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Support the tls_model attribute (PR9788) 

This adds support for the tls_model attribute. This allows the user to
choose a TLS model that is better than what LLVM would select by
default. For example, a variable might be declared as:

  __thread int x __attribute__((tls_model("initial-exec")));

if it will not be used in a shared library that is dlopen'ed.

This depends on LLVM r159077.

llvm-svn: 159078
This commit is contained in:
Hans Wennborg 2012-06-23 11:51:46 +00:00
parent cbe34b4cc9
commit d3b01bc7c6
10 changed files with 124 additions and 9 deletions
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14
clang/docs/ReleaseNotes.html
View File

@ -123,6 +123,20 @@ int f(bool b) {
flag.</li>
</ul>
<h4 id="tlsmodel">Support for <code>tls_model</code> attribute</h4>
<p>Clang now supports the <code>tls_model</code> attribute, allowing code that
uses thread-local storage to explicitly select which model to use. The available
models are <code>"global-dynamic"</code>, <code>"local-dynamic"</code>,
<code>"initial-exec"</code> and <code>"local-exec"</code>. See
<a href="http://www.akkadia.org/drepper/tls.pdf">ELF Handling For Thread-Local
Storage</a> for more information.</p>
<p>The compiler is free to choose a different model if the specified model is not
supported by the target, or if the compiler determines that a more specific
model can be used.
</p>
<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
<h3 id="newflags">New Compiler Flags</h3>
<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

6
clang/include/clang/Basic/Attr.td
View File

@ -160,6 +160,12 @@ def AlwaysInline : InheritableAttr {
let Spellings = [GNU<"always_inline">];
}
def TLSModel : InheritableAttr {
let Spellings = [GNU<"tls_model">];
let Subjects = [Var];
let Args = [StringArgument<"Model">];
}
def AnalyzerNoReturn : InheritableAttr {
let Spellings = [GNU<"analyzer_noreturn">];
}

6
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -1603,6 +1603,8 @@ def err_objc_literal_comparison : Error<
"direct comparison of %select{a string literal|an array literal|"
"a dictionary literal|a numeric literal|a boxed expression|}0 is not "
"allowed%select{|; use -isEqual: instead}1">;
def err_attr_tlsmodel_arg : Error<"tls_model must be \"global-dynamic\", "
"\"local-dynamic\", \"initial-exec\" or \"local-exec\"">;
let CategoryName = "Cocoa API Issue" in {
def warn_objc_redundant_literal_use : Warning<
@ -1670,13 +1672,13 @@ def warn_attribute_wrong_decl_type : Warning<
"functions, methods and blocks|functions, methods, and parameters|"
"classes|variables|methods|variables, functions and labels|"
"fields and global variables|structs|"
"variables, functions and tag types}1">;
"variables, functions and tag types|thread-local variables}1">;
def err_attribute_wrong_decl_type : Error<
"%0 attribute only applies to %select{functions|unions|"
"variables and functions|functions and methods|parameters|"
"functions, methods and blocks|functions, methods, and parameters|"
"classes|variables|methods|variables, functions and labels|"
"fields and global variables|structs}1">;
"fields and global variables|structs|thread-local variables}1">;
def warn_function_attribute_wrong_type : Warning<
"'%0' only applies to function types; type here is %1">;
def warn_pointer_attribute_wrong_type : Warning<

18
clang/lib/CodeGen/CGDecl.cpp
View File

@ -183,12 +183,22 @@ CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
else
Name = GetStaticDeclName(*this, D, Separator);
llvm::GlobalVariable::ThreadLocalMode TLM;
TLM = D.isThreadSpecified() ? llvm::GlobalVariable::GeneralDynamicTLSModel
: llvm::GlobalVariable::NotThreadLocal;
// Set the TLS mode if it it's explicitly specified.
if (D.hasAttr<TLSModelAttr>()) {
assert(D.isThreadSpecified() && "Can't have TLS model on non-tls var.");
const TLSModelAttr *Attr = D.getAttr<TLSModelAttr>();
TLM = CodeGenModule::GetLLVMTLSModel(Attr->getModel());
}
llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(CGM.getModule(), LTy,
Ty.isConstant(getContext()), Linkage,
CGM.EmitNullConstant(D.getType()), Name, 0,
D.isThreadSpecified(),
CGM.EmitNullConstant(D.getType()), Name, 0, TLM,
CGM.getContext().getTargetAddressSpace(Ty));
GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
if (Linkage != llvm::GlobalValue::InternalLinkage)
@ -239,7 +249,7 @@ CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
OldGV->isConstant(),
OldGV->getLinkage(), Init, "",
/*InsertBefore*/ OldGV,
D.isThreadSpecified(),
OldGV->getThreadLocalMode(),
CGM.getContext().getTargetAddressSpace(D.getType()));
GV->setVisibility(OldGV->getVisibility());
@ -1066,7 +1076,7 @@ void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
llvm::GlobalValue::PrivateLinkage,
constant, Name, 0, false, 0);
constant, Name);
GV->setAlignment(alignment.getQuantity());
GV->setUnnamedAddr(true);

3
clang/lib/CodeGen/CGExprConstant.cpp
View File

@ -932,7 +932,8 @@ public:
C = new llvm::GlobalVariable(CGM.getModule(), C->getType(),
E->getType().isConstant(CGM.getContext()),
llvm::GlobalValue::InternalLinkage,
C, ".compoundliteral", 0, false,
C, ".compoundliteral", 0,
llvm::GlobalVariable::NotThreadLocal,
CGM.getContext().getTargetAddressSpace(E->getType()));
return C;
}

8
clang/lib/CodeGen/CodeGenModule.cpp
View File

@ -1187,7 +1187,7 @@ CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName,
new llvm::GlobalVariable(getModule(), Ty->getElementType(), false,
llvm::GlobalValue::ExternalLinkage,
0, MangledName, 0,
false, AddrSpace);
llvm::GlobalVariable::NotThreadLocal, AddrSpace);
// Handle things which are present even on external declarations.
if (D) {
@ -1211,6 +1211,12 @@ CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName,
}
GV->setThreadLocal(D->isThreadSpecified());
// Set the TLS model if it it's explicitly specified.
if (D->hasAttr<TLSModelAttr>()) {
const TLSModelAttr *Attr = D->getAttr<TLSModelAttr>();
GV->setThreadLocalMode(GetLLVMTLSModel(Attr->getModel()));
}
}
if (AddrSpace != Ty->getAddressSpace())

9
clang/lib/CodeGen/CodeGenModule.h
View File

@ -496,6 +496,15 @@ public:
llvm_unreachable("unknown visibility!");
}
static llvm::GlobalVariable::ThreadLocalMode GetLLVMTLSModel(StringRef S) {
return llvm::StringSwitch<llvm::GlobalVariable::ThreadLocalMode>(S)
.Case("global-dynamic", llvm::GlobalVariable::GeneralDynamicTLSModel)
.Case("local-dynamic", llvm::GlobalVariable::LocalDynamicTLSModel)
.Case("initial-exec", llvm::GlobalVariable::InitialExecTLSModel)
.Case("local-exec", llvm::GlobalVariable::LocalExecTLSModel)
.Default(llvm::GlobalVariable::NotThreadLocal);
}
llvm::Constant *GetAddrOfGlobal(GlobalDecl GD) {
if (isa<CXXConstructorDecl>(GD.getDecl()))
return GetAddrOfCXXConstructor(cast<CXXConstructorDecl>(GD.getDecl()),

40
clang/lib/Sema/SemaDeclAttr.cpp
View File

@ -43,7 +43,8 @@ enum AttributeDeclKind {
ExpectedMethod,
ExpectedVariableFunctionOrLabel,
ExpectedFieldOrGlobalVar,
ExpectedStruct
ExpectedStruct,
ExpectedTLSVar
};
//===----------------------------------------------------------------------===//
@ -1440,6 +1441,42 @@ static void handleAlwaysInlineAttr(Sema &S, Decl *D,
D->addAttr(::new (S.Context) AlwaysInlineAttr(Attr.getRange(), S.Context));
}
static void handleTLSModelAttr(Sema &S, Decl *D,
const AttributeList &Attr) {
// Check the attribute arguments.
if (Attr.getNumArgs() != 1) {
S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 1;
return;
}
Expr *Arg = Attr.getArg(0);
Arg = Arg->IgnoreParenCasts();
StringLiteral *Str = dyn_cast<StringLiteral>(Arg);
// Check that it is a string.
if (!Str) {
S.Diag(Attr.getLoc(), diag::err_attribute_not_string) << "tls_model";
return;
}
if (!isa<VarDecl>(D) || !cast<VarDecl>(D)->isThreadSpecified()) {
S.Diag(Attr.getLoc(), diag::err_attribute_wrong_decl_type)
<< Attr.getName() << ExpectedTLSVar;
return;
}
// Check that the value.
StringRef Model = Str->getString();
if (Model != "global-dynamic" && Model != "local-dynamic"
&& Model != "initial-exec" && Model != "local-exec") {
S.Diag(Attr.getLoc(), diag::err_attr_tlsmodel_arg);
return;
}
D->addAttr(::new (S.Context) TLSModelAttr(Attr.getRange(), S.Context,
Model));
}
static void handleMallocAttr(Sema &S, Decl *D, const AttributeList &Attr) {
// Check the attribute arguments.
if (Attr.hasParameterOrArguments()) {
@ -3939,6 +3976,7 @@ static void ProcessInheritableDeclAttr(Sema &S, Scope *scope, Decl *D,
handleAlwaysInlineAttr (S, D, Attr); break;
case AttributeList::AT_AnalyzerNoReturn:
handleAnalyzerNoReturnAttr (S, D, Attr); break;
case AttributeList::AT_TLSModel: handleTLSModelAttr (S, D, Attr); break;
case AttributeList::AT_Annotate: handleAnnotateAttr (S, D, Attr); break;
case AttributeList::AT_Availability:handleAvailabilityAttr(S, D, Attr); break;
case AttributeList::AT_CarriesDependency:

15
clang/test/CodeGen/thread-specifier.c
View File

@ -3,7 +3,13 @@
// CHECK: @b = external thread_local global
// CHECK: @d.e = internal thread_local global
// CHECK: @d.f = internal thread_local global
// CHECK: @f.a = internal thread_local(initialexec) global
// CHECK: @a = thread_local global
// CHECK: @g = thread_local global
// CHECK: @h = thread_local(localdynamic) global
// CHECK: @i = thread_local(initialexec) global
// CHECK: @j = thread_local(localexec) global
__thread int a;
extern __thread int b;
int c() { return *&b; }
@ -13,3 +19,12 @@ int d() {
return 0;
}
__thread int g __attribute__((tls_model("global-dynamic")));
__thread int h __attribute__((tls_model("local-dynamic")));
__thread int i __attribute__((tls_model("initial-exec")));
__thread int j __attribute__((tls_model("local-exec")));
int f() {
__thread static int a __attribute__((tls_model("initial-exec")));
return a++;
}

14
clang/test/Sema/attr-tls_model.c Normal file
View File

@ -0,0 +1,14 @@
// RUN: %clang -Xclang -verify -fsyntax-only %s
#if !__has_attribute(tls_model)
#error "Should support tls_model attribute"
#endif
int f() __attribute((tls_model("global-dynamic"))); // expected-error {{'tls_model' attribute only applies to thread-local variables}}
int x __attribute((tls_model("global-dynamic"))); // expected-error {{'tls_model' attribute only applies to thread-local variables}}
static __thread int y __attribute((tls_model("global-dynamic"))); // no-warning
static __thread int y __attribute((tls_model("local", "dynamic"))); // expected-error {{attribute takes one argument}}
static __thread int y __attribute((tls_model(123))); // expected-error {{argument to tls_model attribute was not a string literal}}
static __thread int y __attribute((tls_model("foobar"))); // expected-error {{tls_model must be "global-dynamic", "local-dynamic", "initial-exec" or "local-exec"}}