[clang] [Sema] atomic_compare_exchange: check failure memory order (PR #74959)

via cfe-commits cfe-commits at lists.llvm.org
Sat Dec 9 18:19:50 PST 2023


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Fangrui Song (MaskRay)

<details>
<summary>Changes</summary>

For
`__atomic_compare_exchange{,_n}/__c11_atomic_compare_exchange_{strong,weak}`,
GCC checks both the success memory order and the failure memory order
under the default -Winvalid-memory-model ("memory model" is confusing
here and "memory order" is much more common in the atomic context).

* The failure memory order cannot be stronger than the success memory
  order.
* The failure memory order, if a constant, must be one of
  relaxed/consume/acquire/seq_cst.

Clang checks just the success memory order under the default
-Watomic-memory-ordering. This patch checks the failure memory order.


---
Full diff: https://github.com/llvm/llvm-project/pull/74959.diff


5 Files Affected:

- (modified) clang/include/clang/Basic/DiagnosticGroups.td (+1) 
- (modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+7-1) 
- (modified) clang/lib/Sema/SemaChecking.cpp (+26-6) 
- (modified) clang/test/Sema/atomic-ops.c (+28-3) 
- (modified) clang/test/SemaCUDA/atomic-ops.cu (+4-4) 


``````````diff
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index caee2dc6daadb6..a282f37292a037 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -822,6 +822,7 @@ def UndeclaredSelector : DiagGroup<"undeclared-selector">;
 def ImplicitAtomic : DiagGroup<"implicit-atomic-properties">;
 def AtomicAlignment : DiagGroup<"atomic-alignment">;
 def CustomAtomic : DiagGroup<"custom-atomic-properties">;
+def AtomicMemoryOrdering : DiagGroup<"atomic-memory-ordering">;
 def AtomicProperties : DiagGroup<"atomic-properties",
                                  [ImplicitAtomic, CustomAtomic]>;
 def SyncAlignment : DiagGroup<"sync-alignment">;
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 28d95ca9b13893..03ed23473c8d32 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8728,7 +8728,13 @@ def err_atomic_op_needs_atomic_int : Error<
   "%select{|atomic }0integer (%1 invalid)">;
 def warn_atomic_op_has_invalid_memory_order : Warning<
   "memory order argument to atomic operation is invalid">,
-  InGroup<DiagGroup<"atomic-memory-ordering">>;
+  InGroup<AtomicMemoryOrdering>;
+def warn_atomic_op_has_invalid_failure_memory_order : Warning<
+  "failure memory order argument to atomic operation is invalid">,
+  InGroup<AtomicMemoryOrdering>;
+def warn_atomic_op_failure_memory_order_stronger_than_success : Warning<
+  "failure memory order cannot be stronger than success memory order">,
+  InGroup<AtomicMemoryOrdering>;
 def err_atomic_op_has_invalid_synch_scope : Error<
   "synchronization scope argument to atomic operation is invalid">;
 def warn_atomic_implicit_seq_cst : Warning<
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 5c97346184470a..4b1f2ccd27c01d 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -8181,13 +8181,33 @@ ExprResult Sema::BuildAtomicExpr(SourceRange CallRange, SourceRange ExprRange,
     break;
   }
 
+  // If the memory orders are constants, check they are valid.
   if (SubExprs.size() >= 2 && Form != Init) {
-    if (std::optional<llvm::APSInt> Result =
-            SubExprs[1]->getIntegerConstantExpr(Context))
-      if (!isValidOrderingForOp(Result->getSExtValue(), Op))
-        Diag(SubExprs[1]->getBeginLoc(),
-             diag::warn_atomic_op_has_invalid_memory_order)
-            << SubExprs[1]->getSourceRange();
+    std::optional<llvm::APSInt> Success =
+        SubExprs[1]->getIntegerConstantExpr(Context);
+    if (Success && !isValidOrderingForOp(Success->getSExtValue(), Op))
+      Diag(SubExprs[1]->getBeginLoc(),
+           diag::warn_atomic_op_has_invalid_memory_order)
+          << SubExprs[1]->getSourceRange();
+    if (SubExprs.size() >= 5) {
+      if (std::optional<llvm::APSInt> Failure =
+              SubExprs[3]->getIntegerConstantExpr(Context)) {
+        if (!llvm::is_contained(
+                {llvm::AtomicOrderingCABI::relaxed,
+                 llvm::AtomicOrderingCABI::consume,
+                 llvm::AtomicOrderingCABI::acquire,
+                 llvm::AtomicOrderingCABI::seq_cst},
+                (llvm::AtomicOrderingCABI)Failure->getSExtValue())) {
+          Diag(SubExprs[3]->getBeginLoc(),
+               diag::warn_atomic_op_has_invalid_failure_memory_order)
+              << SubExprs[3]->getSourceRange();
+        } else if (Success && *Success < *Failure) {
+          Diag(SubExprs[3]->getBeginLoc(),
+               diag::warn_atomic_op_failure_memory_order_stronger_than_success)
+              << SubExprs[3]->getSourceRange();
+        }
+      }
+    }
   }
 
   if (auto ScopeModel = AtomicExpr::getScopeModel(Op)) {
diff --git a/clang/test/Sema/atomic-ops.c b/clang/test/Sema/atomic-ops.c
index 4fa1223b3038f3..d8bf366c44a351 100644
--- a/clang/test/Sema/atomic-ops.c
+++ b/clang/test/Sema/atomic-ops.c
@@ -432,14 +432,28 @@ void memory_checks(_Atomic(int) *Ap, int *p, int val) {
   (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_consume, memory_order_relaxed);
   (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_release, memory_order_relaxed);
   (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_acq_rel, memory_order_relaxed);
-  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_seq_cst, memory_order_relaxed);
+  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_seq_cst, memory_order_acquire);
+  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_seq_cst, memory_order_consume);
+  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_seq_cst, memory_order_release); // expected-warning {{memory order argument to atomic operation is invalid}}
+  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_seq_cst, memory_order_acq_rel); // expected-warning {{memory order argument to atomic operation is invalid}}
+  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_seq_cst, memory_order_seq_cst);
+  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_seq_cst, -1); // expected-warning {{memory order argument to atomic operation is invalid}}
+  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_relaxed, memory_order_acquire); // expected-warning {{failure memory order cannot be stronger than success memory order}}
+  (void)__c11_atomic_compare_exchange_strong(Ap, p, val, memory_order_acquire, memory_order_seq_cst); // expected-warning {{failure memory order cannot be stronger than success memory order}}
 
   (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_relaxed, memory_order_relaxed);
   (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_acquire, memory_order_relaxed);
   (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_consume, memory_order_relaxed);
   (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_release, memory_order_relaxed);
   (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_acq_rel, memory_order_relaxed);
-  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_seq_cst, memory_order_relaxed);
+  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_seq_cst, memory_order_acquire);
+  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_seq_cst, memory_order_consume);
+  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_seq_cst, memory_order_release); // expected-warning {{memory order argument to atomic operation is invalid}}
+  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_seq_cst, memory_order_acq_rel); // expected-warning {{memory order argument to atomic operation is invalid}}
+  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_seq_cst, memory_order_seq_cst);
+  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_seq_cst, -1); // expected-warning {{memory order argument to atomic operation is invalid}}
+  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_relaxed, memory_order_acquire); // expected-warning {{failure memory order cannot be stronger than success memory order}}
+  (void)__c11_atomic_compare_exchange_weak(Ap, p, val, memory_order_acquire, memory_order_seq_cst); // expected-warning {{failure memory order cannot be stronger than success memory order}}
 
   (void)__atomic_load_n(p, memory_order_relaxed);
   (void)__atomic_load_n(p, memory_order_acquire);
@@ -600,7 +614,12 @@ void memory_checks(_Atomic(int) *Ap, int *p, int val) {
   (void)__atomic_compare_exchange(p, p, p, 0, memory_order_consume, memory_order_relaxed);
   (void)__atomic_compare_exchange(p, p, p, 0, memory_order_release, memory_order_relaxed);
   (void)__atomic_compare_exchange(p, p, p, 0, memory_order_acq_rel, memory_order_relaxed);
-  (void)__atomic_compare_exchange(p, p, p, 0, memory_order_seq_cst, memory_order_relaxed);
+  (void)__atomic_compare_exchange(p, p, p, 0, memory_order_seq_cst, memory_order_acquire);
+  (void)__atomic_compare_exchange(p, p, p, 0, memory_order_seq_cst, memory_order_consume);
+  (void)__atomic_compare_exchange(p, p, p, 0, memory_order_seq_cst, memory_order_release); // expected-warning {{failure memory order argument to atomic operation is invalid}}
+  (void)__atomic_compare_exchange(p, p, p, 0, memory_order_seq_cst, memory_order_acq_rel); // expected-warning {{failure memory order argument to atomic operation is invalid}}
+  (void)__atomic_compare_exchange(p, p, p, 0, memory_order_seq_cst, memory_order_seq_cst);
+  (void)__atomic_compare_exchange(p, p, p, 0, memory_order_seq_cst, -1); // expected-warning {{memory order argument to atomic operation is invalid}}
 
   (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_relaxed, memory_order_relaxed);
   (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_acquire, memory_order_relaxed);
@@ -608,6 +627,12 @@ void memory_checks(_Atomic(int) *Ap, int *p, int val) {
   (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_release, memory_order_relaxed);
   (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_acq_rel, memory_order_relaxed);
   (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_seq_cst, memory_order_relaxed);
+  (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_seq_cst, memory_order_acquire);
+  (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_seq_cst, memory_order_consume);
+  (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_seq_cst, memory_order_release); // expected-warning {{failure memory order argument to atomic operation is invalid}}
+  (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_seq_cst, memory_order_acq_rel); // expected-warning {{failure memory order argument to atomic operation is invalid}}
+  (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_seq_cst, memory_order_seq_cst);
+  (void)__atomic_compare_exchange_n(p, p, val, 0, memory_order_seq_cst, -1); // expected-warning {{memory order argument to atomic operation is invalid}}
 }
 
 void nullPointerWarning(void) {
diff --git a/clang/test/SemaCUDA/atomic-ops.cu b/clang/test/SemaCUDA/atomic-ops.cu
index af93b7e1e79448..0b22e81ec9ea3b 100644
--- a/clang/test/SemaCUDA/atomic-ops.cu
+++ b/clang/test/SemaCUDA/atomic-ops.cu
@@ -73,10 +73,10 @@ __device__ bool test_hip_atomic_cmpxchg_weak(int *ptr, int val, int desired) {
   flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_RELAXED, __HIP_MEMORY_SCOPE_WORKGROUP);
   flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_RELAXED, __HIP_MEMORY_SCOPE_AGENT);
   flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_RELAXED, __HIP_MEMORY_SCOPE_SINGLETHREAD);
-  flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_SEQ_CST, __HIP_MEMORY_SCOPE_SINGLETHREAD);
-  flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_CONSUME, __HIP_MEMORY_SCOPE_SINGLETHREAD);
-  flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_ACQUIRE, __HIP_MEMORY_SCOPE_SINGLETHREAD);
-  flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_ACQ_REL, __HIP_MEMORY_SCOPE_SINGLETHREAD);
+  flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_SEQ_CST, __HIP_MEMORY_SCOPE_SINGLETHREAD); // expected-warning {{failure memory order cannot be stronger than success memory order}}
+  flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_CONSUME, __HIP_MEMORY_SCOPE_SINGLETHREAD); // expected-warning {{failure memory order cannot be stronger than success memory order}}
+  flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_ACQUIRE, __HIP_MEMORY_SCOPE_SINGLETHREAD); // expected-warning {{failure memory order cannot be stronger than success memory order}}
+  flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_ACQ_REL, __HIP_MEMORY_SCOPE_SINGLETHREAD); // expected-warning {{failure memory order argument to atomic operation is invalid}}
   flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_RELAXED, __ATOMIC_RELAXED, __HIP_MEMORY_SCOPE_SINGLETHREAD);
   flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED, __HIP_MEMORY_SCOPE_SINGLETHREAD);
   flag = __hip_atomic_compare_exchange_weak(ptr, &val, desired, __ATOMIC_CONSUME, __ATOMIC_RELAXED, __HIP_MEMORY_SCOPE_SINGLETHREAD);

``````````

</details>


https://github.com/llvm/llvm-project/pull/74959


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