Thumb2 Backend: 16-bit instruction encoding helper methods

src/arm/assembler-arm.h

Index: src/arm/assembler-arm.h
diff --git a/src/arm/assembler-arm.h b/src/arm/assembler-arm.h
index 866b1c9024d02ebca6f84fef79ce414aee76515f..09392941715ce7e2f135733fb35bc5437a187e94 100644
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -1364,6 +1364,9 @@ class Assembler : public AssemblerBase {
 
   // Read/patch instructions
   Instr instr_at(int pos) { return *reinterpret_cast<Instr*>(buffer_ + pos); }
+  Instr16 thumb16_instr_at(int pos) {

[rmcilroy_google, 2013/09/17 17:28:16]

thumb2_instr16_at.

+    return *reinterpret_cast<Instr16*>(buffer_ + pos);
+  }
   void instr_at_put(int pos, Instr instr) {
     *reinterpret_cast<Instr*>(buffer_ + pos) = instr;
   }
@@ -1531,6 +1534,7 @@ class Assembler : public AssemblerBase {
   inline void CheckBuffer();
   void GrowBuffer();
   inline void emit(Instr x);
+  inline void emit16(Instr16 x, bool check_buffer = true);
 
   // 32-bit immediate values
   void move_32_bit_immediate(Condition cond,
@@ -1545,6 +1549,53 @@ class Assembler : public AssemblerBase {
   void addrmod4(Instr instr, Register rn, RegList rl);
   void addrmod5(Instr instr, CRegister crd, const MemOperand& x);
 
+  Instr16 thumb16_mode1(ThumbMode1Opcode16 op);  // A6.2.1 -> mode1

[rmcilroy_google, 2013/09/17 17:28:16]

ditto with thumb16->thumb2 here and below. Also, are these really necessary in
the public header? Maybe they could go in assembler-arm-int.h, or if you end up
splitting thumb into a seperate Assembler class (see comment in
assembler-thumb16.cc) then in assembler-thumb2-int.h.

+  Instr16 thumb16_mode2(ThumbMode2Opcode16 op);  // A6.2.2 -> mode2
+  Instr16 thumb16_mode3(ThumbMode3Opcode16 op);  // A6.2.3 -> mode3
+
+  // A6.2.4 -> mode4, opA 0101 -> _1
+  Instr16 thumb16_mode4_1(ThumbMode4_1Opcode16 opB);
+  // A6.2.4 -> mode4, opA 0110 -> _2
+  Instr16 thumb16_mode4_2(ThumbMode4_2Opcode16 opB);
+  // A6.2.4 -> mode4, opA 0111 -> _3
+  Instr16 thumb16_mode4_3(ThumbMode4_3Opcode16 opB);
+  // A6.2.4 -> mode4, opA 1000 -> _4
+  Instr16 thumb16_mode4_4(ThumbMode4_4Opcode16 opB);
+  // A6.2.4 -> mode4, opA 1001 -> _5
+  Instr16 thumb16_mode4_5(ThumbMode4_5Opcode16 opB);
+
+  Instr16 thumb16_2lowreg_encoding(Register rd,
+                                   const Operand& x);
+  Instr16 thumb16_2lowreg_encoding(Register rd,
+                                   Register rs);
+  Instr16 thumb16_2lowreg_imm3_encoding(Register rd,
+                                        Register rn,
+                                        const Operand& x);
+  Instr16 thumb16_2lowreg_imm5_encoding(Register rd,
+                                        Register rn,
+                                        uint32_t offset);
+  Instr16 thumb16_2lowreg_imm5_encoding(Register rd,
+                                        Register rn,
+                                        const Operand& x);
+  Instr16 thumb16_3lowreg_encoding(Register rd,
+                                   Register rn,
+                                   const Operand& x);
+  Instr16 thumb16_3lowreg_encoding(Register rd,
+                                   const MemOperand& x);
+  Instr16 thumb16_anyreg_encoding(const Operand& x);
+  Instr16 thumb16_anyreg_encoding(Register rm);
+  Instr16 thumb16_2anyreg_encoding(Register rd, const Operand& x);
+  Instr16 thumb16_lowreg_imm8_encoding(Register rd, const Operand& x);
+  Instr16 thumb16_lowreg_imm8_encoding(Register rd, uint32_t offset);
+  static Instr16 thumb16_instr_at(Address addr);
+  void thumb16_instr_at_put(int pos, Instr16 instr);
+  bool fits_thumb16_mode_4(Register reg, const MemOperand& op);
+  bool fits_thumb16_mode_4_1(Register reg, const MemOperand& op);
+  bool fits_thumb16_mode_4_5(Register reg, const MemOperand& op);
+
+  bool is_low_reg(Register reg);
+  bool are_low_reg(Register reg1, Register reg2);
+
   // Labels
   void print(Label* L);
   void bind_to(Label* L, int pos);