https://github.com/bcardosolopes updated
https://github.com/llvm/llvm-project/pull/66706
>From 6312dd56ed3a2f47e7291ae32ca044622a317259 Mon Sep 17 00:00:00 2001
From: Bruno Cardoso Lopes <bruno.card...@gmail.com>
Date: Wed, 20 Sep 2023 15:00:06 -0700
Subject: [PATCH] [Clang][LLVM][Coroutines] Prevent __coro_gro from outliving
__promise
When dealing with short-circuiting coroutines (e.g. expected), the deferred
calls that resolve the get_return_object are currently being emitted after we
delete the coroutine frame.
This was caught by ASAN when using optimizations -O1 and above: optimizations
after inlining would place the __coro_gro in the heap, and subsequent delete of
the coroframe followed by the conversion -> BOOM.
This patch forbids the GRO to be placed in the coroutine frame, by adding a new
metadata node that can be attached to `alloca` instructions.
This fixes #49843.
---
clang/lib/CodeGen/CGCoroutine.cpp | 5 +++++
clang/test/CodeGenCoroutines/coro-gro.cpp | 5 ++++-
llvm/docs/LangRef.rst | 16 ++++++++++++++++
llvm/include/llvm/IR/FixedMetadataKinds.def | 1 +
llvm/lib/Transforms/Coroutines/CoroFrame.cpp | 5 +++++
5 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/clang/lib/CodeGen/CGCoroutine.cpp
b/clang/lib/CodeGen/CGCoroutine.cpp
index 448943084acedf3..58310216ecff1f5 100644
--- a/clang/lib/CodeGen/CGCoroutine.cpp
+++ b/clang/lib/CodeGen/CGCoroutine.cpp
@@ -535,6 +535,11 @@ struct GetReturnObjectManager {
Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
+ auto *GroAlloca = dyn_cast_or_null<llvm::AllocaInst>(
+ GroEmission.getOriginalAllocatedAddress().getPointer());
+ assert(GroAlloca && "expected alloca to be emitted");
+ GroAlloca->setMetadata(llvm::LLVMContext::MD_coro_outside_frame,
+ llvm::MDNode::get(CGF.CGM.getLLVMContext(), {}));
// Remember the top of EHStack before emitting the cleanup.
auto old_top = CGF.EHStack.stable_begin();
diff --git a/clang/test/CodeGenCoroutines/coro-gro.cpp
b/clang/test/CodeGenCoroutines/coro-gro.cpp
index b48b769950ae871..ba872e39f4e3de8 100644
--- a/clang/test/CodeGenCoroutines/coro-gro.cpp
+++ b/clang/test/CodeGenCoroutines/coro-gro.cpp
@@ -30,12 +30,13 @@ void doSomething() noexcept;
int f() {
// CHECK: %[[RetVal:.+]] = alloca i32
// CHECK: %[[GroActive:.+]] = alloca i1
+ // CHECK: %[[CoroGro:.+]] = alloca %struct.GroType, {{.*}}
!coro.outside.frame ![[OutFrameMetadata:.+]]
// CHECK: %[[Size:.+]] = call i64 @llvm.coro.size.i64()
// CHECK: call noalias noundef nonnull ptr @_Znwm(i64 noundef %[[Size]])
// CHECK: store i1 false, ptr %[[GroActive]]
// CHECK: call void @_ZNSt16coroutine_traitsIiJEE12promise_typeC1Ev(
- // CHECK: call void
@_ZNSt16coroutine_traitsIiJEE12promise_type17get_return_objectEv(
+ // CHECK: call void
@_ZNSt16coroutine_traitsIiJEE12promise_type17get_return_objectEv({{.*}}
%[[CoroGro]]
// CHECK: store i1 true, ptr %[[GroActive]]
Cleanup cleanup;
@@ -104,3 +105,5 @@ invoker g() {
// CHECK: call void
@_ZN7invoker15invoker_promise17get_return_objectEv({{.*}} %[[AggRes]]
co_return;
}
+
+// CHECK: ![[OutFrameMetadata]] = !{}
\ No newline at end of file
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index f542e70bcfee810..9e3f8962ce1b52e 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -6691,6 +6691,22 @@ sections that the user does not want removed after
linking.
...
!0 = !{}
+'``coro.outside.frame``' Metadata
+^^^^^^^^^^^^^^^^^^^^^^
+
+``coro.outside.frame`` metadata may be attached to an alloca instruction to
+to signify that it shouldn't be promoted to the coroutine frame, useful for
+filtering allocas out by the frontend when emitting internal control
mechanisms.
+Additionally, this metadata is only used as a flag, so the associated
+node must be empty.
+
+.. code-block:: text
+
+ %__coro_gro = alloca %struct.GroType, align 1, !coro.outside.frame !0
+
+ ...
+ !0 = !{}
+
'``unpredictable``' Metadata
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/llvm/include/llvm/IR/FixedMetadataKinds.def
b/llvm/include/llvm/IR/FixedMetadataKinds.def
index 8723bf2a0680c77..b375d0f0912060f 100644
--- a/llvm/include/llvm/IR/FixedMetadataKinds.def
+++ b/llvm/include/llvm/IR/FixedMetadataKinds.def
@@ -50,3 +50,4 @@ LLVM_FIXED_MD_KIND(MD_callsite, "callsite", 35)
LLVM_FIXED_MD_KIND(MD_kcfi_type, "kcfi_type", 36)
LLVM_FIXED_MD_KIND(MD_pcsections, "pcsections", 37)
LLVM_FIXED_MD_KIND(MD_DIAssignID, "DIAssignID", 38)
+LLVM_FIXED_MD_KIND(MD_coro_outside_frame, "coro.outside.frame", 39)
diff --git a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
index a12dd710174f3f8..9c1ee322ce0b177 100644
--- a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -2804,6 +2804,11 @@ static void collectFrameAlloca(AllocaInst *AI,
coro::Shape &Shape,
if (AI == Shape.SwitchLowering.PromiseAlloca)
return;
+ // The __coro_gro alloca should outlive the promise, make sure we
+ // keep it outside the frame.
+ if (MDNode *MD = AI->getMetadata(LLVMContext::MD_coro_outside_frame))
+ return;
+
// The code that uses lifetime.start intrinsic does not work for functions
// with loops without exit. Disable it on ABIs we know to generate such
// code.
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