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Re: [PATCH, AArch64] Add x86 intrinsic headers to GCC AArch64 taget

On Tue, Jun 20, 2017 at 01:51:24PM -0500, Steven Munroe wrote:
> I am not sure this works or is even a good idea.
> As an accident bmiintrin.h can be implemented as C code or common
> builtins. But bmi2intrin.h depends on __builtin_bpermd which to my
> knowledge is PowerISA only.

Right.  And the plan is to only support 64-bit, LE, POWER8 and above
(I hope I got that right -- the point is, only systems with newish
features, not something generic even when considering rs6000 alone).

> As I work on mmx, sse, sse2, etc it gets more complicated. There are
> many X86 intrinsic instances that require altivec.h unique instrisics to
> implement efficiently for the power64le target and some inline __asm.

Yeah.  And even then the expectation is not to get perfectly good
performance, only something good enough as a starting point for a
porting effort.

> Net the current sample size so far is to small to make a reasonable
> assessment.

Right!  And we have only two implementations so far, as well.

> And as you see see below the tests have to be duplicated
> anyway. Even if the C code is common there will many differences in
> dg-options and dg-require-effective-target. Trying to common these
> implementations only creates more small files to manage.

So somewhere in the near future we'll have to pull things apart again,
if we go with merging things now.

It's not like the "common" parts will see much (if any) maintenance,
anyway...  The interface is already set in stone, that's the whole
point of this all.


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