llvm-svn: 81290
us to compile: double test(double X) { return copysign(0.0, X); } into: _test: andpd LCPI1_0(%rip), %xmm0 ret instead of: _test: pxor %xmm1, %xmm1 andpd LCPI1_0(%rip), %xmm1 movapd %xmm0, %xmm2 andpd LCPI1_1(%rip), %xmm2 movapd %xmm1, %xmm0 orpd %xmm2, %xmm0 ret llvm-svn: 46344