Remarks.h

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//===- Remarks.h - MLIR Optimization Remark ----------------------*- C++-*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines utilities for emitting optimization remarks.
//
//===----------------------------------------------------------------------===//
 
#ifndef MLIR_IR_REMARKS_H
#define MLIR_IR_REMARKS_H
 
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/Remarks/Remark.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/Regex.h"
 
#include "mlir/IR/Diagnostics.h"
#include "mlir/IR/MLIRContext.h"
#include "mlir/IR/Value.h"
 
namespace mlir::remark {
 
/// Define an the set of categories to accept. By default none are, the provided
/// regex matches against the category names for each kind of remark.
struct RemarkCategories {
  std::optional<std::string> all, passed, missed, analysis, failed;
};
 
/// Categories describe the outcome of an transformation, not the mechanics of
/// emitting/serializing remarks.
enum class RemarkKind {
  RemarkUnknown = 0,
 
  /// An optimization was applied.
  RemarkPassed,
 
  /// A profitable optimization opportunity was found but not applied.
  RemarkMissed,
 
  /// The compiler attempted the optimization but failed (e.g., legality
  /// checks, or better opportunites).
  RemarkFailure,
 
  /// Informational context (e.g., analysis numbers) without a pass/fail
  /// outcome.
  RemarkAnalysis,
};
 
using namespace llvm;
 
/// Options to create a Remark
struct RemarkOpts {
  StringRef remarkName;      // Identifiable name
  StringRef categoryName;    // Category name (subject to regex filtering)
  StringRef subCategoryName; // Subcategory name
  StringRef functionName;    // Function name if available
 
  // Construct RemarkOpts from a remark name.
  static constexpr RemarkOpts name(StringRef n) {
    return RemarkOpts{n, {}, {}, {}};
  }
  /// Return a copy with the category set.
  constexpr RemarkOpts category(StringRef v) const {
    return {remarkName, v, subCategoryName, functionName};
  }
  /// Return a copy with the subcategory set.
  constexpr RemarkOpts subCategory(StringRef v) const {
    return {remarkName, categoryName, v, functionName};
  }
  /// Return a copy with the function name set.
  constexpr RemarkOpts function(StringRef v) const {
    return {remarkName, categoryName, subCategoryName, v};
  }
};
 
} // namespace mlir::remark
 
namespace mlir::remark::detail {
//===----------------------------------------------------------------------===//
// Remark Base Class
//===----------------------------------------------------------------------===//
class Remark {
 
public:
  Remark(RemarkKind remarkKind, DiagnosticSeverity severity, Location loc,
         RemarkOpts opts)
      : remarkKind(remarkKind), functionName(opts.functionName), loc(loc),
        categoryName(opts.categoryName), subCategoryName(opts.subCategoryName),
        remarkName(opts.remarkName) {
    if (!categoryName.empty() && !subCategoryName.empty()) {
      (llvm::Twine(categoryName) + ":" + subCategoryName)
          .toStringRef(fullCategoryName);
    }
  }
 
  // Remark argument that is a key-value pair that can be printed as machine
  // parsable args.
  struct Arg {
    std::string key;
    std::string val;
    Arg(llvm::StringRef m) : key("Remark"), val(m) {}
    Arg(llvm::StringRef k, llvm::StringRef v) : key(k), val(v) {}
    Arg(llvm::StringRef k, std::string v) : key(k), val(std::move(v)) {}
    Arg(llvm::StringRef k, const char *v) : Arg(k, llvm::StringRef(v)) {}
    Arg(llvm::StringRef k, Value v);
    Arg(llvm::StringRef k, Type t);
    Arg(llvm::StringRef k, bool b) : key(k), val(b ? "true" : "false") {}
 
    // One constructor for all arithmetic types except bool.
    template <typename T, typename = std::enable_if_t<std::is_arithmetic_v<T> &&
                                                      !std::is_same_v<T, bool>>>
    Arg(llvm::StringRef k, T v) : key(k) {
      if constexpr (std::is_floating_point_v<T>) {
        llvm::raw_string_ostream os(val);
        os << v;
      } else if constexpr (std::is_signed_v<T>) {
        val = llvm::itostr(static_cast<long long>(v));
      } else {
        val = llvm::utostr(static_cast<unsigned long long>(v));
      }
    }
  };
 
  void insert(llvm::StringRef s);
  void insert(Arg a);
 
  void print(llvm::raw_ostream &os, bool printLocation = false) const;
 
  Location getLocation() const { return loc; }
  /// Diagnostic -> Remark
  llvm::remarks::Remark generateRemark() const;
 
  StringRef getFunction() const {
    if (!functionName.empty())
      return functionName;
    return "<unknown function>";
  }
 
  llvm::StringRef getCategoryName() const { return categoryName; }
 
  llvm::StringRef getCombinedCategoryName() const {
    if (categoryName.empty() && subCategoryName.empty())
      return {};
    if (subCategoryName.empty())
      return categoryName;
    if (categoryName.empty())
      return subCategoryName;
    return fullCategoryName;
  }
 
  StringRef getRemarkName() const {
    if (remarkName.empty())
      return "<unknown remark name>";
    return remarkName;
  }
 
  std::string getMsg() const;
 
  ArrayRef<Arg> getArgs() const { return args; }
 
  llvm::remarks::Type getRemarkType() const;
 
  StringRef getRemarkTypeString() const;
 
protected:
  /// Keeps the MLIR diagnostic kind, which is used to determine the
  /// diagnostic kind in the LLVM remark streamer.
  RemarkKind remarkKind;
  /// Name of the convering function like interface
  StringRef functionName;
 
  Location loc;
  /// Sub category passname e.g., "Unroll" or "UnrollAndJam"
  StringRef categoryName;
 
  /// Sub category name "Loop Optimizer"
  StringRef subCategoryName;
 
  /// Combined name for category and sub-category
  SmallString<64> fullCategoryName;
 
  /// Remark identifier
  StringRef remarkName;
 
  /// Args collected via the streaming interface.
  SmallVector<Arg, 4> args;
 
private:
  /// Convert the MLIR diagnostic severity to LLVM diagnostic severity.
  static llvm::DiagnosticSeverity
  makeLLVMSeverity(DiagnosticSeverity severity) {
    switch (severity) {
    case DiagnosticSeverity::Note:
      return llvm::DiagnosticSeverity::DS_Note;
    case DiagnosticSeverity::Warning:
      return llvm::DiagnosticSeverity::DS_Warning;
    case DiagnosticSeverity::Error:
      return llvm::DiagnosticSeverity::DS_Error;
    case DiagnosticSeverity::Remark:
      return llvm::DiagnosticSeverity::DS_Remark;
    }
    llvm_unreachable("Unknown diagnostic severity");
  }
  /// Convert the MLIR remark kind to LLVM diagnostic kind.
  static llvm::DiagnosticKind makeLLVMKind(RemarkKind remarkKind) {
    switch (remarkKind) {
    case RemarkKind::RemarkUnknown:
      return llvm::DiagnosticKind::DK_Generic;
    case RemarkKind::RemarkPassed:
      return llvm::DiagnosticKind::DK_OptimizationRemark;
    case RemarkKind::RemarkMissed:
      return llvm::DiagnosticKind::DK_OptimizationRemarkMissed;
    case RemarkKind::RemarkFailure:
      return llvm::DiagnosticKind::DK_OptimizationFailure;
    case RemarkKind::RemarkAnalysis:
      return llvm::DiagnosticKind::DK_OptimizationRemarkAnalysis;
    }
    llvm_unreachable("Unknown diagnostic kind");
  }
};
 
inline Remark &operator<<(Remark &r, StringRef s) {
  r.insert(s);
  return r;
}
inline Remark &&operator<<(Remark &&r, StringRef s) {
  r.insert(s);
  return std::move(r);
}
inline Remark &operator<<(Remark &r, const Remark::Arg &kv) {
  r.insert(kv);
  return r;
}
 
//===----------------------------------------------------------------------===//
// Shorthand aliases for different kinds of remarks.
//===----------------------------------------------------------------------===//
 
template <RemarkKind K, DiagnosticSeverity S>
class OptRemarkBase final : public Remark {
public:
  explicit OptRemarkBase(Location loc, RemarkOpts opts)
      : Remark(K, S, loc, opts) {}
};
 
using OptRemarkAnalysis =
    OptRemarkBase<RemarkKind::RemarkAnalysis, DiagnosticSeverity::Remark>;
 
using OptRemarkPass =
    OptRemarkBase<RemarkKind::RemarkPassed, DiagnosticSeverity::Remark>;
 
using OptRemarkMissed =
    OptRemarkBase<RemarkKind::RemarkMissed, DiagnosticSeverity::Remark>;
 
using OptRemarkFailure =
    OptRemarkBase<RemarkKind::RemarkFailure, DiagnosticSeverity::Remark>;
 
class RemarkEngine;
 
//===----------------------------------------------------------------------===//
// InFlightRemark
//===----------------------------------------------------------------------===//
 
/// Lazy text building for zero cost string formatting.
struct LazyTextBuild {
  llvm::StringRef key;
  std::function<std::string()> thunk;
};
 
/// InFlightRemark is a RAII class that holds a reference to a Remark
/// instance and allows to build the remark using the << operator. The remark
/// is emitted when the InFlightRemark instance is destroyed, which happens
/// when the scope ends or when the InFlightRemark instance is moved.
/// Similar to InFlightDiagnostic, but for remarks.
class InFlightRemark {
public:
  explicit InFlightRemark(std::unique_ptr<Remark> diag)
      : remark(std::move(diag)) {}
 
  InFlightRemark(RemarkEngine &eng, std::unique_ptr<Remark> diag)
      : owner(&eng), remark(std::move(diag)) {}
 
  InFlightRemark() = default; // empty ctor
 
  InFlightRemark &operator<<(const LazyTextBuild &l) {
    if (remark)
      *remark << Remark::Arg(l.key, l.thunk());
    return *this;
  }
 
  // Generic path, but *not* for Lazy
  template <typename T, typename = std::enable_if_t<
                            !std::is_same_v<std::decay_t<T>, LazyTextBuild>>>
  InFlightRemark &operator<<(T &&arg) {
    if (remark)
      *remark << std::forward<T>(arg);
    return *this;
  }
 
  explicit operator bool() const { return remark != nullptr; }
 
  ~InFlightRemark();
 
  InFlightRemark(const InFlightRemark &) = delete;
  InFlightRemark &operator=(const InFlightRemark &) = delete;
  InFlightRemark(InFlightRemark &&) = default;
  InFlightRemark &operator=(InFlightRemark &&) = default;
 
private:
  RemarkEngine *owner{nullptr};
  std::unique_ptr<Remark> remark;
};
 
//===----------------------------------------------------------------------===//
// Pluggable Remark Utilities
//===----------------------------------------------------------------------===//
 
/// Base class for MLIR remark streamers that is used to stream
/// optimization remarks to the underlying remark streamer. The derived classes
/// should implement the `streamOptimizationRemark` method to provide the
/// actual streaming implementation.
class MLIRRemarkStreamerBase {
public:
  virtual ~MLIRRemarkStreamerBase() = default;
  /// Stream an optimization remark to the underlying remark streamer. It is
  /// called by the RemarkEngine to stream the optimization remarks.
  ///
  /// It must be overridden by the derived classes to provide
  /// the actual streaming implementation.
  virtual void streamOptimizationRemark(const Remark &remark) = 0;
 
  virtual void finalize() {} // optional
};
 
using ReportFn = llvm::unique_function<void(const Remark &)>;
 
/// Base class for MLIR remark emitting policies that is used to emit
/// optimization remarks to the underlying remark streamer. The derived classes
/// should implement the `reportRemark` method to provide the actual emitting
/// implementation.
class RemarkEmittingPolicyBase {
protected:
  ReportFn reportImpl;
 
public:
  RemarkEmittingPolicyBase() = default;
  virtual ~RemarkEmittingPolicyBase() = default;
 
  void initialize(ReportFn fn) { reportImpl = std::move(fn); }
 
  virtual void reportRemark(const Remark &remark) = 0;
  virtual void finalize() = 0;
};
 
//===----------------------------------------------------------------------===//
// Remark Engine (MLIR Context will own this class)
//===----------------------------------------------------------------------===//
 
class RemarkEngine {
private:
  /// Regex that filters missed optimization remarks: only matching one are
  /// reported.
  std::optional<llvm::Regex> missFilter;
  /// The category for passed optimization remarks.
  std::optional<llvm::Regex> passedFilter;
  /// The category for analysis remarks.
  std::optional<llvm::Regex> analysisFilter;
  /// The category for failed optimization remarks.
  std::optional<llvm::Regex> failedFilter;
  /// The MLIR remark streamer that will be used to emit the remarks.
  std::unique_ptr<MLIRRemarkStreamerBase> remarkStreamer;
  /// The MLIR remark policy that will be used to emit the remarks.
  std::unique_ptr<RemarkEmittingPolicyBase> remarkEmittingPolicy;
  /// When is enabled, engine also prints remarks as mlir::emitRemarks.
  bool printAsEmitRemarks = false;
 
  /// Return true if missed optimization remarks are enabled, override
  /// to provide different implementation.
  bool isMissedOptRemarkEnabled(StringRef categoryName) const;
 
  /// Return true if passed optimization remarks are enabled, override
  /// to provide different implementation.
  bool isPassedOptRemarkEnabled(StringRef categoryName) const;
 
  /// Return true if analysis optimization remarks are enabled, override
  /// to provide different implementation.
  bool isAnalysisOptRemarkEnabled(StringRef categoryName) const;
 
  /// Return true if analysis optimization remarks are enabled, override
  /// to provide different implementation.
  bool isFailedOptRemarkEnabled(StringRef categoryName) const;
 
  /// Return true if any type of remarks are enabled for this pass.
  bool isAnyRemarkEnabled(StringRef categoryName) const {
    return isMissedOptRemarkEnabled(categoryName) ||
           isPassedOptRemarkEnabled(categoryName) ||
           isFailedOptRemarkEnabled(categoryName) ||
           isAnalysisOptRemarkEnabled(categoryName);
  }
 
  /// Emit a remark using the given maker function, which should return
  /// a Remark instance. The remark will be emitted using the main
  /// remark streamer.
  template <typename RemarkT, typename... Args>
  InFlightRemark makeRemark(Args &&...args);
 
  template <typename RemarkT>
  InFlightRemark emitIfEnabled(Location loc, RemarkOpts opts,
                               bool (RemarkEngine::*isEnabled)(StringRef)
                                   const);
  /// Report a remark.
  void reportImpl(const Remark &remark);
 
public:
  /// Default constructor is deleted, use the other constructor.
  RemarkEngine() = delete;
 
  /// Constructs Remark engine with optional category names. If a category
  /// name is not provided, it is not enabled. The category names are used to
  /// filter the remarks that are emitted.
  RemarkEngine(bool printAsEmitRemarks, const RemarkCategories &cats);
 
  /// Destructor that will close the output file and reset the
  /// main remark streamer.
  ~RemarkEngine();
 
  /// Setup the remark engine with the given output path and format.
  LogicalResult
  initialize(std::unique_ptr<MLIRRemarkStreamerBase> streamer,
             std::unique_ptr<RemarkEmittingPolicyBase> remarkEmittingPolicy,
             std::string *errMsg);
 
  /// Get the remark emitting policy.
  RemarkEmittingPolicyBase *getRemarkEmittingPolicy() const {
    return remarkEmittingPolicy.get();
  }
 
  /// Report a remark.
  void report(const Remark &&remark);
 
  /// Report a successful remark, this will create an InFlightRemark
  /// that can be used to build the remark using the << operator.
  InFlightRemark emitOptimizationRemark(Location loc, RemarkOpts opts);
 
  /// Report a missed optimization remark
  /// that can be used to build the remark using the << operator.
  InFlightRemark emitOptimizationRemarkMiss(Location loc, RemarkOpts opts);
 
  /// Report a failed optimization remark, this will create an InFlightRemark
  /// that can be used to build the remark using the << operator.
  InFlightRemark emitOptimizationRemarkFailure(Location loc, RemarkOpts opts);
 
  /// Report an analysis remark, this will create an InFlightRemark
  /// that can be used to build the remark using the << operator.
  InFlightRemark emitOptimizationRemarkAnalysis(Location loc, RemarkOpts opts);
};
 
template <typename Fn, typename... Args>
inline InFlightRemark withEngine(Fn fn, Location loc, Args &&...args) {
  MLIRContext *ctx = loc->getContext();
 
  RemarkEngine *enginePtr = ctx->getRemarkEngine();
 
  if (LLVM_UNLIKELY(enginePtr))
    return (enginePtr->*fn)(loc, std::forward<Args>(args)...);
 
  return {};
}
 
} // namespace mlir::remark::detail
 
namespace mlir::remark {
 
//===----------------------------------------------------------------------===//
// Remark Emitting Policies
//===----------------------------------------------------------------------===//
 
/// Policy that emits all remarks.
class RemarkEmittingPolicyAll : public detail::RemarkEmittingPolicyBase {
public:
  RemarkEmittingPolicyAll();
 
  void reportRemark(const detail::Remark &remark) override {
    assert(reportImpl && "reportImpl is not set");
    reportImpl(remark);
  }
  void finalize() override {}
};
 
/// Policy that emits final remarks.
class RemarkEmittingPolicyFinal : public detail::RemarkEmittingPolicyBase {
private:
  /// user can intercept them for custom processing via a registered callback,
  /// otherwise they will be reported on engine destruction.
  llvm::DenseSet<detail::Remark> postponedRemarks;
 
public:
  RemarkEmittingPolicyFinal();
 
  void reportRemark(const detail::Remark &remark) override {
    postponedRemarks.erase(remark);
    postponedRemarks.insert(remark);
  }
 
  void finalize() override {
    assert(reportImpl && "reportImpl is not set");
    for (auto &remark : postponedRemarks) {
      if (reportImpl)
        reportImpl(remark);
    }
  }
};
 
/// Create a Reason with llvm::formatv formatting.
template <class... Ts>
inline detail::LazyTextBuild reason(const char *fmt, Ts &&...ts) {
  return {"Reason", [=] { return llvm::formatv(fmt, ts...).str(); }};
}
 
/// Create a Suggestion with llvm::formatv formatting.
template <class... Ts>
inline detail::LazyTextBuild suggest(const char *fmt, Ts &&...ts) {
  return {"Suggestion", [=] { return llvm::formatv(fmt, ts...).str(); }};
}
 
/// Create a Remark with llvm::formatv formatting.
template <class... Ts>
inline detail::LazyTextBuild add(const char *fmt, Ts &&...ts) {
  return {"Remark", [=] { return llvm::formatv(fmt, ts...).str(); }};
}
 
template <class V>
inline detail::LazyTextBuild metric(StringRef key, V &&v) {
  using DV = std::decay_t<V>;
  return {key, [key, vv = DV(std::forward<V>(v))]() mutable {
            // Reuse Arg's formatting logic and return just the value string.
            return detail::Remark::Arg(key, std::move(vv)).val;
          }};
}
//===----------------------------------------------------------------------===//
// Emitters
//===----------------------------------------------------------------------===//
 
/// Report an optimization remark that was passed.
inline detail::InFlightRemark passed(Location loc, RemarkOpts opts) {
  return withEngine(&detail::RemarkEngine::emitOptimizationRemark, loc, opts);
}
 
/// Report an optimization remark that was missed.
inline detail::InFlightRemark missed(Location loc, RemarkOpts opts) {
  return withEngine(&detail::RemarkEngine::emitOptimizationRemarkMiss, loc,
                    opts);
}
 
/// Report an optimization remark that failed.
inline detail::InFlightRemark failed(Location loc, RemarkOpts opts) {
  return withEngine(&detail::RemarkEngine::emitOptimizationRemarkFailure, loc,
                    opts);
}
 
/// Report an optimization analysis remark.
inline detail::InFlightRemark analysis(Location loc, RemarkOpts opts) {
  return withEngine(&detail::RemarkEngine::emitOptimizationRemarkAnalysis, loc,
                    opts);
}
 
//===----------------------------------------------------------------------===//
// Setup
//===----------------------------------------------------------------------===//
 
/// Setup remarks for the context. This function will enable the remark engine
/// and set the streamer to be used for optimization remarks. The remark
/// categories are used to filter the remarks that will be emitted by the
/// remark engine. If a category is not specified, it will not be emitted. If
/// `printAsEmitRemarks` is true, the remarks will be printed as
/// mlir::emitRemarks. 'streamer' must inherit from MLIRRemarkStreamerBase and
/// will be used to stream the remarks.
LogicalResult enableOptimizationRemarks(
    MLIRContext &ctx,
    std::unique_ptr<remark::detail::MLIRRemarkStreamerBase> streamer,
    std::unique_ptr<remark::detail::RemarkEmittingPolicyBase>
        remarkEmittingPolicy,
    const remark::RemarkCategories &cats, bool printAsEmitRemarks = false);
 
} // namespace mlir::remark
 
// DenseMapInfo specialization for Remark
namespace llvm {
template <>
struct DenseMapInfo<mlir::remark::detail::Remark> {
  static constexpr StringRef kEmptyKey = "<EMPTY_KEY>";
  static constexpr StringRef kTombstoneKey = "<TOMBSTONE_KEY>";
 
  /// Helper to provide a static dummy context for sentinel keys.
  static mlir::MLIRContext *getStaticDummyContext() {
    static mlir::MLIRContext dummyContext;
    return &dummyContext;
  }
 
  /// Create an empty remark
  static inline mlir::remark::detail::Remark getEmptyKey() {
    return mlir::remark::detail::Remark(
        mlir::remark::RemarkKind::RemarkUnknown, mlir::DiagnosticSeverity::Note,
        mlir::UnknownLoc::get(getStaticDummyContext()),
        mlir::remark::RemarkOpts::name(kEmptyKey));
  }
 
  /// Create a dead remark
  static inline mlir::remark::detail::Remark getTombstoneKey() {
    return mlir::remark::detail::Remark(
        mlir::remark::RemarkKind::RemarkUnknown, mlir::DiagnosticSeverity::Note,
        mlir::UnknownLoc::get(getStaticDummyContext()),
        mlir::remark::RemarkOpts::name(kTombstoneKey));
  }
 
  /// Compute the hash value of the remark
  static unsigned getHashValue(const mlir::remark::detail::Remark &remark) {
    return llvm::hash_combine(
        remark.getLocation().getAsOpaquePointer(),
        llvm::hash_value(remark.getRemarkName()),
        llvm::hash_value(remark.getCombinedCategoryName()));
  }
 
  static bool isEqual(const mlir::remark::detail::Remark &lhs,
                      const mlir::remark::detail::Remark &rhs) {
    // Check for empty/tombstone keys first
    if (lhs.getRemarkName() == kEmptyKey ||
        lhs.getRemarkName() == kTombstoneKey ||
        rhs.getRemarkName() == kEmptyKey ||
        rhs.getRemarkName() == kTombstoneKey) {
      return lhs.getRemarkName() == rhs.getRemarkName();
    }
 
    // For regular remarks, compare key identifying fields
    return lhs.getLocation() == rhs.getLocation() &&
           lhs.getRemarkName() == rhs.getRemarkName() &&
           lhs.getCombinedCategoryName() == rhs.getCombinedCategoryName();
  }
};
} // namespace llvm
#endif // MLIR_IR_REMARKS_H