[LLVMbugs] [Bug 8657] New: DSE doesn't remove small stores overwritten by later large ones

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=8657

           Summary: DSE doesn't remove small stores overwritten by later
                    large ones
           Product: libraries
           Version: 1.0
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Scalar Optimizations
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: clattner at apple.com
                CC: llvmbugs at cs.uiuc.edu


>From PR8576:

Partial must def case -- gcc cleans up all the stores except the last one --
but LLVM does none:

union U {
  struct C
   {
      char c[4];
   }cc;

   int ii;
} u ;

void foo(int i)
{
   u.cc.c[0] = 10; // Dead
   u.cc.c[1] = 10; // Dead too
   u.cc.c[i] = 10; // Dead too
   u.ii  = 20;
}

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