[Profile] Don't use the override API in all cases.

[jakev]

Summary

We shouldn't be using __llvm_profile_override_default_filename even when a profile output filename isn't specified. This patch uses a flag to enable IRPGO instead.

This is the other half of:
https://reviews.llvm.org/D22608

[davidxl]

lgtm

[jakev]

Sean or David, do you think you could commit the pair of patches for me? I don't yet have commit access so I would appreciate that very much.

include/llvm/Transforms/IPO/PassManagerBuilder.h

public:
   bool DisableGVNLoadPRE;
   bool VerifyInput;
   bool VerifyOutput;
   bool MergeFunctions;
   bool PrepareForLTO;
   bool PrepareForThinLTO;
   bool PerformThinLTO;
 
+  /// Enable profile instrumentation pass.
+  bool EnablePGOInstrGen;
   /// Profile data file name that the instrumentation will be written to.
   std::string PGOInstrGen;
   /// Path of the profile data file.
   std::string PGOInstrUse;
 
 private:
   /// ExtensionList - This is list of all of the extensions that are registered.
   std::vector<std::pair<ExtensionPointTy, ExtensionFn>> Extensions;

lib/Transforms/IPO/PassManagerBuilder.cpp

static cl::opt<bool> EnableNonLTOGlobalsModRef(
     "enable-non-lto-gmr", cl::init(true), cl::Hidden,
     cl::desc(
         "Enable the GlobalsModRef AliasAnalysis outside of the LTO pipeline."));
 
 static cl::opt<bool> EnableLoopLoadElim(
     "enable-loop-load-elim", cl::init(true), cl::Hidden,
     cl::desc("Enable the LoopLoadElimination Pass"));
 
-static cl::opt<std::string> RunPGOInstrGen(
-    "profile-generate", cl::init(""), cl::Hidden,
-    cl::desc("Enable generation phase of PGO instrumentation and specify the "
-             "path of profile data file"));
+static cl::opt<bool> RunPGOInstrGen(
+    "profile-generate", cl::init(false), cl::Hidden,
+    cl::desc("Enable PGO instrumentation."));
+
+static cl::opt<std::string>
+    PGOOutputFile("profile-generate-file", cl::init(""), cl::Hidden,
+                      cl::desc("Specify the path of profile data file."));
 
 static cl::opt<std::string> RunPGOInstrUse(
     "profile-use", cl::init(""), cl::Hidden, cl::value_desc("filename"),
     cl::desc("Enable use phase of PGO instrumentation and specify the path "
              "of profile data file"));
 
 static cl::opt<bool> UseLoopVersioningLICM(
     "enable-loop-versioning-licm", cl::init(false), cl::Hidden,
PassManagerBuilder::PassManagerBuilder() {
     LoopVectorize = RunLoopVectorization;
     RerollLoops = RunLoopRerolling;
     LoadCombine = RunLoadCombine;
     DisableGVNLoadPRE = false;
     VerifyInput = false;
     VerifyOutput = false;
     MergeFunctions = false;
     PrepareForLTO = false;
-    PGOInstrGen = RunPGOInstrGen;
+    EnablePGOInstrGen = RunPGOInstrGen;
+    PGOInstrGen = PGOOutputFile;
     PGOInstrUse = RunPGOInstrUse;
     PrepareForThinLTO = false;
     PerformThinLTO = false;
 }
 
 PassManagerBuilder::~PassManagerBuilder() {
   delete LibraryInfo;
   delete Inliner;
void PassManagerBuilder::populateFunctionPassManager(
   FPM.add(createSROAPass());
   FPM.add(createEarlyCSEPass());
   FPM.add(createGVNHoistPass());
   FPM.add(createLowerExpectIntrinsicPass());
 }
 
 // Do PGO instrumentation generation or use pass as the option specified.
 void PassManagerBuilder::addPGOInstrPasses(legacy::PassManagerBase &MPM) {
-  if (PGOInstrGen.empty() && PGOInstrUse.empty())
+  if (!EnablePGOInstrGen && PGOInstrUse.empty())
     return;
   // Perform the preinline and cleanup passes for O1 and above.
   // And avoid doing them if optimizing for size.
   if (OptLevel > 0 && SizeLevel == 0 && !DisablePreInliner) {
     // Create preinline pass.
     MPM.add(createFunctionInliningPass(PreInlineThreshold));
     MPM.add(createSROAPass());
     MPM.add(createEarlyCSEPass());             // Catch trivial redundancies
     MPM.add(createCFGSimplificationPass());    // Merge & remove BBs
     MPM.add(createInstructionCombiningPass()); // Combine silly seq's
     addExtensionsToPM(EP_Peephole, MPM);
   }
-  if (!PGOInstrGen.empty()) {
+  if (EnablePGOInstrGen) {
     MPM.add(createPGOInstrumentationGenLegacyPass());
     // Add the profile lowering pass.
     InstrProfOptions Options;
+    if (!PGOInstrGen.empty())
       Options.InstrProfileOutput = PGOInstrGen;
     MPM.add(createInstrProfilingLegacyPass(Options));
   }
   if (!PGOInstrUse.empty())
     MPM.add(createPGOInstrumentationUseLegacyPass(PGOInstrUse));
 }
 void PassManagerBuilder::addFunctionSimplificationPasses(
     legacy::PassManagerBase &MPM) {
   // Start of function pass.

test/Transforms/PGOProfile/preinline.ll

-; RUN: opt < %s -O2 -profile-generate=default.profraw -S | FileCheck %s --check-prefix=GEN
+; RUN: opt < %s -O2 -profile-generate -S | FileCheck %s --check-prefix=GEN
+; RUN: opt < %s -O2 -profile-generate -profile-generate-file=default.profraw -S | FileCheck %s --check-prefix=GEN
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 define i32 @foo(i32 %i) {
 entry:
 ; GEN: %pgocount = load i64, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc_foo
 ; GEN-NOT: %pgocount.i = load i64, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__stdin__bar
   %call = call i32 @bar()