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Make deleting and complete dtor variants defer to other dtor variants by
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calling them as subroutines.  This triggers whenever the alias optimization
doesn't, i.e. when the dtor has linkonce linkage or there are virtual bases
or it's the deleting dtor.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@96605 91177308-0d34-0410-b5e6-96231b3b80d8
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@rjmccall
rjmccall committed Feb 18, 2010
1 parent f709fee commit 588e109
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Showing 4 changed files with 131 additions and 54 deletions.
87 changes: 51 additions & 36 deletions lib/CodeGen/CGClass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -477,12 +477,21 @@ static llvm::Value *GetVTTParameter(CodeGenFunction &CGF, GlobalDecl GD) {

const CXXRecordDecl *RD = cast<CXXMethodDecl>(CGF.CurFuncDecl)->getParent();
const CXXRecordDecl *Base = cast<CXXMethodDecl>(GD.getDecl())->getParent();

llvm::Value *VTT;

uint64_t SubVTTIndex =
CGF.CGM.getVtableInfo().getSubVTTIndex(RD, Base);
assert(SubVTTIndex != 0 && "Sub-VTT index must be greater than zero!");
uint64_t SubVTTIndex;

// If the record matches the base, this is the complete ctor/dtor
// variant calling the base variant in a class with virtual bases.
if (RD == Base) {
assert(!CGVtableInfo::needsVTTParameter(CGF.CurGD) &&
"doing no-op VTT offset in base dtor/ctor?");
SubVTTIndex = 0;
} else {
SubVTTIndex = CGF.CGM.getVtableInfo().getSubVTTIndex(RD, Base);
assert(SubVTTIndex != 0 && "Sub-VTT index must be greater than zero!");
}

if (CGVtableInfo::needsVTTParameter(CGF.CurGD)) {
// A VTT parameter was passed to the constructor, use it.
Expand Down Expand Up @@ -962,14 +971,51 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
/// EmitDtorEpilogue - Emit all code that comes at the end of class's
/// destructor. This is to call destructors on members and base classes
/// in reverse order of their construction.
/// FIXME: This needs to take a CXXDtorType.
void CodeGenFunction::EmitDtorEpilogue(const CXXDestructorDecl *DD,
CXXDtorType DtorType) {
assert(!DD->isTrivial() &&
"Should not emit dtor epilogue for trivial dtor!");

const CXXRecordDecl *ClassDecl = DD->getParent();

// In a deleting destructor, we've already called the complete
// destructor as a subroutine, so we just have to delete the
// appropriate value.
if (DtorType == Dtor_Deleting) {
assert(DD->getOperatorDelete() &&
"operator delete missing - EmitDtorEpilogue");
EmitDeleteCall(DD->getOperatorDelete(), LoadCXXThis(),
getContext().getTagDeclType(ClassDecl));
return;
}

// For complete destructors, we've already called the base
// destructor (in GenerateBody), so we just need to destruct all the
// virtual bases.
if (DtorType == Dtor_Complete) {
// Handle virtual bases.
for (CXXRecordDecl::reverse_base_class_const_iterator I =
ClassDecl->vbases_rbegin(), E = ClassDecl->vbases_rend();
I != E; ++I) {
const CXXBaseSpecifier &Base = *I;
CXXRecordDecl *BaseClassDecl
= cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());

// Ignore trivial destructors.
if (BaseClassDecl->hasTrivialDestructor())
continue;
const CXXDestructorDecl *D = BaseClassDecl->getDestructor(getContext());
llvm::Value *V = GetAddressOfBaseOfCompleteClass(LoadCXXThis(),
true,
ClassDecl,
BaseClassDecl);
EmitCXXDestructorCall(D, Dtor_Base, V);
}
return;
}

assert(DtorType == Dtor_Base);

// Collect the fields.
llvm::SmallVector<const FieldDecl *, 16> FieldDecls;
for (CXXRecordDecl::field_iterator I = ClassDecl->field_begin(),
Expand Down Expand Up @@ -1042,37 +1088,6 @@ void CodeGenFunction::EmitDtorEpilogue(const CXXDestructorDecl *DD,
/*NullCheckValue=*/false);
EmitCXXDestructorCall(D, Dtor_Base, V);
}

// If we're emitting a base destructor, we don't want to emit calls to the
// virtual bases.
if (DtorType == Dtor_Base)
return;

// Handle virtual bases.
for (CXXRecordDecl::reverse_base_class_const_iterator I =
ClassDecl->vbases_rbegin(), E = ClassDecl->vbases_rend(); I != E; ++I) {
const CXXBaseSpecifier &Base = *I;
CXXRecordDecl *BaseClassDecl
= cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());

// Ignore trivial destructors.
if (BaseClassDecl->hasTrivialDestructor())
continue;
const CXXDestructorDecl *D = BaseClassDecl->getDestructor(getContext());
llvm::Value *V = GetAddressOfBaseOfCompleteClass(LoadCXXThis(),
true,
ClassDecl,
BaseClassDecl);
EmitCXXDestructorCall(D, Dtor_Base, V);
}

// If we have a deleting destructor, emit a call to the delete operator.
if (DtorType == Dtor_Deleting) {
assert(DD->getOperatorDelete() &&
"operator delete missing - EmitDtorEpilogue");
EmitDeleteCall(DD->getOperatorDelete(), LoadCXXThis(),
getContext().getTagDeclType(ClassDecl));
}
}

/// EmitCXXAggrConstructorCall - This routine essentially creates a (nested)
Expand Down
54 changes: 42 additions & 12 deletions lib/CodeGen/CodeGenFunction.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -248,39 +248,69 @@ void CodeGenFunction::GenerateBody(GlobalDecl GD, llvm::Function *Fn,
Stmt *Body = FD->getBody();
assert((Body || FD->isImplicit()) && "non-implicit function def has no body");

bool SkipBody = false; // should get jump-threaded

// Emit special ctor/dtor prologues.
llvm::BasicBlock *DtorEpilogue = 0;
if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) {
// Emit the constructor prologue, i.e. the base and member initializers.
EmitCtorPrologue(CD, GD.getCtorType());

// TODO: for complete, non-varargs variants, we can get away with
// just emitting the vbase initializers, then calling the base
// constructor.

} else if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD)) {
DtorEpilogue = createBasicBlock("dtor.epilogue");
// In all cases, if there's an exception in the body (or delegate)
// we'll still need to run the epilogue.
llvm::BasicBlock *DtorEpilogue = createBasicBlock("dtor.epilogue");
PushCleanupBlock(DtorEpilogue);

InitializeVtablePtrs(DD->getParent());
// If this is the deleting variant, invoke the complete variant;
// the epilogue will call the appropriate operator delete().
if (GD.getDtorType() == Dtor_Deleting) {
EmitCXXDestructorCall(DD, Dtor_Complete, LoadCXXThis());
SkipBody = true;

// If this is the complete variant, just invoke the base variant;
// the epilogue will destruct the virtual bases.
} else if (GD.getDtorType() == Dtor_Complete) {
EmitCXXDestructorCall(DD, Dtor_Base, LoadCXXThis());
SkipBody = true;

// Otherwise, we're in the base variant, so we need to ensure the
// vtable ptrs are right before emitting the body.
} else {
InitializeVtablePtrs(DD->getParent());
}
}

// Emit the body of the function.
if (!Body)
if (SkipBody) {
// skipped
} else if (!Body) {
SynthesizeImplicitFunctionBody(GD, Fn, Args);
else {
} else {
if (isa<CXXTryStmt>(Body))
OuterTryBlock = cast<CXXTryStmt>(Body);

EmitStmt(Body);
}

// Emit special ctor/ctor epilogues.
// Emit special ctor/dtor epilogues.
if (isa<CXXConstructorDecl>(FD)) {
// If any of the member initializers are temporaries bound to references
// make sure to emit their destructors.
// Be sure to emit any cleanup blocks associated with the member
// or base initializers, which includes (along the exceptional
// path) the destructors for those members and bases that were
// fully constructed.
EmitCleanupBlocks(0);

} else if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD)) {
// Funnel the previously-pushed cleanup block into the epilogue.
CleanupBlockInfo Info = PopCleanupBlock();
assert(Info.CleanupBlock == DtorEpilogue && "Block mismatch!");
EmitBlock(Info.CleanupBlock);

EmitBlock(DtorEpilogue);
EmitDtorEpilogue(DD, GD.getDtorType());


// Go ahead and link in the switch and end blocks.
if (Info.SwitchBlock)
EmitBlock(Info.SwitchBlock);
if (Info.EndBlock)
Expand Down
34 changes: 33 additions & 1 deletion test/CodeGenCXX/virtual-base-destructor-call.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -16,4 +16,36 @@ basic_iostream<char> res;
int main() {
}

// CHECK: call void @_ZN9basic_iosD2Ev
// basic_iostream's complete dtor calls its base dtor, then its
// virtual base's dtor.
// CHECK: define linkonce_odr void @_ZN14basic_iostreamIcED1Ev
// CHECK: call void @_ZN14basic_iostreamIcED2Ev
// CHECK: call void @_ZN9basic_iosD2Ev

// basic_iostream's deleting dtor calls its complete dtor, then
// operator delete().
// CHECK: define linkonce_odr void @_ZN14basic_iostreamIcED0Ev
// CHECK: call void @_ZN14basic_iostreamIcED1Ev
// CHECK: call void @_ZdlPv

// basic_istream's complete dtor calls the base dtor,
// then its virtual base's base dtor.
// CHECK: define linkonce_odr void @_ZN13basic_istreamIcED1Ev
// CHECK: call void @_ZN13basic_istreamIcED2Ev
// CHECK: call void @_ZN9basic_iosD2Ev

// basic_istream's deleting dtor calls the complete dtor, then
// operator delete().
// CHECK: define linkonce_odr void @_ZN13basic_istreamIcED0Ev
// CHECK: call void @_ZN13basic_istreamIcED1Ev
// CHECK: call void @_ZdlPv

// basic_iostream's base dtor calls its non-virtual base dtor.
// CHECK: define linkonce_odr void @_ZN14basic_iostreamIcED2Ev
// CHECK: call void @_ZN13basic_istreamIcED2Ev
// CHECK: }

// basic_istream's base dtor is a no-op.
// CHECK: define linkonce_odr void @_ZN13basic_istreamIcED2Ev
// CHECK-NOT: call
// CHECK: }
10 changes: 5 additions & 5 deletions test/CodeGenCXX/virtual-destructor-calls.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8,15 +8,15 @@ struct B : A {
virtual ~B();
};

// Complete dtor.
// Complete dtor: just an alias because there are no virtual bases.
// CHECK: @_ZN1BD1Ev = alias {{.*}} @_ZN1BD2Ev

// Deleting dtor.
// Deleting dtor: defers to the complete dtor.
// CHECK: define void @_ZN1BD0Ev
// CHECK: call void @_ZN1AD2Ev
// check: call void @_ZdlPv
// CHECK: call void @_ZN1BD1Ev
// CHECK: call void @_ZdlPv

// Base dtor.
// Base dtor: actually calls A's base dtor.
// CHECK: define void @_ZN1BD2Ev
// CHECK: call void @_ZN1AD2Ev

Expand Down

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