[clang] [Clang] CGCoroutines skip emitting try block for value returning `noexcept` init `await_resume` calls (PR #73160)

[Chuanqi Xu via cfe-commits]

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@@ -129,14 +129,48 @@ static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
   return Prefix;
 }
 
-static bool memberCallExpressionCanThrow(const Expr *E) {
-  if (const auto *CE = dyn_cast<CXXMemberCallExpr>(E))
-    if (const auto *Proto =
-            CE->getMethodDecl()->getType()->getAs<FunctionProtoType>())
-      if (isNoexceptExceptionSpec(Proto->getExceptionSpecType()) &&
-          Proto->canThrow() == CT_Cannot)
-        return false;
-  return true;
+// Check if function can throw based on prototype noexcept, also works for
+// destructors which are implicitly noexcept but can be marked noexcept(false).
+static bool FunctionCanThrow(const FunctionDecl *D) {
+  const auto *Proto = D->getType()->getAs<FunctionProtoType>();
+  if (!Proto) {
+    // Function proto is not found, we conservatively assume throwing.
+    return true;
+  }
+  return !isNoexceptExceptionSpec(Proto->getExceptionSpecType()) ||
+         Proto->canThrow() != CT_Cannot;
+}
+
+static bool ResumeStmtCanThrow(const Stmt *S) {
+  if (const auto *CE = dyn_cast<CallExpr>(S)) {
+    const auto *Callee = CE->getDirectCallee();
+    if (!Callee)
+      // We don't have direct callee. Conservatively assume throwing.
+      return true;
+
+    if (FunctionCanThrow(Callee))
+      return true;
----------------
ChuanqiXu9 wrote:

Please don't land it when you have different opinions.

It should be safe to return false directly if we know the function is nothrow. Then it may be slightly more efficient.

https://github.com/llvm/llvm-project/pull/73160