[clang] [Clang][LLVM][Coroutines] Prevent __coro_gro from outliving __promise (PR #66706)
Bruno Cardoso Lopes via cfe-commits
cfe-commits at lists.llvm.org
Thu Sep 21 11:43:57 PDT 2023
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.cardoso at gmail.com>
Date: Wed, 20 Sep 2023 15:00:06 -0700
Subject: [PATCH 1/2] [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.
>From 80a1dae0c5dce57ff5a62c59519105c914176345 Mon Sep 17 00:00:00 2001
From: Bruno Cardoso Lopes <bruno.cardoso at gmail.com>
Date: Thu, 21 Sep 2023 11:41:31 -0700
Subject: [PATCH 2/2] [Clang][Coroutines] Add one more testcase and fix nits
---
clang/test/CodeGenCoroutines/coro-gro.cpp | 1 -
llvm/docs/Coroutines.rst | 19 ++++++
llvm/docs/LangRef.rst | 16 -----
.../Coroutines/coro-alloca-outside-frame.ll | 61 +++++++++++++++++++
4 files changed, 80 insertions(+), 17 deletions(-)
create mode 100644 llvm/test/Transforms/Coroutines/coro-alloca-outside-frame.ll
diff --git a/clang/test/CodeGenCoroutines/coro-gro.cpp b/clang/test/CodeGenCoroutines/coro-gro.cpp
index ba872e39f4e3de8..d4c3ff589e340a8 100644
--- a/clang/test/CodeGenCoroutines/coro-gro.cpp
+++ b/clang/test/CodeGenCoroutines/coro-gro.cpp
@@ -105,5 +105,4 @@ 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/Coroutines.rst b/llvm/docs/Coroutines.rst
index eed160f426d4517..b1d7a5017e612b0 100644
--- a/llvm/docs/Coroutines.rst
+++ b/llvm/docs/Coroutines.rst
@@ -1775,6 +1775,25 @@ CoroCleanup
This pass runs late to lower all coroutine related intrinsics not replaced by
earlier passes.
+Metadata
+========
+
+'``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 = !{}
+
Areas Requiring Attention
=========================
#. When coro.suspend returns -1, the coroutine is suspended, and it's possible
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 9e3f8962ce1b52e..f542e70bcfee810 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -6691,22 +6691,6 @@ 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/test/Transforms/Coroutines/coro-alloca-outside-frame.ll b/llvm/test/Transforms/Coroutines/coro-alloca-outside-frame.ll
new file mode 100644
index 000000000000000..ac6a5752438cedb
--- /dev/null
+++ b/llvm/test/Transforms/Coroutines/coro-alloca-outside-frame.ll
@@ -0,0 +1,61 @@
+; Tests that CoroSplit can succesfully skip allocas that shall not live on the frame
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S -o %t.ll
+; RUN: FileCheck --input-file=%t.ll %s
+
+define ptr @f(i1 %n) presplitcoroutine {
+entry:
+ %x = alloca i64, !coro.outside.frame !{}
+ %y = alloca i64
+ %id = call token @llvm.coro.id(i32 0, ptr null, ptr null, ptr null)
+ %size = call i32 @llvm.coro.size.i32()
+ %alloc = call ptr @malloc(i32 %size)
+ %hdl = call ptr @llvm.coro.begin(token %id, ptr %alloc)
+ br i1 %n, label %flag_true, label %flag_false
+
+flag_true:
+ br label %merge
+
+flag_false:
+ br label %merge
+
+merge:
+ %alias_phi = phi ptr [ %x, %flag_true ], [ %y, %flag_false ]
+ %sp1 = call i8 @llvm.coro.suspend(token none, i1 false)
+ switch i8 %sp1, label %suspend [i8 0, label %resume
+ i8 1, label %cleanup]
+resume:
+ call void @print(ptr %alias_phi)
+ br label %cleanup
+
+cleanup:
+ %mem = call ptr @llvm.coro.free(token %id, ptr %hdl)
+ call void @free(ptr %mem)
+ br label %suspend
+
+suspend:
+ call i1 @llvm.coro.end(ptr %hdl, i1 0, token none)
+ ret ptr %hdl
+}
+
+; %y and %alias_phi would all go to the frame, but not %x
+; CHECK: %f.Frame = type { ptr, ptr, i64, ptr, i1 }
+; CHECK-LABEL: @f(
+; CHECK: %x = alloca i64, align 8, !coro.outside.frame !0
+; CHECK-NOT: %x.reload.addr = getelementptr inbounds %f.Frame, ptr %hdl, i32 0, i32 2
+; CHECK: %y.reload.addr = getelementptr inbounds %f.Frame, ptr %hdl, i32 0, i32 2
+; CHECK: %alias_phi = phi ptr [ %y.reload.addr, %merge.from.flag_false ], [ %x, %entry ]
+
+declare ptr @llvm.coro.free(token, ptr)
+declare i32 @llvm.coro.size.i32()
+declare i8 @llvm.coro.suspend(token, i1)
+declare void @llvm.coro.resume(ptr)
+declare void @llvm.coro.destroy(ptr)
+
+declare token @llvm.coro.id(i32, ptr, ptr, ptr)
+declare i1 @llvm.coro.alloc(token)
+declare ptr @llvm.coro.begin(token, ptr)
+declare i1 @llvm.coro.end(ptr, i1, token)
+
+declare void @print(ptr)
+declare noalias ptr @malloc(i32)
+declare void @free(ptr)
\ No newline at end of file
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