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[clang][RISCV] support BITINT with mixed-type #156592

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Merged
merged 8 commits into from
Oct 14, 2025
Merged

[clang][RISCV] support BITINT with mixed-type #156592

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0927005
[clang][RISCV] support BITINT with mixed-type
BeMg Jun 13, 2025
2629dac
Update format
BeMg Sep 3, 2025
db42cea
Refine the comment
BeMg Sep 8, 2025
a2c03fa
Drop the curly braces
BeMg Sep 8, 2025
ded0caf
Use Indirect when Size > 2 * XLEN
BeMg Sep 12, 2025
04d20af
Add test for RV32 and fforce-enable-int128
BeMg Sep 12, 2025
ca6cae9
Make RV64 _BitInt(32) always signext
BeMg Sep 22, 2025
5333575
!fixup update format
BeMg Sep 23, 2025
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24 changes: 12 additions & 12 deletions clang/lib/CodeGen/Targets/RISCV.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -680,22 +680,22 @@ ABIArgInfo RISCVABIInfo::classifyArgumentType(QualType Ty, bool IsFixed,
if (const auto *ED = Ty->getAsEnumDecl())
Ty = ED->getIntegerType();

// All integral types are promoted to XLen width
if (Size < XLen && Ty->isIntegralOrEnumerationType()) {
return extendType(Ty, CGT.ConvertType(Ty));
}

if (const auto *EIT = Ty->getAs<BitIntType>()) {
if (EIT->getNumBits() < XLen)

if (XLen == 64 && EIT->getNumBits() == 32)
return extendType(Ty, CGT.ConvertType(Ty));
if (EIT->getNumBits() > 128 ||
(!getContext().getTargetInfo().hasInt128Type() &&
EIT->getNumBits() > 64))
return getNaturalAlignIndirect(
Ty, /*AddrSpace=*/getDataLayout().getAllocaAddrSpace(),
/*ByVal=*/false);

if (EIT->getNumBits() <= 2 * XLen)
return ABIArgInfo::getExtend(Ty, CGT.ConvertType(Ty));
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Can we call extendType here and remove the special case for 32 above? Looks like extendType will call ABIArgInfo::getExtend if its not the special case.

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There's something a bit strange happening here.

Ty: BitIntType 0xf7c7930 'unsigned _BitInt(17)

will be treated as 32 in

int TySize = getContext().getTypeSize(Ty);

If we use the extendType directly, unsigned _BitInt(17) will turn into a signed extension in this case.

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I'm guessing the call to getContext().getTypeSize(Ty) in that function returned the size rounded up to a byte.

I guess we can leave it how you have it then.

return getNaturalAlignIndirect(
Ty, /*AddrSpace=*/getDataLayout().getAllocaAddrSpace(),
/*ByVal=*/false);
}

// All integral types are promoted to XLen width
if (Size < XLen && Ty->isIntegralOrEnumerationType())
return extendType(Ty, CGT.ConvertType(Ty));

return ABIArgInfo::getDirect();
}

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