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* [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long
@ 2009-05-07 10:49 rahul at icerasemi dot com
2009-05-07 11:11 ` [Bug tree-optimization/40057] " rahul at icerasemi dot com
` (12 more replies)
0 siblings, 13 replies; 14+ messages in thread
From: rahul at icerasemi dot com @ 2009-05-07 10:49 UTC (permalink / raw)
To: gcc-bugs
The following code compiled with GCC 4.4 and -O1 produces a wrong result for
the SHIFT and AND operation. Bit 31 of the variable 'var' in fucntion shiftTest
computes to '1' instead of a '0'.
Compiling with -O0 however, produces the right result.
#include "stdio.h"
typedef unsigned long long ulonglong;
int shiftTest (const ulonglong var)
{
ulonglong predicate = (var >> 31ULL) & 1ULL;
if (predicate == 0ULL)
{
return 0;
}
return -1;
}
int main (void)
{
ulonglong var = 0x1682a9aaaULL;
printf ("Bit 31 of 0x%llx is %llu\n", var, (var >> 31ULL) & 1ULL);
int result = shiftTest (var);
if (result == 0)
{
printf ("Bit 31 is 0 - Correct!\n");
}
else
{
printf ("Bit 31 is 1 - Incorrect!\n");
}
return 0;
}
--
Summary: Incorrect right shift by 31 with long long
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rahul at icerasemi dot com
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug tree-optimization/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
@ 2009-05-07 11:11 ` rahul at icerasemi dot com
2009-05-07 11:19 ` rguenth at gcc dot gnu dot org
` (11 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: rahul at icerasemi dot com @ 2009-05-07 11:11 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from rahul at icerasemi dot com 2009-05-07 11:11 -------
Suspect tree-ter optimisation pass. Compiling with -O1 -fno-tree-ter produces
the right result. Using -fdump-tree-optimized shows SSA-Gimple to change from
shiftTest (const ulonglong var)
{
int D.1842;
<bb 2>:
if (var >> 31 & 1 == 0)
goto <bb 3>;
else
goto <bb 5>;
<bb 5>:
D.1842 = -1;
goto <bb 4>;
<bb 3>:
D.1842 = 0;
<bb 4>:
return D.1842;
}
to
shiftTest (const ulonglong var)
{
ulonglong predicate;
int D.1842;
const ulonglong D.1839;
<bb 2>:
D.1839 = var >> 31;
predicate = D.1839 & 1;
if (predicate == 0)
goto <bb 3>;
else
goto <bb 5>;
<bb 5>:
D.1842 = -1;
goto <bb 4>;
<bb 3>:
D.1842 = 0;
<bb 4>:
return D.1842;
}
Does the complex expression "var >> 31 & 1 == 0" cause problems during RTL
expansion phase?
Are the precedences of the SHIFT and AND operations maintained by the
expression replacement phase?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug tree-optimization/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
2009-05-07 11:11 ` [Bug tree-optimization/40057] " rahul at icerasemi dot com
@ 2009-05-07 11:19 ` rguenth at gcc dot gnu dot org
2009-05-07 11:30 ` jakub at gcc dot gnu dot org
` (10 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2009-05-07 11:19 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from rguenth at gcc dot gnu dot org 2009-05-07 11:19 -------
Works for me.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug tree-optimization/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
2009-05-07 11:11 ` [Bug tree-optimization/40057] " rahul at icerasemi dot com
2009-05-07 11:19 ` rguenth at gcc dot gnu dot org
@ 2009-05-07 11:30 ` jakub at gcc dot gnu dot org
2009-05-07 11:34 ` jakub at gcc dot gnu dot org
` (9 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 11:30 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from jakub at gcc dot gnu dot org 2009-05-07 11:29 -------
Can't reproduce with x86_64-linux 4.4.0 with -m32, perhaps a 32-bit HWI issue,
will check...
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug tree-optimization/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (2 preceding siblings ...)
2009-05-07 11:30 ` jakub at gcc dot gnu dot org
@ 2009-05-07 11:34 ` jakub at gcc dot gnu dot org
2009-05-07 11:36 ` jakub at gcc dot gnu dot org
` (8 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 11:34 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from jakub at gcc dot gnu dot org 2009-05-07 11:33 -------
Indeed, I can reproduce with 32-bit HWI 20090414 4.4 branch, building now head
of 4.4 branch with 32-bit HWI.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug tree-optimization/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (3 preceding siblings ...)
2009-05-07 11:34 ` jakub at gcc dot gnu dot org
@ 2009-05-07 11:36 ` jakub at gcc dot gnu dot org
2009-05-07 13:02 ` [Bug middle-end/40057] " jakub at gcc dot gnu dot org
` (7 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 11:36 UTC (permalink / raw)
To: gcc-bugs
--
jakub at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |jakub at gcc dot gnu dot org
|dot org |
Status|UNCONFIRMED |ASSIGNED
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2009-05-07 11:36:16
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug middle-end/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (4 preceding siblings ...)
2009-05-07 11:36 ` jakub at gcc dot gnu dot org
@ 2009-05-07 13:02 ` jakub at gcc dot gnu dot org
2009-05-07 13:20 ` jakub at gcc dot gnu dot org
` (6 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 13:02 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from jakub at gcc dot gnu dot org 2009-05-07 13:02 -------
A bug in do_jump and prefer_and_bit_test. Testing a fix.
--
jakub at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|tree-optimization |middle-end
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug middle-end/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (5 preceding siblings ...)
2009-05-07 13:02 ` [Bug middle-end/40057] " jakub at gcc dot gnu dot org
@ 2009-05-07 13:20 ` jakub at gcc dot gnu dot org
2009-05-07 15:28 ` jakub at gcc dot gnu dot org
` (5 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 13:20 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from jakub at gcc dot gnu dot org 2009-05-07 13:19 -------
Created an attachment (id=17818)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17818&action=view)
gcc44-pr40057.patch
Fix I'm going to bootstrap/regtest.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug middle-end/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (6 preceding siblings ...)
2009-05-07 13:20 ` jakub at gcc dot gnu dot org
@ 2009-05-07 15:28 ` jakub at gcc dot gnu dot org
2009-05-07 15:37 ` jakub at gcc dot gnu dot org
` (4 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 15:28 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from jakub at gcc dot gnu dot org 2009-05-07 15:28 -------
Subject: Bug 40057
Author: jakub
Date: Thu May 7 15:27:40 2009
New Revision: 147241
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=147241
Log:
PR middle-end/40057
* dojump.c (prefer_and_bit_test): Use immed_double_const instead of
GEN_INT for 1 << bitnum.
(do_jump) <case BIT_AND_EXPR>: Use build_int_cst_wide_type instead of
build_int_cst_type.
* gcc.c-torture/execute/pr40057.c: New test.
Added:
trunk/gcc/testsuite/gcc.c-torture/execute/pr40057.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/dojump.c
trunk/gcc/testsuite/ChangeLog
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug middle-end/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (7 preceding siblings ...)
2009-05-07 15:28 ` jakub at gcc dot gnu dot org
@ 2009-05-07 15:37 ` jakub at gcc dot gnu dot org
2009-05-07 15:53 ` jakub at gcc dot gnu dot org
` (3 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 15:37 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from jakub at gcc dot gnu dot org 2009-05-07 15:36 -------
Subject: Bug 40057
Author: jakub
Date: Thu May 7 15:36:23 2009
New Revision: 147242
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=147242
Log:
PR middle-end/40057
* dojump.c (prefer_and_bit_test): Use immed_double_const instead of
GEN_INT for 1 << bitnum.
(do_jump) <case BIT_AND_EXPR>: Use build_int_cst_wide_type instead of
build_int_cst_type.
* gcc.c-torture/execute/pr40057.c: New test.
Added:
branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/execute/pr40057.c
Modified:
branches/gcc-4_4-branch/gcc/ChangeLog
branches/gcc-4_4-branch/gcc/dojump.c
branches/gcc-4_4-branch/gcc/testsuite/ChangeLog
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug middle-end/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (8 preceding siblings ...)
2009-05-07 15:37 ` jakub at gcc dot gnu dot org
@ 2009-05-07 15:53 ` jakub at gcc dot gnu dot org
2009-05-07 15:55 ` jakub at gcc dot gnu dot org
` (2 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 15:53 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from jakub at gcc dot gnu dot org 2009-05-07 15:53 -------
Subject: Bug 40057
Author: jakub
Date: Thu May 7 15:53:11 2009
New Revision: 147245
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=147245
Log:
PR middle-end/40057
* dojump.c (prefer_and_bit_test): Use immed_double_const instead of
GEN_INT for 1 << bitnum.
(do_jump) <case BIT_AND_EXPR>: Use build_int_cst_wide_type instead of
build_int_cst_type.
* gcc.c-torture/execute/pr40057.c: New test.
Added:
branches/gcc-4_3-branch/gcc/testsuite/gcc.c-torture/execute/pr40057.c
Modified:
branches/gcc-4_3-branch/gcc/ChangeLog
branches/gcc-4_3-branch/gcc/dojump.c
branches/gcc-4_3-branch/gcc/testsuite/ChangeLog
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug middle-end/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (9 preceding siblings ...)
2009-05-07 15:53 ` jakub at gcc dot gnu dot org
@ 2009-05-07 15:55 ` jakub at gcc dot gnu dot org
2009-05-07 15:57 ` rahul at icerasemi dot com
2009-05-28 11:12 ` jakub at gcc dot gnu dot org
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-07 15:55 UTC (permalink / raw)
To: gcc-bugs
------- Comment #10 from jakub at gcc dot gnu dot org 2009-05-07 15:55 -------
Fixed.
--
jakub at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug middle-end/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (10 preceding siblings ...)
2009-05-07 15:55 ` jakub at gcc dot gnu dot org
@ 2009-05-07 15:57 ` rahul at icerasemi dot com
2009-05-28 11:12 ` jakub at gcc dot gnu dot org
12 siblings, 0 replies; 14+ messages in thread
From: rahul at icerasemi dot com @ 2009-05-07 15:57 UTC (permalink / raw)
To: gcc-bugs
------- Comment #11 from rahul at icerasemi dot com 2009-05-07 15:57 -------
Confirmed issue resolved.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
* [Bug middle-end/40057] Incorrect right shift by 31 with long long
2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
` (11 preceding siblings ...)
2009-05-07 15:57 ` rahul at icerasemi dot com
@ 2009-05-28 11:12 ` jakub at gcc dot gnu dot org
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu dot org @ 2009-05-28 11:12 UTC (permalink / raw)
To: gcc-bugs
------- Comment #12 from jakub at gcc dot gnu dot org 2009-05-28 11:12 -------
*** Bug 40279 has been marked as a duplicate of this bug. ***
--
jakub at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jisooy at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40057
^ permalink raw reply [flat|nested] 14+ messages in thread
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2009-05-07 10:49 [Bug tree-optimization/40057] New: Incorrect right shift by 31 with long long rahul at icerasemi dot com
2009-05-07 11:11 ` [Bug tree-optimization/40057] " rahul at icerasemi dot com
2009-05-07 11:19 ` rguenth at gcc dot gnu dot org
2009-05-07 11:30 ` jakub at gcc dot gnu dot org
2009-05-07 11:34 ` jakub at gcc dot gnu dot org
2009-05-07 11:36 ` jakub at gcc dot gnu dot org
2009-05-07 13:02 ` [Bug middle-end/40057] " jakub at gcc dot gnu dot org
2009-05-07 13:20 ` jakub at gcc dot gnu dot org
2009-05-07 15:28 ` jakub at gcc dot gnu dot org
2009-05-07 15:37 ` jakub at gcc dot gnu dot org
2009-05-07 15:53 ` jakub at gcc dot gnu dot org
2009-05-07 15:55 ` jakub at gcc dot gnu dot org
2009-05-07 15:57 ` rahul at icerasemi dot com
2009-05-28 11:12 ` jakub at gcc dot gnu dot org
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