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diff --git a/include/llvm/CodeGen/GlobalISel/Localizer.h b/include/llvm/CodeGen/GlobalISel/Localizer.h
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+++ b/include/llvm/CodeGen/GlobalISel/Localizer.h
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+//== llvm/CodeGen/GlobalISel/Localizer.h - Localizer -------------*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file This file describes the interface of the Localizer pass.
+/// This pass moves/duplicates constant-like instructions close to their uses.
+/// Its primarily goal is to workaround the deficiencies of the fast register
+/// allocator.
+/// With GlobalISel constants are all materialized in the entry block of
+/// a function. However, the fast allocator cannot rematerialize constants and
+/// has a lot more live-ranges to deal with and will most likely end up
+/// spilling a lot.
+/// By pushing the constants close to their use, we only create small
+/// live-ranges.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_GLOBALISEL_LOCALIZER_H
+#define LLVM_CODEGEN_GLOBALISEL_LOCALIZER_H
+
+#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+
+namespace llvm {
+// Forward declarations.
+class MachineRegisterInfo;
+
+/// This pass implements the localization mechanism described at the
+/// top of this file. One specificity of the implementation is that
+/// it will materialize one and only one instance of a constant per
+/// basic block, thus enabling reuse of that constant within that block.
+/// Moreover, it only materializes constants in blocks where they
+/// are used. PHI uses are considered happening at the end of the
+/// related predecessor.
+class Localizer : public MachineFunctionPass {
+public:
+  static char ID;
+
+private:
+  /// MRI contains all the register class/bank information that this
+  /// pass uses and updates.
+  MachineRegisterInfo *MRI;
+
+  /// Check whether or not \p MI needs to be moved close to its uses.
+  static bool shouldLocalize(const MachineInstr &MI);
+
+  /// Check if \p MOUse is used in the same basic block as \p Def.
+  /// If the use is in the same block, we say it is local.
+  /// When the use is not local, \p InsertMBB will contain the basic
+  /// block when to insert \p Def to have a local use.
+  static bool isLocalUse(MachineOperand &MOUse, const MachineInstr &Def,
+                         MachineBasicBlock *&InsertMBB);
+
+  /// Initialize the field members using \p MF.
+  void init(MachineFunction &MF);
+
+public:
+  Localizer();
+
+  StringRef getPassName() const override { return "Localizer"; }
+
+  MachineFunctionProperties getRequiredProperties() const override {
+    return MachineFunctionProperties()
+        .set(MachineFunctionProperties::Property::IsSSA)
+        .set(MachineFunctionProperties::Property::Legalized)
+        .set(MachineFunctionProperties::Property::RegBankSelected);
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+};
+
+} // End namespace llvm.
+
+#endif