MaskRay marked an inline comment as done.
MaskRay added inline comments.
================
Comment at: clang/lib/Basic/Targets/PPC.h:211
+ case 's': // VSX vector register to hold scalar double data
+ case 'w': // VSX vector register to hold scalar double data
case 'a': // Any VSX register
----------------
jsji wrote:
> Add some more comments for `w` to distinguish it from `s`?
>
> Do we want to keep compatibility with GCC?
> According to
> https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Machine-Constraints.html#Machine-Constraints,
>
> `ww` is `FP or VSX register to perform float operations under -mvsx or
> NO_REGS.`,
> while `ws` is `VSX vector register to hold scalar double values `.
>
> So `ww` can use `FP` while `ws` can NOT ?
I played with "ws" and "ww" but can't find any behavior difference from
assembly produced by powerpc64le-linux-gnu-gcc. I'll keep the current form
(which is known to make musl fmax/fmaxf build) unless the gcc semantics are
clearer.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D64119/new/
https://reviews.llvm.org/D64119
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