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Fix PR19487, PR19505 and PR19506 -- redundant vtordisp thunks when the final overrider is present in both a vbase and nvbase 

Reviewed at http://reviews.llvm.org/D3449

llvm-svn: 206908
This commit is contained in:
Timur Iskhodzhanov 2014-04-22 17:32:02 +00:00
parent f1a311653a
commit 6b12850d27
2 changed files with 68 additions and 17 deletions
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30
clang/lib/AST/VTableBuilder.cpp
View File

@ -64,10 +64,14 @@ public:
/// Method - The method decl of the overrider.
const CXXMethodDecl *Method;
/// VirtualBase - The virtual base class subobject of this overridder.
/// Note that this records the closest derived virtual base class subobject.
const CXXRecordDecl *VirtualBase;
/// Offset - the base offset of the overrider's parent in the layout class.
CharUnits Offset;
OverriderInfo() : Method(0), Offset(CharUnits::Zero()) { }
OverriderInfo() : Method(0), VirtualBase(0), Offset(CharUnits::Zero()) { }
};
private:
@ -201,6 +205,7 @@ FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass,
Overrider.Offset = OverriderOffset;
Overrider.Method = Method.Method;
Overrider.VirtualBase = Method.InVirtualSubobject;
}
}
@ -2716,20 +2721,10 @@ void VFTableBuilder::CalculateVtordispAdjustment(
VBaseMap.find(WhichVFPtr.getVBaseWithVPtr());
assert(VBaseMapEntry != VBaseMap.end());
// If there's no vtordisp, we don't need any vtordisp adjustment.
if (!VBaseMapEntry->second.hasVtorDisp())
return;
const CXXRecordDecl *OverriderRD = Overrider.Method->getParent();
const CXXRecordDecl *OverriderVBase = 0;
if (OverriderRD != MostDerivedClass) {
OverriderVBase =
ComputeBaseOffset(Context, OverriderRD, MostDerivedClass).VirtualBase;
}
// If the final overrider is defined in the same vbase as the initial
// declaration, we don't need a vtordisp thunk at all.
if (OverriderVBase == WhichVFPtr.getVBaseWithVPtr())
// If there's no vtordisp or the final overrider is defined in the same vbase
// as the initial declaration, we don't need any vtordisp adjustment.
if (!VBaseMapEntry->second.hasVtorDisp() ||
Overrider.VirtualBase == WhichVFPtr.getVBaseWithVPtr())
return;
// OK, now we know we need to use a vtordisp thunk.
@ -2740,7 +2735,8 @@ 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 || !OverriderVBase)
if (Overrider.Method->getParent() == MostDerivedClass ||
!Overrider.VirtualBase)
return;
// Otherwise, we need to do use the dynamic offset of the final overrider
@ -2750,7 +2746,7 @@ void VFTableBuilder::CalculateVtordispAdjustment(
MostDerivedClassLayout.getVBPtrOffset()).getQuantity();
TA.Virtual.Microsoft.VBOffsetOffset =
Context.getTypeSizeInChars(Context.IntTy).getQuantity() *
VTables.getVBTableIndex(MostDerivedClass, OverriderVBase);
VTables.getVBTableIndex(MostDerivedClass, Overrider.VirtualBase);
TA.NonVirtual = (ThisOffset - Overrider.Offset).getQuantity();
}

55
clang/test/CodeGenCXX/microsoft-abi-vtables-virtual-inheritance-vtordisps.cpp
View File

@ -480,3 +480,58 @@ struct C : virtual B {
C c;
}
namespace pr19505 {
struct A {
virtual void f();
virtual void z();
};
struct B : A {
virtual void f();
};
struct C : A, B {
virtual void g();
};
struct X : B, virtual C {
X() {}
virtual void g();
// CHECK-LABEL: VFTable for 'pr19505::A' in 'pr19505::B' in 'pr19505::C' in 'pr19505::X' (2 entries).
// CHECK-NEXT: 0 | void pr19505::B::f()
// CHECK-NEXT: 1 | void pr19505::A::z()
// MANGLING-DAG: @"\01??_7X@pr19505@@6BB@1@@" = {{.*}}@"\01?f@B@pr19505@@UAEXXZ"
} x;
void build_vftable(X *obj) { obj->g(); }
}
namespace pr19506 {
struct A {
virtual void f();
virtual void g();
};
struct B : A {
virtual void f();
};
struct C : B {};
struct X : C, virtual B {
virtual void g();
X() {}
// CHECK-LABEL: VFTable for 'pr19506::A' in 'pr19506::B' in 'pr19506::X' (2 entries).
// CHECK-NEXT: 0 | void pr19506::B::f()
// CHECK-NEXT: 1 | void pr19506::X::g()
// CHECK-NEXT: [this adjustment: vtordisp at -4, -12 non-virtual]
// MANGLING-DAG: @"\01??_7X@pr19506@@6BB@1@@" = {{.*}}@"\01?f@B@pr19506@@UAEXXZ"
} x;
void build_vftable(X *obj) { obj->g(); }
}