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* [Bug rtl-optimization/38603]  New: IRA does not accommodate LOAD_EXTEND_OP transformations done by combine
@ 2008-12-21 22:40 hp at gcc dot gnu dot org
  2008-12-21 22:43 ` [Bug rtl-optimization/38603] " hp at gcc dot gnu dot org
                   ` (12 more replies)
  0 siblings, 13 replies; 14+ messages in thread
From: hp at gcc dot gnu dot org @ 2008-12-21 22:40 UTC (permalink / raw)
  To: gcc-bugs

Trunk revision 141361 with the attached patch shows this regression compared to
unpatched:
Running /home/hp/combx/combined/gcc/testsuite/gcc.c-torture/execute/execute.exp
...
FAIL: gcc.c-torture/execute/20040709-1.c execution,  -O2

However, the regression is hidden at revisions 142609 and 142857.

At the time, a quick glance at the RTL dumps pointed at LOAD_EXTEND_OP
optimizations performed by combine not being properly handled in IRA,
specifically a sign-extension optimized away by combine as matching the
implicit sign extension of a memory read through LOAD_EXTEND_OP.
IIRC the memory read was not being transformed (back) into an explicit
sign-extension.
(I intend to fill in details here, but this will have to do for today.)


-- 
           Summary: IRA does not accommodate LOAD_EXTEND_OP transformations
                    done by combine
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hp at gcc dot gnu dot org
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: mmix-knuth-mmixware


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38603


^ permalink raw reply	[flat|nested] 14+ messages in thread
end of thread, other threads:[~2010-04-30  8:59 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2008-12-21 22:40 [Bug rtl-optimization/38603] New: IRA does not accommodate LOAD_EXTEND_OP transformations done by combine hp at gcc dot gnu dot org
2008-12-21 22:43 ` [Bug rtl-optimization/38603] " hp at gcc dot gnu dot org
2008-12-23 11:04 ` hp at gcc dot gnu dot org
2008-12-23 18:42 ` hp at gcc dot gnu dot org
2008-12-24  2:46 ` [Bug rtl-optimization/38603] [4.4 Regression] " pinskia at gcc dot gnu dot org
2008-12-29 23:09 ` rguenth at gcc dot gnu dot org
2008-12-31 10:18 ` hp at gcc dot gnu dot org
2009-04-06 18:19 ` [Bug rtl-optimization/38603] [4.4/4.5 " ubizjak at gmail dot com
2009-04-06 18:21 ` ubizjak at gmail dot com
2009-04-21 16:00 ` jakub at gcc dot gnu dot org
2009-07-22 10:34 ` jakub at gcc dot gnu dot org
2009-10-15 12:55 ` jakub at gcc dot gnu dot org
2010-01-21 13:18 ` jakub at gcc dot gnu dot org
2010-04-30  8:59 ` [Bug rtl-optimization/38603] [4.4/4.5/4.6 Regression] reload inheritance mucks up " jakub at gcc dot gnu dot org

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