47365
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #6 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-21 14:06:55 UTC ---
Fixed.
^ permalink raw reply [flat|nested] 7+ messages in thread
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2011-01-20 12:21 ` rguenth at gcc dot gnu.org
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