fix rdar://8340348, a miscompile of boost that was exposed by r109848.
That revision started classifying truly empty structs like "Y" and "X"
as being NoClass/NoClass and turning them into 'ignore'. The call code
turns around and allocates space for the ignored argument with
GetUndefRValue. The bug is that GetUndefRValue would return the address
as undef, instead of returning an object with a defined address but
undefined contents.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111794 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 0cfd8b6..cf7d01b 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -441,9 +441,12 @@
return RValue::getComplex(std::make_pair(U, U));
}
+ // If this is a use of an undefined aggregate type, the aggregate must have an
+ // identifiable address. Just because the contents of the value are undefined
+ // doesn't mean that the address can't be taken and compared.
if (hasAggregateLLVMType(Ty)) {
- const llvm::Type *LTy = llvm::PointerType::getUnqual(ConvertType(Ty));
- return RValue::getAggregate(llvm::UndefValue::get(LTy));
+ llvm::Value *DestPtr = CreateMemTemp(Ty, "undef.agg.tmp");
+ return RValue::getAggregate(DestPtr);
}
return RValue::get(llvm::UndefValue::get(ConvertType(Ty)));