[PATCH] D135926: [clang] Fix crash with -funique-internal-linkage-names

[Ellis Hoag via Phabricator via cfe-commits]

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Calling `getFunctionLinkage(CalleeInfo.getCalleeDecl())` will crash when the declaration does not have a body, e.g., `extern void foo();`. Instead, we can use `isExternallyVisible()` to see if the delcaration has internal linkage.

I believe using `!isExternallyVisible()` is correct because the clang linkage must be `InternalLinkage` or `UniqueExternalLinkage`, both of which are "internal linkage" in llvm.
https://github.com/llvm/llvm-project/blob/9c26f51f5e178ac0fda98419e3a61d205d3b58b1/clang/include/clang/Basic/Linkage.h#L28-L40

Fixes https://github.com/llvm/llvm-project/issues/54139


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D135926

Files:
  clang/lib/CodeGen/CGCall.cpp
  clang/test/CodeGen/unique-internal-linkage-names.c


Index: clang/test/CodeGen/unique-internal-linkage-names.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/unique-internal-linkage-names.c
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 %s -S -emit-llvm -funique-internal-linkage-names -o - | FileCheck %s
+
+// Check that we do not crash when overloading extern functions.
+
+inline void overloaded_external() {}
+extern void overloaded_external();
+
+// CHECK: define internal void @overloaded_internal() [[ATTR:#[0-9]+]] {
+static void overloaded_internal() {}
+extern void overloaded_internal();
+
+void markUsed() {
+  overloaded_external();
+  overloaded_internal();
+}
+
+// CHECK: attributes [[ATTR]] =
+// CHECK-SAME: "sample-profile-suffix-elision-policy"="selected"
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -2260,9 +2260,8 @@
   // Add "sample-profile-suffix-elision-policy" attribute for internal linkage
   // functions with -funique-internal-linkage-names.
   if (TargetDecl && CodeGenOpts.UniqueInternalLinkageNames) {
-    if (isa<FunctionDecl>(TargetDecl)) {
-      if (this->getFunctionLinkage(CalleeInfo.getCalleeDecl()) ==
-          llvm::GlobalValue::InternalLinkage)
+    if (const auto *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl)) {
+      if (!FD->isExternallyVisible())
         FuncAttrs.addAttribute("sample-profile-suffix-elision-policy",
                                "selected");
     }


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