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diff --git a/llvm/utils/TableGen/Common/GlobalISel/PatternParser.h b/llvm/utils/TableGen/Common/GlobalISel/PatternParser.h
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+++ b/llvm/utils/TableGen/Common/GlobalISel/PatternParser.h
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+//===- PatternParser.h ------------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file Contains tools to parse MIR patterns from TableGen DAG elements.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_UTILS_GLOBALISEL_PATTERNPARSER_H
+#define LLVM_UTILS_GLOBALISEL_PATTERNPARSER_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/STLFunctionalExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Support/SMLoc.h"
+#include <memory>
+
+namespace llvm {
+class CodeGenTarget;
+class DagInit;
+class Init;
+class Record;
+class StringRef;
+class StringInit;
+
+namespace gi {
+class InstructionPattern;
+class Pattern;
+class PatFrag;
+
+/// Helper class to parse MIR Pattern lists.
+///
+/// e.g., `(match (G_FADD $x, $y, $z), (G_FNEG $y, $z))`
+class PatternParser {
+  const CodeGenTarget &CGT;
+  ArrayRef<SMLoc> DiagLoc;
+
+  mutable SmallPtrSet<const PatFrag *, 2> SeenPatFrags;
+
+public:
+  PatternParser(const CodeGenTarget &CGT, ArrayRef<SMLoc> DiagLoc)
+      : CGT(CGT), DiagLoc(DiagLoc) {}
+
+  /// Parses a list of patterns such as:
+  ///   (Operator (Pattern1 ...), (Pattern2 ...))
+  /// \param List         DagInit of the expected pattern list.
+  /// \param ParseAction  Callback to handle a succesfully parsed pattern.
+  /// \param Operator     The name of the operator, e.g. "match"
+  /// \param AnonPatNamePrefix Prefix for anonymous pattern names.
+  /// \return true on success, false on failure.
+  bool
+  parsePatternList(const DagInit &List,
+                   function_ref<bool(std::unique_ptr<Pattern>)> ParseAction,
+                   StringRef Operator, StringRef AnonPatNamePrefix);
+
+  /// \returns all PatFrags encountered by this PatternParser.
+  const auto &getSeenPatFrags() const { return SeenPatFrags; }
+
+private:
+  /// Parse any InstructionPattern from a TableGen Init.
+  /// \param Arg Init to parse.
+  /// \param PatName Name of the pattern that will be parsed.
+  /// \return the parsed pattern on success, nullptr on failure.
+  std::unique_ptr<Pattern> parseInstructionPattern(const Init &Arg,
+                                                   StringRef PatName);
+
+  /// Parse a WipOpcodeMatcher from a TableGen Init.
+  /// \param Arg Init to parse.
+  /// \param PatName Name of the pattern that will be parsed.
+  /// \return the parsed pattern on success, nullptr on failure.
+  std::unique_ptr<Pattern> parseWipMatchOpcodeMatcher(const Init &Arg,
+                                                      StringRef PatName);
+
+  /// Parses an Operand of an InstructionPattern from a TableGen Init.
+  /// \param IP InstructionPattern for which we're parsing.
+  /// \param OpInit Init to parse.
+  /// \param OpName Name of the operand to parse.
+  /// \return true on success, false on failure.
+  bool parseInstructionPatternOperand(InstructionPattern &IP,
+                                      const Init *OpInit,
+                                      const StringInit *OpName);
+
+  /// Parses a MIFlag for an InstructionPattern from a TableGen Init.
+  /// \param IP InstructionPattern for which we're parsing.
+  /// \param Op Init to parse.
+  /// \return true on success, false on failure.
+  bool parseInstructionPatternMIFlags(InstructionPattern &IP,
+                                      const DagInit *Op);
+
+  /// (Uncached) PatFrag parsing implementation.
+  /// \param Def PatFrag def to parsee.
+  /// \return the parsed PatFrag on success, nullptr on failure.
+  std::unique_ptr<PatFrag> parsePatFragImpl(const Record *Def);
+
+  /// Parses the in or out parameter list of a PatFrag.
+  /// \param OpsList Init to parse.
+  /// \param ParseAction Callback on successful parse, with the name of
+  ///                     the parameter and its \ref PatFrag::ParamKind
+  /// \return true on success, false on failure.
+  bool
+  parsePatFragParamList(const DagInit &OpsList,
+                        function_ref<bool(StringRef, unsigned)> ParseAction);
+
+  /// Cached PatFrag parser. This avoids duplicate work by keeping track of
+  /// already-parsed PatFrags.
+  /// \param Def PatFrag def to parsee.
+  /// \return the parsed PatFrag on success, nullptr on failure.
+  const PatFrag *parsePatFrag(const Record *Def);
+};
+
+} // namespace gi
+} // namespace llvm
+
+#endif