[PATCH] Add support for optimization reports.

[Diego Novillo]

+richardsmith +tobias

I could not convince phabricator to add Richard and Tobias to the
reviewers line. I looked in its list of users and neither of you seem
to be registered. Maybe I was looking for the wrong IDs?

Thanks. Diego.

On Mon, Mar 31, 2014 at 12:26 PM, Diego Novillo <dnovillo at google.com> wrote:
> This patch adds a new flag -Rpass=. The flag indicates the name
> of the optimization pass that should emit remarks stating when it
> made a transformation to the code.
>
> This implements the design I proposed in:
>
> https://docs.google.com/document/d/1FYUatSjZZO-zmFBxjOiuOzAy9mhHA8hqdvklZv68WuQ/edit?usp=sharing
>
> The patch is still WIP:
>
> 1- I still need to add tests. Both in the front and middle end.
>
> 2- The diagnostic is emitted with a confusing [-WRpass] suffix. I'm
>    not quite sure how to remove that. I think it's related to diagnostic
>    groups?
>
> http://llvm-reviews.chandlerc.com/D3226
>
> Files:
>   include/clang/Basic/DiagnosticDriverKinds.td
>   include/clang/Basic/DiagnosticFrontendKinds.td
>   include/clang/Basic/DiagnosticGroups.td
>   include/clang/Driver/Options.td
>   include/clang/Frontend/CodeGenOptions.h
>   lib/CodeGen/CodeGenAction.cpp
>   lib/Driver/Tools.cpp
>   lib/Frontend/CompilerInvocation.cpp
>
> Index: include/clang/Basic/DiagnosticDriverKinds.td
> ===================================================================
> --- include/clang/Basic/DiagnosticDriverKinds.td
> +++ include/clang/Basic/DiagnosticDriverKinds.td
> @@ -111,6 +111,8 @@
>    "unknown or ill-formed Objective-C runtime '%0'">;
>  def err_drv_emit_llvm_link : Error<
>     "-emit-llvm cannot be used when linking">;
> +def err_drv_optimization_report_pattern : Error<
> +  "%0 in '%1'">;
>
>  def warn_O4_is_O3 : Warning<"-O4 is equivalent to -O3">, InGroup<Deprecated>;
>  def warn_drv_optimization_value : Warning<"optimization level '%0' is unsupported; using '%1%2' instead">,
> Index: include/clang/Basic/DiagnosticFrontendKinds.td
> ===================================================================
> --- include/clang/Basic/DiagnosticFrontendKinds.td
> +++ include/clang/Basic/DiagnosticFrontendKinds.td
> @@ -32,6 +32,9 @@
>  def remark_fe_backend_plugin: Remark<"%0">, CatBackend, InGroup<RemarkBackendPlugin>;
>  def note_fe_backend_plugin: Note<"%0">, CatBackend;
>
> +def remark_fe_backend_optimization_report: Remark<"%0">, CatBackend,
> +    InGroup<BackendOptimizationReport>;
> +
>  def err_fe_invalid_code_complete_file : Error<
>      "cannot locate code-completion file %0">, DefaultFatal;
>  def err_fe_stdout_binary : Error<"unable to change standard output to binary">,
> Index: include/clang/Basic/DiagnosticGroups.td
> ===================================================================
> --- include/clang/Basic/DiagnosticGroups.td
> +++ include/clang/Basic/DiagnosticGroups.td
> @@ -662,3 +662,4 @@
>  def BackendFrameLargerThan : DiagGroup<"frame-larger-than">;
>  def BackendPlugin : DiagGroup<"backend-plugin">;
>  def RemarkBackendPlugin : DiagGroup<"remark-backend-plugin">;
> +def BackendOptimizationReport : DiagGroup<"Rpass">;
> Index: include/clang/Driver/Options.td
> ===================================================================
> --- include/clang/Driver/Options.td
> +++ include/clang/Driver/Options.td
> @@ -60,6 +60,7 @@
>  def M_Group               : OptionGroup<"<M group>">, Group<CompileOnly_Group>;
>  def T_Group               : OptionGroup<"<T group>">;
>  def O_Group               : OptionGroup<"<O group>">, Group<CompileOnly_Group>;
> +def R_Group               : OptionGroup<"<R group>">, Group<CompileOnly_Group>;
>  def W_Group               : OptionGroup<"<W group>">, Group<CompileOnly_Group>;
>  def d_Group               : OptionGroup<"<d group>">;
>  def f_Group               : OptionGroup<"<f group>">, Group<CompileOnly_Group>;
> @@ -253,7 +254,8 @@
>  def Qunused_arguments : Flag<["-"], "Qunused-arguments">, Flags<[DriverOption, CoreOption]>,
>    HelpText<"Don't emit warning for unused driver arguments">;
>  def Q : Flag<["-"], "Q">;
> -def R : Flag<["-"], "R">;
> +def Rpass_EQ : Joined<["-"], "Rpass=">, Group<R_Group>, Flags<[CC1Option]>,
> +  HelpText<"Report transformations performed by optimization passes">;
>  def S : Flag<["-"], "S">, Flags<[DriverOption,CC1Option]>, Group<Action_Group>,
>    HelpText<"Only run preprocess and compilation steps">;
>  def Tbss : JoinedOrSeparate<["-"], "Tbss">, Group<T_Group>;
> Index: include/clang/Frontend/CodeGenOptions.h
> ===================================================================
> --- include/clang/Frontend/CodeGenOptions.h
> +++ include/clang/Frontend/CodeGenOptions.h
> @@ -16,6 +16,7 @@
>
>  #include <string>
>  #include <vector>
> +#include "llvm/Support/Regex.h"
>
>  namespace clang {
>
> @@ -145,6 +146,13 @@
>    /// Name of the profile file to use as input for -fprofile-instr-use
>    std::string InstrProfileInput;
>
> +  /// Regular expression to select optimizations for which we should enable
> +  /// optimization reports. Transformation passes whose name matches this
> +  /// expression (and support this feature), will emit a diagnostic
> +  /// whenever they perform a transformation. This is enabled by the
> +  /// -Rpass=regexp flag.
> +  llvm::Regex *OptimizationReportPattern;
> +
>  public:
>    // Define accessors/mutators for code generation options of enumeration type.
>  #define CODEGENOPT(Name, Bits, Default)
> Index: lib/CodeGen/CodeGenAction.cpp
> ===================================================================
> --- lib/CodeGen/CodeGenAction.cpp
> +++ lib/CodeGen/CodeGenAction.cpp
> @@ -20,6 +20,7 @@
>  #include "clang/Frontend/FrontendDiagnostic.h"
>  #include "llvm/ADT/SmallString.h"
>  #include "llvm/Bitcode/ReaderWriter.h"
> +#include "llvm/IR/DebugInfo.h"
>  #include "llvm/IR/DiagnosticInfo.h"
>  #include "llvm/IR/DiagnosticPrinter.h"
>  #include "llvm/IR/LLVMContext.h"
> @@ -220,6 +221,11 @@
>      /// \return True if the diagnostic has been successfully reported, false
>      /// otherwise.
>      bool StackSizeDiagHandler(const llvm::DiagnosticInfoStackSize &D);
> +    /// \brief Specialized handler for the optimization report diagnostic.
> +    /// \return True if the diagnostic has been successfully reported, false
> +    /// otherwise.
> +    bool
> +    OptimizationReportHandler(const llvm::DiagnosticInfoOptimizationReport &D);
>    };
>
>    void BackendConsumer::anchor() {}
> @@ -374,6 +380,27 @@
>    return true;
>  }
>
> +bool BackendConsumer::OptimizationReportHandler(
> +    const llvm::DiagnosticInfoOptimizationReport &D) {
> +  if (CodeGenOpts.OptimizationReportPattern->match(D.getPassName())) {
> +    SourceLocation Loc;
> +    // FIXME: This should be done earlier.
> +    Diags.setDiagnosticMapping(diag::remark_fe_backend_optimization_report,
> +                               diag::Mapping::MAP_REMARK, Loc);
> +    // FIXME: There should be a way of transferring the DILocation
> +    // content into a SourceLocation. We are building the location string
> +    // unnecessarily.
> +    DILocation DIL(D.getDebugLoc().getAsMDNode(D.getFunction().getContext()));
> +    StringRef FileName = DIL.getFilename();
> +    unsigned LineNum = DIL.getLineNumber();
> +    unsigned ColumnNum = DIL.getColumnNumber();
> +    Diags.Report(Loc, diag::remark_fe_backend_optimization_report)
> +        << Twine(FileName + ":" + Twine(LineNum) + ":" + Twine(ColumnNum) +
> +                 ": " + D.getMsg()).str();
> +  }
> +  return true;
> +}
> +
>  /// \brief This function is invoked when the backend needs
>  /// to report something to the user.
>  void BackendConsumer::DiagnosticHandlerImpl(const DiagnosticInfo &DI) {
> @@ -391,6 +418,10 @@
>        return;
>      ComputeDiagID(Severity, backend_frame_larger_than, DiagID);
>      break;
> +  case llvm::DK_OptimizationReport:
> +    if (CodeGenOpts.OptimizationReportPattern)
> +      OptimizationReportHandler(cast<DiagnosticInfoOptimizationReport>(DI));
> +    return;
>    default:
>      // Plugin IDs are not bound to any value as they are set dynamically.
>      ComputeDiagRemarkID(Severity, backend_plugin, DiagID);
> Index: lib/Driver/Tools.cpp
> ===================================================================
> --- lib/Driver/Tools.cpp
> +++ lib/Driver/Tools.cpp
> @@ -3293,6 +3293,10 @@
>        A->render(Args, CmdArgs);
>    }
>
> +  if (Arg *A = Args.getLastArg(options::OPT_Rpass_EQ)) {
> +    A->render(Args, CmdArgs);
> +  }
> +
>    if (Args.hasArg(options::OPT_mkernel)) {
>      if (!Args.hasArg(options::OPT_fapple_kext) && types::isCXX(InputType))
>        CmdArgs.push_back("-fapple-kext");
> Index: lib/Frontend/CompilerInvocation.cpp
> ===================================================================
> --- lib/Frontend/CompilerInvocation.cpp
> +++ lib/Frontend/CompilerInvocation.cpp
> @@ -520,6 +520,23 @@
>
>    Opts.DependentLibraries = Args.getAllArgValues(OPT_dependent_lib);
>
> +  if (Arg *A = Args.getLastArg(OPT_Rpass_EQ)) {
> +    StringRef Val = A->getValue();
> +    std::string RegexError;
> +    Opts.OptimizationReportPattern = new llvm::Regex(Val);
> +    if (!Opts.OptimizationReportPattern->isValid(RegexError)) {
> +      Diags.Report(diag::err_drv_optimization_report_pattern)
> +          << RegexError << A->getAsString(Args);
> +      delete Opts.OptimizationReportPattern;
> +      Opts.OptimizationReportPattern = 0;
> +    } else {
> +      // Optimization report diagnostics need to extract location information
> +      // from the instructions they are emitted on. When -Rpass is used,
> +      // enable line table generation.
> +      Opts.setDebugInfo(CodeGenOptions::DebugLineTablesOnly);
> +    }
> +  }
> +
>    return Success;
>  }