Do away with variable length memcpy to Set/Get registers in simulator

About a 32% boost.

Before - 5:31

Richards: 84.5
DeltaBlue: 128
Crypto: 65.3
RayTrace: 203
EarleyBoyer: 149
RegExp: 23.4
Splay: 121
NavierStokes: 98.9
----
Score (version 7): 93.8

After - 4:10

Richards: 107
DeltaBlue: 175
Crypto: 93.9
RayTrace: 258
EarleyBoyer: 186
RegExp: 32.7
Splay: 165
NavierStokes: 124
----
Score (version 7): 124

R=jacob.bramley@arm.com, svenpanne@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=21448

Review URL: https://codereview.chromium.org/213943002

Patch from Fritz Koenig <frkoenig@google.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21804 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm64/simulator-arm64.h

@@ -133,35 +133,28 @@ class SimSystemRegister {
 
 
 // Represent a register (r0-r31, v0-v31).
-template<int kSizeInBytes>
 class SimRegisterBase {
  public:
   template<typename T>
-  void Set(T new_value, unsigned size = sizeof(T)) {
-    ASSERT(size <= kSizeInBytes);
-    ASSERT(size <= sizeof(new_value));
-    // All AArch64 registers are zero-extending; Writing a W register clears the
-    // top bits of the corresponding X register.
-    memset(value_, 0, kSizeInBytes);
-    memcpy(value_, &new_value, size);
+  void Set(T new_value) {
+    value_ = 0;
+    memcpy(&value_, &new_value, sizeof(T));
   }
 
-  // Copy 'size' bytes of the register to the result, and zero-extend to fill
-  // the result.
   template<typename T>
-  T Get(unsigned size = sizeof(T)) const {
-    ASSERT(size <= kSizeInBytes);
+  T Get() const {
     T result;
-    memset(&result, 0, sizeof(result));
-    memcpy(&result, value_, size);
+    memcpy(&result, &value_, sizeof(T));
     return result;
   }
 
  protected:
-  uint8_t value_[kSizeInBytes];
+  int64_t value_;
 };
-typedef SimRegisterBase<kXRegSize> SimRegister;      // r0-r31
-typedef SimRegisterBase<kDRegSize> SimFPRegister;    // v0-v31
+
+
+typedef SimRegisterBase SimRegister;      // r0-r31
+typedef SimRegisterBase SimFPRegister;    // v0-v31
 
 
 class Simulator : public DecoderVisitor {
@@ -328,86 +321,53 @@ class Simulator : public DecoderVisitor {
   VISITOR_LIST(DECLARE)
   #undef DECLARE
 
-  // Register accessors.
+  bool IsZeroRegister(unsigned code, Reg31Mode r31mode) const {
+    return ((code == 31) && (r31mode == Reg31IsZeroRegister));
+  }
 
+  // Register accessors.
   // Return 'size' bits of the value of an integer register, as the specified
   // type. The value is zero-extended to fill the result.
   //
-  // The only supported values of 'size' are kXRegSizeInBits and
-  // kWRegSizeInBits.
   template<typename T>
-  T reg(unsigned size, unsigned code,
-        Reg31Mode r31mode = Reg31IsZeroRegister) const {
-    unsigned size_in_bytes = size / 8;
-    ASSERT(size_in_bytes <= sizeof(T));
-    ASSERT((size == kXRegSizeInBits) || (size == kWRegSizeInBits));
+  T reg(unsigned code, Reg31Mode r31mode = Reg31IsZeroRegister) const {
     ASSERT(code < kNumberOfRegisters);
-
-    if ((code == 31) && (r31mode == Reg31IsZeroRegister)) {
-      T result;
-      memset(&result, 0, sizeof(result));
-      return result;
+    if (IsZeroRegister(code, r31mode)) {
+      return 0;
     }
-    return registers_[code].Get<T>(size_in_bytes);
-  }
-
-  // Like reg(), but infer the access size from the template type.
-  template<typename T>
-  T reg(unsigned code, Reg31Mode r31mode = Reg31IsZeroRegister) const {
-    return reg<T>(sizeof(T) * 8, code, r31mode);
+    return registers_[code].Get<T>();
   }
 
   // Common specialized accessors for the reg() template.
-  int32_t wreg(unsigned code,
-               Reg31Mode r31mode = Reg31IsZeroRegister) const {
+  int32_t wreg(unsigned code, Reg31Mode r31mode = Reg31IsZeroRegister) const {
     return reg<int32_t>(code, r31mode);
   }
 
-  int64_t xreg(unsigned code,
-               Reg31Mode r31mode = Reg31IsZeroRegister) const {
+  int64_t xreg(unsigned code, Reg31Mode r31mode = Reg31IsZeroRegister) const {
     return reg<int64_t>(code, r31mode);
   }
 
-  int64_t reg(unsigned size, unsigned code,
-              Reg31Mode r31mode = Reg31IsZeroRegister) const {
-    return reg<int64_t>(size, code, r31mode);
-  }
-
   // Write 'size' bits of 'value' into an integer register. The value is
   // zero-extended. This behaviour matches AArch64 register writes.
-  //
-  // The only supported values of 'size' are kXRegSizeInBits and
-  // kWRegSizeInBits.
-  template<typename T>
-  void set_reg(unsigned size, unsigned code, T value,
-               Reg31Mode r31mode = Reg31IsZeroRegister) {
-    unsigned size_in_bytes = size / 8;
-    ASSERT(size_in_bytes <= sizeof(T));
-    ASSERT((size == kXRegSizeInBits) || (size == kWRegSizeInBits));
-    ASSERT(code < kNumberOfRegisters);
-
-    if ((code == 31) && (r31mode == Reg31IsZeroRegister)) {
-      return;
-    }
-    return registers_[code].Set(value, size_in_bytes);
-  }
 
   // Like set_reg(), but infer the access size from the template type.
   template<typename T>
   void set_reg(unsigned code, T value,
                Reg31Mode r31mode = Reg31IsZeroRegister) {
-    set_reg(sizeof(value) * 8, code, value, r31mode);
+    ASSERT(code < kNumberOfRegisters);
+    if (!IsZeroRegister(code, r31mode))
+      registers_[code].Set(value);
   }
 
   // Common specialized accessors for the set_reg() template.
   void set_wreg(unsigned code, int32_t value,
                 Reg31Mode r31mode = Reg31IsZeroRegister) {
-    set_reg(kWRegSizeInBits, code, value, r31mode);
+    set_reg(code, value, r31mode);
   }
 
   void set_xreg(unsigned code, int64_t value,
                 Reg31Mode r31mode = Reg31IsZeroRegister) {
-    set_reg(kXRegSizeInBits, code, value, r31mode);
+    set_reg(code, value, r31mode);
   }
 
   // Commonly-used special cases.
@@ -432,24 +392,10 @@ class Simulator : public DecoderVisitor {
 
   Address get_sp() { return reg<Address>(31, Reg31IsStackPointer); }
 
-  // Return 'size' bits of the value of a floating-point register, as the
-  // specified type. The value is zero-extended to fill the result.
-  //
-  // The only supported values of 'size' are kDRegSizeInBits and
-  // kSRegSizeInBits.
-  template<typename T>
-  T fpreg(unsigned size, unsigned code) const {
-    unsigned size_in_bytes = size / 8;
-    ASSERT(size_in_bytes <= sizeof(T));
-    ASSERT((size == kDRegSizeInBits) || (size == kSRegSizeInBits));
-    ASSERT(code < kNumberOfFPRegisters);
-    return fpregisters_[code].Get<T>(size_in_bytes);
-  }
-
-  // Like fpreg(), but infer the access size from the template type.
   template<typename T>
   T fpreg(unsigned code) const {
-    return fpreg<T>(sizeof(T) * 8, code);
+    ASSERT(code < kNumberOfRegisters);
+    return fpregisters_[code].Get<T>();
   }
 
   // Common specialized accessors for the fpreg() template.
@@ -485,7 +431,7 @@ class Simulator : public DecoderVisitor {
   void set_fpreg(unsigned code, T value) {
     ASSERT((sizeof(value) == kDRegSize) || (sizeof(value) == kSRegSize));
     ASSERT(code < kNumberOfFPRegisters);
-    fpregisters_[code].Set(value, sizeof(value));
+    fpregisters_[code].Set(value);
   }
 
   // Common specialized accessors for the set_fpreg() template.
@@ -625,14 +571,19 @@ class Simulator : public DecoderVisitor {
     return !ConditionPassed(cond);
   }
 
-  void AddSubHelper(Instruction* instr, int64_t op2);
-  int64_t AddWithCarry(unsigned reg_size,
-                       bool set_flags,
-                       int64_t src1,
-                       int64_t src2,
-                       int64_t carry_in = 0);
-  void LogicalHelper(Instruction* instr, int64_t op2);
-  void ConditionalCompareHelper(Instruction* instr, int64_t op2);
+  template<typename T>
+  void AddSubHelper(Instruction* instr, T op2);
+  template<typename T>
+  T AddWithCarry(bool set_flags,
+                 T src1,
+                 T src2,
+                 T carry_in = 0);
+  template<typename T>
+  void AddSubWithCarry(Instruction* instr);
+  template<typename T>
+  void LogicalHelper(Instruction* instr, T op2);
+  template<typename T>
+  void ConditionalCompareHelper(Instruction* instr, T op2);
   void LoadStoreHelper(Instruction* instr,
                        int64_t offset,
                        AddrMode addrmode);
@@ -659,18 +610,21 @@ class Simulator : public DecoderVisitor {
   void MemoryWrite64(uint8_t* address, uint64_t value);
   void MemoryWriteFP64(uint8_t* address, double value);
 
-  int64_t ShiftOperand(unsigned reg_size,
-                       int64_t value,
-                       Shift shift_type,
-                       unsigned amount);
-  int64_t Rotate(unsigned reg_width,
-                 int64_t value,
+
+  template <typename T>
+  T ShiftOperand(T value,
                  Shift shift_type,
                  unsigned amount);
-  int64_t ExtendValue(unsigned reg_width,
-                      int64_t value,
-                      Extend extend_type,
-                      unsigned left_shift = 0);
+  template <typename T>
+  T ExtendValue(T value,
+                Extend extend_type,
+                unsigned left_shift = 0);
+  template <typename T>
+  void Extract(Instruction* instr);
+  template <typename T>
+  void DataProcessing2Source(Instruction* instr);
+  template <typename T>
+  void BitfieldHelper(Instruction* instr);
 
   uint64_t ReverseBits(uint64_t value, unsigned num_bits);
   uint64_t ReverseBytes(uint64_t value, ReverseByteMode mode);
@@ -796,8 +750,9 @@ class Simulator : public DecoderVisitor {
     // is irrelevant, and is not checked here.
   }
 
-  static int CalcNFlag(uint64_t result, unsigned reg_size) {
-    return (result >> (reg_size - 1)) & 1;
+  template <typename T>
+  static int CalcNFlag(T result) {
+    return (result >> (sizeof(T) * 8 - 1)) & 1;
   }
 
   static int CalcZFlag(uint64_t result) {

src/utils.h

@@ -234,6 +234,25 @@ inline int32_t WhichPowerOf2Abs(int32_t x) {
 }
 
 
+// Obtains the unsigned type corresponding to T
+// available in C++11 as std::make_unsigned
+template<typename T>
+struct make_unsigned {
+  typedef T type;
+};
+
+
+// Template specializations necessary to have make_unsigned work
+template<> struct make_unsigned<int32_t> {
+  typedef uint32_t type;
+};
+
+
+template<> struct make_unsigned<int64_t> {
+  typedef uint64_t type;
+};
+
+
 // ----------------------------------------------------------------------------
 // BitField is a help template for encoding and decode bitfield with
 // unsigned content.