// Emit suspend expression which roughly looks like:
//
// auto && x = CommonExpr();
// if (!x.await_ready()) {
// llvm_coro_save();
// x.await_suspend(...); (*)
// llvm_coro_suspend(); (**)
// }
// x.await_resume();
//
// where the result of the entire expression is the result of x.await_resume()
//
// (*) If x.await_suspend return type is bool, it allows to veto a suspend:
// if (x.await_suspend(...))
// llvm_coro_suspend();
//
// (**) llvm_coro_suspend() encodes three possible continuations as
// a switch instruction:
//
// %where-to = call i8 @llvm.coro.suspend(...)
// switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
// i8 0, label %yield.ready ; go here when resumed
// i8 1, label %yield.cleanup ; go here when destroyed
// ]
//
// See llvm's docs/Coroutines.rst for more details.
//
static RValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
CoroutineSuspendExpr const &S,
AwaitKind Kind, AggValueSlot aggSlot,
bool ignoreResult) {
auto *E = S.getCommonExpr();
auto Binder =
CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
auto Prefix = buildSuspendPrefixStr(Coro, Kind);
BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
// If expression is ready, no need to suspend.
CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
// Otherwise, emit suspend logic.
CGF.EmitBlock(SuspendBlock);
auto &Builder = CGF.Builder;
llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
if (SuspendRet != nullptr) {
// Veto suspension if requested by bool returning await_suspend.
assert(SuspendRet->getType()->isIntegerTy(1) &&
"Sema should have already checked that it is void or bool");
BasicBlock *RealSuspendBlock =
CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
SuspendBlock = RealSuspendBlock;
CGF.EmitBlock(RealSuspendBlock);
}
// Emit the suspend point.
const bool IsFinalSuspend = (Kind == AwaitKind::Final);
llvm::Function *CoroSuspend =
CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
auto *SuspendResult = Builder.CreateCall(
CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
// Create a switch capturing three possible continuations.
auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
Switch->addCase(Builder.getInt8(0), ReadyBlock);
Switch->addCase(Builder.getInt8(1), CleanupBlock);
// Emit cleanup for this suspend point.
CGF.EmitBlock(CleanupBlock);
CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
// Emit await_resume expression.
CGF.EmitBlock(ReadyBlock);
return CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
}
void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
const ObjCAtTryStmt &S,
llvm::Constant *beginCatchFn,
llvm::Constant *endCatchFn,
llvm::Constant *exceptionRethrowFn) {
// Jump destination for falling out of catch bodies.
CodeGenFunction::JumpDest Cont;
if (S.getNumCatchStmts())
Cont = CGF.getJumpDestInCurrentScope("eh.cont");
CodeGenFunction::FinallyInfo FinallyInfo;
if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
FinallyInfo.enter(CGF, Finally->getFinallyBody(),
beginCatchFn, endCatchFn, exceptionRethrowFn);
SmallVector<CatchHandler, 8> Handlers;
// Enter the catch, if there is one.
if (S.getNumCatchStmts()) {
for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
Handlers.push_back(CatchHandler());
CatchHandler &Handler = Handlers.back();
Handler.Variable = CatchDecl;
Handler.Body = CatchStmt->getCatchBody();
Handler.Block = CGF.createBasicBlock("catch");
// @catch(...) always matches.
if (!CatchDecl) {
Handler.TypeInfo = 0; // catch-all
// Don't consider any other catches.
break;
}
Handler.TypeInfo = GetEHType(CatchDecl->getType());
}
EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
}
// Emit the try body.
CGF.EmitStmt(S.getTryBody());
// Leave the try.
if (S.getNumCatchStmts())
CGF.popCatchScope();
// Remember where we were.
CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
// Emit the handlers.
for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
CatchHandler &Handler = Handlers[I];
CGF.EmitBlock(Handler.Block);
llvm::Value *RawExn = CGF.getExceptionFromSlot();
// Enter the catch.
llvm::Value *Exn = RawExn;
if (beginCatchFn) {
Exn = CGF.Builder.CreateCall(beginCatchFn, RawExn, "exn.adjusted");
cast<llvm::CallInst>(Exn)->setDoesNotThrow();
}
CodeGenFunction::RunCleanupsScope cleanups(CGF);
if (endCatchFn) {
// Add a cleanup to leave the catch.
bool EndCatchMightThrow = (Handler.Variable == 0);
CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
EndCatchMightThrow,
endCatchFn);
}
// Bind the catch parameter if it exists.
if (const VarDecl *CatchParam = Handler.Variable) {
llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
CGF.EmitAutoVarDecl(*CatchParam);
CGF.Builder.CreateStore(CastExn, CGF.GetAddrOfLocalVar(CatchParam));
}
CGF.ObjCEHValueStack.push_back(Exn);
CGF.EmitStmt(Handler.Body);
CGF.ObjCEHValueStack.pop_back();
// Leave any cleanups associated with the catch.
cleanups.ForceCleanup();
CGF.EmitBranchThroughCleanup(Cont);
}
// Go back to the try-statement fallthrough.
CGF.Builder.restoreIP(SavedIP);
// Pop out of the finally.
if (S.getFinallyStmt())
FinallyInfo.exit(CGF);
if (Cont.isValid())
CGF.EmitBlock(Cont.getBlock());
}
