================
@@ -118,6 +124,37 @@ llvm::Type *CodeGenTypes::ConvertTypeForMem(QualType T,
bool ForBitField) {
return R;
}
+bool CodeGenTypes::LLVMTypeLayoutMatchesAST(QualType ASTTy,
+ llvm::Type *LLVMTy) {
+ CharUnits ASTSize = Context.getTypeSizeInChars(ASTTy);
+ CharUnits LLVMSize =
+ CharUnits::fromQuantity(getDataLayout().getTypeAllocSize(LLVMTy));
+ return ASTSize == LLVMSize;
+}
+
+llvm::Type *CodeGenTypes::convertTypeForLoadStore(QualType T,
+ llvm::Type *LLVMTy) {
+ if (!LLVMTy)
+ LLVMTy = ConvertType(T);
+
+ if (!T->isBitIntType() && LLVMTy->isIntegerTy(1))
+ return llvm::IntegerType::get(getLLVMContext(),
+ (unsigned)Context.getTypeSize(T));
+
+ if (T->isBitIntType()) {
+ llvm::Type *R = ConvertType(T);
+ if (!LLVMTypeLayoutMatchesAST(T, R))
+ return llvm::Type::getIntNTy(
+ getLLVMContext(), Context.getTypeSizeInChars(T).getQuantity() * 8);
----------------
momchil-velikov wrote:
Getting back to this...
> I wonder making it unconditional that requires to have different in-memory
> type for all _BitInt types?
The in-memory representation is a whole number of bytes, so in general the
number of in-memory bits will be different from the declared number on a
`_BitInt` type.
If you have `_BitInt(K)` and a load/store type `iN`, then loading/storing `iK`
won't necessarily write to the same bytes as loading/storing `iN` would. That
means we won't be writing to all the bytes of the in-memory representation
which might be incorrect (e.g. for AArch32 ABI which requires padding bits to
be sign- or zero- extended). It can also be inefficient, because LLVM requires
memory accesses to be the minimum number of bytes sufficient to hold an `iK` -
e.g. `i17` will end up as a load store of `i16` followed by a load store of
`i8`, whereas the in-memory representation is 4 bytes and can be accesses as a
single `i32`.
https://github.com/llvm/llvm-project/pull/91364
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