LGTM
These are nits, IMO this is the right interface. There's no reason to push
InitializeVTablePointers into CGCXXABI. We initialize the same set of vtable
pointers for Itanium and Microsoft.
================
Comment at: lib/CodeGen/CGCXXABI.h:240
@@ +239,3 @@
+ virtual void
+ initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
+ const CXXRecordDecl *RD) {}
----------------
OK, this can't be part of EmitCtorCompleteObjectHandler.
================
Comment at: lib/CodeGen/MicrosoftCXXABI.cpp:464-469
@@ +463,8 @@
+ CodeGenFunction &CGF, const CXXRecordDecl *RD) {
+ // In most cases, an override for a vbase virtual method can adjust
+ // the "this" parameter by applying a constant offset.
+ // However, this is not always enough when we execute a constructor or a
+ // destructor of some class X with virtual bases,
+ // X overrides a virtual method M of a vbase Y and
+ // X itself is a vbase of the most derived class.
+ // vtorDisp for vbase Y is a hidden member of X which holds the extra amount
----------------
nit: this text is oddly ragged. Maybe the two conditions should be bulletted?
================
Comment at: lib/CodeGen/MicrosoftCXXABI.cpp:484-489
@@ +483,8 @@
+
+ llvm::Value *VBaseOffset = CGM.getCXXABI().GetVirtualBaseClassOffset(
+ CGF, getThisValue(CGF), RD, I->first);
+ uint64_t ConstantVBaseOffset =
+ Layout.getVBaseClassOffset(I->first).getQuantity();
+ llvm::Value *VtorDispValue = Builder.CreateSub(
+ VBaseOffset, llvm::ConstantInt::get(CGM.IntPtrTy,
ConstantVBaseOffset));
+
----------------
Can you write a pseudo-code comment for this? Something like:
// this->vtordisp_i = this->vbptr[vbase_idx] - offsetof(RD, VBase);
================
Comment at: lib/CodeGen/MicrosoftCXXABI.cpp:491-494
@@ +490,6 @@
+
+ unsigned AS = cast<llvm::PointerType>(getThisValue(CGF)->getType())
+ ->getAddressSpace();
+ llvm::Value *Int8This =
+ Builder.CreateBitCast(getThisValue(CGF), CGF.Int8Ty->getPointerTo(AS));
+ llvm::Value *VtorDispPtr = Builder.CreateInBoundsGEP(Int8This,
VBaseOffset);
----------------
Hoist this out of the loop for cleaner IR.
================
Comment at: lib/CodeGen/MicrosoftCXXABI.cpp:500
@@ +499,3 @@
+ VtorDispPtr, CGF.Int32Ty->getPointerTo(AS), "vtordisp.ptr");
+ VtorDispValue = Builder.CreateTruncOrBitCast(VtorDispValue, CGF.Int32Ty,
+ "vtordisp.val");
----------------
Do we need this? We can use Int32Ty above instead of IntTy if you're worried
about mismatch.
http://llvm-reviews.chandlerc.com/D1867
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