[Bug rtl-optimization/41862] valgrind warns about using uninitialized variable with -fgcse-sm

[zsojka at seznam dot cz]

--- Comment #1 from zsojka at seznam dot cz  2009-10-29 00:04 ---
Created an attachment (id=18928)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18928&action=view)
partially reduced testcase


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41862

[Bug rtl-optimization/41862] valgrind warns about using uninitialized variable with -fgcse-sm

[zsojka at seznam dot cz]

--- Comment #2 from zsojka at seznam dot cz  2009-10-29 00:06 ---
Created an attachment (id=18929)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18929&action=view)
warning disappears when this diff is applied


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41862

[Bug rtl-optimization/41862] valgrind warns about using uninitialized variable with -fgcse-sm

[rguenth at gcc dot gnu dot org]

--- Comment #3 from rguenth at gcc dot gnu dot org  2009-10-29 10:25 ---
Steven knows this code best.


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rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

 CC||stevenb dot gcc at gmail dot
   ||com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41862

[Bug rtl-optimization/41862] valgrind warns about using uninitialized variable with -fgcse-sm

[steven at gcc dot gnu dot org]

--- Comment #4 from steven at gcc dot gnu dot org  2009-10-29 10:57 ---
Mine. Investigating.


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steven at gcc dot gnu dot org changed:

   What|Removed |Added

 CC|stevenb dot gcc at gmail dot|
   |com |
 AssignedTo|unassigned at gcc dot gnu   |steven at gcc dot gnu dot
   |dot org |org
 Status|UNCONFIRMED |ASSIGNED
 Ever Confirmed|0   |1
   Last reconfirmed|-00-00 00:00:00 |2009-10-29 10:57:51
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41862

[Bug rtl-optimization/41862] valgrind warns about using uninitialized variable with -fgcse-sm

[zsojka at seznam dot cz]

--- Comment #5 from zsojka at seznam dot cz  2009-11-17 18:34 ---
Created an attachment (id=19029)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19029&action=view)
reduced testcase

BINARY=/mnt/svn/gcc-trunk/binary-154190-lto/libexec/gcc/x86_64-unknown-linux-gnu/4.5.0/cc1

valgrind --malloc-fill=0x00 $BINARY -O1 -fgcse-sm -fPIC -m32 -o malloc-00.S
pr41862.i
valgrind --malloc-fill=0xff $BINARY -O1 -fgcse-sm -fPIC -m32 -o malloc-ff.S
pr41862.i
diff malloc-00.S malloc-ff.S

Gives:
13a14
>   movl%esi, g...@gotoff(%ebx)
21,22c22,23
<   leal1(%esi), %eax
<   movl%eax, g...@gotoff(%ebx)
---
>   addl$1, %esi
>   movl%esi, g...@gotoff(%ebx)

The first store is redundant, caused by using uninitialised memory by gcc.


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zsojka at seznam dot cz changed:

   What|Removed |Added

  Attachment #18928|0   |1
is obsolete||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41862

[Bug rtl-optimization/41862] valgrind warns about using uninitialized variable with -fgcse-sm

[zsojka at seznam dot cz]

--- Comment #6 from zsojka at seznam dot cz  2009-11-25 10:45 ---
Also it causes bootstrap comparison failures for me at x86_64-pc-linux-gnu,
r154643

export CFLAGS="-O2 -fgcse-sm"
export CXXFLAGS="-O2 -fgcse-sm"
../configure --enable-languages=c,c++
--prefix=/mnt/svn/gcc-trunk/binary-154643-O2-gcse-sm
make

...

Comparing stages 2 and 3
warning: gcc/cc1plus-checksum.o differs
warning: gcc/cc1-checksum.o differs
Bootstrap comparison failure!
x86_64-unknown-linux-gnu/32/libgcc/multf3_s.o differs
x86_64-unknown-linux-gnu/32/libgcc/bid128_div.o differs
x86_64-unknown-linux-gnu/32/libgcc/addtf3_s.o differs
x86_64-unknown-linux-gnu/32/libgcc/fixtfsi.o differs
make[2]: *** [compare] Error 1

Should this be marked as regression?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41862