Miscellaneous codegen cleanups. Mostly, don't create new basic blocks
just to save the current insertion state! This change significantly
simplifies the IR CFG in exceptions code.
llvm-svn: 101996
diff --git a/clang/lib/CodeGen/CGException.cpp b/clang/lib/CodeGen/CGException.cpp
index 1e15066..04c76df 100644
--- a/clang/lib/CodeGen/CGException.cpp
+++ b/clang/lib/CodeGen/CGException.cpp
@@ -270,7 +270,7 @@
// Now allocate the exception object.
const llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
- uint64_t TypeSize = getContext().getTypeSize(ThrowType) / 8;
+ uint64_t TypeSize = getContext().getTypeSizeInChars(ThrowType).getQuantity();
llvm::Constant *AllocExceptionFn = getAllocateExceptionFn(*this);
llvm::Value *ExceptionPtr =
@@ -649,38 +649,46 @@
}
CodeGenFunction::EHCleanupBlock::~EHCleanupBlock() {
- llvm::BasicBlock *Cont1 = CGF.createBasicBlock("cont");
- CGF.EmitBranch(Cont1);
CGF.setInvokeDest(PreviousInvokeDest);
+ llvm::BasicBlock *EndOfCleanup = CGF.Builder.GetInsertBlock();
- CGF.EmitBlock(CleanupHandler);
-
+ // Jump to the beginning of the cleanup.
+ CGF.Builder.SetInsertPoint(CleanupHandler, CleanupHandler->begin());
+
+ // The libstdc++ personality function.
+ // TODO: generalize to work with other libraries.
llvm::Constant *Personality =
CGF.CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
(CGF.VMContext),
true),
"__gxx_personality_v0");
Personality = llvm::ConstantExpr::getBitCast(Personality, CGF.PtrToInt8Ty);
+
+ // %exception = call i8* @llvm.eh.exception()
+ // Magic intrinsic which tells gives us a handle to the caught
+ // exception.
llvm::Value *llvm_eh_exception =
CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
+ llvm::Value *Exc = CGF.Builder.CreateCall(llvm_eh_exception, "exc");
+
+ llvm::Constant *Null = llvm::ConstantPointerNull::get(CGF.PtrToInt8Ty);
+
+ // %ignored = call i32 @llvm.eh.selector(i8* %exception,
+ // i8* @__gxx_personality_v0,
+ // i8* null)
+ // Magic intrinsic which tells LLVM that this invoke landing pad is
+ // just a cleanup block.
+ llvm::Value *Args[] = { Exc, Personality, Null };
llvm::Value *llvm_eh_selector =
CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_selector);
-
- llvm::Value *Exc = CGF.Builder.CreateCall(llvm_eh_exception, "exc");
- const llvm::IntegerType *Int8Ty;
- const llvm::PointerType *PtrToInt8Ty;
- Int8Ty = llvm::Type::getInt8Ty(CGF.VMContext);
- // C string type. Used in lots of places.
- PtrToInt8Ty = llvm::PointerType::getUnqual(Int8Ty);
- llvm::Constant *Null = llvm::ConstantPointerNull::get(PtrToInt8Ty);
- llvm::Value *Args[] = { Exc, Personality, Null };
CGF.Builder.CreateCall(llvm_eh_selector, &Args[0], llvm::array_endof(Args));
- CGF.EmitBlock(CleanupEntryBB);
+ // And then we fall through into the code that the user put there.
+ // Jump back to the end of the cleanup.
+ CGF.Builder.SetInsertPoint(EndOfCleanup);
- CGF.EmitBlock(Cont1);
-
+ // Rethrow the exception.
if (CGF.getInvokeDest()) {
llvm::BasicBlock *Cont = CGF.createBasicBlock("invoke.cont");
CGF.Builder.CreateInvoke(getUnwindResumeOrRethrowFn(CGF), Cont,
@@ -688,10 +696,11 @@
CGF.EmitBlock(Cont);
} else
CGF.Builder.CreateCall(getUnwindResumeOrRethrowFn(CGF), Exc);
-
CGF.Builder.CreateUnreachable();
- CGF.EmitBlock(Cont);
+ // Resume inserting where we started, but put the new cleanup
+ // handler in place.
+ CGF.Builder.SetInsertPoint(PreviousInsertionBlock);
if (CGF.Exceptions)
CGF.setInvokeDest(CleanupHandler);
}
@@ -700,12 +709,11 @@
if (TerminateHandler)
return TerminateHandler;
- llvm::BasicBlock *Cont = 0;
-
- if (HaveInsertPoint()) {
- Cont = createBasicBlock("cont");
- EmitBranch(Cont);
- }
+ // We don't want to change anything at the current location, so
+ // save it aside and clear the insert point.
+ llvm::BasicBlock *SavedInsertBlock = Builder.GetInsertBlock();
+ llvm::BasicBlock::iterator SavedInsertPoint = Builder.GetInsertPoint();
+ Builder.ClearInsertionPoint();
llvm::Constant *Personality =
CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
@@ -735,11 +743,8 @@
TerminateCall->setDoesNotThrow();
Builder.CreateUnreachable();
- // Clear the insertion point to indicate we are in unreachable code.
- Builder.ClearInsertionPoint();
-
- if (Cont)
- EmitBlock(Cont);
+ // Restore the saved insertion state.
+ Builder.SetInsertPoint(SavedInsertBlock, SavedInsertPoint);
return TerminateHandler;
}