[coroutines] Add __builtin_coro_noop => llvm.coro.noop

[GorNishanov]

Summary

A recent addition to Coroutines TS (https://wg21.link/p0913) adds a pre-defined
coroutine noop_coroutine that does nothing. To implement this feature, we implemented
an llvm.coro.noop intrinsic that returns a coroutine handle to a coroutine that
does nothing when resumed or destroyed.

This patch adds a builtin __builtin_coro_noop() that maps to llvm.coro.noop intrinsic.

Related llvm change: https://reviews.llvm.org/D45114

[modocache]

Great, thanks!

[GorNishanov]

Committed:

https://reviews.llvm.org/rC328993

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@328993 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/Builtins.def

 // Coroutine intrinsics.
 BUILTIN(__builtin_coro_resume, "vv*", "")
 BUILTIN(__builtin_coro_destroy, "vv*", "")
 BUILTIN(__builtin_coro_done, "bv*", "n")
 BUILTIN(__builtin_coro_promise, "v*v*IiIb", "n")
 
 BUILTIN(__builtin_coro_size, "z", "n")
 BUILTIN(__builtin_coro_frame, "v*", "n")
+BUILTIN(__builtin_coro_noop, "v*", "n")
 BUILTIN(__builtin_coro_free, "v*v*", "n")
 
 BUILTIN(__builtin_coro_id, "v*Iiv*v*v*", "n")
 BUILTIN(__builtin_coro_alloc, "b", "n")
 BUILTIN(__builtin_coro_begin, "v*v*", "n")
 BUILTIN(__builtin_coro_end, "bv*Ib", "n")
 BUILTIN(__builtin_coro_suspend, "cIb", "n")
 BUILTIN(__builtin_coro_param, "bv*v*", "n")

lib/CodeGen/CGBuiltin.cpp

   case Builtin::BI__builtin_coro_id:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_id);
   case Builtin::BI__builtin_coro_promise:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_promise);
   case Builtin::BI__builtin_coro_resume:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_resume);
   case Builtin::BI__builtin_coro_frame:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_frame);
+  case Builtin::BI__builtin_coro_noop:
+    return EmitCoroutineIntrinsic(E, Intrinsic::coro_noop);
   case Builtin::BI__builtin_coro_free:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_free);
   case Builtin::BI__builtin_coro_destroy:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_destroy);
   case Builtin::BI__builtin_coro_done:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_done);
   case Builtin::BI__builtin_coro_alloc:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_alloc);

test/CodeGenCoroutines/coro-builtins.c

void f(int n) {
 
   // CHECK: %[[PROM_ADDR:.+]] = bitcast i32* %promise to i8*
   // CHECK-NEXT: %[[COROID:.+]] = call token @llvm.coro.id(i32 32, i8* %[[PROM_ADDR]], i8* null, i8* null)
   __builtin_coro_id(32, &promise, 0, 0);
 
   // CHECK-NEXT: call i1 @llvm.coro.alloc(token %[[COROID]])
   __builtin_coro_alloc();
 
+  // CHECK-NEXT: call i8* @llvm.coro.noop()
+  __builtin_coro_noop();
+
   // CHECK-NEXT: %[[SIZE:.+]] = call i64 @llvm.coro.size.i64()
   // CHECK-NEXT: %[[MEM:.+]] = call i8* @myAlloc(i64 %[[SIZE]])
   // CHECK-NEXT: %[[FRAME:.+]] = call i8* @llvm.coro.begin(token %[[COROID]], i8* %[[MEM]])
   __builtin_coro_begin(myAlloc(__builtin_coro_size()));
 
   // CHECK-NEXT: call void @llvm.coro.resume(i8* %[[FRAME]])
   __builtin_coro_resume(__builtin_coro_frame());