================
@@ -1822,6 +1826,29 @@ void X86_64ABIInfo::postMerge(unsigned AggregateSize,
Class &Lo,
Hi = SSE;
}
+static X86AVXABILevel getEffectiveX86AVXABILevel(CodeGenTypes &CGT,
+ X86AVXABILevel GlobalAVXLevel,
+ const FunctionDecl *FD) {
+ // Always return global AVX level on PlayStation.
+ if (CGT.getTarget().getTriple().isPS() ||
+ CGT.getContext().getLangOpts().getClangABICompat() <=
+ LangOptions::ClangABI::Ver23) {
+ return GlobalAVXLevel;
+ }
+
+ X86AVXABILevel Level = GlobalAVXLevel;
+ if (!FD || !FD->hasAttr<TargetAttr>())
----------------
freaknbigpanda wrote:
So after thinking about this more over the weekend & this morning, I actually
think it is fine as is. This change implemented the following semantics:
1. Call site ABI is determined based on caller target attributes
2. Callee’s target attributes affects how the callee itself is compiled
3. Do not force callers with a lower target attribute AVX level to change their
calling convention, but emit warnings
And the current behaviour with Function Multiversioning matches this, GCC also
doesn't bother making sure this always produces ABI safe code, and instead just
emits warnings in cases where it is problematic. For example see
https://godbolt.org/z/9xKnzdYa1, note that the avx clone of f expects x in ymm
but the caller doesn't put anything in ymm.
> do you need to check for all of those attributes here?
TLDR: Not in this PR, but there should be a follow up to implement this later.
More detail:
Of the other 3 attributes we only care about `FD->getAttr<TargetClonesAttr>()`
which is created using __attribute__((target_clones(....)) and
`FD->getAttr<CPUSpecificAttr>()` which is created using
`__attribute__((cpu_specific(...))`. The remaining one
`FD->getAttr<TargetVersionAttr>()` is only relevant for AArch64 and RISC-V.
We need to update both `__attribute__((target_clones(....))` and
`__attribute__((cpu_specific(...))` to also implement the above semantics, but
this is a pretty big change, so I think this is best done as a follow up to
this PR. We can't simply update the if statement to make it work, a lot more
needs to be done.
https://github.com/llvm/llvm-project/pull/210349
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