Return a StringRef from getSection.

This is similar to how getName is handled.

llvm-svn: 269218

llvm/include/llvm/IR/GlobalObject.h

@@ -54,8 +54,8 @@ public:
   unsigned getGlobalObjectSubClassData() const;
   void setGlobalObjectSubClassData(unsigned Val);
 
-  bool hasSection() const { return !StringRef(getSection()).empty(); }
-  const char *getSection() const { return Section.c_str(); }
+  bool hasSection() const { return !getSection().empty(); }
+  StringRef getSection() const { return Section; }
   void setSection(StringRef S);
 
   bool hasComdat() const { return getComdat() != nullptr; }

llvm/include/llvm/IR/GlobalValue.h

@@ -198,14 +198,8 @@ public:
   }
   void setDLLStorageClass(DLLStorageClassTypes C) { DllStorageClass = C; }
 
-  bool hasSection() const { return !StringRef(getSection()).empty(); }
-  // It is unfortunate that we have to use "char *" in here since this is
-  // always non NULL, but:
-  // * The C API expects a null terminated string, so we cannot use StringRef.
-  // * The C API expects us to own it, so we cannot use a std:string.
-  // * For GlobalAliases we can fail to find the section and we have to
-  //   return "", so we cannot use a "const std::string &".
-  const char *getSection() const;
+  bool hasSection() const { return !getSection().empty(); }
+  StringRef getSection() const;
 
   /// Global values are always pointers.
   PointerType *getType() const { return cast<PointerType>(User::getType()); }

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1528,7 +1528,7 @@ bool AsmPrinter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
   }
 
   // Ignore debug and non-emitted data.  This handles llvm.compiler.used.
-  if (StringRef(GV->getSection()) == "llvm.metadata" ||
+  if (GV->getSection() == "llvm.metadata" ||
       GV->hasAvailableExternallyLinkage())
     return true;
 

llvm/lib/IR/Core.cpp

@@ -1485,7 +1485,9 @@ void LLVMSetLinkage(LLVMValueRef Global, LLVMLinkage Linkage) {
 }
 
 const char *LLVMGetSection(LLVMValueRef Global) {
-  return unwrap<GlobalValue>(Global)->getSection();
+  // Using .data() is safe because of how GlobalObject::setSection is
+  // implemented.
+  return unwrap<GlobalValue>(Global)->getSection().data();
 }
 
 void LLVMSetSection(LLVMValueRef Global, const char *Section) {

llvm/lib/IR/Globals.cpp

@@ -128,7 +128,7 @@ std::string GlobalValue::getGlobalIdentifier() const {
                              getParent()->getSourceFileName());
 }
 
-const char *GlobalValue::getSection() const {
+StringRef GlobalValue::getSection() const {
   if (auto *GA = dyn_cast<GlobalAlias>(this)) {
     // In general we cannot compute this at the IR level, but we try.
     if (const GlobalObject *GO = GA->getBaseObject())
@@ -151,7 +151,12 @@ Comdat *GlobalValue::getComdat() {
   return cast<GlobalObject>(this)->getComdat();
 }
 
-void GlobalObject::setSection(StringRef S) { Section = S; }
+void GlobalObject::setSection(StringRef S) {
+  Section = S;
+
+  // The C api requires this to be null terminated.
+  Section.c_str();
+}
 
 bool GlobalValue::isDeclaration() const {
   // Globals are definitions if they have an initializer.

llvm/lib/Linker/IRMover.cpp

@@ -786,7 +786,7 @@ Constant *IRLinker::linkAppendingVarProto(GlobalVariable *DstGV,
       return nullptr;
     }
 
-    if (StringRef(DstGV->getSection()) != SrcGV->getSection()) {
+    if (DstGV->getSection() != SrcGV->getSection()) {
       emitError(
           "Appending variables with different section name need to be linked!");
       return nullptr;

llvm/lib/Object/IRObjectFile.cpp

@@ -248,7 +248,7 @@ uint32_t IRObjectFile::getSymbolFlags(DataRefImpl Symb) const {
   if (GV->getName().startswith("llvm."))
     Res |= BasicSymbolRef::SF_FormatSpecific;
   else if (auto *Var = dyn_cast<GlobalVariable>(GV)) {
-    if (Var->getSection() == StringRef("llvm.metadata"))
+    if (Var->getSection() == "llvm.metadata")
       Res |= BasicSymbolRef::SF_FormatSpecific;
   }
 

llvm/lib/Target/NVPTX/NVPTXAsmPrinter.cpp

@@ -1041,7 +1041,7 @@ void NVPTXAsmPrinter::printModuleLevelGV(const GlobalVariable *GVar,
 
   // Skip meta data
   if (GVar->hasSection()) {
-    if (GVar->getSection() == StringRef("llvm.metadata"))
+    if (GVar->getSection() == "llvm.metadata")
       return;
   }
 

llvm/lib/Target/XCore/XCoreISelLowering.cpp

@@ -258,7 +258,7 @@ SDValue XCoreTargetLowering::getGlobalAddressWrapper(SDValue GA,
     return DAG.getNode(XCoreISD::PCRelativeWrapper, dl, MVT::i32, GA);
 
   const auto *GVar = dyn_cast<GlobalVariable>(GV);
-  if ((GV->hasSection() && StringRef(GV->getSection()).startswith(".cp.")) ||
+  if ((GV->hasSection() && GV->getSection().startswith(".cp.")) ||
       (GVar && GVar->isConstant() && GV->hasLocalLinkage()))
     return DAG.getNode(XCoreISD::CPRelativeWrapper, dl, MVT::i32, GA);
 

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -1242,7 +1242,7 @@ bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
   if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
 
   if (G->hasSection()) {
-    StringRef Section(G->getSection());
+    StringRef Section = G->getSection();
 
     // Globals from llvm.metadata aren't emitted, do not instrument them.
     if (Section == "llvm.metadata") return false;