Allow for the possibility that __cxa_end_catch might throw for a catch-all block
or a catch of a record type by value or reference. Also convert this to a
lazy cleanup.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@108287 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGException.cpp b/lib/CodeGen/CGException.cpp
index d3949ba..5e91adc 100644
--- a/lib/CodeGen/CGException.cpp
+++ b/lib/CodeGen/CGException.cpp
@@ -1020,18 +1020,45 @@
return LP;
}
+namespace {
+ /// A cleanup to call __cxa_end_catch. In many cases, the caught
+ /// exception type lets us state definitively that the thrown exception
+ /// type does not have a destructor. In particular:
+ /// - Catch-alls tell us nothing, so we have to conservatively
+ /// assume that the thrown exception might have a destructor.
+ /// - Catches by reference behave according to their base types.
+ /// - Catches of non-record types will only trigger for exceptions
+ /// of non-record types, which never have destructors.
+ /// - Catches of record types can trigger for arbitrary subclasses
+ /// of the caught type, so we have to assume the actual thrown
+ /// exception type might have a throwing destructor, even if the
+ /// caught type's destructor is trivial or nothrow.
+ struct CallEndCatch : EHScopeStack::LazyCleanup {
+ CallEndCatch(bool MightThrow) : MightThrow(MightThrow) {}
+ bool MightThrow;
+
+ void Emit(CodeGenFunction &CGF, bool IsForEH) {
+ if (!MightThrow) {
+ CGF.Builder.CreateCall(getEndCatchFn(CGF))->setDoesNotThrow();
+ return;
+ }
+
+ CGF.EmitCallOrInvoke(getEndCatchFn(CGF), 0, 0);
+ }
+ };
+}
+
/// Emits a call to __cxa_begin_catch and enters a cleanup to call
/// __cxa_end_catch.
-static llvm::Value *CallBeginCatch(CodeGenFunction &CGF, llvm::Value *Exn) {
+///
+/// \param EndMightThrow - true if __cxa_end_catch might throw
+static llvm::Value *CallBeginCatch(CodeGenFunction &CGF,
+ llvm::Value *Exn,
+ bool EndMightThrow) {
llvm::CallInst *Call = CGF.Builder.CreateCall(getBeginCatchFn(CGF), Exn);
Call->setDoesNotThrow();
- {
- CodeGenFunction::CleanupBlock EndCatchCleanup(CGF, NormalAndEHCleanup);
-
- // __cxa_end_catch never throws, so this can just be a call.
- CGF.Builder.CreateCall(getEndCatchFn(CGF))->setDoesNotThrow();
- }
+ CGF.EHStack.pushLazyCleanup<CallEndCatch>(NormalAndEHCleanup, EndMightThrow);
return Call;
}
@@ -1051,8 +1078,11 @@
// If we're catching by reference, we can just cast the object
// pointer to the appropriate pointer.
if (isa<ReferenceType>(CatchType)) {
+ bool EndCatchMightThrow = cast<ReferenceType>(CatchType)->getPointeeType()
+ ->isRecordType();
+
// __cxa_begin_catch returns the adjusted object pointer.
- llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn);
+ llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, EndCatchMightThrow);
llvm::Value *ExnCast =
CGF.Builder.CreateBitCast(AdjustedExn, LLVMCatchTy, "exn.byref");
CGF.Builder.CreateStore(ExnCast, ParamAddr);
@@ -1063,7 +1093,7 @@
bool IsComplex = false;
if (!CGF.hasAggregateLLVMType(CatchType) ||
(IsComplex = CatchType->isAnyComplexType())) {
- llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn);
+ llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, false);
// If the catch type is a pointer type, __cxa_begin_catch returns
// the pointer by value.
@@ -1098,7 +1128,7 @@
const llvm::Type *PtrTy = LLVMCatchTy->getPointerTo(0); // addrspace 0 ok
if (RD->hasTrivialCopyConstructor()) {
- llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn);
+ llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, true);
llvm::Value *Cast = CGF.Builder.CreateBitCast(AdjustedExn, PtrTy);
CGF.EmitAggregateCopy(ParamAddr, Cast, CatchType);
return;
@@ -1131,7 +1161,7 @@
CGF.EHStack.popTerminate();
// Finally we can call __cxa_begin_catch.
- CallBeginCatch(CGF, Exn);
+ CallBeginCatch(CGF, Exn, true);
}
/// Begins a catch statement by initializing the catch variable and
@@ -1164,7 +1194,7 @@
VarDecl *CatchParam = S->getExceptionDecl();
if (!CatchParam) {
llvm::Value *Exn = CGF.Builder.CreateLoad(CGF.getExceptionSlot(), "exn");
- CallBeginCatch(CGF, Exn);
+ CallBeginCatch(CGF, Exn, true);
return;
}
@@ -1298,7 +1328,7 @@
Builder.CreateLoad(ForEHVar, "finally.endcatch");
Builder.CreateCondBr(ShouldEndCatch, EndCatchBB, CleanupContBB);
EmitBlock(EndCatchBB);
- Builder.CreateCall(EndCatchFn)->setDoesNotThrow();
+ EmitCallOrInvoke(EndCatchFn, 0, 0); // catch-all, so might throw
EmitBlock(CleanupContBB);
}