r288869 - [MS-ABI]V-base dtor called more than needed when throw happens in v-base ctor in window. Need add "complete object flag" check in eh cleanup code.
Erich Keane via cfe-commits
cfe-commits at lists.llvm.org
Tue Dec 6 16:21:46 PST 2016
Author: erichkeane
Date: Tue Dec 6 18:21:45 2016
New Revision: 288869
URL: http://llvm.org/viewvc/llvm-project?rev=288869&view=rev
Log:
[MS-ABI]V-base dtor called more than needed when throw happens in v-base ctor in window. Need add "complete object flag" check in eh cleanup code.
The problem only happen on window ( A MS-ABI issuer )
The nature of the problem is virtual base dtor called more than it is needed after exception throw in inheriting base class(with virtual bases) ctor.
The root problem is when throw happen, not all virtual base classes have been contructed, so not all virtual base dtors are need to call for ehcleanup.
clang has code to handle vbase initialization: basically add check for "complete object flag" before call to v-base ctor.
But that part is missing for cleanup code.
To fix this add similar code as v-base init to cleanup code, same algorithm.
1> Add new routine:
EmitDtorCompleteObjectHandler
With corresponding to EmitCtorCompleteObjectHandler
2> In the EmitDestructorCal
Call EmitDtorCompleteObjectHandler when generate ehcleanup inside ctor.
Just add check for "complete object flag" before call to v-base dtor.
Without my change:
ehcleanup: ; preds = %ctor.skip_vbases
%13 = cleanuppad within none [], !dbg !66
%14 = bitcast %struct.class_0* %this1 to i8*, !dbg !66
%15 = getelementptr inbounds i8, i8* %14, i64 8, !dbg !66
%16 = bitcast i8* %15 to %struct.class_2*, !dbg !66
call void @"\01??1class_2@@UEAA at XZ"(%struct.class_2* %16) #6 [ "funclet"(token
%13) ], !dbg !66
cleanupret from %13 unwind to caller, !dbg !66
with my change:
ehcleanup: ; preds = %ctor.skip_vbases
%13 = cleanuppad within none [], !dbg !66
%14 = bitcast %struct.class_0* %this1 to i8*, !dbg !66
%15 = getelementptr inbounds i8, i8* %14, i64 8, !dbg !66
%16 = bitcast i8* %15 to %struct.class_2*, !dbg !66
%is_complete_object4 = icmp ne i32 %is_most_derived2, 0, !dbg !66
br i1 %is_complete_object4, label %Dtor.dtor_vbase, label %Dtor.skip_vbase, !d
bg !66
Dtor.dtor_vbase: ; preds = %ehcleanup
call void @"\01??1class_2@@UEAA at XZ"(%struct.class_2* %16) #6 [ "funclet"(token
%13) ], !dbg !66
br label %Dtor.skip_vbase, !dbg !66
Dtor.skip_vbase: ; preds = %Dtor.dtor_vbase, %ehcleanup
cleanupret from %13 unwind to caller, !dbg !66
Please let me know you need more info.
Patch by Jennifer Yu.
Differential Revision: https://reviews.llvm.org/D27358
Modified:
cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp
cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-cleanups.cpp
Modified: cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp?rev=288869&r1=288868&r2=288869&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp (original)
+++ cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp Tue Dec 6 18:21:45 2016
@@ -165,6 +165,9 @@ public:
llvm::BasicBlock *
EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
const CXXRecordDecl *RD) override;
+
+ llvm::BasicBlock *
+ EmitDtorCompleteObjectHandler(CodeGenFunction &CGF);
void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
const CXXRecordDecl *RD) override;
@@ -1135,6 +1138,25 @@ MicrosoftCXXABI::EmitCtorCompleteObjectH
return SkipVbaseCtorsBB;
}
+llvm::BasicBlock *
+MicrosoftCXXABI::EmitDtorCompleteObjectHandler(CodeGenFunction &CGF) {
+ llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
+ assert(IsMostDerivedClass &&
+ "ctor for a class with virtual bases must have an implicit parameter");
+ llvm::Value *IsCompleteObject =
+ CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
+
+ llvm::BasicBlock *CallVbaseDtorsBB = CGF.createBasicBlock("Dtor.dtor_vbases");
+ llvm::BasicBlock *SkipVbaseDtorsBB = CGF.createBasicBlock("Dtor.skip_vbases");
+ CGF.Builder.CreateCondBr(IsCompleteObject,
+ CallVbaseDtorsBB, SkipVbaseDtorsBB);
+
+ CGF.EmitBlock(CallVbaseDtorsBB);
+ // CGF will put the base dtor calls in this basic block for us later.
+
+ return SkipVbaseDtorsBB;
+}
+
void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers(
CodeGenFunction &CGF, const CXXRecordDecl *RD) {
// In most cases, an override for a vbase virtual method can adjust
@@ -1512,11 +1534,21 @@ void MicrosoftCXXABI::EmitDestructorCall
This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type),
This, false);
}
+
+ llvm::BasicBlock *BaseDtorEndBB = nullptr;
+ if (ForVirtualBase && isa<CXXConstructorDecl>(CGF.CurCodeDecl)) {
+ BaseDtorEndBB = EmitDtorCompleteObjectHandler(CGF);
+ }
CGF.EmitCXXDestructorCall(DD, Callee, This.getPointer(),
/*ImplicitParam=*/nullptr,
/*ImplicitParamTy=*/QualType(), nullptr,
getFromDtorType(Type));
+ if (BaseDtorEndBB) {
+ // Complete object handler should continue to be the remaining
+ CGF.Builder.CreateBr(BaseDtorEndBB);
+ CGF.EmitBlock(BaseDtorEndBB);
+ }
}
void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info,
Modified: cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-cleanups.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-cleanups.cpp?rev=288869&r1=288868&r2=288869&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-cleanups.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-cleanups.cpp Tue Dec 6 18:21:45 2016
@@ -278,3 +278,38 @@ void f() {
// WIN32-LIFETIME: %[[bc2:.*]] = bitcast %"struct.lifetime_marker::C"* %[[c]] to i8*
// WIN32-LIFETIME: call void @llvm.lifetime.end(i64 1, i8* %[[bc2]])
}
+
+struct class_2 {
+ class_2();
+ virtual ~class_2();
+};
+struct class_1 : virtual class_2 {
+ class_1(){throw "Unhandled exception";}
+ virtual ~class_1() {}
+};
+struct class_0 : class_1 {
+ class_0() ;
+ virtual ~class_0() {}
+};
+
+class_0::class_0() {
+ // WIN32: define x86_thiscallcc %struct.class_0* @"\01??0class_0@@QAE at XZ"(%struct.class_0* returned %this, i32 %is_most_derived)
+ // WIN32: store i32 %is_most_derived, i32* %[[IS_MOST_DERIVED_VAR:.*]], align 4
+ // WIN32: %[[IS_MOST_DERIVED_VAL:.*]] = load i32, i32* %[[IS_MOST_DERIVED_VAR]]
+ // WIN32: %[[SHOULD_CALL_VBASE_CTORS:.*]] = icmp ne i32 %[[IS_MOST_DERIVED_VAL]], 0
+ // WIN32: br i1 %[[SHOULD_CALL_VBASE_CTORS]], label %[[INIT_VBASES:.*]], label %[[SKIP_VBASES:.*]]
+ // WIN32: [[INIT_VBASES]]
+ // WIN32: br label %[[SKIP_VBASES]]
+ // WIN32: [[SKIP_VBASES]]
+// ehcleanup:
+ // WIN32: %[[CLEANUPPAD:.*]] = cleanuppad within none []
+ // WIN32-NEXT: bitcast %{{.*}}* %{{.*}} to i8*
+ // WIN32-NEXT: getelementptr inbounds i8, i8* %{{.*}}, i{{.*}} {{.}}
+ // WIN32-NEXT: bitcast i8* %{{.*}} to %{{.*}}*
+ // WIN32-NEXT: %[[SHOULD_CALL_VBASE_DTOR:.*]] = icmp ne i32 %[[IS_MOST_DERIVED_VAL]], 0
+ // WIN32-NEXT: br i1 %[[SHOULD_CALL_VBASE_DTOR]], label %[[DTOR_VBASE:.*]], label %[[SKIP_VBASE:.*]]
+ // WIN32: [[DTOR_VBASE]]
+ // WIN32-NEXT: call x86_thiscallcc void @"\01??1class_2@@UAE at XZ"
+ // WIN32: br label %[[SKIP_VBASE]]
+ // WIN32: [[SKIP_VBASE]]
+}
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