jsji added a comment.
It is great to add `ww` for compatibility.
However if we are going to add `ww`, looks like we should update `ws` as well?
================
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
----------------
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 ?
================
Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:14080
return std::make_pair(0U, &PPC::VSRCRegClass);
- } else if (Constraint == "ws" && Subtarget.hasVSX()) {
+ } else if ((Constraint == "ws" || Constraint == "ww") && Subtarget.hasVSX())
{
if (VT == MVT::f32 && Subtarget.hasP8Vector())
----------------
Should we exclude `FP` for `ws` and return `VFRCRegClass` instead of
`VSFRCRegClass` ?
================
Comment at: llvm/test/CodeGen/PowerPC/inlineasm-vsx-reg.ll:42
+
+define float @test_ww(float %x, float %y) {
+ %1 = tail call float asm "xsmaxdp ${0:x}, ${1:x}, ${2:x}",
"=^ww,^ww,^ww"(float %x, float %y)
----------------
Maybe we should add another test for ws as well? The above test is actually for
'x' modifier?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D64119/new/
https://reviews.llvm.org/D64119
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