[clang] [AIX] recognize vsr in inline asm for AIX (PR #68476)

[Chen Zheng via cfe-commits]

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@@ -807,7 +807,7 @@ ArrayRef<TargetInfo::GCCRegAlias> PPCTargetInfo::getGCCRegAliases() const {
 // PPC ELFABIv2 DWARF Definitoin "Table 2.26. Mappings of Common Registers".
 // vs0 ~ vs31 is mapping to 32 - 63,
 // vs32 ~ vs63 is mapping to 77 - 108.
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chenzheng1030 wrote:

@hubert-reinterpretcast I think you are right. There is a legacy issue in the function `getNormalizedGCCRegisterName()`. Once `ReturnCanonical` is true for that function, current clang(without this patch) will use name f0 ~ f31 and v0 ~ v31 for vs0 ~ vs63 on ELFABIV2. And this patch extends this "issue" to AIX.

The `ReturnCanonical` was introduced in https://reviews.llvm.org/D15075 which was targeted for X86. Seems for X86, physically overlapping registers have canonical names, for example X86 ([eax|rax|al|ah] -> ax). But targets like PPC and SystemZ do not have such canonical register names, for example, PPC (vs0 -> f0), SystemZ(v0 -> f0) which are not right.

I prefer to solve this in another patch with solution: for targets that have no canonical name for physically overlapping registers, `ReturnCanonical` should always be false.

What do you think?

https://github.com/llvm/llvm-project/pull/68476