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MS ABI: Aligned tentative definitions don't have CommonLinkage 

int __declspec(align(16)) foo; is a tentative definition but the storage
for that variable should not have CommonLinkage.

llvm-svn: 214828
This commit is contained in:
David Majnemer 2014-08-05 00:01:13 +00:00
parent 755ffa9b54
commit c017d3613e
2 changed files with 25 additions and 2 deletions
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12
clang/lib/CodeGen/CodeGenModule.cpp
View File

@ -1951,7 +1951,8 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
DI->EmitGlobalVariable(GV, D);
}
static bool isVarDeclStrongDefinition(const VarDecl *D, bool NoCommon) {
static bool isVarDeclStrongDefinition(const ASTContext &Context,
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>())
@ -1976,6 +1977,12 @@ static bool isVarDeclStrongDefinition(const VarDecl *D, bool NoCommon) {
if (D->hasAttr<WeakImportAttr>())
return true;
// Declarations with a required alignment do not have common linakge in MSVC
// mode.
if (Context.getLangOpts().MSVCCompat &&
(Context.isAlignmentRequired(D->getType()) || D->hasAttr<AlignedAttr>()))
return true;
return false;
}
@ -2022,7 +2029,8 @@ llvm::GlobalValue::LinkageTypes CodeGenModule::getLLVMLinkageForDeclarator(
// C++ doesn't have tentative definitions and thus cannot have common
// linkage.
if (!getLangOpts().CPlusPlus && isa<VarDecl>(D) &&
!isVarDeclStrongDefinition(cast<VarDecl>(D), CodeGenOpts.NoCommon))
!isVarDeclStrongDefinition(Context, cast<VarDecl>(D),
CodeGenOpts.NoCommon))
return llvm::GlobalVariable::CommonLinkage;
// selectany symbols are externally visible, so use weak instead of

15
clang/test/CodeGen/ms-align-tentative.c Normal file
View File

@ -0,0 +1,15 @@
// RUN: %clang_cc1 -triple i386-pc-win32 %s -emit-llvm -fms-compatibility -o - | FileCheck %s
char __declspec(align(8192)) x;
// CHECK-DAG: @x = global i8 0, align 8192
typedef char __declspec(align(8192)) T;
T y;
// CHECK-DAG: @y = global i8 0, align 8192
T __declspec(align(8192)) z;
// CHECK-DAG: @z = global i8 0, align 8192
int __declspec(align(16)) redef;
int __declspec(align(32)) redef = 8;
// CHECK-DAG: @redef = global i32 8, align 32