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* [Bug target/21715] New: code-generation regression
@ 2005-05-23  8:25 markus at oberhumer dot com
  2005-05-23 18:22 ` [Bug target/21715] [4.0/4.1 regression] code-generation performance regression pinskia at gcc dot gnu dot org
                   ` (3 more replies)
  0 siblings, 4 replies; 14+ messages in thread
From: markus at oberhumer dot com @ 2005-05-23  8:25 UTC (permalink / raw)
  To: gcc-bugs

During recent performance testing I have identified a number of small code
fragments where gcc 4.x produces worse code than gcc 3.4.3. Some of these may be
target specific, and I plan to gradually enter such small performance
regressions into the bug database unless there is a better way to report these.


$ cat test.c
long foo(long v) { return v & -v; }

$ gcc-3.4.3 -O3 -c test.c && objdump -d test.o

test.o:     file format elf64-x86-64

Disassembly of section .text:

0000000000000000 <foo>:
   0:   48 89 f8                mov    %rdi,%rax
   3:   48 f7 d8                neg    %rax
   6:   48 21 f8                and    %rdi,%rax
   9:   c3                      retq

$ gcc-4.1-20050516 -O3 -c test.c && objdump -d test.o

test.o:     file format elf64-x86-64

Disassembly of section .text:

0000000000000000 <foo>:
   0:   48 89 f8                mov    %rdi,%rax
   3:   48 f7 d8                neg    %rax
   6:   48 21 c7                and    %rax,%rdi
   9:   48 89 f8                mov    %rdi,%rax
   c:   c3                      retq

-- 
           Summary: code-generation regression
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: markus at oberhumer dot com
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: x86_64-pc-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21715


^ permalink raw reply	[flat|nested] 14+ messages in thread
end of thread, other threads:[~2008-02-20 22:36 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
     [not found] <bug-21715-4672@http.gcc.gnu.org/bugzilla/>
2005-10-22  3:07 ` [Bug target/21715] [4.0/4.1 regression] code-generation performance regression pinskia at gcc dot gnu dot org
2005-10-31  3:40 ` mmitchel at gcc dot gnu dot org
2005-11-06 16:35 ` pinskia at gcc dot gnu dot org
2005-12-19  2:30 ` kazu at gcc dot gnu dot org
2006-01-07 18:42 ` steven at gcc dot gnu dot org
2006-01-10 17:50 ` steven at gcc dot gnu dot org
2006-02-24  0:30 ` mmitchel at gcc dot gnu dot org
2006-05-25  2:43 ` mmitchel at gcc dot gnu dot org
2007-02-14  9:13 ` mmitchel at gcc dot gnu dot org
2008-02-20 22:36 ` rguenth at gcc dot gnu dot org
2005-05-23  8:25 [Bug target/21715] New: code-generation regression markus at oberhumer dot com
2005-05-23 18:22 ` [Bug target/21715] [4.0/4.1 regression] code-generation performance regression pinskia at gcc dot gnu dot org
2005-07-08  1:40 ` mmitchel at gcc dot gnu dot org
2005-09-16 19:04 ` pinskia at gcc dot gnu dot org
2005-09-27 16:07 ` mmitchel at gcc dot gnu dot org

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