Start setting dso_local in clang.
This starts adding dso_local to clang.
The hope is to eventually have TargetMachine::shouldAssumeDsoLocal go
away. My objective for now is to move enough of it to clang to remove
the need for the TargetMachine one to handle PIE copy relocations and
-fno-plt. With that it should then be easy to implement a
-fno-copy-reloc in clang.
This patch just adds the cases where we assume a symbol to be local
based on the file being compiled for an executable or a shared
library.
llvm-svn: 324107
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 04585a8..5de8691 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -240,7 +240,7 @@
getModule(), LTy, Ty.isConstant(getContext()), Linkage, Init, Name,
nullptr, llvm::GlobalVariable::NotThreadLocal, TargetAS);
GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
- setGlobalVisibility(GV, &D, ForDefinition);
+ setGVProperties(GV, &D, ForDefinition);
if (supportsCOMDAT() && GV->isWeakForLinker())
GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
@@ -344,6 +344,7 @@
OldGV->getThreadLocalMode(),
CGM.getContext().getTargetAddressSpace(D.getType()));
GV->setVisibility(OldGV->getVisibility());
+ GV->setDSOLocal(OldGV->isDSOLocal());
GV->setComdat(OldGV->getComdat());
// Steal the name of the old global
diff --git a/clang/lib/CodeGen/CGVTT.cpp b/clang/lib/CodeGen/CGVTT.cpp
index 78928d0..85e5298 100644
--- a/clang/lib/CodeGen/CGVTT.cpp
+++ b/clang/lib/CodeGen/CGVTT.cpp
@@ -100,7 +100,7 @@
VTT->setComdat(CGM.getModule().getOrInsertComdat(VTT->getName()));
// Set the right visibility.
- CGM.setGlobalVisibility(VTT, RD, ForDefinition);
+ CGM.setGVProperties(VTT, RD, ForDefinition);
}
llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTT(const CXXRecordDecl *RD) {
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index 2d9bf3b..a3336d9 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -51,7 +51,7 @@
static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD,
const ThunkInfo &Thunk, llvm::Function *Fn) {
- CGM.setGlobalVisibility(Fn, MD, ForDefinition);
+ CGM.setGVProperties(Fn, MD, ForDefinition);
}
static void setThunkProperties(CodeGenModule &CGM, const ThunkInfo &Thunk,
@@ -730,7 +730,7 @@
// Create the variable that will hold the construction vtable.
llvm::GlobalVariable *VTable =
CGM.CreateOrReplaceCXXRuntimeVariable(Name, VTType, Linkage);
- CGM.setGlobalVisibility(VTable, RD, ForDefinition);
+ CGM.setGVProperties(VTable, RD, ForDefinition);
// V-tables are always unnamed_addr.
VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 760327d..12af14b 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -717,6 +717,63 @@
GV->setVisibility(GetLLVMVisibility(LV.getVisibility()));
}
+static bool shouldAssumeDSOLocal(const CodeGenModule &CGM,
+ llvm::GlobalValue *GV, const NamedDecl *D,
+ ForDefinition_t IsForDefinition) {
+ const llvm::Triple &TT = CGM.getTriple();
+ // Only handle ELF for now.
+ if (!TT.isOSBinFormatELF())
+ return false;
+
+ // If this is not an executable, don't assume anything is local.
+ const auto &CGOpts = CGM.getCodeGenOpts();
+ llvm::Reloc::Model RM = CGOpts.RelocationModel;
+ const auto &LOpts = CGM.getLangOpts();
+ if (RM != llvm::Reloc::Static && !LOpts.PIE)
+ return false;
+
+ // A definition cannot be preempted from an executable.
+ if (IsForDefinition)
+ return true;
+
+ // Most PIC code sequences that assume that a symbol is local cannot produce a
+ // 0 if it turns out the symbol is undefined. While this is ABI and relocation
+ // depended, it seems worth it to handle it here.
+ if (RM == llvm::Reloc::PIC_ && GV->hasExternalWeakLinkage())
+ return false;
+
+ // PPC has no copy relocations and cannot use a plt entry as a symbol address.
+ llvm::Triple::ArchType Arch = TT.getArch();
+ if (Arch == llvm::Triple::ppc || Arch == llvm::Triple::ppc64 ||
+ Arch == llvm::Triple::ppc64le)
+ return false;
+
+ // If we can use copy relocations we can assume it is local.
+ if (isa<VarDecl>(D) &&
+ (RM == llvm::Reloc::Static || CGOpts.PIECopyRelocations))
+ return true;
+
+ // If we can use a plt entry as the symbol address we can assume it
+ // is local.
+ if (isa<FunctionDecl>(D) && !CGOpts.NoPLT)
+ return true;
+
+ // Otherwise don't assue it is local.
+ return false;
+}
+
+void CodeGenModule::setDSOLocal(llvm::GlobalValue *GV, const NamedDecl *D,
+ ForDefinition_t IsForDefinition) const {
+ if (shouldAssumeDSOLocal(*this, GV, D, IsForDefinition))
+ GV->setDSOLocal(true);
+}
+
+void CodeGenModule::setGVProperties(llvm::GlobalValue *GV, const NamedDecl *D,
+ ForDefinition_t IsForDefinition) const {
+ setGlobalVisibility(GV, D, IsForDefinition);
+ setDSOLocal(GV, D, IsForDefinition);
+}
+
static llvm::GlobalVariable::ThreadLocalMode GetLLVMTLSModel(StringRef S) {
return llvm::StringSwitch<llvm::GlobalVariable::ThreadLocalMode>(S)
.Case("global-dynamic", llvm::GlobalVariable::GeneralDynamicTLSModel)
@@ -1174,7 +1231,7 @@
void CodeGenModule::SetCommonAttributes(const Decl *D,
llvm::GlobalValue *GV) {
if (const auto *ND = dyn_cast_or_null<NamedDecl>(D))
- setGlobalVisibility(GV, ND, ForDefinition);
+ setGVProperties(GV, ND, ForDefinition);
else
GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
@@ -1316,7 +1373,7 @@
// overridden by a definition.
setLinkageForGV(F, FD);
- setGlobalVisibility(F, FD, NotForDefinition);
+ setGVProperties(F, FD, NotForDefinition);
if (FD->getAttr<PragmaClangTextSectionAttr>()) {
F->addFnAttr("implicit-section-name");
@@ -2638,7 +2695,7 @@
GV->setAlignment(getContext().getDeclAlign(D).getQuantity());
setLinkageForGV(GV, D);
- setGlobalVisibility(GV, D, NotForDefinition);
+ setGVProperties(GV, D, NotForDefinition);
if (D->getTLSKind()) {
if (D->getTLSKind() == VarDecl::TLS_Dynamic)
@@ -3457,7 +3514,7 @@
setFunctionDLLStorageClass(GD, Fn);
// FIXME: this is redundant with part of setFunctionDefinitionAttributes
- setGlobalVisibility(Fn, D, ForDefinition);
+ setGVProperties(Fn, D, ForDefinition);
MaybeHandleStaticInExternC(D, Fn);
@@ -4053,7 +4110,7 @@
getModule(), Type, Constant, Linkage, InitialValue, Name.c_str(),
/*InsertBefore=*/nullptr, llvm::GlobalVariable::NotThreadLocal, TargetAS);
if (emitter) emitter->finalize(GV);
- setGlobalVisibility(GV, VD, ForDefinition);
+ setGVProperties(GV, VD, ForDefinition);
GV->setAlignment(Align.getQuantity());
if (supportsCOMDAT() && GV->isWeakForLinker())
GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 42e9e1b..3ae041e 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -722,6 +722,12 @@
void setGlobalVisibility(llvm::GlobalValue *GV, const NamedDecl *D,
ForDefinition_t IsForDefinition) const;
+ void setDSOLocal(llvm::GlobalValue *GV, const NamedDecl *D,
+ ForDefinition_t IsForDefinition) const;
+
+ void setGVProperties(llvm::GlobalValue *GV, const NamedDecl *D,
+ ForDefinition_t IsForDefinition) const;
+
/// Set the TLS mode for the given LLVM GlobalValue for the thread-local
/// variable declaration D.
void setTLSMode(llvm::GlobalValue *GV, const VarDecl &D) const;
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 8fd0839..3ccdf85 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -1531,7 +1531,7 @@
VTable->setComdat(CGM.getModule().getOrInsertComdat(VTable->getName()));
// Set the right visibility.
- CGM.setGlobalVisibility(VTable, RD, ForDefinition);
+ CGM.setGVProperties(VTable, RD, ForDefinition);
// Use pointer alignment for the vtable. Otherwise we would align them based
// on the size of the initializer which doesn't make sense as only single
@@ -1641,7 +1641,7 @@
VTable = CGM.CreateOrReplaceCXXRuntimeVariable(
Name, VTableType, llvm::GlobalValue::ExternalLinkage);
VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
- CGM.setGlobalVisibility(VTable, RD, NotForDefinition);
+ CGM.setGVProperties(VTable, RD, NotForDefinition);
if (RD->hasAttr<DLLImportAttr>())
VTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
@@ -2052,6 +2052,7 @@
false, var->getLinkage(),
llvm::ConstantInt::get(guardTy, 0),
guardName.str());
+ guard->setDSOLocal(var->isDSOLocal());
guard->setVisibility(var->getVisibility());
// If the variable is thread-local, so is its guard variable.
guard->setThreadLocalMode(var->getThreadLocalMode());
@@ -3212,7 +3213,10 @@
llvmVisibility = CodeGenModule::GetLLVMVisibility(Ty->getVisibility());
TypeName->setVisibility(llvmVisibility);
+ CGM.setDSOLocal(TypeName, Ty->getAsCXXRecordDecl(), ForDefinition);
+
GV->setVisibility(llvmVisibility);
+ CGM.setDSOLocal(GV, Ty->getAsCXXRecordDecl(), ForDefinition);
if (CGM.getTriple().isWindowsItaniumEnvironment()) {
auto RD = Ty->getAsCXXRecordDecl();