Remove compile time PreserveName in favor of a runtime cc1 -discard-value-names option

Summary:
This flag is enabled by default in the driver when NDEBUG is set. It
is forwarded on the LLVMContext to discard all value names (but
GlobalValue) for performance purpose.

This an improved version of D18024

Reviewers: echristo, chandlerc

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D18127

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 263394

clang/include/clang/Driver/CC1Options.td

@@ -367,6 +367,8 @@ def code_completion_brief_comments : Flag<["-"], "code-completion-brief-comments
   HelpText<"Include brief documentation comments in code-completion results.">;
 def disable_free : Flag<["-"], "disable-free">,
   HelpText<"Disable freeing of memory on exit">;
+def discard_value_names : Flag<["-"], "discard-value-names">,
+  HelpText<"Discard value names in LLVM IR">;
 def load : Separate<["-"], "load">, MetaVarName<"<dsopath>">,
   HelpText<"Load the named plugin (dynamic shared object)">;
 def plugin : Separate<["-"], "plugin">, MetaVarName<"<name>">,

clang/include/clang/Frontend/CodeGenOptions.def

@@ -43,6 +43,7 @@ CODEGENOPT(DataSections      , 1, 0) ///< Set when -fdata-sections is enabled.
 CODEGENOPT(UniqueSectionNames, 1, 1) ///< Set for -funique-section-names.
 CODEGENOPT(DisableFPElim     , 1, 0) ///< Set when -fomit-frame-pointer is enabled.
 CODEGENOPT(DisableFree       , 1, 0) ///< Don't free memory.
+CODEGENOPT(DiscardValueNames , 1, 0) ///< Discard Value Names from the IR (LLVMContext flag)
 CODEGENOPT(DisableGCov       , 1, 0) ///< Don't run the GCov pass, for testing.
 CODEGENOPT(DisableLLVMOpts   , 1, 0) ///< Don't run any optimizations, for use in
                                      ///< getting .bc files that correspond to the

clang/lib/CodeGen/CGBuilder.h

@@ -23,9 +23,7 @@ class CodeGenFunction;
 /// \brief This is an IRBuilder insertion helper that forwards to
 /// CodeGenFunction::InsertHelper, which adds necessary metadata to
 /// instructions.
-template <bool PreserveNames>
-class CGBuilderInserter
-    : protected llvm::IRBuilderDefaultInserter<PreserveNames> {
+class CGBuilderInserter : protected llvm::IRBuilderDefaultInserter {
 public:
   CGBuilderInserter() = default;
   explicit CGBuilderInserter(CodeGenFunction *CGF) : CGF(CGF) {}
@@ -39,17 +37,10 @@ private:
   CodeGenFunction *CGF = nullptr;
 };
 
-// Don't preserve names on values in an optimized build.
-#ifdef NDEBUG
-#define PreserveNames false
-#else
-#define PreserveNames true
-#endif
+typedef CGBuilderInserter CGBuilderInserterTy;
 
-typedef CGBuilderInserter<PreserveNames> CGBuilderInserterTy;
-
-typedef llvm::IRBuilder<PreserveNames, llvm::ConstantFolder,
-                        CGBuilderInserterTy> CGBuilderBaseTy;
+typedef llvm::IRBuilder<llvm::ConstantFolder, CGBuilderInserterTy>
+    CGBuilderBaseTy;
 
 class CGBuilderTy : public CGBuilderBaseTy {
   /// Storing a reference to the type cache here makes it a lot easier
@@ -305,8 +296,6 @@ public:
   }
 };
 
-#undef PreserveNames
-
 }  // end namespace CodeGen
 }  // end namespace clang
 

clang/lib/CodeGen/CGCall.cpp

@@ -3840,7 +3840,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
   }
 
   llvm::Instruction *CI = CS.getInstruction();
-  if (Builder.isNamePreserving() && !CI->getType()->isVoidTy())
+  if (!CI->getType()->isVoidTy())
     CI->setName("call");
 
   // Emit any writebacks immediately.  Arguably this should happen

clang/lib/CodeGen/CGExpr.cpp

@@ -66,8 +66,6 @@ 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);
 }
 

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -747,9 +747,7 @@ 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, "", EntryBB);
-  if (Builder.isNamePreserving())
-    AllocaInsertPt->setName("allocapt");
+  AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "allocapt", EntryBB);
 
   ReturnBlock = getJumpDestInCurrentScope("return");
 
@@ -1862,26 +1860,14 @@ void CodeGenFunction::InsertHelper(llvm::Instruction *I,
     CGM.getSanitizerMetadata()->disableSanitizerForInstruction(I);
 }
 
-template <bool PreserveNames>
-void CGBuilderInserter<PreserveNames>::InsertHelper(
+void CGBuilderInserter::InsertHelper(
     llvm::Instruction *I, const llvm::Twine &Name, llvm::BasicBlock *BB,
     llvm::BasicBlock::iterator InsertPt) const {
-  llvm::IRBuilderDefaultInserter<PreserveNames>::InsertHelper(I, Name, BB,
-                                                              InsertPt);
+  llvm::IRBuilderDefaultInserter::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) {

clang/lib/CodeGen/ModuleBuilder.cpp

@@ -64,8 +64,9 @@ namespace {
                       CoverageSourceInfo *CoverageInfo = nullptr)
         : Diags(diags), Ctx(nullptr), HeaderSearchOpts(HSO),
           PreprocessorOpts(PPO), CodeGenOpts(CGO), HandlingTopLevelDecls(0),
-          CoverageInfo(CoverageInfo),
-          M(new llvm::Module(ModuleName, C)) {}
+          CoverageInfo(CoverageInfo), M(new llvm::Module(ModuleName, C)) {
+      C.setDiscardValueNames(CGO.DiscardValueNames);
+    }
 
     ~CodeGeneratorImpl() override {
       // There should normally not be any leftover inline method definitions.

clang/lib/Driver/Tools.cpp

@@ -3712,6 +3712,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 // Disable the verification pass in -asserts builds.
 #ifdef NDEBUG
   CmdArgs.push_back("-disable-llvm-verifier");
+  // Discard LLVM value names in -asserts builds.
+  CmdArgs.push_back("-discard-value-names");
 #endif
 
   // Set the main file name, so that debug info works even with

clang/lib/Frontend/CompilerInvocation.cpp

@@ -541,6 +541,7 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.DisableFPElim =
       (Args.hasArg(OPT_mdisable_fp_elim) || Args.hasArg(OPT_pg));
   Opts.DisableFree = Args.hasArg(OPT_disable_free);
+  Opts.DiscardValueNames = Args.hasArg(OPT_discard_value_names);
   Opts.DisableTailCalls = Args.hasArg(OPT_mdisable_tail_calls);
   Opts.FloatABI = Args.getLastArgValue(OPT_mfloat_abi);
   if (Arg *A = Args.getLastArg(OPT_meabi)) {

clang/test/CodeGen/mips-byval-arg.c

@@ -1,5 +1,5 @@
-// RUN: %clang -target mipsel-unknown-linux -O3 -S -o - -emit-llvm %s | FileCheck %s -check-prefix=O32
-// RUN: %clang -target mips64el-unknown-linux -O3 -S -mabi=n64 -o - -emit-llvm %s | FileCheck %s -check-prefix=N64
+// RUN: %clang_cc1 -triple mipsel-unknown-linux -O3 -S -o - -emit-llvm %s | FileCheck %s -check-prefix=O32
+// RUN: %clang_cc1 -triple mips64el-unknown-linux -O3 -S -target-abi n64 -o - -emit-llvm %s | FileCheck %s -check-prefix=N64
 
 typedef struct {
   float f[3];

clang/test/CodeGen/mips-vector-arg.c

@@ -1,5 +1,5 @@
-// RUN: %clang -target mipsel-unknown-linux -O3 -S -o - -emit-llvm %s | FileCheck %s -check-prefix=O32
-// RUN: %clang -target mips64el-unknown-linux -O3 -S -mabi=n64 -o - -emit-llvm %s | FileCheck %s -check-prefix=N64
+// RUN: %clang_cc1 -triple mipsel-unknown-linux -O3 -S -o - -emit-llvm %s | FileCheck %s -check-prefix=O32
+// RUN: %clang_cc1 -triple mips64el-unknown-linux -O3 -S -target-abi n64 -o - -emit-llvm %s | FileCheck %s -check-prefix=N64
 
 // check that
 // 1. vector arguments are passed in integer registers

clang/test/CodeGen/mips-zero-sized-struct.c

@@ -1,9 +1,9 @@
-// RUN: %clang -target mips-unknown-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefix=O32 %s
-// RUN: %clang -target mipsel-unknown-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefix=O32 %s
-// RUN: %clang -target mips64-unknown-linux-gnu -S -emit-llvm -o - %s -mabi=n32 | FileCheck -check-prefix=N32 %s
-// RUN: %clang -target mips64el-unknown-linux-gnu -S -emit-llvm -o - %s -mabi=n32 | FileCheck -check-prefix=N32 %s
-// RUN: %clang -target mips64-unknown-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefix=N64 %s
-// RUN: %clang -target mips64el-unknown-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefix=N64 %s
+// RUN: %clang_cc1 -triple mips-unknown-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefix=O32 %s
+// RUN: %clang_cc1 -triple mipsel-unknown-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefix=O32 %s
+// RUN: %clang_cc1 -triple mips64-unknown-linux-gnu -S -emit-llvm -o - %s  -target-abi n32 | FileCheck -check-prefix=N32 %s
+// RUN: %clang_cc1 -triple mips64el-unknown-linux-gnu -S -emit-llvm -o - %s  -target-abi n32 | FileCheck -check-prefix=N32 %s
+// RUN: %clang_cc1 -triple mips64-unknown-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefix=N64 %s
+// RUN: %clang_cc1 -triple mips64el-unknown-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefix=N64 %s
 
 // O32: define void @fn28(%struct.T2* noalias sret %agg.result, i8 signext %arg0)
 // N32: define void @fn28(i8 signext %arg0)

clang/test/CodeGen/mips64-class-return.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang -target mips64el-unknown-linux -O3 -S -mabi=n64 -o - -emit-llvm %s | FileCheck %s
+// RUN: %clang_cc1 -triple mips64el-unknown-linux -O3 -S -target-abi n64 -o - -emit-llvm %s | FileCheck %s
 
 class B0 {
   double d;

clang/test/CodeGen/mips64-padding-arg.c

@@ -1,6 +1,6 @@
-// RUN: %clang -target mipsel-unknown-linux -O3 -S -o - -emit-llvm %s | FileCheck %s -check-prefix=O32
-// RUN: %clang -target mips64el-unknown-linux -O3 -S -mabi=n64 -o - -emit-llvm %s | FileCheck %s -check-prefix=N64
-// RUN: %clang -target mipsel-unknown-linux -mfp64 -O3 -S -o - -emit-llvm %s | FileCheck %s -check-prefix=O32
+// RUN: %clang_cc1 -triple mipsel-unknown-linux -O3 -S -o - -emit-llvm %s | FileCheck %s -check-prefix=O32
+// RUN: %clang_cc1 -triple mips64el-unknown-linux -O3 -S -target-abi n64 -o - -emit-llvm %s | FileCheck %s -check-prefix=N64
+// RUN: %clang_cc1 -triple mipsel-unknown-linux -target-feature "+fp64" -O3 -S -o - -emit-llvm %s | FileCheck %s -check-prefix=O32
 
 typedef struct {
   double d;

clang/test/CodeGenCXX/debug-info-class.cpp

@@ -83,9 +83,9 @@ int main(int argc, char **argv) {
   return 0;
 }
 
-// RUN: %clang -target x86_64-unknown_unknown -emit-llvm -g -S %s -o - | FileCheck %s
-// RUN: %clang -target i686-cygwin -emit-llvm -g -S %s -o - | FileCheck %s
-// RUN: %clang -target armv7l-unknown-linux-gnueabihf -emit-llvm -g -S %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-unknown_unknown -emit-llvm -debug-info-kind=limited -fexceptions %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple i686-cygwin -emit-llvm -debug-info-kind=limited -fexceptions %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple armv7l-unknown-linux-gnueabihf -emit-llvm -debug-info-kind=limited -fexceptions %s -o - | FileCheck %s
 
 // CHECK: invoke {{.+}} @_ZN1BD1Ev(%class.B* %b)
 // CHECK-NEXT: unwind label %{{.+}}, !dbg ![[EXCEPTLOC:.*]]

clang/test/CodeGenCXX/discard-name-values.cpp

@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -emit-llvm  -triple=armv7-apple-darwin -emit-llvm -std=c++11 %s -o - -O1 | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm  -triple=armv7-apple-darwin -emit-llvm -std=c++11 %s -o - -O1 -discard-value-names | FileCheck %s --check-prefix=DISCARDVALUE
+
+int foo(int bar) {
+  return bar;
+}
+
+// CHECK: ret i32 %bar
+// DISCARDVALUE: ret i32 %0
+

clang/test/CodeGenCXX/stack-reuse.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang -target armv7l-unknown-linux-gnueabihf -S %s -o - -emit-llvm -O1 -disable-llvm-optzns | FileCheck %s
+// RUN: %clang_cc1 -triple armv7-unknown-linux-gnueabihf %s -o - -emit-llvm -O1 | FileCheck %s
 
 // Stack should be reused when possible, no need to allocate two separate slots
 // if they have disjoint lifetime.
@@ -21,7 +21,7 @@ struct Combiner {
   S_large a, b;
 
   Combiner(S_large);
-  Combiner f();  
+  Combiner f();
 };
 
 extern S_small foo_small();