First patch for Mips subzero compiler

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4167

Move issue https://codereview.chromium.org/1159823004/ here so that
it's under the proper email.

Review URL: https://codereview.chromium.org/1169533003

src/IceTargetLoweringMIPS32.h

diff --git a/src/IceTargetLoweringMIPS32.h b/src/IceTargetLoweringMIPS32.h
new file mode 100644
index 0000000..cb583b5
--- /dev/null
+++ b/src/IceTargetLoweringMIPS32.h
@@ -0,0 +1,149 @@
+//===- subzero/src/IceTargetLoweringMIPS32.h - MIPS32 lowering ---*- C++-*-===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the TargetLoweringMIPS32 class, which implements the
+// TargetLowering interface for the MIPS 32-bit architecture.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H
+#define SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H
+
+#include "IceDefs.h"
+#include "IceInstMIPS32.h"
+#include "IceRegistersMIPS32.h"
+#include "IceTargetLowering.h"
+
+namespace Ice {
+
+class TargetMIPS32 : public TargetLowering {
+  TargetMIPS32() = delete;
+  TargetMIPS32(const TargetMIPS32 &) = delete;
+  TargetMIPS32 &operator=(const TargetMIPS32 &) = delete;
+
+public:
+  // TODO(jvoung): return a unique_ptr.
+  static TargetMIPS32 *create(Cfg *Func) { return new TargetMIPS32(Func); }
+
+  void translateOm1() override;
+  void translateO2() override;
+  bool doBranchOpt(Inst *I, const CfgNode *NextNode) override;
+
+  SizeT getNumRegisters() const override { return RegMIPS32::Reg_NUM; }
+  Variable *getPhysicalRegister(SizeT RegNum, Type Ty = IceType_void) override;
+  IceString getRegName(SizeT RegNum, Type Ty) const override;
+  llvm::SmallBitVector getRegisterSet(RegSetMask Include,
+                                      RegSetMask Exclude) const override;
+  const llvm::SmallBitVector &getRegisterSetForType(Type Ty) const override {
+    return TypeToRegisterSet[Ty];
+  }
+  bool hasFramePointer() const override { return UsesFramePointer; }
+  SizeT getFrameOrStackReg() const override {
+    return UsesFramePointer ? RegMIPS32::Reg_FP : RegMIPS32::Reg_SP;
+  }
+  size_t typeWidthInBytesOnStack(Type Ty) const override {
+    // Round up to the next multiple of 4 bytes.  In particular, i1,
+    // i8, and i16 are rounded up to 4 bytes.
+    return (typeWidthInBytes(Ty) + 3) & ~3;
+  }
+  void emitVariable(const Variable *Var) const override;
+
+  const char *getConstantPrefix() const final { return ""; }
+  void emit(const ConstantUndef *C) const final {
+    llvm::report_fatal_error("Not yet implemented");
+  }
+  void emit(const ConstantInteger32 *C) const final {
+    llvm::report_fatal_error("Not yet implemented");
+  }
+  void emit(const ConstantInteger64 *C) const final {
+    llvm::report_fatal_error("Not yet implemented");
+  }
+  void emit(const ConstantFloat *C) const final {
+    llvm::report_fatal_error("Not yet implemented");
+  }
+  void emit(const ConstantDouble *C) const final {
+    llvm::report_fatal_error("Not yet implemented");
+  }
+
+  void lowerArguments() override;
+  void addProlog(CfgNode *Node) override;
+  void addEpilog(CfgNode *Node) override;
+
+protected:
+  explicit TargetMIPS32(Cfg *Func);
+
+  void postLower() override;
+
+  void lowerAlloca(const InstAlloca *Inst) override;
+  void lowerArithmetic(const InstArithmetic *Inst) override;
+  void lowerAssign(const InstAssign *Inst) override;
+  void lowerBr(const InstBr *Inst) override;
+  void lowerCall(const InstCall *Inst) override;
+  void lowerCast(const InstCast *Inst) override;
+  void lowerExtractElement(const InstExtractElement *Inst) override;
+  void lowerFcmp(const InstFcmp *Inst) override;
+  void lowerIcmp(const InstIcmp *Inst) override;
+  void lowerIntrinsicCall(const InstIntrinsicCall *Inst) override;
+  void lowerInsertElement(const InstInsertElement *Inst) override;
+  void lowerLoad(const InstLoad *Inst) override;
+  void lowerPhi(const InstPhi *Inst) override;
+  void lowerRet(const InstRet *Inst) override;
+  void lowerSelect(const InstSelect *Inst) override;
+  void lowerStore(const InstStore *Inst) override;
+  void lowerSwitch(const InstSwitch *Inst) override;
+  void lowerUnreachable(const InstUnreachable *Inst) override;
+  void prelowerPhis() override;
+  void lowerPhiAssignments(CfgNode *Node,
+                           const AssignList &Assignments) override;
+  void doAddressOptLoad() override;
+  void doAddressOptStore() override;
+  void randomlyInsertNop(float Probability) override;
+  void makeRandomRegisterPermutation(
+      llvm::SmallVectorImpl<int32_t> &Permutation,
+      const llvm::SmallBitVector &ExcludeRegisters) const override;
+
+  static Type stackSlotType();
+
+  bool UsesFramePointer;
+  bool NeedsStackAlignment;
+  llvm::SmallBitVector TypeToRegisterSet[IceType_NUM];
+  llvm::SmallBitVector ScratchRegs;
+  llvm::SmallBitVector RegsUsed;
+  VarList PhysicalRegisters[IceType_NUM];
+  static IceString RegNames[];
+
+private:
+  ~TargetMIPS32() override {}
+};
+
+class TargetDataMIPS32 : public TargetDataLowering {
+  TargetDataMIPS32() = delete;
+  TargetDataMIPS32(const TargetDataMIPS32 &) = delete;
+  TargetDataMIPS32 &operator=(const TargetDataMIPS32 &) = delete;
+
+public:
+  static TargetDataLowering *create(GlobalContext *Ctx) {
+    return new TargetDataMIPS32(Ctx);
+  }
+
+  void lowerGlobals(std::unique_ptr<VariableDeclarationList> Vars) const final;
+  void lowerConstants() const final;
+
+protected:
+  explicit TargetDataMIPS32(GlobalContext *Ctx);
+
+private:
+  void lowerGlobal(const VariableDeclaration &Var) const;
+  ~TargetDataMIPS32() override {}
+  template <typename T> static void emitConstantPool(GlobalContext *Ctx);
+};
+
+} // end of namespace Ice
+
+#endif // SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H