Don't crash when a selectany symbol would get common linkage

Things can't both be in comdats and have common linkage, so never give things
in comdats common linkage. Common linkage is only used in .c files, and the
only thing that can trigger a comdat in c is selectany from what I can tell.
Fixes PR23243.

Also address an over-the-shoulder review comment from rnk by moving the
hasAttr<SelectAnyAttr>() in Decl.cpp around a bit. It only makes a minor
difference for selectany on global variables, so it goes well with the rest of
this patch.

http://reviews.llvm.org/D9042

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@235053 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 1cdc24e65fc05a02be9325537d991ba1f81ae042..628c9b053ea4cb07ea121074c3c837d020307694 100644 (file)
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -1915,7 +1915,7 @@ VarDecl::isThisDeclarationADefinition(ASTContext &C) const {
   if (hasInit())
     return Definition;
 
-  if (hasAttr<AliasAttr>())
+  if (hasAttr<AliasAttr>() || hasAttr<SelectAnyAttr>())
     return Definition;
 
   // A variable template specialization (other than a static data member
@@ -1925,14 +1925,14 @@ VarDecl::isThisDeclarationADefinition(ASTContext &C) const {
       getTemplateSpecializationKind() != TSK_ExplicitSpecialization)
     return DeclarationOnly;
 
-  if (!hasAttr<SelectAnyAttr>() && hasExternalStorage())
+  if (hasExternalStorage())
     return DeclarationOnly;
 
   // [dcl.link] p7:
   //   A declaration directly contained in a linkage-specification is treated
   //   as if it contains the extern specifier for the purpose of determining
   //   the linkage of the declared name and whether it is a definition.
-  if (!hasAttr<SelectAnyAttr>() && isSingleLineLanguageLinkage(*this))
+  if (isSingleLineLanguageLinkage(*this))
     return DeclarationOnly;
 
   // C99 6.9.2p2:

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index f60a68ab01158c088b1b95f1209b34f7d9bdfefa..17b7ddc7683dc61ae03dfd7a7d655c37f21525c4 100644 (file)
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -2134,7 +2134,8 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
 }
 
 static bool isVarDeclStrongDefinition(const ASTContext &Context,
-                                      const VarDecl *D, bool NoCommon) {
+                                      CodeGenModule &CGM, const VarDecl *D,
+                                      bool NoCommon) {
   // Don't give variables common linkage if -fno-common was specified unless it
   // was overridden by a NoCommon attribute.
   if ((NoCommon || D->hasAttr<NoCommonAttr>()) && !D->hasAttr<CommonAttr>())
@@ -2159,6 +2160,10 @@ static bool isVarDeclStrongDefinition(const ASTContext &Context,
   if (D->hasAttr<WeakImportAttr>())
     return true;
 
+  // A variable cannot be both common and exist in a comdat.
+  if (shouldBeInCOMDAT(CGM, *D))
+    return true;
+
   // Declarations with a required alignment do not have common linakge in MSVC
   // mode.
   if (Context.getLangOpts().MSVCCompat) {
@@ -2227,7 +2232,7 @@ llvm::GlobalValue::LinkageTypes CodeGenModule::getLLVMLinkageForDeclarator(
   // C++ doesn't have tentative definitions and thus cannot have common
   // linkage.
   if (!getLangOpts().CPlusPlus && isa<VarDecl>(D) &&
-      !isVarDeclStrongDefinition(Context, cast<VarDecl>(D),
+      !isVarDeclStrongDefinition(Context, *this, cast<VarDecl>(D),
                                  CodeGenOpts.NoCommon))
     return llvm::GlobalVariable::CommonLinkage;
 

diff --git a/test/CodeGen/ms-declspecs.c b/test/CodeGen/ms-declspecs.c
index 985c227faa36b147f5586c625262880a43566dbb..c32733e65ff647b792872a0e80ce809dea873bab 100644 (file)
--- a/test/CodeGen/ms-declspecs.c
+++ b/test/CodeGen/ms-declspecs.c
@@ -6,8 +6,10 @@ const __declspec(selectany) int x2 = 2;
 // CHECK: @x2 = weak_odr constant i32 2, comdat, align 4
 
 // selectany turns extern variable declarations into definitions.
-extern __declspec(selectany) int x3;
+__declspec(selectany) int x3;
+extern __declspec(selectany) int x4;
 // CHECK: @x3 = weak_odr global i32 0, comdat, align 4
+// CHECK: @x4 = weak_odr global i32 0, comdat, align 4
 
 struct __declspec(align(16)) S {
   char x;

diff --git a/test/CodeGen/ms-declspecs.cpp b/test/CodeGen/ms-declspecs.cpp
index f77c7cb89169e0b5ebfafe3a405a555acc5c4f11..decf5d6fcb229e6af3b62095b8906e29477a8c65 100644 (file)
--- a/test/CodeGen/ms-declspecs.cpp
+++ b/test/CodeGen/ms-declspecs.cpp
@@ -7,7 +7,9 @@ extern "C++" __declspec(selectany) int x3;
 extern "C" {
 __declspec(selectany) int x4;
 }
+__declspec(selectany) int x5;
 // CHECK: @"\01?x1@@3HA" = weak_odr global i32 0, comdat, align 4
 // CHECK: @x2 = weak_odr global i32 0, comdat, align 4
 // CHECK: @"\01?x3@@3HA"  = weak_odr global i32 0, comdat, align 4
 // CHECK: @x4 = weak_odr global i32 0, comdat, align 4
+// CHECK: @"\01?x5@@3HA"  = weak_odr global i32 0, comdat, align 4