[clang] [ClangIR] Support bool-returning await_suspend (PR #227527)
Aman Maurya via cfe-commits
cfe-commits at lists.llvm.org
Wed Oct 14 19:48:22 PDT 2026
https://github.com/amanmaurya92 updated https://github.com/llvm/llvm-project/pull/227527
>From 412ca3f1aa48d9a08ebab1680738a7ed5d656b7e Mon Sep 17 00:00:00 2001
From: amanmaurya92 <amanmaurya9209 at gmail.com>
Date: Wed, 30 Sep 2026 06:05:37 +0530
Subject: [PATCH 1/3] [ClangIR] Support bool-returning await_suspend
Support bool-returning await_suspend in cir.await and CIRGen.
Closes #227404
Assisted-by: Antigravity
---
clang/include/clang/CIR/Dialect/IR/CIROps.td | 2 +
clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp | 23 ++++++----
clang/lib/CIR/Dialect/IR/CIRDialect.cpp | 39 ++++++++++++----
.../coro-await-suspend-bool.cpp | 44 +++++++++++++++++++
clang/test/CIR/IR/await.cir | 37 ++++++++++++++++
clang/test/CIR/IR/invalid-await.cir | 33 +++++++++++++-
6 files changed, 160 insertions(+), 18 deletions(-)
create mode 100644 clang/test/CIR/CodeGenCoroutines/coro-await-suspend-bool.cpp
diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index 89e93a716424dd..b1db8791268118 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -1129,6 +1129,8 @@ def CIR_ConditionOp : CIR_Op<"condition", [
if true, or exits it if false.
- When in the `ready` region of a `cir.await`, it branches to the `resume`
region when true, and to the `suspend` region when false.
+ - When in the `suspend` region of a `cir.await`, it suspends (exits `cir.await`)
+ when true, or branches to the `resume` region when false (veto suspension).
Example:
diff --git a/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp b/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp
index 71bf3424c087ab..560f1bca98fc7a 100644
--- a/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp
@@ -662,16 +662,21 @@ emitSuspendExpression(CIRGenFunction &cgf, CGCoroData &coro,
// and coro.suspend here, that should be done as part of lowering this
// to LLVM dialect (or some other MLIR dialect)
- // A invalid suspendRet indicates "void returning await_suspend"
- mlir::Value suspendRet = cgf.emitScalarExpr(s.getSuspendExpr());
-
- // Veto suspension if requested by bool returning await_suspend.
- if (suspendRet) {
- cgf.cgm.errorNYI("Veto await_suspend");
+ if (s.getSuspendReturnType() ==
+ CoroutineSuspendExpr::SuspendReturnType::SuspendBool) {
+ mlir::Value suspendRet = cgf.evaluateExprAsBool(s.getSuspendExpr());
+ // Veto suspension if requested by bool returning await_suspend.
+ builder.createCondition(suspendRet);
+ } else if (s.getSuspendReturnType() ==
+ CoroutineSuspendExpr::SuspendReturnType::SuspendVoid) {
+ cgf.emitScalarExpr(s.getSuspendExpr());
+ // Signals the parent that execution flows to next region.
+ cir::CoroSuspendPoint::create(builder, loc);
+ } else {
+ cgf.cgm.errorNYI(s.getSourceRange(),
+ "await_suspend returning handle");
+ cir::CoroSuspendPoint::create(builder, loc);
}
-
- // Signals the parent that execution flows to next region.
- cir::CoroSuspendPoint::create(builder, loc);
},
/*resumeBuilder=*/
[&](mlir::OpBuilder &b, mlir::Location loc) {
diff --git a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
index c4ed6697b869f3..c14c38c00c37a6 100644
--- a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
@@ -702,10 +702,21 @@ void cir::ConditionOp::getSuccessorRegions(
return;
}
- // Parent is an await: condition may branch to resume or suspend regions.
+ // Parent is an await: condition in ready region branches to resume or
+ // suspend regions. Condition in suspend region branches to resume (veto) or
+ // exits to parent op (suspend).
auto await = cast<AwaitOp>(getOperation()->getParentOp());
- regions.emplace_back(&await.getResume());
- regions.emplace_back(&await.getSuspend());
+ mlir::Region *parentRegion = getOperation()->getBlock()->getParent();
+ if (parentRegion == &await.getReady()) {
+ regions.emplace_back(&await.getResume());
+ regions.emplace_back(&await.getSuspend());
+ return;
+ }
+ if (parentRegion == &await.getSuspend()) {
+ regions.emplace_back(getOperation());
+ regions.emplace_back(&await.getResume());
+ return;
+ }
}
MutableOperandRange
@@ -3575,17 +3586,29 @@ void cir::AwaitOp::getSuccessorRegions(
return;
}
+ // Branching from suspend: if terminated by cir.condition, it may branch to
+ // exit to parent op (suspend) or resume (veto).
+ if (&getSuspend() == parentRegion) {
+ if (isa<ConditionOp>(point.getTerminatorPredecessorOrNull())) {
+ regions.emplace_back(getOperation());
+ regions.emplace_back(&getResume());
+ return;
+ }
+ }
+
// Branching from suspend or resume: exit to the parent operation.
regions.emplace_back(getOperation());
}
LogicalResult cir::AwaitOp::verify() {
- if (!isa<ConditionOp>(this->getReady().back().getTerminator()))
+ if (this->getReady().empty() ||
+ !isa<ConditionOp>(this->getReady().back().getTerminator()))
return emitOpError("ready region must end with cir.condition");
- if (this->getSuspend().empty())
- return emitOpError("suspend region must not be empty");
- if (!isa<CoroSuspendPoint>(this->getSuspend().back().getTerminator()))
- return emitOpError("suspend region must end with cir.coro.suspend_point");
+ if (this->getSuspend().empty() ||
+ !isa<CoroSuspendPoint, ConditionOp>(
+ this->getSuspend().back().getTerminator()))
+ return emitOpError(
+ "suspend region must end with cir.coro.suspend_point or cir.condition");
return success();
}
diff --git a/clang/test/CIR/CodeGenCoroutines/coro-await-suspend-bool.cpp b/clang/test/CIR/CodeGenCoroutines/coro-await-suspend-bool.cpp
new file mode 100644
index 00000000000000..f88531206b0e98
--- /dev/null
+++ b/clang/test/CIR/CodeGenCoroutines/coro-await-suspend-bool.cpp
@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -Wno-coroutine-missing-unhandled-exception -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -emit-llvm -disable-llvm-passes -Wno-coroutine-missing-unhandled-exception %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
+
+#include "Inputs/coroutine.h"
+
+struct Task {
+ struct promise_type {
+ Task get_return_object() { return {}; }
+ std::suspend_never initial_suspend() noexcept { return {}; }
+ std::suspend_never final_suspend() noexcept { return {}; }
+ void return_void() {}
+ void unhandled_exception() {}
+ };
+};
+
+struct BoolAwaiter {
+ bool await_ready() { return false; }
+ bool await_suspend(std::coroutine_handle<>) { return false; }
+ void await_resume() {}
+};
+
+// CIR-LABEL: cir.func coroutine {{.*}} @_Z15await_bool_vetov
+// OGCG-LABEL: define dso_local void @_Z15await_bool_vetov
+Task await_bool_veto() {
+ // CIR: cir.await(user, ready : {
+ // CIR: %[[READY:.*]] = cir.call @_ZN11BoolAwaiter11await_readyEv(%{{.*}}) : (!cir.ptr<!rec_BoolAwaiter>{{.*}}) -> (!cir.bool{{.*}})
+ // CIR: cir.condition(%[[READY]])
+ // CIR: }, suspend : {
+ // CIR: %[[SUSPEND_RET:.*]] = cir.call @_ZN11BoolAwaiter13await_suspendESt16coroutine_handleIvE(%{{.*}}) : (!cir.ptr<!rec_BoolAwaiter>{{.*}}) -> (!cir.bool{{.*}})
+ // CIR: cir.condition(%[[SUSPEND_RET]])
+ // CIR: }, resume : {
+ // CIR: cir.call @_ZN11BoolAwaiter12await_resumeEv(%{{.*}}) : (!cir.ptr<!rec_BoolAwaiter>{{.*}}) -> ()
+ // CIR: cir.yield
+ // CIR: },)
+
+ // OGCG: %[[READY_RES:.*]] = call noundef zeroext i1 @_ZN11BoolAwaiter11await_readyEv(ptr {{.*}})
+ // OGCG: br i1 %[[READY_RES]], label %[[AWAIT_READY_DEST:.*]], label %[[AWAIT_SUSPEND:.*]]
+ // OGCG: [[AWAIT_SUSPEND]]:
+ // OGCG: %[[SUSP_RET:.*]] = call i1 @llvm.coro.await.suspend.bool(ptr {{.*}}, ptr {{.*}}, ptr {{.*}})
+ // OGCG: br i1 %[[SUSP_RET]], label %{{.*}}, label %[[AWAIT_READY_DEST]]
+ co_await BoolAwaiter{};
+}
diff --git a/clang/test/CIR/IR/await.cir b/clang/test/CIR/IR/await.cir
index b5d3df6175b9c2..e3f09df0d73f6b 100644
--- a/clang/test/CIR/IR/await.cir
+++ b/clang/test/CIR/IR/await.cir
@@ -36,3 +36,40 @@ cir.func coroutine @checkPrintParse(%arg0 : !cir.bool) {
// CHECK: }, resume : {
// CHECK: cir.yield
// CHECK: },)
+
+cir.func coroutine @checkPrintParseBoolSuspend(%arg0 : !cir.bool) {
+ cir.coroutine initialSuspend : {
+ cir.await(init, ready : {
+ cir.condition(%arg0)
+ }, suspend : {
+ cir.coro.suspend_point
+ }, resume : {
+ cir.yield
+ },)
+ cir.yield
+ }, body : {
+ cir.await(user, ready : {
+ cir.condition(%arg0)
+ }, suspend : {
+ cir.condition(%arg0)
+ }, resume : {
+ cir.yield
+ },)
+ cir.yield
+ }, finalSuspend : {
+ cir.yield
+ }, destroy : {
+ cir.yield
+ }, exit : {
+ cir.return
+ }
+ cir.trap
+}
+
+// CHECK: cir.await(user, ready : {
+// CHECK: cir.condition(%arg0)
+// CHECK: }, suspend : {
+// CHECK: cir.condition(%arg0)
+// CHECK: }, resume : {
+// CHECK: cir.yield
+// CHECK: },)
diff --git a/clang/test/CIR/IR/invalid-await.cir b/clang/test/CIR/IR/invalid-await.cir
index 813f10b65b519b..cbb85cd7248738 100644
--- a/clang/test/CIR/IR/invalid-await.cir
+++ b/clang/test/CIR/IR/invalid-await.cir
@@ -31,7 +31,7 @@ cir.func coroutine @missing_condition() {
cir.func coroutine @missing_suspend_point(%arg0 : !cir.bool) {
cir.coroutine initialSuspend : {
- cir.await(init, ready : { // expected-error {{suspend region must end with cir.coro.suspend_point}}
+ cir.await(init, ready : { // expected-error {{suspend region must end with cir.coro.suspend_point or cir.condition}}
cir.condition(%arg0)
}, suspend : {
cir.yield
@@ -50,3 +50,34 @@ cir.func coroutine @missing_suspend_point(%arg0 : !cir.bool) {
}
cir.trap
}
+
+// -----
+
+cir.func coroutine @invalid_suspend_terminator(%arg0 : !cir.bool) {
+ cir.coroutine initialSuspend : {
+ cir.await(init, ready : {
+ cir.condition(%arg0)
+ }, suspend : {
+ cir.coro.suspend_point
+ }, resume : {
+ cir.yield
+ },)
+ cir.yield
+ }, body : {
+ cir.await(user, ready : { // expected-error {{suspend region must end with cir.coro.suspend_point or cir.condition}}
+ cir.condition(%arg0)
+ }, suspend : {
+ cir.unreachable
+ }, resume : {
+ cir.yield
+ },)
+ cir.yield
+ }, finalSuspend : {
+ cir.yield
+ }, destroy : {
+ cir.yield
+ }, exit : {
+ cir.return
+ }
+ cir.trap
+}
>From 8984e0b33ece618b70b50e1c300d6a1a28a5d3b0 Mon Sep 17 00:00:00 2001
From: amanmaurya92 <amanmaurya9209 at gmail.com>
Date: Tue, 13 Oct 2026 17:37:29 +0530
Subject: [PATCH 2/3] [ClangIR] Address review feedback on bool await_suspend
- Switch on SuspendReturnType in CIRGenCoroutine
- Remove redundant ready region empty check in AwaitOp::verify
---
clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp | 13 ++++++++-----
clang/lib/CIR/Dialect/IR/CIRDialect.cpp | 3 +--
2 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp b/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp
index 5b3c82f8e2e309..c69b4b8408961b 100644
--- a/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp
@@ -717,20 +717,23 @@ emitSuspendExpression(CIRGenFunction &cgf, CGCoroData &coro,
// and coro.suspend here, that should be done as part of lowering this
// to LLVM dialect (or some other MLIR dialect)
- if (s.getSuspendReturnType() ==
- CoroutineSuspendExpr::SuspendReturnType::SuspendBool) {
+ switch (s.getSuspendReturnType()) {
+ case CoroutineSuspendExpr::SuspendReturnType::SuspendBool: {
mlir::Value suspendRet = cgf.evaluateExprAsBool(s.getSuspendExpr());
// Veto suspension if requested by bool returning await_suspend.
cir::CoroSuspendPoint::create(builder, loc, suspendRet);
- } else if (s.getSuspendReturnType() ==
- CoroutineSuspendExpr::SuspendReturnType::SuspendVoid) {
+ break;
+ }
+ case CoroutineSuspendExpr::SuspendReturnType::SuspendVoid:
cgf.emitScalarExpr(s.getSuspendExpr());
// Signals the parent that execution flows to next region.
cir::CoroSuspendPoint::create(builder, loc);
- } else {
+ break;
+ case CoroutineSuspendExpr::SuspendReturnType::SuspendHandle:
cgf.cgm.errorNYI(s.getSourceRange(),
"await_suspend returning handle");
cir::CoroSuspendPoint::create(builder, loc);
+ break;
}
},
/*resumeBuilder=*/
diff --git a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
index 7494521472a71b..c937f85f1a6c7b 100644
--- a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
@@ -3742,8 +3742,7 @@ void cir::AwaitOp::getSuccessorRegions(
}
LogicalResult cir::AwaitOp::verify() {
- if (this->getReady().empty() ||
- !isa<ConditionOp>(this->getReady().back().getTerminator()))
+ if (!isa<ConditionOp>(this->getReady().back().getTerminator()))
return emitOpError("ready region must end with cir.condition");
if (this->getSuspend().empty())
return emitOpError("suspend region must not be empty");
>From f64d08711ca00b76d75bc8679c8f1f127d9d7ee8 Mon Sep 17 00:00:00 2001
From: amanmaurya92 <amanmaurya9209 at gmail.com>
Date: Thu, 15 Oct 2026 08:17:06 +0530
Subject: [PATCH 3/3] [ClangIR] Drop redundant invalid_suspend_terminator test
---
clang/test/CIR/IR/invalid-await.cir | 31 -----------------------------
1 file changed, 31 deletions(-)
diff --git a/clang/test/CIR/IR/invalid-await.cir b/clang/test/CIR/IR/invalid-await.cir
index ce5e3f0ccc6388..813f10b65b519b 100644
--- a/clang/test/CIR/IR/invalid-await.cir
+++ b/clang/test/CIR/IR/invalid-await.cir
@@ -50,34 +50,3 @@ cir.func coroutine @missing_suspend_point(%arg0 : !cir.bool) {
}
cir.trap
}
-
-// -----
-
-cir.func coroutine @invalid_suspend_terminator(%arg0 : !cir.bool) {
- cir.coroutine initialSuspend : {
- cir.await(init, ready : {
- cir.condition(%arg0)
- }, suspend : {
- cir.coro.suspend_point
- }, resume : {
- cir.yield
- },)
- cir.yield
- }, body : {
- cir.await(user, ready : { // expected-error {{suspend region must end with cir.coro.suspend_point}}
- cir.condition(%arg0)
- }, suspend : {
- cir.unreachable
- }, resume : {
- cir.yield
- },)
- cir.yield
- }, finalSuspend : {
- cir.yield
- }, destroy : {
- cir.yield
- }, exit : {
- cir.return
- }
- cir.trap
-}
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