varungandhi-apple added a comment.
> The way you'd test it on the Clang side would be to just write a test case
> that passes such an aggregate and tests that it's passed as an `i8`.
Ah, I just noticed an attribute `__attribute__((swiftcall))` that is used in
some test cases, I can add a test for it.
---
> But I'm not sure it's at all unreasonable to pass this as an i1 rather than
> an i8; seems like something that Swift should handle correctly in its
> call-lowering code.
Here is the code in the compiler which is creating the `i8`.
void addStructField(const clang::FieldDecl *clangField,
VarDecl *swiftField) {
unsigned fieldOffset =
ClangLayout.getFieldOffset(clangField->getFieldIndex());
assert(!clangField->isBitField());
Size offset(fieldOffset / 8);
// If we have a Swift import of this type, use our lowered information.
if (swiftField) { /* snip */ }
// Otherwise, add it as an opaque blob.
auto fieldSize = ClangContext.getTypeSizeInChars(clangField->getType());
return addOpaqueField(offset, Size(fieldSize.getQuantity()));
}
From what I understand, the `i8` is actually correct. (I looked at LLVM IR
generated by small examples and those seem to use `i8` for loads, stores and
layout.)
That said, there is special handling in `NativeConventionSchema::mapIntoNative`
and `NativeConventionSchema::mapFromNative`. Here's the code in `mapIntoNative`.
if (fromNonNative.size() == 1) {
auto *elt = fromNonNative.claimNext();
if (nativeTy != elt->getType()) {
if (isa<llvm::IntegerType>(nativeTy) &&
isa<llvm::IntegerType>(elt->getType()))
elt = IGF.Builder.CreateZExt(elt, nativeTy);
This ends up trying to zext from i8 to i1 and trips over.
Are you suggesting that I change the code in `mapIntoNative`/`mapFromNative` to
flip the zext/trunc the other way around based on sizes? Should I be adding the
special case to `addStructField`? Something else?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D94854/new/
https://reviews.llvm.org/D94854
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