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* [Bug rtl-optimization/67830] New: wrong code at -O1 and above on x86_64-linux-gnu
@ 2015-10-03 5:38 su at cs dot ucdavis.edu
2015-10-05 8:32 ` [Bug tree-optimization/67830] [6 Regression] " rguenth at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: su at cs dot ucdavis.edu @ 2015-10-03 5:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67830
Bug ID: 67830
Summary: wrong code at -O1 and above on x86_64-linux-gnu
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
Target Milestone: ---
The current gcc trunk mis-compiles the following code on x86_64-linux-gnu at
-O1 and above in both 32-bit and 64-bit modes.
This is a regression from 5.2.x.
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-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 20151002 (experimental) [trunk revision 228389] (GCC)
$
$ gcc-trunk -O0 small.c; ./a.out
$ gcc-5.2 -O1 small.c; ./a.out
$
$ gcc-trunk -O1 small.c
$ ./a.out
Aborted (core dumped)
$
----------------------------
int a, b, *g, h;
unsigned char c, d;
int
main ()
{
int f, e = -2;
b = e;
g = &b;
h = c = a + 1;
f = d - h;
*g &= f;
if (b != -2)
__builtin_abort ();
return 0;
}
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/67830] [6 Regression] wrong code at -O1 and above on x86_64-linux-gnu
2015-10-03 5:38 [Bug rtl-optimization/67830] New: wrong code at -O1 and above on x86_64-linux-gnu su at cs dot ucdavis.edu
@ 2015-10-05 8:32 ` rguenth at gcc dot gnu.org
2015-10-05 8:43 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-10-05 8:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67830
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2015-10-05
Component|rtl-optimization |tree-optimization
Target Milestone|--- |6.0
Summary|wrong code at -O1 and above |[6 Regression] wrong code
|on x86_64-linux-gnu |at -O1 and above on
| |x86_64-linux-gnu
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. .optimized already has an unconditional abort() call and forwprop2
changes it to that.
Applying pattern match.pd:2322, gimple-match.c:2002
gimple_simplified to _15 = d.2_9 - _5;
_16 = _15 & 254;
_12 = (int) _16;
Applying pattern match.pd:1853, generic-match.c:5128
Replaced '_12 != -2' with '1'
gimple_simplified to if (1 != 0)
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/67830] [6 Regression] wrong code at -O1 and above on x86_64-linux-gnu
2015-10-03 5:38 [Bug rtl-optimization/67830] New: wrong code at -O1 and above on x86_64-linux-gnu su at cs dot ucdavis.edu
2015-10-05 8:32 ` [Bug tree-optimization/67830] [6 Regression] " rguenth at gcc dot gnu.org
@ 2015-10-05 8:43 ` rguenth at gcc dot gnu.org
2015-10-05 10:11 ` mpolacek at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-10-05 8:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67830
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |NEW
CC| |law at gcc dot gnu.org
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
_7 = (int) _5;
_10 = (int) d.2_9;
f_11 = _10 - _7;
_12 = f_11 & -2;
with _5 and d.2_9 being of type unsigned char is transformed to
_15 = d.2_9 - _5;
_16 = _15 & 254;
_12 = (int) _16;
with _16 being unsigned char. That looks wrong as it changes a
sign-extended subtraction result to a zero-extended one.
CCing Jeff who added that pattern.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/67830] [6 Regression] wrong code at -O1 and above on x86_64-linux-gnu
2015-10-03 5:38 [Bug rtl-optimization/67830] New: wrong code at -O1 and above on x86_64-linux-gnu su at cs dot ucdavis.edu
2015-10-05 8:32 ` [Bug tree-optimization/67830] [6 Regression] " rguenth at gcc dot gnu.org
2015-10-05 8:43 ` rguenth at gcc dot gnu.org
@ 2015-10-05 10:11 ` mpolacek at gcc dot gnu.org
2015-10-05 18:54 ` law at redhat dot com
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2015-10-05 10:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67830
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mpolacek at gcc dot gnu.org
--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r222877.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/67830] [6 Regression] wrong code at -O1 and above on x86_64-linux-gnu
2015-10-03 5:38 [Bug rtl-optimization/67830] New: wrong code at -O1 and above on x86_64-linux-gnu su at cs dot ucdavis.edu
` (2 preceding siblings ...)
2015-10-05 10:11 ` mpolacek at gcc dot gnu.org
@ 2015-10-05 18:54 ` law at redhat dot com
2015-10-23 19:17 ` law at gcc dot gnu.org
2015-10-23 19:17 ` law at redhat dot com
5 siblings, 0 replies; 7+ messages in thread
From: law at redhat dot com @ 2015-10-05 18:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67830
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |law at redhat dot com
--- Comment #4 from Jeffrey A. Law <law at redhat dot com> ---
The discrepancy between the release checking and development build is the
ENABLE_GC_CHECKING is not enabled in the former, but is enabled in the latter.
We're looking at a gc_free'd blob of memory in the threader due to a case which
I initially didn't think could happen because of some oddities in the FSM bits
that I'd forgotten about.
I'm pondering the best way forward.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/67830] [6 Regression] wrong code at -O1 and above on x86_64-linux-gnu
2015-10-03 5:38 [Bug rtl-optimization/67830] New: wrong code at -O1 and above on x86_64-linux-gnu su at cs dot ucdavis.edu
` (3 preceding siblings ...)
2015-10-05 18:54 ` law at redhat dot com
@ 2015-10-23 19:17 ` law at gcc dot gnu.org
2015-10-23 19:17 ` law at redhat dot com
5 siblings, 0 replies; 7+ messages in thread
From: law at gcc dot gnu.org @ 2015-10-23 19:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67830
--- Comment #6 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Author: law
Date: Fri Oct 23 19:16:53 2015
New Revision: 229267
URL: https://gcc.gnu.org/viewcvs?rev=229267&root=gcc&view=rev
Log:
[RFA] Fix pr67830, another type narrowing problem
PR tree-optimization/67830
* match.pd ((bit_and (plus/minus (convert @0) (convert @1)) mask)):
Explicitly verify the mask has no bits outside the type of
the innermost operands.
PR tree-optimization/67830
* gcc.dg/pr67830.c: New test.
Added:
trunk/gcc/testsuite/gcc.dg/pr67830.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/match.pd
trunk/gcc/testsuite/ChangeLog
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/67830] [6 Regression] wrong code at -O1 and above on x86_64-linux-gnu
2015-10-03 5:38 [Bug rtl-optimization/67830] New: wrong code at -O1 and above on x86_64-linux-gnu su at cs dot ucdavis.edu
` (4 preceding siblings ...)
2015-10-23 19:17 ` law at gcc dot gnu.org
@ 2015-10-23 19:17 ` law at redhat dot com
5 siblings, 0 replies; 7+ messages in thread
From: law at redhat dot com @ 2015-10-23 19:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67830
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #7 from Jeffrey A. Law <law at redhat dot com> ---
Fixed on the trunk.
^ permalink raw reply [flat|nested] 7+ messages in thread
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2015-10-03 5:38 [Bug rtl-optimization/67830] New: wrong code at -O1 and above on x86_64-linux-gnu su at cs dot ucdavis.edu
2015-10-05 8:32 ` [Bug tree-optimization/67830] [6 Regression] " rguenth at gcc dot gnu.org
2015-10-05 8:43 ` rguenth at gcc dot gnu.org
2015-10-05 10:11 ` mpolacek at gcc dot gnu.org
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