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Don't eagerly emit a global static merged with a local extern. 

When we are visiting the extern declaration of 'i' in

static int i = 99;
int foo() {
  extern int i;
  return i;
}

We should not try to handle it as if it was an function static. That is, we
must consider the written storage class.

Fixing this then exposes that the assert in EmitGlobalVarDeclLValue and the
if leading to its call are not completely accurate. They were passing before
because the second decl was marked as having external storage. I changed them
to check the linkage, which I find easier to understand.

Last but not least, there is something strange going on with cuda and opencl.
My guess is that the linkage computation for these languages needs to be
audited, but I didn't want to change that in this patch so I just updated
the storage classes to keep the current behavior.

Thanks to Reed Kotler for reporting this.

llvm-svn: 170827
This commit is contained in:
Rafael Espindola 2012-12-21 01:21:33 +00:00
parent 77ca7f1bbe
commit 2be6b72ce0
4 changed files with 19 additions and 7 deletions
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2
clang/lib/CodeGen/CGDecl.cpp
View File

@ -107,7 +107,7 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
/// EmitVarDecl - This method handles emission of any variable declaration
/// inside a function, including static vars etc.
void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
switch (D.getStorageClass()) {
switch (D.getStorageClassAsWritten()) {
case SC_None:
case SC_Auto:
case SC_Register:

5
clang/lib/CodeGen/CGExpr.cpp
View File

@ -1583,8 +1583,7 @@ EmitBitCastOfLValueToProperType(CodeGenFunction &CGF,
static LValue EmitGlobalVarDeclLValue(CodeGenFunction &CGF,
const Expr *E, const VarDecl *VD) {
assert((VD->hasExternalStorage() || VD->isFileVarDecl()) &&
"Var decl must have external storage or be a file var decl!");
assert(VD->hasLinkage() && "Var decl must have linkage!");
llvm::Value *V = CGF.CGM.GetAddrOfGlobalVar(VD);
llvm::Type *RealVarTy = CGF.getTypes().ConvertTypeForMem(VD->getType());
@ -1658,7 +1657,7 @@ LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
if (const VarDecl *VD = dyn_cast<VarDecl>(ND)) {
// Check if this is a global variable.
if (VD->hasExternalStorage() || VD->isFileVarDecl())
if (VD->hasLinkage())
return EmitGlobalVarDeclLValue(*this, E, VD);
bool isBlockVariable = VD->hasAttr<BlocksAttr>();

9
clang/lib/Sema/SemaDecl.cpp
View File

@ -4284,8 +4284,10 @@ Sema::ActOnVariableDeclarator(Scope *S, Declarator &D, DeclContext *DC,
if (getLangOpts().OpenCL) {
// Set up the special work-group-local storage class for variables in the
// OpenCL __local address space.
if (R.getAddressSpace() == LangAS::opencl_local)
if (R.getAddressSpace() == LangAS::opencl_local) {
SC = SC_OpenCLWorkGroupLocal;
SCAsWritten = SC_OpenCLWorkGroupLocal;
}
}
bool isExplicitSpecialization = false;
@ -4420,8 +4422,11 @@ Sema::ActOnVariableDeclarator(Scope *S, Declarator &D, DeclContext *DC,
// CUDA B.2.5: "__shared__ and __constant__ variables have implied static
// storage [duration]."
if (SC == SC_None && S->getFnParent() != 0 &&
(NewVD->hasAttr<CUDASharedAttr>() || NewVD->hasAttr<CUDAConstantAttr>()))
(NewVD->hasAttr<CUDASharedAttr>() ||
NewVD->hasAttr<CUDAConstantAttr>())) {
NewVD->setStorageClass(SC_Static);
NewVD->setStorageClassAsWritten(SC_Static);
}
}
// In auto-retain/release, infer strong retension for variables of

10
clang/test/CodeGen/linkage-redecl.c
View File

@ -1,4 +1,11 @@
// RUN: %clang_cc1 -emit-llvm %s -o - |grep internal
// RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
// CHECK: @test2_i = internal global i32 99
static int test2_i = 99;
int test2_f() {
extern int test2_i;
return test2_i;
}
// C99 6.2.2p3
// PR3425
@ -9,3 +16,4 @@ void g0() {
}
extern void f(int x) { } // still has internal linkage
// CHECK: define internal void @f