Fix and reapply IR PGO support for Flang (#142892)

This PR resubmits the changes from #136098, which was previously
reverted due to a build failure during the linking stage:

```
undefined reference to `llvm::DebugInfoCorrelate'  
undefined reference to `llvm::ProfileCorrelate'
```

The root cause was that `llvm/lib/Frontend/Driver/CodeGenOptions.cpp`
references symbols from the `Instrumentation` component, but the
`LINK_COMPONENTS` in the `llvm/lib/Frontend/CMakeLists.txt` for
`LLVMFrontendDriver` did not include it. As a result, linking failed in
configurations where these components were not transitively linked.

### Fix:

This updated patch explicitly adds `Instrumentation` to
`LINK_COMPONENTS` in the relevant `llvm/lib/Frontend/CMakeLists.txt`
file to ensure the required symbols are properly resolved.

---------

Co-authored-by: ict-ql <168183727+ict-ql@users.noreply.github.com>
Co-authored-by: Chyaka <52224511+liliumshade@users.noreply.github.com>
Co-authored-by: Tarun Prabhu <tarunprabhu@gmail.com>

clang/include/clang/Basic/CodeGenOptions.def

@@ -223,9 +223,11 @@ AFFECTING_VALUE_CODEGENOPT(OptimizeSize, 2, 0) ///< If -Os (==1) or -Oz (==2) is
 CODEGENOPT(AtomicProfileUpdate , 1, 0) ///< Set -fprofile-update=atomic
 CODEGENOPT(ContinuousProfileSync, 1, 0) ///< Enable continuous instrumentation profiling
 /// Choose profile instrumenation kind or no instrumentation.
-ENUM_CODEGENOPT(ProfileInstr, ProfileInstrKind, 4, ProfileNone)
+
+ENUM_CODEGENOPT(ProfileInstr, llvm::driver::ProfileInstrKind, 4, llvm::driver::ProfileInstrKind::ProfileNone)
+
 /// Choose profile kind for PGO use compilation.
-ENUM_CODEGENOPT(ProfileUse, ProfileInstrKind, 2, ProfileNone)
+ENUM_CODEGENOPT(ProfileUse, llvm::driver::ProfileInstrKind, 2, llvm::driver::ProfileInstrKind::ProfileNone)
 /// Partition functions into N groups and select only functions in group i to be
 /// instrumented. Selected group numbers can be 0 to N-1 inclusive.
 VALUE_CODEGENOPT(ProfileTotalFunctionGroups, 32, 1)

clang/include/clang/Basic/CodeGenOptions.h

@@ -80,16 +80,6 @@ public:
     SRCK_InRegs    // Small structs in registers (-freg-struct-return).
   };
 
-  enum ProfileInstrKind {
-    ProfileNone,       // Profile instrumentation is turned off.
-    ProfileClangInstr, // Clang instrumentation to generate execution counts
-                       // to use with PGO.
-    ProfileIRInstr,    // IR level PGO instrumentation in LLVM.
-    ProfileCSIRInstr, // IR level PGO context sensitive instrumentation in LLVM.
-    ProfileIRSampleColdCov, // IR level sample pgo based cold function coverage
-                            // instrumentation in LLVM.
-  };
-
   enum EmbedBitcodeKind {
     Embed_Off,      // No embedded bitcode.
     Embed_All,      // Embed both bitcode and commandline in the output.
@@ -522,35 +512,41 @@ public:
 
   /// Check if Clang profile instrumenation is on.
   bool hasProfileClangInstr() const {
-    return getProfileInstr() == ProfileClangInstr;
+    return getProfileInstr() ==
+           llvm::driver::ProfileInstrKind::ProfileClangInstr;
   }
 
   /// Check if IR level profile instrumentation is on.
   bool hasProfileIRInstr() const {
-    return getProfileInstr() == ProfileIRInstr;
+    return getProfileInstr() == llvm::driver::ProfileInstrKind::ProfileIRInstr;
   }
 
   /// Check if CS IR level profile instrumentation is on.
   bool hasProfileCSIRInstr() const {
-    return getProfileInstr() == ProfileCSIRInstr;
+    return getProfileInstr() ==
+           llvm::driver::ProfileInstrKind::ProfileCSIRInstr;
   }
 
   /// Check if any form of instrumentation is on.
-  bool hasProfileInstr() const { return getProfileInstr() != ProfileNone; }
+  bool hasProfileInstr() const {
+    return getProfileInstr() != llvm::driver::ProfileInstrKind::ProfileNone;
+  }
 
   /// Check if Clang profile use is on.
   bool hasProfileClangUse() const {
-    return getProfileUse() == ProfileClangInstr;
+    return getProfileUse() == llvm::driver::ProfileInstrKind::ProfileClangInstr;
   }
 
   /// Check if IR level profile use is on.
   bool hasProfileIRUse() const {
-    return getProfileUse() == ProfileIRInstr ||
-           getProfileUse() == ProfileCSIRInstr;
+    return getProfileUse() == llvm::driver::ProfileInstrKind::ProfileIRInstr ||
+           getProfileUse() == llvm::driver::ProfileInstrKind::ProfileCSIRInstr;
   }
 
   /// Check if CSIR profile use is on.
-  bool hasProfileCSIRUse() const { return getProfileUse() == ProfileCSIRInstr; }
+  bool hasProfileCSIRUse() const {
+    return getProfileUse() == llvm::driver::ProfileInstrKind::ProfileCSIRInstr;
+  }
 
   /// Check if type and variable info should be emitted.
   bool hasReducedDebugInfo() const {

clang/include/clang/Basic/ProfileList.h

@@ -49,17 +49,16 @@ public:
   ~ProfileList();
 
   bool isEmpty() const { return Empty; }
-  ExclusionType getDefault(CodeGenOptions::ProfileInstrKind Kind) const;
+  ExclusionType getDefault(llvm::driver::ProfileInstrKind Kind) const;
 
   std::optional<ExclusionType>
   isFunctionExcluded(StringRef FunctionName,
-                     CodeGenOptions::ProfileInstrKind Kind) const;
+                     llvm::driver::ProfileInstrKind Kind) const;
   std::optional<ExclusionType>
   isLocationExcluded(SourceLocation Loc,
-                     CodeGenOptions::ProfileInstrKind Kind) const;
+                     llvm::driver::ProfileInstrKind Kind) const;
   std::optional<ExclusionType>
-  isFileExcluded(StringRef FileName,
-                 CodeGenOptions::ProfileInstrKind Kind) const;
+  isFileExcluded(StringRef FileName, llvm::driver::ProfileInstrKind Kind) const;
 };
 
 } // namespace clang

clang/include/clang/Driver/Options.td

@@ -1772,7 +1772,7 @@ def fmcdc_max_test_vectors_EQ : Joined<["-"], "fmcdc-max-test-vectors=">,
   HelpText<"Maximum number of test vectors in MC/DC coverage">,
   MarshallingInfoInt<CodeGenOpts<"MCDCMaxTVs">, "0x7FFFFFFE">;
 def fprofile_generate : Flag<["-"], "fprofile-generate">,
-    Group<f_Group>, Visibility<[ClangOption, CLOption]>,
+    Group<f_Group>, Visibility<[ClangOption, CLOption, FlangOption, FC1Option]>,
     HelpText<"Generate instrumented code to collect execution counts into default.profraw (overridden by LLVM_PROFILE_FILE env var)">;
 def fprofile_generate_EQ : Joined<["-"], "fprofile-generate=">,
     Group<f_Group>, Visibility<[ClangOption, CLOption]>,
@@ -1789,7 +1789,7 @@ def fprofile_use : Flag<["-"], "fprofile-use">, Group<f_Group>,
     Visibility<[ClangOption, CLOption]>, Alias<fprofile_instr_use>;
 def fprofile_use_EQ : Joined<["-"], "fprofile-use=">,
     Group<f_Group>,
-    Visibility<[ClangOption, CLOption]>,
+    Visibility<[ClangOption, CLOption, FlangOption, FC1Option]>,
     MetaVarName<"<pathname>">,
     HelpText<"Use instrumentation data for profile-guided optimization. If pathname is a directory, it reads from <pathname>/default.profdata. Otherwise, it reads from file <pathname>.">;
 def fno_profile_instr_generate : Flag<["-"], "fno-profile-instr-generate">,
@@ -7761,7 +7761,7 @@ def fpatchable_function_entry_section_EQ
       MarshallingInfoString<CodeGenOpts<"PatchableFunctionEntrySection">>;
 def fprofile_instrument_EQ : Joined<["-"], "fprofile-instrument=">,
     HelpText<"Enable PGO instrumentation">, Values<"none,clang,llvm,csllvm,sample-coldcov">,
-    NormalizedValuesScope<"CodeGenOptions">,
+    NormalizedValuesScope<"llvm::driver::ProfileInstrKind">,
     NormalizedValues<["ProfileNone", "ProfileClangInstr", "ProfileIRInstr", "ProfileCSIRInstr", "ProfileIRSampleColdCov"]>,
     MarshallingInfoEnum<CodeGenOpts<"ProfileInstr">, "ProfileNone">;
 def fprofile_instrument_path_EQ : Joined<["-"], "fprofile-instrument-path=">,

clang/lib/Basic/ProfileList.cpp

@@ -69,24 +69,24 @@ ProfileList::ProfileList(ArrayRef<std::string> Paths, SourceManager &SM)
 
 ProfileList::~ProfileList() = default;
 
-static StringRef getSectionName(CodeGenOptions::ProfileInstrKind Kind) {
+static StringRef getSectionName(llvm::driver::ProfileInstrKind Kind) {
   switch (Kind) {
-  case CodeGenOptions::ProfileNone:
+  case llvm::driver::ProfileInstrKind::ProfileNone:
     return "";
-  case CodeGenOptions::ProfileClangInstr:
+  case llvm::driver::ProfileInstrKind::ProfileClangInstr:
     return "clang";
-  case CodeGenOptions::ProfileIRInstr:
+  case llvm::driver::ProfileInstrKind::ProfileIRInstr:
     return "llvm";
-  case CodeGenOptions::ProfileCSIRInstr:
+  case llvm::driver::ProfileInstrKind::ProfileCSIRInstr:
     return "csllvm";
-  case CodeGenOptions::ProfileIRSampleColdCov:
+  case llvm::driver::ProfileInstrKind::ProfileIRSampleColdCov:
     return "sample-coldcov";
   }
-  llvm_unreachable("Unhandled CodeGenOptions::ProfileInstrKind enum");
+  llvm_unreachable("Unhandled llvm::driver::ProfileInstrKind enum");
 }
 
 ProfileList::ExclusionType
-ProfileList::getDefault(CodeGenOptions::ProfileInstrKind Kind) const {
+ProfileList::getDefault(llvm::driver::ProfileInstrKind Kind) const {
   StringRef Section = getSectionName(Kind);
   // Check for "default:<type>"
   if (SCL->inSection(Section, "default", "allow"))
@@ -117,7 +117,7 @@ ProfileList::inSection(StringRef Section, StringRef Prefix,
 
 std::optional<ProfileList::ExclusionType>
 ProfileList::isFunctionExcluded(StringRef FunctionName,
-                                CodeGenOptions::ProfileInstrKind Kind) const {
+                                llvm::driver::ProfileInstrKind Kind) const {
   StringRef Section = getSectionName(Kind);
   // Check for "function:<regex>=<case>"
   if (auto V = inSection(Section, "function", FunctionName))
@@ -131,13 +131,13 @@ ProfileList::isFunctionExcluded(StringRef FunctionName,
 
 std::optional<ProfileList::ExclusionType>
 ProfileList::isLocationExcluded(SourceLocation Loc,
-                                CodeGenOptions::ProfileInstrKind Kind) const {
+                                llvm::driver::ProfileInstrKind Kind) const {
   return isFileExcluded(SM.getFilename(SM.getFileLoc(Loc)), Kind);
 }
 
 std::optional<ProfileList::ExclusionType>
 ProfileList::isFileExcluded(StringRef FileName,
-                            CodeGenOptions::ProfileInstrKind Kind) const {
+                            llvm::driver::ProfileInstrKind Kind) const {
   StringRef Section = getSectionName(Kind);
   // Check for "source:<regex>=<case>"
   if (auto V = inSection(Section, "source", FileName))

clang/lib/CodeGen/BackendUtil.cpp

@@ -124,17 +124,10 @@ namespace clang {
 extern llvm::cl::opt<bool> ClSanitizeGuardChecks;
 }
 
-// Default filename used for profile generation.
-static std::string getDefaultProfileGenName() {
-  return DebugInfoCorrelate || ProfileCorrelate != InstrProfCorrelator::NONE
-             ? "default_%m.proflite"
-             : "default_%m.profraw";
-}
-
 // Path and name of file used for profile generation
 static std::string getProfileGenName(const CodeGenOptions &CodeGenOpts) {
   std::string FileName = CodeGenOpts.InstrProfileOutput.empty()
-                             ? getDefaultProfileGenName()
+                             ? llvm::driver::getDefaultProfileGenName()
                              : CodeGenOpts.InstrProfileOutput;
   if (CodeGenOpts.ContinuousProfileSync)
     FileName = "%c" + FileName;

clang/lib/CodeGen/CodeGenAction.cpp

@@ -273,8 +273,8 @@ void BackendConsumer::HandleTranslationUnit(ASTContext &C) {
   std::unique_ptr<llvm::ToolOutputFile> OptRecordFile =
     std::move(*OptRecordFileOrErr);
 
-  if (OptRecordFile &&
-      CodeGenOpts.getProfileUse() != CodeGenOptions::ProfileNone)
+  if (OptRecordFile && CodeGenOpts.getProfileUse() !=
+                           llvm::driver::ProfileInstrKind::ProfileNone)
     Ctx.setDiagnosticsHotnessRequested(true);
 
   if (CodeGenOpts.MisExpect) {

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -943,7 +943,8 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
     }
   }
 
-  if (CGM.getCodeGenOpts().getProfileInstr() != CodeGenOptions::ProfileNone) {
+  if (CGM.getCodeGenOpts().getProfileInstr() !=
+      llvm::driver::ProfileInstrKind::ProfileNone) {
     switch (CGM.isFunctionBlockedFromProfileInstr(Fn, Loc)) {
     case ProfileList::Skip:
       Fn->addFnAttr(llvm::Attribute::SkipProfile);

clang/lib/CodeGen/CodeGenModule.cpp

@@ -3608,7 +3608,7 @@ CodeGenModule::isFunctionBlockedByProfileList(llvm::Function *Fn,
   // If the profile list is empty, then instrument everything.
   if (ProfileList.isEmpty())
     return ProfileList::Allow;
-  CodeGenOptions::ProfileInstrKind Kind = getCodeGenOpts().getProfileInstr();
+  llvm::driver::ProfileInstrKind Kind = getCodeGenOpts().getProfileInstr();
   // First, check the function name.
   if (auto V = ProfileList.isFunctionExcluded(Fn->getName(), Kind))
     return *V;

clang/lib/Driver/ToolChains/Flang.cpp

@@ -887,6 +887,10 @@ void Flang::ConstructJob(Compilation &C, const JobAction &JA,
   // TODO: Handle interactions between -w, -pedantic, -Wall, -WOption
   Args.AddLastArg(CmdArgs, options::OPT_w);
 
+  // recognise options: fprofile-generate -fprofile-use=
+  Args.addAllArgs(
+      CmdArgs, {options::OPT_fprofile_generate, options::OPT_fprofile_use_EQ});
+
   // Forward flags for OpenMP. We don't do this if the current action is an
   // device offloading action other than OpenMP.
   if (Args.hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1492,11 +1492,11 @@ static void setPGOUseInstrumentor(CodeGenOptions &Opts,
   // which is available (might be one or both).
   if (PGOReader->isIRLevelProfile() || PGOReader->hasMemoryProfile()) {
     if (PGOReader->hasCSIRLevelProfile())
-      Opts.setProfileUse(CodeGenOptions::ProfileCSIRInstr);
+      Opts.setProfileUse(llvm::driver::ProfileInstrKind::ProfileCSIRInstr);
     else
-      Opts.setProfileUse(CodeGenOptions::ProfileIRInstr);
+      Opts.setProfileUse(llvm::driver::ProfileInstrKind::ProfileIRInstr);
   } else
-    Opts.setProfileUse(CodeGenOptions::ProfileClangInstr);
+    Opts.setProfileUse(llvm::driver::ProfileInstrKind::ProfileClangInstr);
 }
 
 void CompilerInvocation::setDefaultPointerAuthOptions(

flang/include/flang/Frontend/CodeGenOptions.def

@@ -24,8 +24,15 @@ CODEGENOPT(OptimizationLevel, 2, 0) ///< The -O[0-3] option specified.
 CODEGENOPT(DebugPassManager, 1, 0) ///< Prints debug information for the new
                                    ///< pass manager.
 
+
+/// Choose profile instrumenation kind or no instrumentation.
+ENUM_CODEGENOPT(ProfileInstr, llvm::driver::ProfileInstrKind, 2, llvm::driver::ProfileInstrKind::ProfileNone)
+/// Choose profile kind for PGO use compilation.
+ENUM_CODEGENOPT(ProfileUse, llvm::driver::ProfileInstrKind, 2, llvm::driver::ProfileInstrKind::ProfileNone)
+
 CODEGENOPT(InstrumentFunctions, 1, 0) ///< Set when -finstrument_functions is
                                       ///< enabled on the compile step.
+
 CODEGENOPT(IsPIE, 1, 0) ///< PIE level is the same as PIC Level.
 CODEGENOPT(PICLevel, 2, 0) ///< PIC level of the LLVM module.
 CODEGENOPT(PrepareForFullLTO , 1, 0) ///< Set when -flto is enabled on the

flang/include/flang/Frontend/CodeGenOptions.h

@@ -154,6 +154,44 @@ public:
   /// OpenMP is enabled.
   using DoConcurrentMappingKind = flangomp::DoConcurrentMappingKind;
 
+  /// Name of the profile file to use as output for -fprofile-instr-generate,
+  /// -fprofile-generate, and -fcs-profile-generate.
+  std::string InstrProfileOutput;
+
+  /// Name of the profile file to use as input for -fmemory-profile-use.
+  std::string MemoryProfileUsePath;
+
+  /// Name of the profile file to use as input for -fprofile-instr-use
+  std::string ProfileInstrumentUsePath;
+
+  /// Name of the profile remapping file to apply to the profile data supplied
+  /// by -fprofile-sample-use or -fprofile-instr-use.
+  std::string ProfileRemappingFile;
+
+  /// Check if Clang profile instrumenation is on.
+  bool hasProfileClangInstr() const {
+    return getProfileInstr() == llvm::driver::ProfileClangInstr;
+  }
+
+  /// Check if IR level profile instrumentation is on.
+  bool hasProfileIRInstr() const {
+    return getProfileInstr() == llvm::driver::ProfileIRInstr;
+  }
+
+  /// Check if CS IR level profile instrumentation is on.
+  bool hasProfileCSIRInstr() const {
+    return getProfileInstr() == llvm::driver::ProfileCSIRInstr;
+  }
+  /// Check if IR level profile use is on.
+  bool hasProfileIRUse() const {
+    return getProfileUse() == llvm::driver::ProfileIRInstr ||
+           getProfileUse() == llvm::driver::ProfileCSIRInstr;
+  }
+  /// Check if CSIR profile use is on.
+  bool hasProfileCSIRUse() const {
+    return getProfileUse() == llvm::driver::ProfileCSIRInstr;
+  }
+
   // Define accessors/mutators for code generation options of enumeration type.
 #define CODEGENOPT(Name, Bits, Default)
 #define ENUM_CODEGENOPT(Name, Type, Bits, Default)                             \

flang/lib/Frontend/CompilerInvocation.cpp

@@ -29,6 +29,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Frontend/Debug/Options.h"
+#include "llvm/Frontend/Driver/CodeGenOptions.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/OptTable.h"
@@ -441,6 +442,15 @@ static void parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
       opts.IsPIE = 1;
   }
 
+  if (args.hasArg(clang::driver::options::OPT_fprofile_generate)) {
+    opts.setProfileInstr(llvm::driver::ProfileInstrKind::ProfileIRInstr);
+  }
+
+  if (auto A = args.getLastArg(clang::driver::options::OPT_fprofile_use_EQ)) {
+    opts.setProfileUse(llvm::driver::ProfileInstrKind::ProfileIRInstr);
+    opts.ProfileInstrumentUsePath = A->getValue();
+  }
+
   // -mcmodel option.
   if (const llvm::opt::Arg *a =
           args.getLastArg(clang::driver::options::OPT_mcmodel_EQ)) {

flang/lib/Frontend/FrontendActions.cpp

@@ -56,10 +56,12 @@
 #include "llvm/Passes/PassBuilder.h"
 #include "llvm/Passes/PassPlugin.h"
 #include "llvm/Passes/StandardInstrumentations.h"
+#include "llvm/ProfileData/InstrProfCorrelator.h"
 #include "llvm/Support/AMDGPUAddrSpace.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/PGOOptions.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/ToolOutputFile.h"
@@ -67,6 +69,7 @@
 #include "llvm/TargetParser/RISCVISAInfo.h"
 #include "llvm/TargetParser/RISCVTargetParser.h"
 #include "llvm/Transforms/IPO/Internalize.h"
+#include "llvm/Transforms/Instrumentation/InstrProfiling.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 #include <memory>
 #include <system_error>
@@ -919,6 +922,29 @@ void CodeGenAction::runOptimizationPipeline(llvm::raw_pwrite_stream &os) {
   llvm::PassInstrumentationCallbacks pic;
   llvm::PipelineTuningOptions pto;
   std::optional<llvm::PGOOptions> pgoOpt;
+
+  if (opts.hasProfileIRInstr()) {
+    // -fprofile-generate.
+    pgoOpt = llvm::PGOOptions(opts.InstrProfileOutput.empty()
+                                  ? llvm::driver::getDefaultProfileGenName()
+                                  : opts.InstrProfileOutput,
+                              "", "", opts.MemoryProfileUsePath, nullptr,
+                              llvm::PGOOptions::IRInstr,
+                              llvm::PGOOptions::NoCSAction,
+                              llvm::PGOOptions::ColdFuncOpt::Default, false,
+                              /*PseudoProbeForProfiling=*/false, false);
+  } else if (opts.hasProfileIRUse()) {
+    llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS =
+        llvm::vfs::getRealFileSystem();
+    // -fprofile-use.
+    auto CSAction = opts.hasProfileCSIRUse() ? llvm::PGOOptions::CSIRUse
+                                             : llvm::PGOOptions::NoCSAction;
+    pgoOpt = llvm::PGOOptions(
+        opts.ProfileInstrumentUsePath, "", opts.ProfileRemappingFile,
+        opts.MemoryProfileUsePath, VFS, llvm::PGOOptions::IRUse, CSAction,
+        llvm::PGOOptions::ColdFuncOpt::Default, false);
+  }
+
   llvm::StandardInstrumentations si(llvmModule->getContext(),
                                     opts.DebugPassManager);
   si.registerCallbacks(pic, &mam);

flang/test/Driver/flang-f-opts.f90

@@ -8,3 +8,8 @@
 ! CHECK-LABEL: "-fc1"
 ! CHECK: -ffp-contract=off
 ! CHECK: -O3
+
+! RUN: %flang -### -S -fprofile-generate %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-GENERATE-LLVM %s
+! CHECK-PROFILE-GENERATE-LLVM: "-fprofile-generate"
+! RUN: %flang -### -S -fprofile-use=%S %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-USE-DIR %s
+! CHECK-PROFILE-USE-DIR: "-fprofile-use={{.*}}"

flang/test/Profile/Inputs/gcc-flag-compatibility_IR.proftext

@@ -0,0 +1,18 @@
+# IR level Instrumentation Flag
+:ir
+_QQmain
+# Func Hash:
+146835646621254984
+# Num Counters:
+2
+# Counter Values:
+100
+1
+
+main
+# Func Hash:
+742261418966908927
+# Num Counters:
+1
+# Counter Values:
+1

flang/test/Profile/Inputs/gcc-flag-compatibility_IR_entry.proftext

@@ -0,0 +1,11 @@
+# IR level Instrumentation Flag
+:ir
+:entry_first
+_QQmain
+# Func Hash:
+146835646621254984
+# Num Counters:
+2
+# Counter Values:
+100
+1

flang/test/Profile/gcc-flag-compatibility.f90

@@ -0,0 +1,32 @@
+! Tests for -fprofile-generate and -fprofile-use flag compatibility. These two
+! flags behave similarly to their GCC counterparts:
+!
+! -fprofile-generate         Generates the profile file ./default.profraw
+! -fprofile-use=<dir>/file   Uses the profile file <dir>/file
+
+! On AIX, -flto used to be required with -fprofile-generate. gcc-flag-compatibility-aix.c is used to do the testing on AIX with -flto
+! RUN: %flang %s -c -S -o - -emit-llvm -fprofile-generate | FileCheck -check-prefix=PROFILE-GEN %s
+! PROFILE-GEN: @__profc_{{_?}}main = {{(private|internal)}} global [1 x i64] zeroinitializer, section
+! PROFILE-GEN: @__profd_{{_?}}main =
+
+! Check that -fprofile-use=some/path/file.prof reads some/path/file.prof
+! This uses LLVM IR format profile.
+! RUN: rm -rf %t.dir
+! RUN: mkdir -p %t.dir/some/path
+! RUN: llvm-profdata merge %S/Inputs/gcc-flag-compatibility_IR.proftext -o %t.dir/some/path/file.prof
+! RUN: %flang %s -o - -emit-llvm -S -fprofile-use=%t.dir/some/path/file.prof | FileCheck -check-prefix=PROFILE-USE-IR1 %s
+! RUN: llvm-profdata merge %S/Inputs/gcc-flag-compatibility_IR_entry.proftext -o %t.dir/some/path/file.prof
+! RUN: %flang %s -o - -emit-llvm -S -fprofile-use=%t.dir/some/path/file.prof | FileCheck -check-prefix=PROFILE-USE-IR2 %s
+! PROFILE-USE-IR1: = !{!"branch_weights", i32 100, i32 1}
+! PROFILE-USE-IR2: = !{!"branch_weights", i32 1, i32 100}
+
+program main
+  implicit none
+  integer :: i
+  integer :: X = 0
+
+  do i = 0, 99
+     X = X + i
+  end do
+
+end program main

llvm/include/llvm/Frontend/Driver/CodeGenOptions.h

@@ -14,6 +14,7 @@
 #define LLVM_FRONTEND_DRIVER_CODEGENOPTIONS_H
 
 #include "llvm/Support/Compiler.h"
+#include <string>
 
 namespace llvm {
 class Triple;
@@ -51,6 +52,18 @@ enum class VectorLibrary {
 LLVM_ABI TargetLibraryInfoImpl *createTLII(const llvm::Triple &TargetTriple,
                                            VectorLibrary Veclib);
 
+enum ProfileInstrKind {
+  ProfileNone,       // Profile instrumentation is turned off.
+  ProfileClangInstr, // Clang instrumentation to generate execution counts
+                     // to use with PGO.
+  ProfileIRInstr,    // IR level PGO instrumentation in LLVM.
+  ProfileCSIRInstr,  // IR level PGO context sensitive instrumentation in LLVM.
+  ProfileIRSampleColdCov, // IR level sample pgo based cold function coverage
+                          // instrumentation in LLVM.
+};
+
+// Default filename used for profile generation.
+std::string getDefaultProfileGenName();
 } // end namespace llvm::driver
 
 #endif

llvm/lib/Frontend/Driver/CMakeLists.txt

@@ -12,4 +12,5 @@ add_llvm_component_library(LLVMFrontendDriver
   Core
   Support
   Analysis
+  Instrumentation
   )

llvm/lib/Frontend/Driver/CodeGenOptions.cpp

@@ -8,8 +8,15 @@
 
 #include "llvm/Frontend/Driver/CodeGenOptions.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/ProfileData/InstrProfCorrelator.h"
 #include "llvm/TargetParser/Triple.h"
 
+namespace llvm {
+extern llvm::cl::opt<bool> DebugInfoCorrelate;
+extern llvm::cl::opt<llvm::InstrProfCorrelator::ProfCorrelatorKind>
+    ProfileCorrelate;
+} // namespace llvm
+
 namespace llvm::driver {
 
 TargetLibraryInfoImpl *createTLII(const llvm::Triple &TargetTriple,
@@ -56,4 +63,10 @@ TargetLibraryInfoImpl *createTLII(const llvm::Triple &TargetTriple,
   return TLII;
 }
 
+std::string getDefaultProfileGenName() {
+  return llvm::DebugInfoCorrelate ||
+                 llvm::ProfileCorrelate != InstrProfCorrelator::NONE
+             ? "default_%m.proflite"
+             : "default_%m.profraw";
+}
 } // namespace llvm::driver