[Bug target/57954] AVX missing vxorps (zeroing) before vcvtsi2s %edx, slow down AVX code

[dushistov at mail dot ru]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57954

--- Comment #11 from Evgeniy Dushistov <dushistov at mail dot ru> ---
(In reply to Yuri Rumyantsev from comment #9)
> I checked that zeroing of xmm register before conversion leads to
> performance slowdown on SLM (-5%) for proveded test-case. I assume that
> 
> with H.J patch we got the following assembly (I compiled it for slm but it
> does not matter):
> 
> .L3:
> 	xorps	%xmm0, %xmm0
> 	cvtsi2ss	%eax, %xmm0
> 	movss	%xmm0, (%ecx,%eax,4)
> 	addl	$1, %eax
> 	cmpl	%edx, %eax
> 	jne	.L3
> 

By the way, I tried compile my sample
(http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57988) for atom, icc(13.1.3
20130607) produce:


xorps  %xmm2,%xmm2
cvtsi2sd %rax,%xmm2

may be 5% measuring error?