Clean up JNI calling convention callee saves.

Precalculate callee saves at compile time and return them
as ArrayRef<> instead of keeping then in a std::vector<>.

Change-Id: I4fd7d2bbf6138dc31b0fe8554eac35b0777ec9ef
diff --git a/compiler/utils/mips/assembler_mips.cc b/compiler/utils/mips/assembler_mips.cc
index a1798c0..9368301 100644
--- a/compiler/utils/mips/assembler_mips.cc
+++ b/compiler/utils/mips/assembler_mips.cc
@@ -2438,8 +2438,9 @@
 
 constexpr size_t kFramePointerSize = 4;
 
-void MipsAssembler::BuildFrame(size_t frame_size, ManagedRegister method_reg,
-                               const std::vector<ManagedRegister>& callee_save_regs,
+void MipsAssembler::BuildFrame(size_t frame_size,
+                               ManagedRegister method_reg,
+                               ArrayRef<const ManagedRegister> callee_save_regs,
                                const ManagedRegisterEntrySpills& entry_spills) {
   CHECK_ALIGNED(frame_size, kStackAlignment);
   DCHECK(!overwriting_);
@@ -2453,7 +2454,7 @@
   cfi_.RelOffset(DWARFReg(RA), stack_offset);
   for (int i = callee_save_regs.size() - 1; i >= 0; --i) {
     stack_offset -= kFramePointerSize;
-    Register reg = callee_save_regs.at(i).AsMips().AsCoreRegister();
+    Register reg = callee_save_regs[i].AsMips().AsCoreRegister();
     StoreToOffset(kStoreWord, reg, SP, stack_offset);
     cfi_.RelOffset(DWARFReg(reg), stack_offset);
   }
@@ -2482,7 +2483,7 @@
 }
 
 void MipsAssembler::RemoveFrame(size_t frame_size,
-                                const std::vector<ManagedRegister>& callee_save_regs) {
+                                ArrayRef<const ManagedRegister> callee_save_regs) {
   CHECK_ALIGNED(frame_size, kStackAlignment);
   DCHECK(!overwriting_);
   cfi_.RememberState();
@@ -2490,7 +2491,7 @@
   // Pop callee saves and return address.
   int stack_offset = frame_size - (callee_save_regs.size() * kFramePointerSize) - kFramePointerSize;
   for (size_t i = 0; i < callee_save_regs.size(); ++i) {
-    Register reg = callee_save_regs.at(i).AsMips().AsCoreRegister();
+    Register reg = callee_save_regs[i].AsMips().AsCoreRegister();
     LoadFromOffset(kLoadWord, reg, SP, stack_offset);
     cfi_.Restore(DWARFReg(reg));
     stack_offset += kFramePointerSize;
diff --git a/compiler/utils/mips/assembler_mips.h b/compiler/utils/mips/assembler_mips.h
index ecb67bd..d5e6285 100644
--- a/compiler/utils/mips/assembler_mips.h
+++ b/compiler/utils/mips/assembler_mips.h
@@ -414,11 +414,11 @@
   // Emit code that will create an activation on the stack.
   void BuildFrame(size_t frame_size,
                   ManagedRegister method_reg,
-                  const std::vector<ManagedRegister>& callee_save_regs,
+                  ArrayRef<const ManagedRegister> callee_save_regs,
                   const ManagedRegisterEntrySpills& entry_spills) OVERRIDE;
 
   // Emit code that will remove an activation from the stack.
-  void RemoveFrame(size_t frame_size, const std::vector<ManagedRegister>& callee_save_regs)
+  void RemoveFrame(size_t frame_size, ArrayRef<const ManagedRegister> callee_save_regs)
       OVERRIDE;
 
   void IncreaseFrameSize(size_t adjust) OVERRIDE;
diff --git a/compiler/utils/mips/managed_register_mips.h b/compiler/utils/mips/managed_register_mips.h
index 5e7ed11..66204e7 100644
--- a/compiler/utils/mips/managed_register_mips.h
+++ b/compiler/utils/mips/managed_register_mips.h
@@ -87,70 +87,70 @@
 // There is a one-to-one mapping between ManagedRegister and register id.
 class MipsManagedRegister : public ManagedRegister {
  public:
-  Register AsCoreRegister() const {
+  constexpr Register AsCoreRegister() const {
     CHECK(IsCoreRegister());
     return static_cast<Register>(id_);
   }
 
-  FRegister AsFRegister() const {
+  constexpr FRegister AsFRegister() const {
     CHECK(IsFRegister());
     return static_cast<FRegister>(id_ - kNumberOfCoreRegIds);
   }
 
-  DRegister AsDRegister() const {
+  constexpr DRegister AsDRegister() const {
     CHECK(IsDRegister());
     return static_cast<DRegister>(id_ - kNumberOfCoreRegIds - kNumberOfFRegIds);
   }
 
-  FRegister AsOverlappingDRegisterLow() const {
+  constexpr FRegister AsOverlappingDRegisterLow() const {
     CHECK(IsOverlappingDRegister());
     DRegister d_reg = AsDRegister();
     return static_cast<FRegister>(d_reg * 2);
   }
 
-  FRegister AsOverlappingDRegisterHigh() const {
+  constexpr FRegister AsOverlappingDRegisterHigh() const {
     CHECK(IsOverlappingDRegister());
     DRegister d_reg = AsDRegister();
     return static_cast<FRegister>(d_reg * 2 + 1);
   }
 
-  Register AsRegisterPairLow() const {
+  constexpr Register AsRegisterPairLow() const {
     CHECK(IsRegisterPair());
     // Appropriate mapping of register ids allows to use AllocIdLow().
     return FromRegId(AllocIdLow()).AsCoreRegister();
   }
 
-  Register AsRegisterPairHigh() const {
+  constexpr Register AsRegisterPairHigh() const {
     CHECK(IsRegisterPair());
     // Appropriate mapping of register ids allows to use AllocIdHigh().
     return FromRegId(AllocIdHigh()).AsCoreRegister();
   }
 
-  bool IsCoreRegister() const {
+  constexpr bool IsCoreRegister() const {
     CHECK(IsValidManagedRegister());
     return (0 <= id_) && (id_ < kNumberOfCoreRegIds);
   }
 
-  bool IsFRegister() const {
+  constexpr bool IsFRegister() const {
     CHECK(IsValidManagedRegister());
     const int test = id_ - kNumberOfCoreRegIds;
     return (0 <= test) && (test < kNumberOfFRegIds);
   }
 
-  bool IsDRegister() const {
+  constexpr bool IsDRegister() const {
     CHECK(IsValidManagedRegister());
     const int test = id_ - (kNumberOfCoreRegIds + kNumberOfFRegIds);
     return (0 <= test) && (test < kNumberOfDRegIds);
   }
 
   // Returns true if this DRegister overlaps FRegisters.
-  bool IsOverlappingDRegister() const {
+  constexpr bool IsOverlappingDRegister() const {
     CHECK(IsValidManagedRegister());
     const int test = id_ - (kNumberOfCoreRegIds + kNumberOfFRegIds);
     return (0 <= test) && (test < kNumberOfOverlappingDRegIds);
   }
 
-  bool IsRegisterPair() const {
+  constexpr bool IsRegisterPair() const {
     CHECK(IsValidManagedRegister());
     const int test =
         id_ - (kNumberOfCoreRegIds + kNumberOfFRegIds + kNumberOfDRegIds);
@@ -164,32 +164,32 @@
   // then false is returned.
   bool Overlaps(const MipsManagedRegister& other) const;
 
-  static MipsManagedRegister FromCoreRegister(Register r) {
+  static constexpr MipsManagedRegister FromCoreRegister(Register r) {
     CHECK_NE(r, kNoRegister);
     return FromRegId(r);
   }
 
-  static MipsManagedRegister FromFRegister(FRegister r) {
+  static constexpr MipsManagedRegister FromFRegister(FRegister r) {
     CHECK_NE(r, kNoFRegister);
     return FromRegId(r + kNumberOfCoreRegIds);
   }
 
-  static MipsManagedRegister FromDRegister(DRegister r) {
+  static constexpr MipsManagedRegister FromDRegister(DRegister r) {
     CHECK_NE(r, kNoDRegister);
     return FromRegId(r + kNumberOfCoreRegIds + kNumberOfFRegIds);
   }
 
-  static MipsManagedRegister FromRegisterPair(RegisterPair r) {
+  static constexpr MipsManagedRegister FromRegisterPair(RegisterPair r) {
     CHECK_NE(r, kNoRegisterPair);
     return FromRegId(r + (kNumberOfCoreRegIds + kNumberOfFRegIds + kNumberOfDRegIds));
   }
 
  private:
-  bool IsValidManagedRegister() const {
+  constexpr bool IsValidManagedRegister() const {
     return (0 <= id_) && (id_ < kNumberOfRegIds);
   }
 
-  int RegId() const {
+  constexpr int RegId() const {
     CHECK(!IsNoRegister());
     return id_;
   }
@@ -205,9 +205,9 @@
 
   friend class ManagedRegister;
 
-  explicit MipsManagedRegister(int reg_id) : ManagedRegister(reg_id) {}
+  explicit constexpr MipsManagedRegister(int reg_id) : ManagedRegister(reg_id) {}
 
-  static MipsManagedRegister FromRegId(int reg_id) {
+  static constexpr MipsManagedRegister FromRegId(int reg_id) {
     MipsManagedRegister reg(reg_id);
     CHECK(reg.IsValidManagedRegister());
     return reg;
@@ -218,7 +218,7 @@
 
 }  // namespace mips
 
-inline mips::MipsManagedRegister ManagedRegister::AsMips() const {
+constexpr inline mips::MipsManagedRegister ManagedRegister::AsMips() const {
   mips::MipsManagedRegister reg(id_);
   CHECK(reg.IsNoRegister() || reg.IsValidManagedRegister());
   return reg;