[PATCH] D29208: Prevent ICE in dllexport class with _Atomic() data member

[Warren Ristow via Phabricator via cfe-commits]

wristow created this revision.

Guard against a null pointer dereference that caused Clang to crash
when processing a class containing an _Atomic(<typ>) data member,
and that is tagged with 'dllexport'.


https://reviews.llvm.org/D29208

Files:
  lib/CodeGen/CGClass.cpp
  test/CodeGenCXX/atomic-dllexport.cpp


Index: test/CodeGenCXX/atomic-dllexport.cpp
===================================================================
--- test/CodeGenCXX/atomic-dllexport.cpp
+++ test/CodeGenCXX/atomic-dllexport.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -triple i686-windows-msvc -emit-llvm -std=c++11 -fms-extensions -O0 -o - %s | FileCheck --check-prefix=M32 %s
+// RUN: %clang_cc1 -triple x86_64-windows-msvc -emit-llvm -std=c++11 -fms-extensions -O0 -o - %s | FileCheck --check-prefix=M64 %s
+
+struct __declspec(dllexport) SomeStruct {
+  // Copy assignment operator should be produced, and exported:
+  // M32: define weak_odr dllexport x86_thiscallcc dereferenceable({{[0-9]+}}) %struct.SomeStruct* @"\01??4SomeStruct@@QAEAAU0 at ABU0@@Z"
+  // M64: define weak_odr dllexport                dereferenceable({{[0-9]+}}) %struct.SomeStruct* @"\01??4SomeStruct@@QEAAAEAU0 at AEBU0@@Z"
+  _Atomic(int) mData;
+};
Index: lib/CodeGen/CGClass.cpp
===================================================================
--- lib/CodeGen/CGClass.cpp
+++ lib/CodeGen/CGClass.cpp
@@ -1132,7 +1132,7 @@
         if (!RHS)
           return nullptr;
         MemberExpr *ME2 = dyn_cast<MemberExpr>(RHS);
-        if (dyn_cast<FieldDecl>(ME2->getMemberDecl()) != Field)
+        if (!ME2 || dyn_cast<FieldDecl>(ME2->getMemberDecl()) != Field)
           return nullptr;
         return Field;
       } else if (CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(S)) {


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