[Bug tree-optimization/27469] New: zero extension not eliminated

[falk at debian dot org]

unsigned parity(unsigned x) {
    x ^= x >> 16;
    x ^= x >> 8;
    x ^= x >> 4;
    x &= 0xf;
    return (0x6996 >> x) & 1;
}

gcc 4.2.0 20060506 produces:
        extwl   a0,0x2,t2
        lda     v0,27030
        xor     t2,a0,t2
        zapnot  t2,0xf,t1 # redundant zero-extension
        srl     t1,0x8,t1
        xor     t1,t2,t1
        zapnot  t1,0xf,t0 # redundant zero-extension
        srl     t0,0x4,t0
        xor     t0,t1,t0
        and     t0,0xf,t0
        sra     v0,t0,v0
        and     v0,0x1,v0

-fsee doesn't change anything here.


-- 
           Summary: zero extension not eliminated
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: falk at debian dot org
 GCC build triplet: alphaev68-unknown-linux-gnu
  GCC host triplet: alphaev68-unknown-linux-gnu
GCC target triplet: alphaev68-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27469