[LLVMbugs] [Bug 9127] New: Load not being folded

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Wed Feb 2 13:04:41 PST 2011


           Summary: Load not being folded
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: rafael.espindola at gmail.com
                CC: llvmbugs at cs.uiuc.edu

extern double sin( double );
typedef double (*UnaryFunType)(double);
struct Entry {
  double in;
  double out;
double foobar(double d, struct Entry *x) {
  if (d == x->in)
    return x->out;
  return  d;

gcc will produce

    ucomisd    (%rdi), %xmm0
    jne    L2
    jp    L2
    movsd    8(%rdi), %xmm0
    rep ; ret

llvm produces

        movsd   (%rdi), %xmm1
        ucomisd %xmm0, %xmm1
        jne     LBB0_2
        jp      LBB0_2
        movsd   8(%rdi), %xmm0

Note that gcc folded the load into ucomisd.

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