================
@@ -197,12 +206,20 @@ ABIArgInfo
AMDGPUABIInfo::classifyKernelArgumentType(QualType Ty) const {
return ABIArgInfo::getDirect(LTy, 0, nullptr, false);
}
-ABIArgInfo AMDGPUABIInfo::classifyArgumentType(QualType Ty,
+ABIArgInfo AMDGPUABIInfo::classifyArgumentType(QualType Ty, bool Variadic,
unsigned &NumRegsLeft) const {
----------------
JonChesterfield wrote:
This was subtle. Structs that aren't packed into integers and passed in
registers fall through to default handling which sets CanBeFlattened, saying
that it's OK to spread the struct across multiple arguments. This is then very
difficult to reassemble robustly using the va_arg(x, type) interface - one
needs to compute how type is likely to have been spread out across part of the
call frame.
Noting that these values aren't being usefully passed in registers anyway, the
`if (Variadic) {}` sets up call instructions that pass values by value (not
byval) and declares that every value shall be exactly four byte aligned
(including doubles, as that's something Matt suggested for amdgpu some time
ago). This means the frame setup implementation and the case analysis for
testing are very straightforward.
https://github.com/llvm/llvm-project/pull/93362
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