Use movw/movt instead of constant pool on ARMv7

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 005c78d5d8f6aef5760a98c160bbd37984819ce4..2381720f97851408009c0528aacd092a4a058e79 100644
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -425,7 +425,7 @@ class Operand BASE_EMBEDDED {
   // actual instruction to use is required for this calculation. For other
   // instructions instr is ignored.
   bool is_single_instruction(const Assembler* assembler, Instr instr = 0) const;
-  bool must_use_constant_pool(const Assembler* assembler) const;
+  bool must_output_reloc_info(const Assembler* assembler) const;
 
   inline int32_t immediate() const {
     ASSERT(!rm_.is_valid());
@@ -693,6 +693,9 @@ class Assembler : public AssemblerBase {
   INLINE(static Address target_address_at(Address pc));
   INLINE(static void set_target_address_at(Address pc, Address target));
 
+  INLINE(static Address target_address_from_return_address(Address pc));

[Michael Starzinger, 2012/10/10 14:19:29]

Can we have a one-liner comment of what this method does (also on other
architectures).

[danno, 2012/10/17 10:04:44]

Done.

+  INLINE(static Address return_address_from_call_start(Address pc));
+
   // This sets the branch destination (which is in the constant pool on ARM).
   // This is for calls and branches within generated code.
   inline static void deserialization_set_special_target_at(
@@ -711,22 +714,6 @@ class Assembler : public AssemblerBase {
   // Size of an instruction.
   static const int kInstrSize = sizeof(Instr);
 
-  // Distance between the instruction referring to the address of the call
-  // target and the return address.
-#ifdef USE_BLX
-  // Call sequence is:
-  //  ldr  ip, [pc, #...] @ call address
-  //  blx  ip
-  //                      @ return address
-  static const int kCallTargetAddressOffset = 2 * kInstrSize;
-#else
-  // Call sequence is:
-  //  mov  lr, pc
-  //  ldr  pc, [pc, #...] @ call address
-  //                      @ return address
-  static const int kCallTargetAddressOffset = kInstrSize;
-#endif
-
   // Distance between start of patched return sequence and the emitted address
   // to jump to.
 #ifdef USE_BLX
@@ -755,6 +742,8 @@ class Assembler : public AssemblerBase {
   static const int kPatchDebugBreakSlotAddressOffset =  kInstrSize;
 #endif
 
+  static const int kPatchDebugBreakSlotReturnOffset = 2 * kInstrSize;
+
   // Difference between address of current opcode and value read from pc
   // register.
   static const int kPcLoadDelta = 8;
@@ -1182,6 +1171,12 @@ class Assembler : public AssemblerBase {
 
   bool predictable_code_size() const { return predictable_code_size_; }
 
+  static bool allow_immediate_constant_pool_loads(
+      const Assembler* assembler) {
+    return CpuFeatures::IsSupported(ARMv7) &&
+        (assembler == NULL || !assembler->predictable_code_size());
+  }
+
   // Check the code size generated from label to here.
   int SizeOfCodeGeneratedSince(Label* label) {
     return pc_offset() - label->pos();
@@ -1302,6 +1297,8 @@ class Assembler : public AssemblerBase {
   static Register GetCmpImmediateRegister(Instr instr);
   static int GetCmpImmediateRawImmediate(Instr instr);
   static bool IsNop(Instr instr, int type = NON_MARKING_NOP);
+  static bool IsMovT(Instr instr);
+  static bool IsMovW(Instr instr);
 
   // Constants in pools are accessed via pc relative addressing, which can
   // reach +/-4KB thereby defining a maximum distance between the instruction
@@ -1440,6 +1437,12 @@ class Assembler : public AssemblerBase {
   void GrowBuffer();
   inline void emit(Instr x);
 
+  // 32-bit immediate values
+  void move_32_bit_immediate(Condition cond,
+                             Register rd,
+                             SBit s,
+                             const Operand& x);
+
   // Instruction generation
   void addrmod1(Instr instr, Register rn, Register rd, const Operand& x);
   void addrmod2(Instr instr, Register rd, const MemOperand& x);
@@ -1453,8 +1456,14 @@ class Assembler : public AssemblerBase {
   void link_to(Label* L, Label* appendix);
   void next(Label* L);
 
+  enum UseConstantPoolMode {
+    USE_CONSTANT_POOL,
+    DONT_USE_CONSTANT_POOL
+  };
+
   // Record reloc info for current pc_
-  void RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data = 0);
+  void RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data = 0,
+                       UseConstantPoolMode mode = USE_CONSTANT_POOL);
 
   friend class RegExpMacroAssemblerARM;
   friend class RelocInfo;
@@ -1479,6 +1488,26 @@ class EnsureSpace BASE_EMBEDDED {
 };
 
 
+class ScopedPredictableCodeSize {

[Michael Starzinger, 2012/10/10 14:19:29]

I would call this PredictableCodeSizeScope instead.

[danno, 2012/10/17 10:04:44]

Done.

+ public:
+  explicit ScopedPredictableCodeSize(Assembler* assembler)
+      : asm_(assembler) {
+    old_value_ = assembler->predictable_code_size();
+    assembler->set_predictable_code_size(true);
+  }
+
+  ~ScopedPredictableCodeSize() {
+    if (!old_value_) {
+      asm_->set_predictable_code_size(false);
+    }
+  }
+
+ private:
+  Assembler* asm_;
+  bool old_value_;
+};
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_ASSEMBLER_ARM_H_