Reland "Cherry-pick 51d5d7b from LLVM mainline" (#8199)

* Update coroutine intrinsics documentation and few remaining tests to opaque pointers (llvm#65698)

* Extend `retcon.once` coroutines lowering to optionally produce a normal result (llvm#66333)

One of the main user of these kind of coroutines is swift. There yield-once (`retcon.once`) coroutines are used to temporary "expose" pointers to internal fields of various objects creating borrow scopes.

However, in some cases it might be useful also to allow these coroutines to produce a normal result, but there is no convenient way to represent this (as compared to switched-resume kind of coroutines where C++ `co_return` is transformed to a member / callback call on promise object).

The extension is simple: we allow continuation function to have a non-void result and accept optional extra arguments via a special `llvm.coro.end.result` intrinsic that would essentially forward them as normal results.

Author: asl

clang/lib/CodeGen/CGCoroutine.cpp

@@ -402,8 +402,11 @@ struct CallCoroEnd final : public EHScopeStack::Cleanup {
     llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
     // See if we have a funclet bundle to associate coro.end with. (WinEH)
     auto Bundles = getBundlesForCoroEnd(CGF);
-    auto *CoroEnd = CGF.Builder.CreateCall(
-        CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
+    auto *CoroEnd =
+      CGF.Builder.CreateCall(CoroEndFn,
+                             {NullPtr, CGF.Builder.getTrue(),
+                              llvm::ConstantTokenNone::get(CoroEndFn->getContext())},
+                             Bundles);
     if (Bundles.empty()) {
       // Otherwise, (landingpad model), create a conditional branch that leads
       // either to a cleanup block or a block with EH resume instruction.
@@ -754,7 +757,9 @@ void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
   // Emit coro.end before getReturnStmt (and parameter destructors), since
   // resume and destroy parts of the coroutine should not include them.
   llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
-  Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
+  Builder.CreateCall(CoroEnd,
+                     {NullPtr, Builder.getFalse(),
+                      llvm::ConstantTokenNone::get(CoroEnd->getContext())});
 
   if (Stmt *Ret = S.getReturnStmt()) {
     // Since we already emitted the return value above, so we shouldn't
@@ -823,7 +828,11 @@ RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
   }
   for (const Expr *Arg : E->arguments())
     Args.push_back(EmitScalarExpr(Arg));
-
+  // @llvm.coro.end takes a token parameter. Add token 'none' as the last
+  // argument.
+  if (IID == llvm::Intrinsic::coro_end)
+    Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
+  
   llvm::Function *F = CGM.getIntrinsic(IID);
   llvm::CallInst *Call = Builder.CreateCall(F, Args);
 

clang/test/CodeGenCoroutines/coro-builtins.c

@@ -37,7 +37,7 @@ void f(int n) {
   // CHECK-NEXT: call ptr @llvm.coro.free(token %[[COROID]], ptr %[[FRAME]])
   __builtin_coro_free(__builtin_coro_frame());
 
-  // CHECK-NEXT: call i1 @llvm.coro.end(ptr %[[FRAME]], i1 false)
+  // CHECK-NEXT: call i1  @llvm.coro.end(ptr %[[FRAME]], i1 false, token none)
   __builtin_coro_end(__builtin_coro_frame(), 0);
 
   // CHECK-NEXT: call i8 @llvm.coro.suspend(token none, i1 true)

clang/test/CodeGenCoroutines/coro-eh-cleanup.cpp

@@ -60,7 +60,7 @@ coro_t f() {
 
 // CHECK: [[COROENDBB]]:
 // CHECK-NEXT: %[[CLPAD:.+]] = cleanuppad within none
-// CHECK-NEXT: call i1 @llvm.coro.end(ptr null, i1 true) [ "funclet"(token %[[CLPAD]]) ]
+// CHECK-NEXT: call i1 @llvm.coro.end(ptr null, i1 true, token none) [ "funclet"(token %[[CLPAD]]) ]
 // CHECK-NEXT: cleanupret from %[[CLPAD]] unwind label
 
 // CHECK-LPAD: @_Z1fv(
@@ -76,7 +76,7 @@ coro_t f() {
 // CHECK-LPAD:             to label %{{.+}} unwind label %[[UNWINDBB:.+]]
 
 // CHECK-LPAD: [[UNWINDBB]]:
-// CHECK-LPAD:   %[[I1RESUME:.+]] = call i1 @llvm.coro.end(ptr null, i1 true)
+// CHECK-LPAD:   %[[I1RESUME:.+]] = call i1 @llvm.coro.end(ptr null, i1 true, token none)
 // CHECK-LPAD:   br i1  %[[I1RESUME]], label %[[EHRESUME:.+]], label
 // CHECK-LPAD: [[EHRESUME]]:
 // CHECK-LPAD-NEXT:  %[[exn:.+]] = load ptr, ptr %exn.slot, align 8