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Follow-up to r206457 -- fix static adjustments for some subtle virtual inheritance cases 

Reviewed at http://reviews.llvm.org/D3410

llvm-svn: 206504
This commit is contained in:
Timur Iskhodzhanov 2014-04-17 22:01:48 +00:00
parent e80bfcd048
commit ed11ae3d21
2 changed files with 82 additions and 27 deletions
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42
clang/lib/AST/VTableBuilder.cpp
View File

@ -2649,6 +2649,8 @@ VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) {
CharUnits Ret;
bool First = true;
const ASTRecordLayout &OverriderRDLayout =
Context.getASTRecordLayout(Overrider.Method->getParent());
for (CXXBasePaths::paths_iterator I = Paths.begin(), E = Paths.end();
I != E; ++I) {
const CXXBasePath &Path = (*I);
@ -2665,19 +2667,18 @@ VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) {
const ASTRecordLayout &Layout = Context.getASTRecordLayout(PrevRD);
if (Element.Base->isVirtual()) {
LastVBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(CurRD);
if (Overrider.Method->getParent() == PrevRD) {
// This one's interesting. If the final overrider is in a vbase B of the
// most derived class and it overrides a method of the B's own vbase A,
// it uses A* as "this". In its prologue, it can cast A* to B* with
// a static offset. This offset is used regardless of the actual
// offset of A from B in the most derived class, requiring an
// this-adjusting thunk in the vftable if A and B are laid out
// differently in the most derived class.
ThisOffset += Layout.getVBaseClassOffset(CurRD);
} else {
ThisOffset = LastVBaseOffset;
}
// The interesting things begin when you have virtual inheritance.
// The final overrider will use a static adjustment equal to the offset
// of the vbase in the final overrider class.
// For example, if the final overrider is in a vbase B of the most
// derived class and it overrides a method of the B's own vbase A,
// it uses A* as "this". In its prologue, it can cast A* to B* with
// a static offset. This offset is used regardless of the actual
// offset of A from B in the most derived class, requiring an
// this-adjusting thunk in the vftable if A and B are laid out
// differently in the most derived class.
LastVBaseOffset = ThisOffset =
Overrider.Offset + OverriderRDLayout.getVBaseClassOffset(CurRD);
} else {
ThisOffset += Layout.getBaseClassOffset(CurRD);
}
@ -2739,22 +2740,9 @@ void VFTableBuilder::CalculateVtordispAdjustment(
// A simple vtordisp thunk will suffice if the final overrider is defined
// in either the most derived class or its non-virtual base.
if (OverriderRD == MostDerivedClass)
if (OverriderRD == MostDerivedClass || !OverriderVBase)
return;
if (!OverriderVBase) {
MethodVFTableLocation ML = VTables.getMethodVFTableLocation(Overrider.Method);
assert(ML.VBase && "why would we need a vtordisp if we can call the method "
"without a vfptr of a vbase?");
// We need to offset the this parameter if the offset of the vbase is
// different between the overrider class and the most derived class.
const ASTRecordLayout &OverriderRDLayout =
Context.getASTRecordLayout(OverriderRD);
TA.NonVirtual += (OverriderRDLayout.getVBaseClassOffset(ML.VBase) +
ML.VFPtrOffset - ThisOffset).getQuantity();
return;
}
// Otherwise, we need to do use the dynamic offset of the final overrider
// in order to get "this" adjustment right.
TA.Virtual.Microsoft.VBPtrOffset =

67
clang/test/CodeGenCXX/microsoft-abi-vtables-virtual-inheritance.cpp
View File

@ -455,6 +455,35 @@ struct W : virtual X, A {};
W w;
}
namespace Test12 {
struct X : B, A { };
struct Y : X {
virtual void f(); // Overrides A::f.
};
struct Z : virtual Y {
// CHECK-LABEL: VFTable for 'A' in 'Test12::X' in 'Test12::Y' in 'Test12::Z' (2 entries).
// CHECK-NEXT: 0 | void Test12::Y::f()
// CHECK-NEXT: 1 | void A::z()
int z;
// MANGLING-DAG: @"\01??_7Z@Test12@@6BA@@@" = {{.*}}@"\01?f@Y@Test12@@UAEXXZ"
};
struct W : Z {
// CHECK-LABEL: VFTable for 'A' in 'Test12::X' in 'Test12::Y' in 'Test12::Z' in 'Test12::W' (2 entries).
// CHECK-NEXT: 0 | void Test12::Y::f()
// CHECK-NEXT: 1 | void A::z()
W();
int w;
// MANGLING-DAG: @"\01??_7W@Test12@@6BA@@@" = {{.*}}@"\01?f@Y@Test12@@UAEXXZ"
};
W::W() {}
}
namespace vdtors {
struct X {
virtual ~X();
@ -697,3 +726,41 @@ D obj;
// MANGLING-DAG: @"\01??_7B@pr19240@@6B@"
}
namespace pr19408 {
// This test is a non-vtordisp version of the reproducer for PR19408.
struct X : virtual A {
int x;
};
struct Y : X {
virtual void f();
int y;
};
struct Z : Y {
// CHECK-LABEL: VFTable for 'A' in 'pr19408::X' in 'pr19408::Y' in 'pr19408::Z' (2 entries).
// CHECK-NEXT: 0 | void pr19408::Y::f()
// CHECK-NEXT: [this adjustment: -4 non-virtual]
// CHECK-NEXT: 1 | void A::z()
Z();
int z;
// MANGLING-DAG: @"\01??_7Z@pr19408@@6B@" = {{.*}}@"\01?f@Y@pr19408@@W3AEXXZ"
};
Z::Z() {}
struct W : B, Y {
// CHECK-LABEL: VFTable for 'A' in 'pr19408::X' in 'pr19408::Y' in 'pr19408::W' (2 entries).
// CHECK-NEXT: 0 | void pr19408::Y::f()
// CHECK-NEXT: [this adjustment: -4 non-virtual]
// CHECK-NEXT: 1 | void A::z()
W();
int w;
// MANGLING-DAG: @"\01??_7W@pr19408@@6BY@1@@" = {{.*}}@"\01?f@Y@pr19408@@W3AEXXZ"
};
W::W() {}
}