[Bug tree-optimization/33705] New: gcc generates dead struct stores

[astrange at ithinksw dot com]

> /usr/local/gcc43/bin/gcc -O3 -fno-pic -fomit-frame-pointer -m64 -S 
> gcc-struct-stores.i -v
Using built-in specs.
Target: i386-apple-darwin8.10.1
Configured with: ../gcc/configure --prefix=/usr/local/gcc43 --with-arch=nocona
--with-tune=nocona --with-gmp=/sw --with-system-zlib
--enable-languages=c,c++,objc,obj-c++ --disable-bootstrap
Thread model: posix
gcc version 4.3.0 20071008 (experimental) (GCC) 

GCC updates c->low and c->range in the middle of the function:
        movl    %r8d, (%rdi)
        movl    %edx, 4(%rdi)

but they're overwritten at the end:
        movl    %edx, 4(%rdi)
        sall    %cl, (%rdi)

I don't know if there are aliasing issues, but marking it __restrict doesn't
affect it.


-- 
           Summary: gcc generates dead struct stores
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: astrange at ithinksw dot com
 GCC build triplet: i386-apple-darwin8.10.1
  GCC host triplet: i386-apple-darwin8.10.1
GCC target triplet: i386-apple-darwin8.10.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33705