[Bug target/98962] New: Perform bitops on floats directly with SSE

[glisse at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98962

            Bug ID: 98962
           Summary: Perform bitops on floats directly with SSE
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glisse at gcc dot gnu.org
  Target Milestone: ---
            Target: x86_64-*-*

(from https://stackoverflow.com/q/66023408/1918193 )

float f(float a){
  unsigned ai;
  __builtin_memcpy(&ai, &a, 4);
  unsigned ri = ai ^ (1U << 31);
  float r;
  __builtin_memcpy(&r, &ri, 4);
  return r;
}

results in

        movd    %xmm0, %eax
        addl    $-2147483648, %eax
        movd    %eax, %xmm0

while llvm simplifies it to

        xorps   .LCPI0_0(%rip), %xmm0