[llvm-bugs] [Bug 51745] New: LLVM 13 regression: lost transformation x < C && y < C && z < C to (x | y | z) < C

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51745

            Bug ID: 51745
           Summary: LLVM 13 regression: lost transformation x < C && y < C
                    && z < C to  (x | y | z) < C
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

x < C && y < C && z < C to  (x | y | z) < C  where C is power of two.


bool
src1 (unsigned x, unsigned y, unsigned z, unsigned w)
{
  return x < 1024 && y < 1024 && z < 1024 && w < 1024;
}

bool
tgt1 (unsigned x, unsigned y, unsigned z, unsigned w)
{
  return (x | y | z | w) < 1024;
}



GCC:
src1(unsigned int, unsigned int, unsigned int, unsigned int):
        or      edx, ecx
        or      edx, esi
        or      edx, edi
        cmp     edx, 1023
        setbe   al
        ret
tgt1(unsigned int, unsigned int, unsigned int, unsigned int):
        or      edx, ecx
        or      edx, esi
        or      edx, edi
        cmp     edx, 1023
        setbe   al
        ret

Clang trunk:
src1(unsigned int, unsigned int, unsigned int, unsigned int):                  
         # @src1(unsigned int, unsigned int, unsigned int, unsigned int)
        cmp     edi, 1024
        setb    al
        cmp     esi, 1024
        setb    sil
        and     sil, al
        cmp     edx, 1024
        setb    dl
        cmp     ecx, 1024
        setb    al
        and     al, dl
        and     al, sil
        ret
tgt1(unsigned int, unsigned int, unsigned int, unsigned int):                  
         # @tgt1(unsigned int, unsigned int, unsigned int, unsigned int)
        or      edi, esi
        or      edx, ecx
        or      edx, edi
        cmp     edx, 1024
        setb    al
        ret


Regressed with LLVM 13 which disabled select-to-or optimization.

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