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* [Bug c++/27045] New: c++ is generating incorrect optimized code for xor operations on long long
@ 2006-04-05 15:14 l_heldt at poczta dot onet dot pl
2006-04-05 15:17 ` [Bug c++/27045] " l_heldt at poczta dot onet dot pl
` (5 more replies)
0 siblings, 6 replies; 9+ messages in thread
From: l_heldt at poczta dot onet dot pl @ 2006-04-05 15:14 UTC (permalink / raw)
To: gcc-bugs
c++ is generating incorrect optimized code for xor operations on long long.
Version which is affected is:
g++ (GCC) 4.0.2 20051125 (Red Hat 4.0.2-8)
Following (proper) code is inlined into bad assembly when optimization is
turned on:
namespace __gnu_cxx
{
/**
hash specialization for uint64
*/
template <>
class hash<uint64>
{
public:
size_t operator()(uint64 const & number) const
{
hash<uint32> uint32Hasher;
uint32 const *p = (uint32 *)&number;
return uint32Hasher(p[0]) ^ uint32Hasher(p[1]);
}
};
/**
hash specialization for RequestId
*/
template<>
class hash<RequestId>
{
public:
size_t operator()(RequestId const & requestId) const
{
hash<uint64> uint64Hasher;
return uint64Hasher(requestId.getV1()) ^
uint64Hasher(requestId.getV2());
}
};
}
Part of bad assembly:
call _ZNK9RequestId5getV1Ev
movl -20(%ebp), %ebx
movl %esi, (%esp)
movl %eax, -24(%ebp)
movl -24(%ebp), %eax
movl %edx, -20(%ebp)
xorl %eax, %ebx
call _ZNK9RequestId5getV2Ev
movl -16(%ebp), %ecx
movl %eax, -16(%ebp)
movl -12(%ebp), %eax
movl %edx, -12(%ebp)
xorl %ecx, %eax
and it probably should be something like:
call _ZNK9RequestId5getV1Ev
movl %eax, -24(%ebp)
movl %edx, -20(%ebp)
movl -20(%ebp), %ebx
movl %esi, (%esp)
movl -24(%ebp), %eax
xorl %eax, %ebx
call _ZNK9RequestId5getV2Ev
movl %eax, -16(%ebp)
movl %edx, -12(%ebp)
movl -16(%ebp), %ecx
movl -12(%ebp), %eax
xorl %ecx, %eax
It seems that compiler reads values from stack before setting them after call
to getV1() or getV2().
Bug shows up only when optimization is turned on.
I am attaching simple demo program which should run when optimization is set to
0 and crash when it is set to 2 or 3.
--
Summary: c++ is generating incorrect optimized code for xor
operations on long long
Product: gcc
Version: 4.0.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: l_heldt at poczta dot onet dot pl
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27045
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug c++/27045] c++ is generating incorrect optimized code for xor operations on long long
2006-04-05 15:14 [Bug c++/27045] New: c++ is generating incorrect optimized code for xor operations on long long l_heldt at poczta dot onet dot pl
@ 2006-04-05 15:17 ` l_heldt at poczta dot onet dot pl
2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
` (4 subsequent siblings)
5 siblings, 0 replies; 9+ messages in thread
From: l_heldt at poczta dot onet dot pl @ 2006-04-05 15:17 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from l_heldt at poczta dot onet dot pl 2006-04-05 15:17 -------
Created an attachment (id=11212)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=11212&action=view)
File containing hash specifications
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27045
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug c++/27045] c++ is generating incorrect optimized code for xor operations on long long
2006-04-05 15:14 [Bug c++/27045] New: c++ is generating incorrect optimized code for xor operations on long long l_heldt at poczta dot onet dot pl
2006-04-05 15:17 ` [Bug c++/27045] " l_heldt at poczta dot onet dot pl
2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
@ 2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
2006-04-05 16:00 ` graham dot stott at btinternet dot com
` (2 subsequent siblings)
5 siblings, 0 replies; 9+ messages in thread
From: l_heldt at poczta dot onet dot pl @ 2006-04-05 15:18 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from l_heldt at poczta dot onet dot pl 2006-04-05 15:17 -------
Created an attachment (id=11213)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=11213&action=view)
Implementation of RequestId
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27045
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug c++/27045] c++ is generating incorrect optimized code for xor operations on long long
2006-04-05 15:14 [Bug c++/27045] New: c++ is generating incorrect optimized code for xor operations on long long l_heldt at poczta dot onet dot pl
2006-04-05 15:17 ` [Bug c++/27045] " l_heldt at poczta dot onet dot pl
@ 2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
2006-04-05 16:00 ` Graham Stott
2006-04-05 16:00 ` Graham Stott
2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
` (3 subsequent siblings)
5 siblings, 2 replies; 9+ messages in thread
From: l_heldt at poczta dot onet dot pl @ 2006-04-05 15:18 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from l_heldt at poczta dot onet dot pl 2006-04-05 15:18 -------
After compilation:
g++ test.cpp req.cpp -O0
program works fine. After compilation with:
g++ test.cpp req.cpp -O2
it breaks with SIGABRT.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27045
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug c++/27045] c++ is generating incorrect optimized code for xor operations on long long
2006-04-05 15:14 [Bug c++/27045] New: c++ is generating incorrect optimized code for xor operations on long long l_heldt at poczta dot onet dot pl
` (3 preceding siblings ...)
2006-04-05 16:00 ` graham dot stott at btinternet dot com
@ 2006-04-05 16:00 ` graham dot stott at btinternet dot com
2006-04-05 16:14 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 9+ messages in thread
From: graham dot stott at btinternet dot com @ 2006-04-05 16:00 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from graham dot stott at btinternet dot com 2006-04-05 16:00 -------
Subject: Re: c++ is generating incorrect optimized code for xor operations on
long long
All,
Not a bug, this is yet another case of type pruning.
Use -fno-strict-aliasing or fix your code.
Graham
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27045
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Bug c++/27045] c++ is generating incorrect optimized code for xor operations on long long
2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
@ 2006-04-05 16:00 ` Graham Stott
2006-04-05 16:00 ` Graham Stott
1 sibling, 0 replies; 9+ messages in thread
From: Graham Stott @ 2006-04-05 16:00 UTC (permalink / raw)
To: gcc-bugzilla, gcc-bugs
All,
Not a bug, this is yet another case of type pruning.
Use -fno-strict-aliasing or fix your code.
Graham
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug c++/27045] c++ is generating incorrect optimized code for xor operations on long long
2006-04-05 15:14 [Bug c++/27045] New: c++ is generating incorrect optimized code for xor operations on long long l_heldt at poczta dot onet dot pl
` (2 preceding siblings ...)
2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
@ 2006-04-05 16:00 ` graham dot stott at btinternet dot com
2006-04-05 16:00 ` graham dot stott at btinternet dot com
2006-04-05 16:14 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 9+ messages in thread
From: graham dot stott at btinternet dot com @ 2006-04-05 16:00 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from graham dot stott at btinternet dot com 2006-04-05 16:00 -------
Subject: Re: c++ is generating incorrect optimized code for xor operations on
long long
All,
Not a bug, this is yet another case of type pruning.
Use -fno-strict-aliasing or fix your code.
Graham
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27045
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Bug c++/27045] c++ is generating incorrect optimized code for xor operations on long long
2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
2006-04-05 16:00 ` Graham Stott
@ 2006-04-05 16:00 ` Graham Stott
1 sibling, 0 replies; 9+ messages in thread
From: Graham Stott @ 2006-04-05 16:00 UTC (permalink / raw)
To: gcc-bugzilla, gcc-bugs
All,
Not a bug, this is yet another case of type pruning.
Use -fno-strict-aliasing or fix your code.
Graham
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug c++/27045] c++ is generating incorrect optimized code for xor operations on long long
2006-04-05 15:14 [Bug c++/27045] New: c++ is generating incorrect optimized code for xor operations on long long l_heldt at poczta dot onet dot pl
` (4 preceding siblings ...)
2006-04-05 16:00 ` graham dot stott at btinternet dot com
@ 2006-04-05 16:14 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2006-04-05 16:14 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from pinskia at gcc dot gnu dot org 2006-04-05 16:13 -------
*** This bug has been marked as a duplicate of 21920 ***
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |DUPLICATE
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27045
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2006-04-05 16:14 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2006-04-05 15:14 [Bug c++/27045] New: c++ is generating incorrect optimized code for xor operations on long long l_heldt at poczta dot onet dot pl
2006-04-05 15:17 ` [Bug c++/27045] " l_heldt at poczta dot onet dot pl
2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
2006-04-05 16:00 ` Graham Stott
2006-04-05 16:00 ` Graham Stott
2006-04-05 15:18 ` l_heldt at poczta dot onet dot pl
2006-04-05 16:00 ` graham dot stott at btinternet dot com
2006-04-05 16:00 ` graham dot stott at btinternet dot com
2006-04-05 16:14 ` pinskia at gcc dot gnu dot org
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