[Bug tree-optimization/23449] New: vortex fails without -fno-strict-aliasing

[Bug tree-optimization/23449] New: vortex fails without -fno-strict-aliasing

[janis at gcc dot gnu dot org]

The SPEC CPU2000 test vortex segfaults on powerpc64-linux with current
mainline for either -m32 or -m64 with -O2.  It succeeds when compiled
with -fno-strict-aliasing.  It's quite likely that this is due to
invalid code in vortex itself, but nothing jumped out at me.  I'm
about to go on a two-week vacation, so I'm recording this in case
someone else would like to continue the investigation.
                                                                                
If mem00.c is compiled with "-O2 -fno-strict-aliasing" and the rest
of vortex is compiled with "-O2", the test passes.
                                                                                
Variables ChunkAddrChunk and NumChunkChunks, defined in mem00.h, are
static and their values never change.  If either one is made global
instead, the test passes.  If either variable is replaced with a
global variable with the same value at lines 240-248, the test passes.
If the for loop at line 240 is changed to increment ChunkChunk as the
third expression in for loop instead of in the second expression, the
test passes.

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           Summary: vortex fails without -fno-strict-aliasing
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: janis at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: powerpc-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23449

[Bug tree-optimization/23449] vortex fails without -fno-strict-aliasing

[janis at gcc dot gnu dot org]

------- Additional Comments From janis at gcc dot gnu dot org  2005-09-02 20:34 -------
The function Mem_NewOry in vortex's mem00.c uses lots of casts to void **,
so the failure is due to invalid code rather than a GCC bug.  I'll investigate
further and report this to SPEC.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23449

[Bug tree-optimization/23449] vortex fails without -fno-strict-aliasing

[janis at gcc dot gnu dot org]

------- Additional Comments From janis at gcc dot gnu dot org  2005-09-07 21:07 -------
The code in mem*.[ch] is much messier than I originally thought.  There are
lots of casts in assignments of pointer variables.  The macros in mem00.h
starting with Unit_Size, which are used in both lvalues and rvalues,
dereference through pointer casts.

I'm no longer planning to suggest a fix to SPEC.  The code in vortex violates
aliasing rules and any fix would not be portable C; we'll need to work around
it by compiling with -fno-strict-aliasing until someone comes up with a better
solution.

Closing this PR as INVALID.

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           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23449

[Bug tree-optimization/23449] vortex fails without -fno-strict-aliasing

[raksit at google dot com]

------- Comment #4 from raksit at google dot com  2009-01-15 19:32 -------
*** Bug 38858 has been marked as a duplicate of this bug. ***


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raksit at google dot com changed:

           What    |Removed                     |Added
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                 CC|                            |raksit at google dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23449

[Bug tree-optimization/23449] vortex fails without -fno-strict-aliasing

[ubizjak at gmail dot com]

------- Comment #3 from ubizjak at gmail dot com  2007-10-12 10:16 -------
*** Bug 31024 has been marked as a duplicate of this bug. ***


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ubizjak at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kenneth dot hoste at elis
                   |                            |dot ugent dot be


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23449