[GlobalISel] Add a MachineIRBuilder class.

Helper class to build machine instrs. This is a higher abstraction
than MachineInstrBuilder.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@260547 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h

@@ -0,0 +1,97 @@
+//===-- llvm/CodeGen/GlobalISel/MachineIRBuilder.h - MIBuilder --*- 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 declares the MachineIRBuilder class.
+/// This is a helper class to build MachineInstr.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_GLOBALISEL_MACHINEIRBUILDER_H
+#define LLVM_CODEGEN_GLOBALISEL_MACHINEIRBUILDER_H
+
+#include "llvm/CodeGen/GlobalISel/Types.h"
+
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/IR/DebugLoc.h"
+
+namespace llvm {
+
+// Forward declarations.
+class MachineFunction;
+class MachineInstr;
+class TargetInstrInfo;
+
+/// Helper class to build MachineInstr.
+/// It keeps internally the insertion point and debug location for all
+/// the new instructions we want to create.
+/// This information can be modify via the related setters.
+class MachineIRBuilder {
+  /// MachineFunction under construction.
+  MachineFunction *MF;
+  /// Information used to access the description of the opcodes.
+  const TargetInstrInfo *TII;
+  /// Debug location to be set to any instruction we create.
+  DebugLoc DL;
+
+  /// Fields describing the insertion point.
+  /// @{
+  MachineBasicBlock *MBB;
+  MachineInstr *MI;
+  bool Before;
+  /// @}
+
+  MachineBasicBlock &getMBB() {
+    assert(MBB && "MachineBasicBlock is not set");
+    return *MBB;
+  }
+
+  const TargetInstrInfo &getTII() {
+    assert(TII && "TargetInstrInfo is not set");
+    return *TII;
+  }
+
+  /// Current insertion point for new instructions.
+  MachineBasicBlock::iterator getInsertPt();
+
+public:
+  /// Getter for the function we currently build.
+  MachineFunction &getMF() {
+    assert(MF && "MachineFunction is not set");
+    return *MF;
+  }
+
+  /// Setters for the insertion point.
+  /// @{
+  /// Set MachineFunction where to build instructions.
+  void setFunction(MachineFunction &);
+
+  /// Set the insertion point to the beginning (\p Beginning = true) or end
+  /// (\p Beginning = false) of \p MBB.
+  /// \pre \p MBB must be contained by getMF().
+  void setBasicBlock(MachineBasicBlock &MBB, bool Beginning = false);
+
+  /// Set the insertion point to before (\p Before = true) or after
+  /// (\p Before = false) \p MI.
+  /// \pre MI must be in getMF().
+  void setInstr(MachineInstr &MI, bool Before = false);
+  /// @}
+
+  /// Set the debug location to \p DL for all the next build instructions.
+  void setDebugLoc(const DebugLoc &DL) { this->DL = DL; }
+
+  /// Build and insert \p Res<def> = \p Opcode \p Op0, \p Op1.
+  ///
+  /// \pre setBasicBlock or setMI must have been called.
+  ///
+  /// \return The newly created instruction.
+  MachineInstr *buildInstr(unsigned Opcode, unsigned Res, unsigned Op0,
+                           unsigned Op1);
+};
+
+} // End namespace llvm.
+#endif // LLVM_CODEGEN_GLOBALISEL_MACHINEIRBUILDER_H

lib/CodeGen/GlobalISel/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_llvm_library(LLVMGlobalISel
         IRTranslator.cpp
+        MachineIRBuilder.cpp
   )
 
 add_dependencies(LLVMGlobalISel intrinsics_gen)

lib/CodeGen/GlobalISel/MachineIRBuilder.cpp

@@ -0,0 +1,61 @@
+//===-- llvm/CodeGen/GlobalISel/MachineIRBuilder.cpp - MIBuilder--*- 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 implements the MachineIRBuidler class.
+//===----------------------------------------------------------------------===//
+#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
+
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+
+using namespace llvm;
+
+void MachineIRBuilder::setFunction(MachineFunction &MF) {
+  this->MF = &MF;
+  this->MBB = nullptr;
+  this->TII = MF.getSubtarget().getInstrInfo();
+  this->DL = DebugLoc();
+  this->MI = nullptr;
+}
+
+void MachineIRBuilder::setBasicBlock(MachineBasicBlock &MBB, bool Beginning) {
+  this->MBB = &MBB;
+  Before = Beginning;
+  assert(&getMF() == MBB.getParent() &&
+         "Basic block is in a different function");
+}
+
+void MachineIRBuilder::setInstr(MachineInstr &MI, bool Before) {
+  assert(MI.getParent() && "Instruction is not part of a basic block");
+  setBasicBlock(*MI.getParent());
+  this->MI = &MI;
+  this->Before = Before;
+}
+
+MachineBasicBlock::iterator MachineIRBuilder::getInsertPt() {
+  if (MI) {
+    if (Before)
+      return MI;
+    if (!MI->getNextNode())
+      return getMBB().end();
+    return MI->getNextNode();
+  }
+  return Before ? getMBB().begin() : getMBB().end();
+}
+
+MachineInstr *MachineIRBuilder::buildInstr(unsigned Opcode, unsigned Res,
+                                           unsigned Op0, unsigned Op1) {
+  MachineInstr *NewMI =
+      BuildMI(getMF(), DL, getTII().get(Opcode), Res).addReg(Op0).addReg(Op1);
+  getMBB().insert(getInsertPt(), NewMI);
+  return NewMI;
+}