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[coro] Lower llvm.coro.await.suspend.handle to resume with tail call #89751

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Merged
merged 9 commits into from
May 15, 2024
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[coro] Lower llvm.coro.await.suspend.handle to resume with tail call #89751

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33b07ef
stuff
zmodem Mar 26, 2024
6d23b16
format
zmodem Apr 23, 2024
862b5d1
reinstate fixme
zmodem Apr 24, 2024
7192d93
llvm.coro.await.suspend.handle calls must not be nounwind
zmodem Apr 24, 2024
2b2f267
Merge remote-tracking branch 'origin/main' into coro_aggressive_mustt…
zmodem Apr 29, 2024
8fac76b
remove clang/.../coro-symmetric-transfer-01.cpp
zmodem Apr 29, 2024
17d0967
tweaks
zmodem Apr 29, 2024
02aa262
tweak 'Follow the await_suspend' comment
zmodem May 15, 2024
3593520
Merge remote-tracking branch 'origin/main' into coro_aggressive_mustt…
zmodem May 15, 2024
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11 changes: 6 additions & 5 deletions clang/lib/CodeGen/CGCoroutine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -278,7 +278,11 @@ static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Co

llvm::Function *AwaitSuspendIntrinsic = CGF.CGM.getIntrinsic(AwaitSuspendIID);

const auto AwaitSuspendCanThrow = StmtCanThrow(S.getSuspendExpr());
// SuspendHandle might throw since it also resumes the returned handle.
const bool AwaitSuspendCanThrow =
SuspendReturnType ==
CoroutineSuspendExpr::SuspendReturnType::SuspendHandle ||
StmtCanThrow(S.getSuspendExpr());

llvm::CallBase *SuspendRet = nullptr;
// FIXME: add call attributes?
Expand Down Expand Up @@ -307,10 +311,7 @@ static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Co
break;
}
case CoroutineSuspendExpr::SuspendReturnType::SuspendHandle: {
assert(SuspendRet->getType()->isPointerTy());

auto ResumeIntrinsic = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_resume);
Builder.CreateCall(ResumeIntrinsic, SuspendRet);
assert(SuspendRet->getType()->isVoidTy());
break;
}
}
Expand Down
4 changes: 2 additions & 2 deletions clang/test/CodeGenCoroutines/coro-await.cpp
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Expand Up @@ -370,8 +370,8 @@ extern "C" void TestTailcall() {
// ---------------------------
// Call coro.await.suspend
// ---------------------------
// CHECK-NEXT: %[[RESUMED:.+]] = call ptr @llvm.coro.await.suspend.handle(ptr %[[AWAITABLE]], ptr %[[FRAME]], ptr @TestTailcall.__await_suspend_wrapper__await)
// CHECK-NEXT: call void @llvm.coro.resume(ptr %[[RESUMED]])
// Note: The call must not be nounwind since the resumed function could throw.
// CHECK-NEXT: call void @llvm.coro.await.suspend.handle(ptr %[[AWAITABLE]], ptr %[[FRAME]], ptr @TestTailcall.__await_suspend_wrapper__await){{$}}
// CHECK-NEXT: %[[OUTCOME:.+]] = call i8 @llvm.coro.suspend(token %[[SUSPEND_ID]], i1 false)
// CHECK-NEXT: switch i8 %[[OUTCOME]], label %[[RET_BB:.+]] [
// CHECK-NEXT: i8 0, label %[[READY_BB]]
Expand Down
54 changes: 0 additions & 54 deletions clang/test/CodeGenCoroutines/coro-symmetric-transfer-01.cpp
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This was testing that "the lifetime of the coroutine handle used to obtain
the address is contained within single basic block, and hence does not
live across suspension points"

Since we no longer separately obtain the handle and pass it to
@llvm.coro.resume, this test doesn't really test anything.

This file was deleted.

6 changes: 2 additions & 4 deletions clang/test/CodeGenCoroutines/coro-symmetric-transfer-02.cpp
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Expand Up @@ -89,8 +89,7 @@ Task bar() {
// CHECK: br i1 %{{.+}}, label %[[CASE1_AWAIT_READY:.+]], label %[[CASE1_AWAIT_SUSPEND:.+]]
// CHECK: [[CASE1_AWAIT_SUSPEND]]:
// CHECK-NEXT: %{{.+}} = call token @llvm.coro.save(ptr null)
// CHECK-NEXT: %[[HANDLE1_PTR:.+]] = call ptr @llvm.coro.await.suspend.handle
// CHECK-NEXT: call void @llvm.coro.resume(ptr %[[HANDLE1_PTR]])
// CHECK-NEXT: call void @llvm.coro.await.suspend.handle
// CHECK-NEXT: %{{.+}} = call i8 @llvm.coro.suspend
// CHECK-NEXT: switch i8 %{{.+}}, label %coro.ret [
// CHECK-NEXT: i8 0, label %[[CASE1_AWAIT_READY]]
Expand All @@ -104,8 +103,7 @@ Task bar() {
// CHECK: br i1 %{{.+}}, label %[[CASE2_AWAIT_READY:.+]], label %[[CASE2_AWAIT_SUSPEND:.+]]
// CHECK: [[CASE2_AWAIT_SUSPEND]]:
// CHECK-NEXT: %{{.+}} = call token @llvm.coro.save(ptr null)
// CHECK-NEXT: %[[HANDLE2_PTR:.+]] = call ptr @llvm.coro.await.suspend.handle
// CHECK-NEXT: call void @llvm.coro.resume(ptr %[[HANDLE2_PTR]])
// CHECK-NEXT: call void @llvm.coro.await.suspend.handle
// CHECK-NEXT: %{{.+}} = call i8 @llvm.coro.suspend
// CHECK-NEXT: switch i8 %{{.+}}, label %coro.ret [
// CHECK-NEXT: i8 0, label %[[CASE2_AWAIT_READY]]
Expand Down
19 changes: 10 additions & 9 deletions llvm/docs/Coroutines.rst
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Expand Up @@ -1922,7 +1922,7 @@ Example:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
::

declare ptr @llvm.coro.await.suspend.handle(
declare void @llvm.coro.await.suspend.handle(
ptr <awaiter>,
ptr <handle>,
ptr <await_suspend_function>)
Expand Down Expand Up @@ -1967,7 +1967,9 @@ The intrinsic must be used between corresponding `coro.save`_ and
`await_suspend_function` call during `CoroSplit`_ pass.

`await_suspend_function` must return a pointer to a valid
coroutine frame, which is immediately resumed
coroutine frame. The intrinsic will be lowered to a tail call resuming the
returned coroutine frame. It will be marked `musttail` on targets that support
that. Instructions following the intrinsic will become unreachable.

Example:
""""""""
Expand All @@ -1977,11 +1979,10 @@ Example:
; before lowering
await.suspend:
%save = call token @llvm.coro.save(ptr %hdl)
%next = call ptr @llvm.coro.await.suspend.handle(
ptr %awaiter,
ptr %hdl,
ptr @await_suspend_function)
call void @llvm.coro.resume(%next)
call void @llvm.coro.await.suspend.handle(
ptr %awaiter,
ptr %hdl,
ptr @await_suspend_function)
%suspend = call i8 @llvm.coro.suspend(token %save, i1 false)
...

Expand All @@ -1992,8 +1993,8 @@ Example:
%next = call ptr @await_suspend_function(
ptr %awaiter,
ptr %hdl)
call void @llvm.coro.resume(%next)
%suspend = call i8 @llvm.coro.suspend(token %save, i1 false)
musttail call void @llvm.coro.resume(%next)
ret void
...

; wrapper function example
Expand Down
2 changes: 1 addition & 1 deletion llvm/include/llvm/IR/Intrinsics.td
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Expand Up @@ -1716,7 +1716,7 @@ def int_coro_await_suspend_bool : Intrinsic<[llvm_i1_ty],
[llvm_ptr_ty, llvm_ptr_ty, llvm_ptr_ty],
[Throws]>;

def int_coro_await_suspend_handle : Intrinsic<[llvm_ptr_ty],
def int_coro_await_suspend_handle : Intrinsic<[],
[llvm_ptr_ty, llvm_ptr_ty, llvm_ptr_ty],
[Throws]>;

Expand Down
3 changes: 2 additions & 1 deletion llvm/lib/Transforms/Coroutines/CoroInternal.h
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Expand Up @@ -47,7 +47,7 @@ struct LowererBase {
ConstantPointerNull *const NullPtr;

LowererBase(Module &M);
Value *makeSubFnCall(Value *Arg, int Index, Instruction *InsertPt);
CallInst *makeSubFnCall(Value *Arg, int Index, Instruction *InsertPt);
};

enum class ABI {
Expand Down Expand Up @@ -85,6 +85,7 @@ struct LLVM_LIBRARY_VISIBILITY Shape {
SmallVector<AnyCoroSuspendInst *, 4> CoroSuspends;
SmallVector<CallInst*, 2> SwiftErrorOps;
SmallVector<CoroAwaitSuspendInst *, 4> CoroAwaitSuspends;
SmallVector<CallInst *, 2> SymmetricTransfers;

// Field indexes for special fields in the switch lowering.
struct SwitchFieldIndex {
Expand Down
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