Validated by nightly-test runs on x86 and x86-64 darwin, including after
self-host. Hopefully these results hold up on different platforms.
I tried to keep the GNU ObjC runtime happy, but it's hard for me to test.
Reimplement how clang generates IR for exceptions. Instead of creating new
invoke destinations which sequentially chain to the previous destination,
push a more semantic representation of *why* we need the cleanup/catch/filter
behavior, then collect that information into a single landing pad upon request.
Also reorganizes how normal cleanups (i.e. cleanups triggered by non-exceptional
control flow) are generated, since it's actually fairly closely tied in with
the former. Remove the need to track which cleanup scope a block is associated
with.
Document a lot of previously poorly-understood (by me, at least) behavior.
The new framework implements the Horrible Hack (tm), which requires every
landing pad to have a catch-all so that inlining will work. Clang no longer
requires the Horrible Hack just to make exceptions flow correctly within
a function, however. The HH is an unfortunate requirement of LLVM's EH IR.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@107631 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDeclCXX.cpp b/lib/CodeGen/CGDeclCXX.cpp
index 803ee10..d7d0184 100644
--- a/lib/CodeGen/CGDeclCXX.cpp
+++ b/lib/CodeGen/CGDeclCXX.cpp
@@ -347,8 +347,6 @@
EmitBlock(InitCheckBlock);
// Variables used when coping with thread-safe statics and exceptions.
- llvm::BasicBlock *SavedLandingPad = 0;
- llvm::BasicBlock *LandingPad = 0;
if (ThreadsafeStatics) {
// Call __cxa_guard_acquire.
V = Builder.CreateCall(getGuardAcquireFn(*this), GuardVariable);
@@ -358,10 +356,10 @@
Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"),
InitBlock, EndBlock);
+ // Call __cxa_guard_abort along the exceptional edge.
if (Exceptions) {
- SavedLandingPad = getInvokeDest();
- LandingPad = createBasicBlock("guard.lpad");
- setInvokeDest(LandingPad);
+ CleanupBlock Cleanup(*this, EHCleanup);
+ Builder.CreateCall(getGuardAbortFn(*this), GuardVariable);
}
EmitBlock(InitBlock);
@@ -376,7 +374,7 @@
EmitDeclInit(*this, D, GV);
if (ThreadsafeStatics) {
- // Call __cxa_guard_release.
+ // Call __cxa_guard_release. This cannot throw.
Builder.CreateCall(getGuardReleaseFn(*this), GuardVariable);
} else {
llvm::Value *One =
@@ -388,58 +386,6 @@
if (!D.getType()->isReferenceType())
EmitDeclDestroy(*this, D, GV);
- if (ThreadsafeStatics && Exceptions) {
- // If an exception is thrown during initialization, call __cxa_guard_abort
- // along the exceptional edge.
- EmitBranch(EndBlock);
-
- // Construct the landing pad.
- EmitBlock(LandingPad);
-
- // Personality function and LLVM intrinsics.
- llvm::Constant *Personality =
- CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
- (VMContext),
- true),
- "__gxx_personality_v0");
- Personality = llvm::ConstantExpr::getBitCast(Personality, PtrToInt8Ty);
- llvm::Value *llvm_eh_exception =
- CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
- llvm::Value *llvm_eh_selector =
- CGM.getIntrinsic(llvm::Intrinsic::eh_selector);
-
- // Exception object
- llvm::Value *Exc = Builder.CreateCall(llvm_eh_exception, "exc");
- llvm::Value *RethrowPtr = CreateTempAlloca(Exc->getType(), "_rethrow");
-
- // Call the selector function.
- const llvm::PointerType *PtrToInt8Ty
- = llvm::PointerType::getUnqual(llvm::Type::getInt8Ty(VMContext));
- llvm::Constant *Null = llvm::ConstantPointerNull::get(PtrToInt8Ty);
- llvm::Value* SelectorArgs[3] = { Exc, Personality, Null };
- Builder.CreateCall(llvm_eh_selector, SelectorArgs, SelectorArgs + 3,
- "selector");
- Builder.CreateStore(Exc, RethrowPtr);
-
- // Call __cxa_guard_abort along the exceptional edge.
- Builder.CreateCall(getGuardAbortFn(*this), GuardVariable);
-
- setInvokeDest(SavedLandingPad);
-
- // Rethrow the current exception.
- if (getInvokeDest()) {
- llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
- Builder.CreateInvoke(getUnwindResumeOrRethrowFn(), Cont,
- getInvokeDest(),
- Builder.CreateLoad(RethrowPtr));
- EmitBlock(Cont);
- } else
- Builder.CreateCall(getUnwindResumeOrRethrowFn(),
- Builder.CreateLoad(RethrowPtr));
-
- Builder.CreateUnreachable();
- }
-
EmitBlock(EndBlock);
}