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* [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu
@ 2015-07-20 19:52 su at cs dot ucdavis.edu
2015-07-20 19:56 ` [Bug tree-optimization/66952] [6 Regression] " mpolacek at gcc dot gnu.org
` (8 more replies)
0 siblings, 9 replies; 10+ messages in thread
From: su at cs dot ucdavis.edu @ 2015-07-20 19:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
Bug ID: 66952
Summary: wrong code at -O2 and -O3 on x86_64-linux-gnu
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
Target Milestone: ---
The current gcc trunk miscompiles the following code on x86_64-linux at -O2 and
-O3 in both 32-bit and 64-bit modes.
This is a regression from 5.1.x.
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 6.0.0 20150719 (experimental) [trunk revision 225987] (GCC)
$
$ gcc-trunk -Os small.c; ./a.out
$ gcc-5.1 -O2 small.c; ./a.out
$
$ gcc-trunk -O2 small.c
$ ./a.out
Aborted (core dumped)
$
-----------------------------------------------
int a = 128, b;
int
fn1 (char p1, int p2)
{
return p1 < 0 || p1 > 1 >> p2 ? 0 : p1 << 1;
}
int
fn2 ()
{
char c = a;
b = fn1 (c, 1);
if ((128 | c) < 0 ? 1 : 0)
return 1;
return 0;
}
int
main ()
{
if (fn2 () != 1)
__builtin_abort ();
return 0;
}
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
@ 2015-07-20 19:56 ` mpolacek at gcc dot gnu.org
2015-07-20 20:54 ` mpolacek at gcc dot gnu.org
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2015-07-20 19:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-07-20
CC| |mpolacek at gcc dot gnu.org
Target Milestone|--- |6.0
Summary|wrong code at -O2 and -O3 |[6 Regression] wrong code
|on x86_64-linux-gnu |at -O2 and -O3 on
| |x86_64-linux-gnu
Ever confirmed|0 |1
--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
2015-07-20 19:56 ` [Bug tree-optimization/66952] [6 Regression] " mpolacek at gcc dot gnu.org
@ 2015-07-20 20:54 ` mpolacek at gcc dot gnu.org
2015-07-21 8:06 ` rguenth at gcc dot gnu.org
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2015-07-20 20:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r225861.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
2015-07-20 19:56 ` [Bug tree-optimization/66952] [6 Regression] " mpolacek at gcc dot gnu.org
2015-07-20 20:54 ` mpolacek at gcc dot gnu.org
@ 2015-07-21 8:06 ` rguenth at gcc dot gnu.org
2015-07-22 7:57 ` rguenth at gcc dot gnu.org
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-07-21 8:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Mine.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
` (2 preceding siblings ...)
2015-07-21 8:06 ` rguenth at gcc dot gnu.org
@ 2015-07-22 7:57 ` rguenth at gcc dot gnu.org
2015-07-22 11:32 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-07-22 7:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, I can't see what is wrong with the pattern. We just replace
_13 = (int) c_4;
if (_13 <= 0)
with
<bb 3>:
_13 = (int) c_4;
if (c_4 <= 0)
with c_4 being signed char. Something else must go wrong here. Still
-fno-tree-forwprop fixes the bug.
There is a missed optimization in VRP1 which ends up ifcombine doing sth.
VRP2 manages to mess things up then:
<bb 2>:
a.0_4 = a;
c_5 = (char) a.0_4;
_6 = (int) c_5;
if (c_5 == 0)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
b = 0;
goto <bb 5>;
<bb 4>:
_9 = ASSERT_EXPR <_6, _6 != 0>;
b = 0;
_10 = _9 | 128;
if (_10 < 0)
a.0_4: VARYING
c_5: VARYING
_6: [0, 127]
_9: [1, 127] EQUIVALENCES: { _6 } (1 elements)
_10: [128, 255]
.MEM_15: VARYING
as you can see _6 is already bogus. Which is because of
<bb 2>:
a.0_4 = a;
c_5 = (char) a.0_4;
# RANGE [0, 127] NONZERO 127
_6 = (int) c_5;
which is because of ifcombine hoisting the def of _6 in
if (c_5 >= 0)
goto <bb 3>;
else
goto <bb 5>;
<bb 3>:
# RANGE [0, 127] NONZERO 127
_6 = (int) c_5;
if (c_5 == 0)
goto <bb 4>;
else
goto <bb 5>;
above the guarding check!
<bb 2>:
a.0_4 = a;
c_5 = (char) a.0_4;
# RANGE [0, 127] NONZERO 127
_6 = (int) c_5;
if (c_5 == 0)
goto <bb 3>;
else
goto <bb 4>;
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
` (3 preceding siblings ...)
2015-07-22 7:57 ` rguenth at gcc dot gnu.org
@ 2015-07-22 11:32 ` rguenth at gcc dot gnu.org
2015-07-23 11:20 ` rguenth at gcc dot gnu.org
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-07-22 11:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Wed Jul 22 11:31:50 2015
New Revision: 226062
URL: https://gcc.gnu.org/viewcvs?rev=226062&root=gcc&view=rev
Log:
2015-07-22 Richard Biener <rguenther@suse.de>
PR tree-optimization/66952
* tree-ssa-ifcombine.c (pass_tree_ifcombine::execute): For
blocks we end up executing unconditionally reset all SSA
info such as range and alignment.
* tree-ssanames.h (reset_flow_sensitive_info): Declare.
* tree-ssanames.c (reset_flow_sensitive_info): New function.
* gcc.dg/torture/pr66952.c: New testcase.
Added:
trunk/gcc/testsuite/gcc.dg/torture/pr66952.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-ifcombine.c
trunk/gcc/tree-ssanames.c
trunk/gcc/tree-ssanames.h
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
` (4 preceding siblings ...)
2015-07-22 11:32 ` rguenth at gcc dot gnu.org
@ 2015-07-23 11:20 ` rguenth at gcc dot gnu.org
2015-09-21 9:57 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-07-23 11:20 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu Jul 23 11:19:26 2015
New Revision: 226104
URL: https://gcc.gnu.org/viewcvs?rev=226104&root=gcc&view=rev
Log:
2015-07-23 Richard Biener <rguenther@suse.de>
PR tree-optimization/66952
* gcc.dg/torture/pr66952.c: Use signed char.
Modified:
trunk/gcc/testsuite/ChangeLog
trunk/gcc/testsuite/gcc.dg/torture/pr66952.c
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
` (5 preceding siblings ...)
2015-07-23 11:20 ` rguenth at gcc dot gnu.org
@ 2015-09-21 9:57 ` rguenth at gcc dot gnu.org
2015-09-21 9:57 ` rguenth at gcc dot gnu.org
2015-09-22 7:47 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-09-21 9:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work| |6.0
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Also backported now.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
` (6 preceding siblings ...)
2015-09-21 9:57 ` rguenth at gcc dot gnu.org
@ 2015-09-21 9:57 ` rguenth at gcc dot gnu.org
2015-09-22 7:47 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-09-21 9:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Mon Sep 21 09:55:57 2015
New Revision: 227961
URL: https://gcc.gnu.org/viewcvs?rev=227961&root=gcc&view=rev
Log:
2015-09-21 Richard Biener <rguenther@suse.de>
Backport from mainline
2015-07-08 Richard Biener <rguenther@suse.de>
PR tree-optimization/66793
* gimple-ssa-isolate-paths.c
(insert_trap_and_remove_trailing_statemen):
Properly split the block after stmts ending it.
* gcc.dg/torture/pr66793.c: New testcase.
2015-08-05 Richard Biener <rguenther@suse.de>
PR tree-optimization/67055
* tree-ssa-ccp.c (fold_builtin_alloca_with_align): Handle
NULL gimple_block.
* g++.dg/torture/pr67055.C: New testcase.
2015-08-05 Richard Biener <rguenther@suse.de>
PR tree-optimization/67121
* tree-if-conv.c (combine_blocks): Clear range-info produced
by stmts no longer executed conditionally.
* gcc.dg/torture/pr67121.c: New testcase.
2015-09-16 Richard Biener <rguenther@suse.de>
PR middle-end/67271
* fold-const.c (native_encode_expr): Bail out on bogus offsets.
* gcc.dg/pr67271.c: New testcase.
2015-07-22 Richard Biener <rguenther@suse.de>
PR tree-optimization/66952
* tree-ssa-ifcombine.c (pass_tree_ifcombine::execute): For
blocks we end up executing unconditionally reset all SSA
info such as range and alignment.
* tree-ssanames.h (reset_flow_sensitive_info): Declare.
* tree-ssanames.c (reset_flow_sensitive_info): New function.
* gcc.dg/torture/pr66952.c: New testcase.
2015-09-15 Richard Biener <rguenther@suse.de>
PR tree-optimization/67470
* tree-ssa-loop-im.c (execute_sm_if_changed): Preserve PHI
structure for PHI hoisting by inserting a forwarder block
if appropriate.
* gcc.dg/torture/pr67470.c: New testcase.
Added:
branches/gcc-5-branch/gcc/testsuite/g++.dg/torture/pr67055.C
branches/gcc-5-branch/gcc/testsuite/gcc.dg/pr67271.c
branches/gcc-5-branch/gcc/testsuite/gcc.dg/torture/pr66793.c
branches/gcc-5-branch/gcc/testsuite/gcc.dg/torture/pr66952.c
branches/gcc-5-branch/gcc/testsuite/gcc.dg/torture/pr67121.c
branches/gcc-5-branch/gcc/testsuite/gcc.dg/torture/pr67470.c
Modified:
branches/gcc-5-branch/gcc/ChangeLog
branches/gcc-5-branch/gcc/fold-const.c
branches/gcc-5-branch/gcc/gimple-ssa-isolate-paths.c
branches/gcc-5-branch/gcc/testsuite/ChangeLog
branches/gcc-5-branch/gcc/tree-if-conv.c
branches/gcc-5-branch/gcc/tree-ssa-ccp.c
branches/gcc-5-branch/gcc/tree-ssa-ifcombine.c
branches/gcc-5-branch/gcc/tree-ssa-loop-im.c
branches/gcc-5-branch/gcc/tree-ssanames.c
branches/gcc-5-branch/gcc/tree-ssanames.h
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/66952] [6 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu
2015-07-20 19:52 [Bug tree-optimization/66952] New: wrong code at -O2 and -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
` (7 preceding siblings ...)
2015-09-21 9:57 ` rguenth at gcc dot gnu.org
@ 2015-09-22 7:47 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-09-22 7:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66952
--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Tue Sep 22 07:47:21 2015
New Revision: 227995
URL: https://gcc.gnu.org/viewcvs?rev=227995&root=gcc&view=rev
Log:
2015-09-22 Richard Biener <rguenther@suse.de>
Backport from mainline
2015-07-23 Richard Biener <rguenther@suse.de>
PR tree-optimization/66952
* gcc.dg/torture/pr66952.c: Use signed char.
Modified:
branches/gcc-5-branch/gcc/testsuite/ChangeLog
branches/gcc-5-branch/gcc/testsuite/gcc.dg/torture/pr66952.c
^ permalink raw reply [flat|nested] 10+ messages in thread
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2015-07-20 19:56 ` [Bug tree-optimization/66952] [6 Regression] " mpolacek at gcc dot gnu.org
2015-07-20 20:54 ` mpolacek at gcc dot gnu.org
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