x86: whitespace in {}-enclosed syntax elements

[Jan Beulich]

Hello,

in the context of my scrubber rework and further emphasized by Lili's
processing of {dfv=...} for CCMPcc/CTESTcc (permitting whitespace
everywhere it makes sense) I came to notice that for pseudo prefixes as
well as AVX512 syntax elements (broadcast, static rounding, SAE) we
presently don't permit whitespace inside the figure braces. With [1]
making comments work as intended, sensible things like

	{/*e*/vex} vmaxps ymm0, ymm1, ymm2
	{vex/*2*/} vmaxps ymm0, ymm1, ymm2
	vmaxps	zmm0, zmm1, zmm2{/*rn-*/sae}

are going to break, simply because right now

	{ vex} vmaxps ymm0, ymm1, ymm2
	{vex } vmaxps ymm0, ymm1, ymm2
	vmaxps	zmm0, zmm1, zmm2{ sae}

don't work. Question therefore is: Was there any particular reason to
not permit whitespace there? If there was, and if there is a reason to
stick to that, what's the suggestion for the examples above? Otherwise
my plan would be to make an up-front patch permitting whitespace
immediately inside figure braces, yet perhaps not around the '-' in
e.g. {rn-sae}.

Jan

[1] https://sourceware.org/pipermail/binutils/2024-June/135212.html