[Bug target/88834] [SVE] Poor addressing mode choices for LD2 and ST2

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88834

--- Comment #7 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Thanks for looking at this.

(In reply to kugan from comment #6)
> 	cmp	w3, 0
> 	ble	.L1
> 	sub	w3, w3, #1
> 	mov	x4, 0
> 	cntw	x5
> 	ptrue	p1.s, all
> 	lsr	w3, w3, 1
> 	add	w3, w3, 1
> 	whilelo	p0.s, xzr, x3
> 	.p2align 3,,7
> .L3:
> 	ld2w	{z4.s - z5.s}, p0/z, [x1, x4, lsl 2]
> 	ld2w	{z2.s - z3.s}, p0/z, [x2, x4, lsl 2]
> 	add	z0.s, z4.s, z2.s
> 	sub	z1.s, z5.s, z3.s
> 	st2w	{z0.s - z1.s}, p0, [x0, x4, lsl 2]
> 	whilelo	p0.s, x5, x3
> 	incb	x4, all, mul #2
> 	incw	x5
> 	ptest	p1, p0.b
> 	bne	.L3
> .L1:
> 	ret
> 	.cfi_endproc

This doesn't look right.  x4 is an index, so it should be
incremented by the number of words in two vectors, rather than
the number of bytes in two vectors.