[clang] Effect analysis: correctly detect `(f ? a : b)` as nonblocking when a and b are (PR #111224)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Doug Wyatt (dougsonos)

<details>
<summary>Changes</summary>

Fix: Effect analysis: correctly detect `(f ? a : b)` as nonblocking when a and b are

---
Full diff: https://github.com/llvm/llvm-project/pull/111224.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaFunctionEffects.cpp (+5-6) 
- (modified) clang/test/Sema/attr-nonblocking-constraints.cpp (+10) 


``````````diff
diff --git a/clang/lib/Sema/SemaFunctionEffects.cpp b/clang/lib/Sema/SemaFunctionEffects.cpp
index 0fb18d207a50ba..0ac5de29f66aa7 100644
--- a/clang/lib/Sema/SemaFunctionEffects.cpp
+++ b/clang/lib/Sema/SemaFunctionEffects.cpp
@@ -1048,15 +1048,14 @@ class Analyzer {
     }
 
     void checkIndirectCall(CallExpr *Call, QualType CalleeType) {
-      auto *FPT =
-          CalleeType->getAs<FunctionProtoType>(); // Null if FunctionType.
       FunctionEffectKindSet CalleeEffects;
-      if (FPT)
-        CalleeEffects.insert(FPT->getFunctionEffects());
+      if (FunctionEffectsRef Effects = FunctionEffectsRef::get(CalleeType);
+          !Effects.empty())
+        CalleeEffects.insert(Effects);
 
       auto Check1Effect = [&](FunctionEffect Effect, bool Inferring) {
-        if (FPT == nullptr || Effect.shouldDiagnoseFunctionCall(
-                                  /*direct=*/false, CalleeEffects))
+        if (Effect.shouldDiagnoseFunctionCall(
+                /*direct=*/false, CalleeEffects))
           addViolation(Inferring, Effect, ViolationID::CallsExprWithoutEffect,
                        Call->getBeginLoc());
       };
diff --git a/clang/test/Sema/attr-nonblocking-constraints.cpp b/clang/test/Sema/attr-nonblocking-constraints.cpp
index c694860069c960..ff8caf0e573403 100644
--- a/clang/test/Sema/attr-nonblocking-constraints.cpp
+++ b/clang/test/Sema/attr-nonblocking-constraints.cpp
@@ -156,6 +156,16 @@ void nb10(
 	static_cast<void (*)()>(fp1)(); // expected-warning {{function with 'nonblocking' attribute must not call non-'nonblocking' expression}}
 }
 
+// Expression involving indirection
+int nb10a() [[clang::nonblocking]];
+int nb10b() [[clang::nonblocking]];
+
+int nb10c(bool x) [[clang::nonblocking]]
+{
+	// Warns that the expression is not nonblocking.
+	return (x ? nb10a : nb10b)();
+}
+
 // Interactions with nonblocking(false)
 void nb11_no_inference_1() [[clang::nonblocking(false)]] // expected-note {{function does not permit inference of 'nonblocking'}}
 {

``````````

</details>


https://github.com/llvm/llvm-project/pull/111224