[Interpreter] Add support for short (16 bit) operands.

src/interpreter/bytecodes.h

Index: src/interpreter/bytecodes.h
diff --git a/src/interpreter/bytecodes.h b/src/interpreter/bytecodes.h
index 70be2f58177b5fd94daa6924bb9dadde950197de..e85966bdb7c2494b35ea4dabef1e2cee8cee7d23 100644
--- a/src/interpreter/bytecodes.h
+++ b/src/interpreter/bytecodes.h
@@ -16,12 +16,19 @@ namespace internal {
 namespace interpreter {
 
 // The list of operand types used by bytecodes.
-#define OPERAND_TYPE_LIST(V) \
-  V(None)                    \
-  V(Count)                   \
-  V(Imm8)                    \
-  V(Idx)                     \
-  V(Reg)
+#define OPERAND_TYPE_LIST(V)   \
+                               \
+  /* None operand. */          \
+  V(None, OperandSize::kNone)  \
+                               \
+  /* Byte operands. */         \
+  V(Count, OperandSize::kByte) \
+  V(Imm8, OperandSize::kByte)  \
+  V(Idx, OperandSize::kByte)   \
+  V(Reg, OperandSize::kByte)   \
+                               \
+  /* Wide operands. */         \
+  V(WideIdx, OperandSize::kWide)

[oth, 2015/09/28 09:21:25]

Wide is a loose term. It's currently a 16-bit operand, though there's a 32-bit
operand coming after this lands (ExtraWide).

Open question - can we clean up the names in this CL? Suggest putting the width
in the name. Should be fairly mechanical:

/OperandType::Count/OperandType::Count8/g
/OperandType::Idx/OperandType::Idx8/g
/OperandType::Reg/OperandType::Reg8/g
/OperandType::WideIdx/OperandType::Idx16/g

[rmcilroy, 2015/10/01 14:09:14]

Renamed OperandSize::kWide to OperandSize::kShort, and changed operand types to
include size as requested.

 
 // The list of bytecodes which are interpreted by the interpreter.
 #define BYTECODE_LIST(V)                                                   \
@@ -86,12 +93,20 @@ namespace interpreter {
   V(Return, OperandType::kNone)
 
 
+// Enumeration of the size classes of operand types used by bytecodes.
+enum class OperandSize : uint8_t {
+  kNone = 0,
+  kByte = 1,
+  kWide = 2,

[oth, 2015/09/28 09:21:25]

More descriptive names to avoid wide? kOneByte kTwoByte

[rmcilroy, 2015/10/01 14:09:14]

Made it kByte, kShort and will be kLong for 32.

+};
+
+
 // Enumeration of operand types used by bytecodes.
 enum class OperandType : uint8_t {
-#define DECLARE_OPERAND_TYPE(Name) k##Name,
+#define DECLARE_OPERAND_TYPE(Name, _) k##Name,
   OPERAND_TYPE_LIST(DECLARE_OPERAND_TYPE)
 #undef DECLARE_OPERAND_TYPE
-#define COUNT_OPERAND_TYPES(x) +1
+#define COUNT_OPERAND_TYPES(x, _) +1
   // The COUNT_OPERAND macro will turn this into kLast = -1 +1 +1... which will
   // evaluate to the same value as the last operand.
   kLast = -1 OPERAND_TYPE_LIST(COUNT_OPERAND_TYPES)
@@ -169,14 +184,21 @@ class Bytecodes {
   // Return the i-th operand of |bytecode|.
   static OperandType GetOperandType(Bytecode bytecode, int i);
 
+  // Returns the offset of the i-th operand of |bytecode| relative to the start
+  // of the bytecode.
+  static int GetOperandOffset(Bytecode bytecode, int i);
+
   // Returns the size of the bytecode including its operands.
   static int Size(Bytecode bytecode);
 
-  // The maximum number of operands across all bytecodes.
-  static int MaximumNumberOfOperands();
+  // Returns the size of operand.
+  static OperandSize SizeOfOperand(OperandType operand);
+
+  // Converts bytes[0] and bytes[1] to a 16 bit wide operand value.
+  static uint16_t WideOperandFromBytes(const uint8_t* bytes);
 
-  // Maximum size of a bytecode and its operands.
-  static int MaximumSize();
+  // Converts 16 bit wide |operand| into bytes_out[0] and bytes_out[1].
+  static void WideOperandToBytes(uint16_t operand, uint8_t* bytes_out);
 
   // Decode a single bytecode and operands to |os|.
   static std::ostream& Decode(std::ostream& os, const uint8_t* bytecode_start,