[CodeGen] Pass objects that are expensive to copy by const ref.

No functionality change. Found by clang-tidy's
performance-unnecessary-value-param.

llvm-svn: 287894

clang/lib/CodeGen/CGLoopInfo.cpp

@@ -20,7 +20,8 @@ using namespace clang::CodeGen;
 using namespace llvm;
 
 static MDNode *createMetadata(LLVMContext &Ctx, const LoopAttributes &Attrs,
-                              llvm::DebugLoc StartLoc, llvm::DebugLoc EndLoc) {
+                              const llvm::DebugLoc &StartLoc,
+                              const llvm::DebugLoc &EndLoc) {
 
   if (!Attrs.IsParallel && Attrs.VectorizeWidth == 0 &&
       Attrs.InterleaveCount == 0 && Attrs.UnrollCount == 0 &&
@@ -121,13 +122,13 @@ void LoopAttributes::clear() {
 }
 
 LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs,
-                   llvm::DebugLoc StartLoc, llvm::DebugLoc EndLoc)
+                   const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc)
     : LoopID(nullptr), Header(Header), Attrs(Attrs) {
   LoopID = createMetadata(Header->getContext(), Attrs, StartLoc, EndLoc);
 }
 
-void LoopInfoStack::push(BasicBlock *Header, llvm::DebugLoc StartLoc,
+void LoopInfoStack::push(BasicBlock *Header, const llvm::DebugLoc &StartLoc,
-                         llvm::DebugLoc EndLoc) {
+                         const llvm::DebugLoc &EndLoc) {
   Active.push_back(LoopInfo(Header, StagedAttrs, StartLoc, EndLoc));
   // Clear the attributes so nested loops do not inherit them.
   StagedAttrs.clear();
@@ -135,7 +136,8 @@ void LoopInfoStack::push(BasicBlock *Header, llvm::DebugLoc StartLoc,
 
 void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
                          ArrayRef<const clang::Attr *> Attrs,
-                         llvm::DebugLoc StartLoc, llvm::DebugLoc EndLoc) {
+                         const llvm::DebugLoc &StartLoc,
+                         const llvm::DebugLoc &EndLoc) {
 
   // Identify loop hint attributes from Attrs.
   for (const auto *Attr : Attrs) {

clang/lib/CodeGen/CGLoopInfo.h

@@ -67,7 +67,7 @@ class LoopInfo {
 public:
   /// \brief Construct a new LoopInfo for the loop with entry Header.
   LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs,
-           llvm::DebugLoc StartLoc, llvm::DebugLoc EndLoc);
+           const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc);
 
   /// \brief Get the loop id metadata for this loop.
   llvm::MDNode *getLoopID() const { return LoopID; }
@@ -99,14 +99,14 @@ public:
 
   /// \brief Begin a new structured loop. The set of staged attributes will be
   /// applied to the loop and then cleared.
-  void push(llvm::BasicBlock *Header, llvm::DebugLoc StartLoc,
+  void push(llvm::BasicBlock *Header, const llvm::DebugLoc &StartLoc,
-            llvm::DebugLoc EndLoc);
+            const llvm::DebugLoc &EndLoc);
 
   /// \brief Begin a new structured loop. Stage attributes from the Attrs list.
   /// The staged attributes are applied to the loop and then cleared.
   void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,
-            llvm::ArrayRef<const Attr *> Attrs, llvm::DebugLoc StartLoc,
+            llvm::ArrayRef<const Attr *> Attrs, const llvm::DebugLoc &StartLoc,
-            llvm::DebugLoc EndLoc);
+            const llvm::DebugLoc &EndLoc);
 
   /// \brief End the current loop.
   void pop();

clang/lib/CodeGen/CGObjCGNU.cpp

@@ -175,14 +175,14 @@ protected:
   /// string value.  This allows the linker to combine the strings between
   /// different modules.  Used for EH typeinfo names, selector strings, and a
   /// few other things.
-  llvm::Constant *ExportUniqueString(const std::string &Str,
+  llvm::Constant *ExportUniqueString(const std::string &Str, StringRef Prefix) {
-                                     const std::string prefix) {
+    std::string Name = Prefix.str() + Str;
-    std::string name = prefix + Str;
+    auto *ConstStr = TheModule.getGlobalVariable(Name);
-    auto *ConstStr = TheModule.getGlobalVariable(name);
     if (!ConstStr) {
       llvm::Constant *value = llvm::ConstantDataArray::getString(VMContext,Str);
       ConstStr = new llvm::GlobalVariable(TheModule, value->getType(), true,
-              llvm::GlobalValue::LinkOnceODRLinkage, value, prefix + Str);
+                                          llvm::GlobalValue::LinkOnceODRLinkage,
+                                          value, Name);
     }
     return llvm::ConstantExpr::getGetElementPtr(ConstStr->getValueType(),
                                                 ConstStr, Zeros);

clang/lib/CodeGen/CGOpenMPRuntime.cpp

@@ -6517,7 +6517,7 @@ static unsigned evaluateCDTSize(const FunctionDecl *FD,
 
 static void
 emitX86DeclareSimdFunction(const FunctionDecl *FD, llvm::Function *Fn,
-                           llvm::APSInt VLENVal,
+                           const llvm::APSInt &VLENVal,
                            ArrayRef<ParamAttrTy> ParamAttrs,
                            OMPDeclareSimdDeclAttr::BranchStateTy State) {
   struct ISADataTy {