https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114591
Hongtao Liu <liuhongt at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |liuhongt at gcc dot gnu.org
--- Comment #4 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
(In reply to Uroš Bizjak from comment #3)
> (In reply to Jakub Jelinek from comment #2)
> > This changed with r12-5584-gca5667e867252db3c8642ee90f55427149cd92b6
>
> Strange, if I revert the constraints to the previous setting with:
>
> --cut here--
> diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
> index 10ae3113ae8..262dd25a8e0 100644
> --- a/gcc/config/i386/i386.md
> +++ b/gcc/config/i386/i386.md
> @@ -2870,9 +2870,9 @@ (define_peephole2
>
> (define_insn "*movhi_internal"
> [(set (match_operand:HI 0 "nonimmediate_operand"
> - "=r,r,r,m ,*k,*k ,r ,m ,*k ,?r,?*v,*Yv,*v,*v,jm,m")
> + "=r,r,r,m ,*k,*k ,*r ,*m ,*k ,?r,?v,*Yv,*v,*v,*jm,*m")
> (match_operand:HI 1 "general_operand"
> - "r ,n,m,rn,r ,*km,*k,*k,CBC,*v,r ,C ,*v,m ,*x,*v"))]
> + "r ,n,m,rn,*r ,*km,*k,*k,CBC,v,r ,C ,v,m ,x,v"))]
> "!(MEM_P (operands[0]) && MEM_P (operands[1]))
> && ix86_hardreg_mov_ok (operands[0], operands[1])"
> {
> --cut here--
>
> I still get:
>
> movl v1(%rip), %eax # 6 [c=6 l=6] *zero_extendsidi2/3
> movq %rax, v2(%rip) # 16 [c=4 l=7] *movdi_internal/5
> movzwl v1(%rip), %eax # 7 [c=5 l=7] *movhi_internal/2
My experience is memory cost for the operand with rm or separate r, m is
different which impacts RA decision.
https://gcc.gnu.org/pipermail/gcc-patches/2022-May/595573.html
