[CodeGen] Use the non-virtual alignment when emitting the base
constructor.
Previously, clang would emit an over-aligned (16-byte) store to
initialize B::x in B's base constructor when compiling the following
code:
struct A {
__attribute__((aligned(16))) double data1;
};
struct B : public virtual A {
B() : x(123) {}
double a;
int x;
};
struct C : public virtual B {};
void test() { B b; C c; }
This was happening because the code in IRGen that does member
initialization was using the alignment of a complete object instead of
the non-virtual alignment.
This commit fixes the bug.
rdar://problem/36382481
Differential Revision: https://reviews.llvm.org/D42521
llvm-svn: 323578
diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index b1496a8..56bd250 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -615,7 +615,14 @@
llvm::Value *ThisPtr = CGF.LoadCXXThis();
QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
- LValue LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
+ LValue LHS;
+
+ // If a base constructor is being emitted, create an LValue that has the
+ // non-virtual alignment.
+ if (CGF.CurGD.getCtorType() == Ctor_Base)
+ LHS = CGF.MakeNaturalAlignPointeeAddrLValue(ThisPtr, RecordTy);
+ else
+ LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
EmitLValueForAnyFieldInitialization(CGF, MemberInit, LHS);