Thumb2 Backend: Enable Assembler to encode Thumb2 instructions

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 c0f0125803c285f1b87e820c537ebb1f4f736342..54f77794e2f87cef2c0decc9a0bf6fc6ad87d97b 100644
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -697,6 +697,9 @@ extern const Instr kCmpCmnFlip;
 extern const Instr kAddSubFlip;
 extern const Instr kAndBicFlip;
 
+extern const Instr kThumbLdrPCMask;
+extern const Instr kThumbLdrPCPattern;
+
 struct VmovIndex {
   unsigned char index;
 };
@@ -806,6 +809,7 @@ class Assembler : public AssemblerBase {
   // Difference between address of current opcode and value read from pc
   // register.
   static const int kPcLoadDelta = 8;
+  static const int kThumbPcLoadDelta = 4;
 
   static const int kJSReturnSequenceInstructions = 4;
   static const int kDebugBreakSlotInstructions = 3;
@@ -1578,6 +1582,8 @@ class Assembler : public AssemblerBase {
   static bool IsNop(Instr instr, int type = NON_MARKING_NOP);
   static bool IsMovT(Instr instr);
   static bool IsMovW(Instr instr);
+  static bool IsMovTThumb(Instr instr);
+  static bool IsMovWThumb(Instr instr);
 
   // Constants in pools are accessed via pc relative addressing, which can
   // reach +/-4KB for integer PC-relative loads and +/-1KB for floating-point
@@ -1595,6 +1601,11 @@ class Assembler : public AssemblerBase {
   // Check if is time to emit a constant pool.
   void CheckConstPool(bool force_emit, bool require_jump);
 
+  void set_thumb_mode() { thumb_mode_ = true; }
+  void set_arm_mode() { thumb_mode_ = false; }
+
+  bool is_thumb_mode() {return thumb_mode_; }
+
  protected:
   // Relocation for a type-recording IC has the AST id added to it.  This
   // member variable is a way to pass the information from the call site to
@@ -1605,9 +1616,11 @@ class Assembler : public AssemblerBase {
 
   // Decode branch instruction at pos and return branch target pos
   int target_at(int pos);
+  int target_at_thumb(int pos);
 
   // Patch branch instruction at pos to branch to given branch target pos
   void target_at_put(int pos, int target_pos);
+  void target_at_put_thumb(int pos, int target_pos);
 
   // Prevent contant pool emission until EndBlockConstPool is called.
   // Call to this function can be nested but must be followed by an equal
@@ -1851,6 +1864,8 @@ class Assembler : public AssemblerBase {
   PositionsRecorder positions_recorder_;
   friend class PositionsRecorder;
   friend class EnsureSpace;
+
+  bool thumb_mode_;
 };