5 files changed, 36 insertions, 15 deletions
diff --git a/clang/lib/CodeGen/CGBuilder.h b/clang/lib/CodeGen/CGBuilder.h
index 027435d7c59..baba30d5bf6 100644
--- a/clang/lib/CodeGen/CGBuilder.h
+++ b/clang/lib/CodeGen/CGBuilder.h
@@ -23,7 +23,9 @@ class CodeGenFunction;
 /// \brief This is an IRBuilder insertion helper that forwards to
 /// CodeGenFunction::InsertHelper, which adds necessary metadata to
 /// instructions.
-class CGBuilderInserter : protected llvm::IRBuilderDefaultInserter {
+template <bool PreserveNames>
+class CGBuilderInserter
+    : protected llvm::IRBuilderDefaultInserter<PreserveNames> {
 public:
   CGBuilderInserter() = default;
   explicit CGBuilderInserter(CodeGenFunction *CGF) : CGF(CGF) {}
@@ -37,10 +39,17 @@ private:
   CodeGenFunction *CGF = nullptr;
 };
 
-typedef CGBuilderInserter CGBuilderInserterTy;
+// Don't preserve names on values in an optimized build.
+#ifdef NDEBUG
+#define PreserveNames false
+#else
+#define PreserveNames true
+#endif
+
+typedef CGBuilderInserter<PreserveNames> CGBuilderInserterTy;
 
-typedef llvm::IRBuilder<llvm::ConstantFolder, CGBuilderInserterTy>
-    CGBuilderBaseTy;
+typedef llvm::IRBuilder<PreserveNames, llvm::ConstantFolder,
+                        CGBuilderInserterTy> CGBuilderBaseTy;
 
 class CGBuilderTy : public CGBuilderBaseTy {
   /// Storing a reference to the type cache here makes it a lot easier
@@ -296,6 +305,8 @@ public:
   }
 };
 
+#undef PreserveNames
+
 }  // end namespace CodeGen
 }  // end namespace clang
 
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 7fb301c8c36..19f8c7cfd24 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -3840,7 +3840,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
   }
 
   llvm::Instruction *CI = CS.getInstruction();
-  if (!CI->getType()->isVoidTy())
+  if (Builder.isNamePreserving() && !CI->getType()->isVoidTy())
     CI->setName("call");
 
   // Emit any writebacks immediately.  Arguably this should happen
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index ccda7f4d1aa..4a0f149b969 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -66,6 +66,8 @@ Address CodeGenFunction::CreateTempAlloca(llvm::Type *Ty, CharUnits Align,
 /// block.
 llvm::AllocaInst *CodeGenFunction::CreateTempAlloca(llvm::Type *Ty,
                                                     const Twine &Name) {
+  if (!Builder.isNamePreserving())
+    return new llvm::AllocaInst(Ty, nullptr, "", AllocaInsertPt);
   return new llvm::AllocaInst(Ty, nullptr, Name, AllocaInsertPt);
 }
 
diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 5e939accdba..638f79a2452 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -656,13 +656,7 @@ void BackendConsumer::DiagnosticHandlerImpl(const DiagnosticInfo &DI) {
 
 CodeGenAction::CodeGenAction(unsigned _Act, LLVMContext *_VMContext)
     : Act(_Act), VMContext(_VMContext ? _VMContext : new LLVMContext),
-      OwnsVMContext(!_VMContext) {
-#ifdef NDEBUG
-  // FIXME: change this to be controlled by a cc1 flag that the driver passes,
-  // on the model of --disable-free
-  VMContext->setDiscardValueNames(true);
-#endif
-}
+      OwnsVMContext(!_VMContext) {}
 
 CodeGenAction::~CodeGenAction() {
   TheModule.reset();
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index ac0322303a2..0e118b8f6f7 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -747,7 +747,9 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
   // later.  Don't create this with the builder, because we don't want it
   // folded.
   llvm::Value *Undef = llvm::UndefValue::get(Int32Ty);
-  AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "allocapt", EntryBB);
+  AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB);
+  if (Builder.isNamePreserving())
+    AllocaInsertPt->setName("allocapt");
 
   ReturnBlock = getJumpDestInCurrentScope("return");
 
@@ -1860,14 +1862,26 @@ void CodeGenFunction::InsertHelper(llvm::Instruction *I,
     CGM.getSanitizerMetadata()->disableSanitizerForInstruction(I);
 }
 
-void CGBuilderInserter::InsertHelper(
+template <bool PreserveNames>
+void CGBuilderInserter<PreserveNames>::InsertHelper(
     llvm::Instruction *I, const llvm::Twine &Name, llvm::BasicBlock *BB,
     llvm::BasicBlock::iterator InsertPt) const {
-  llvm::IRBuilderDefaultInserter::InsertHelper(I, Name, BB, InsertPt);
+  llvm::IRBuilderDefaultInserter<PreserveNames>::InsertHelper(I, Name, BB,
+                                                              InsertPt);
   if (CGF)
     CGF->InsertHelper(I, Name, BB, InsertPt);
 }
 
+#ifdef NDEBUG
+#define PreserveNames false
+#else
+#define PreserveNames true
+#endif
+template void CGBuilderInserter<PreserveNames>::InsertHelper(
+    llvm::Instruction *I, const llvm::Twine &Name, llvm::BasicBlock *BB,
+    llvm::BasicBlock::iterator InsertPt) const;
+#undef PreserveNames
+
 static bool hasRequiredFeatures(const SmallVectorImpl<StringRef> &ReqFeatures,
                                 CodeGenModule &CGM, const FunctionDecl *FD,
                                 std::string &FirstMissing) {