[Bug target/89071] AVX vcvtsd2ss lets us avoid PXOR dependency breaking for scalar float<->double and other scalar xmm,xmm instructions

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89071

--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> ---
I fixed assembly codes and run it on different AVX machines.
I got similar results:

./test
sse      : 28346518
sse_clear: 28046302
avx      : 28214775
avx2     : 28251195
avx_clear: 28092687

avx_clear:
        vxorps  %xmm0, %xmm0, %xmm0
        vcvtsd2ss       %xmm1, %xmm0, %xmm0
        ret

is slightly faster.