Update V8 to r7427: Initial merge by git

As required by WebKit r82507

Change-Id: I7ae83ef3f689356043b4929255b7c1dd31d8c5df
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index f6cd570..52aca63 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -93,8 +93,8 @@
   //  rbp - frame pointer
   //  rsi - context register
   //  r10 - fixed scratch register
+  //  r12 - smi constant register
   //  r13 - root register
-  //  r15 - smi constant register
   static const int kNumRegisters = 16;
   static const int kNumAllocatableRegisters = 10;
 
@@ -120,7 +120,7 @@
       "r9",
       "r11",
       "r14",
-      "r12"
+      "r15"
     };
     return names[index];
   }
@@ -395,6 +395,13 @@
   // Does not check the "reg" part of the Operand.
   bool AddressUsesRegister(Register reg) const;
 
+  // Queries related to the size of the generated instruction.
+  // Whether the generated instruction will have a REX prefix.
+  bool requires_rex() const { return rex_ != 0; }
+  // Size of the ModR/M, SIB and displacement parts of the generated
+  // instruction.
+  int operand_size() const { return len_; }
+
  private:
   byte rex_;
   byte buf_[6];
@@ -427,13 +434,14 @@
 //   } else {
 //     // Generate standard x87 or SSE2 floating point code.
 //   }
-class CpuFeatures : public AllStatic {
+class CpuFeatures {
  public:
   // Detect features of the target CPU. Set safe defaults if the serializer
   // is enabled (snapshots must be portable).
-  static void Probe(bool portable);
+  void Probe(bool portable);
+
   // Check whether a feature is supported by the target CPU.
-  static bool IsSupported(CpuFeature f) {
+  bool IsSupported(CpuFeature f) const {
     if (f == SSE2 && !FLAG_enable_sse2) return false;
     if (f == SSE3 && !FLAG_enable_sse3) return false;
     if (f == CMOV && !FLAG_enable_cmov) return false;
@@ -442,39 +450,56 @@
     return (supported_ & (V8_UINT64_C(1) << f)) != 0;
   }
   // Check whether a feature is currently enabled.
-  static bool IsEnabled(CpuFeature f) {
+  bool IsEnabled(CpuFeature f) const {
     return (enabled_ & (V8_UINT64_C(1) << f)) != 0;
   }
   // Enable a specified feature within a scope.
   class Scope BASE_EMBEDDED {
 #ifdef DEBUG
    public:
-    explicit Scope(CpuFeature f) {
+    explicit Scope(CpuFeature f)
+        : cpu_features_(Isolate::Current()->cpu_features()),
+          isolate_(Isolate::Current()) {
       uint64_t mask = (V8_UINT64_C(1) << f);
-      ASSERT(CpuFeatures::IsSupported(f));
-      ASSERT(!Serializer::enabled() || (found_by_runtime_probing_ & mask) == 0);
-      old_enabled_ = CpuFeatures::enabled_;
-      CpuFeatures::enabled_ |= mask;
+      ASSERT(cpu_features_->IsSupported(f));
+      ASSERT(!Serializer::enabled() ||
+          (cpu_features_->found_by_runtime_probing_ & mask) == 0);
+      old_enabled_ = cpu_features_->enabled_;
+      cpu_features_->enabled_ |= mask;
     }
-    ~Scope() { CpuFeatures::enabled_ = old_enabled_; }
+    ~Scope() {
+      ASSERT_EQ(Isolate::Current(), isolate_);
+      cpu_features_->enabled_ = old_enabled_;
+    }
    private:
     uint64_t old_enabled_;
+    CpuFeatures* cpu_features_;
+    Isolate* isolate_;
 #else
    public:
     explicit Scope(CpuFeature f) {}
 #endif
   };
  private:
+  CpuFeatures();
+
   // Safe defaults include SSE2 and CMOV for X64. It is always available, if
   // anyone checks, but they shouldn't need to check.
+  // The required user mode extensions in X64 are (from AMD64 ABI Table A.1):
+  //   fpu, tsc, cx8, cmov, mmx, sse, sse2, fxsr, syscall
   static const uint64_t kDefaultCpuFeatures = (1 << SSE2 | 1 << CMOV);
-  static uint64_t supported_;
-  static uint64_t enabled_;
-  static uint64_t found_by_runtime_probing_;
+
+  uint64_t supported_;
+  uint64_t enabled_;
+  uint64_t found_by_runtime_probing_;
+
+  friend class Isolate;
+
+  DISALLOW_COPY_AND_ASSIGN(CpuFeatures);
 };
 
 
-class Assembler : public Malloced {
+class Assembler : public AssemblerBase {
  private:
   // We check before assembling an instruction that there is sufficient
   // space to write an instruction and its relocation information.
@@ -504,6 +529,9 @@
   Assembler(void* buffer, int buffer_size);
   ~Assembler();
 
+  // Overrides the default provided by FLAG_debug_code.
+  void set_emit_debug_code(bool value) { emit_debug_code_ = value; }
+
   // GetCode emits any pending (non-emitted) code and fills the descriptor
   // desc. GetCode() is idempotent; it returns the same result if no other
   // Assembler functions are invoked in between GetCode() calls.
@@ -649,7 +677,7 @@
 
   // Move sign extended immediate to memory location.
   void movq(const Operand& dst, Immediate value);
-  // New x64 instructions to load a 64-bit immediate into a register.
+  // Instructions to load a 64-bit immediate into a register.
   // All 64-bit immediates must have a relocation mode.
   void movq(Register dst, void* ptr, RelocInfo::Mode rmode);
   void movq(Register dst, int64_t value, RelocInfo::Mode rmode);
@@ -674,7 +702,7 @@
   void repmovsl();
   void repmovsq();
 
-  // New x64 instruction to load from an immediate 64-bit pointer into RAX.
+  // Instruction to load from an immediate 64-bit pointer into RAX.
   void load_rax(void* ptr, RelocInfo::Mode rmode);
   void load_rax(ExternalReference ext);
 
@@ -1109,6 +1137,7 @@
 
   // Miscellaneous
   void clc();
+  void cld();
   void cpuid();
   void hlt();
   void int3();
@@ -1343,6 +1372,9 @@
   static const int kMaximalBufferSize = 512*MB;
   static const int kMinimalBufferSize = 4*KB;
 
+ protected:
+  bool emit_debug_code() const { return emit_debug_code_; }
+
  private:
   byte* addr_at(int pos)  { return buffer_ + pos; }
   byte byte_at(int pos)  { return buffer_[pos]; }
@@ -1536,8 +1568,6 @@
   int buffer_size_;
   // True if the assembler owns the buffer, false if buffer is external.
   bool own_buffer_;
-  // A previously allocated buffer of kMinimalBufferSize bytes, or NULL.
-  static byte* spare_buffer_;
 
   // code generation
   byte* pc_;  // the program counter; moves forward
@@ -1548,6 +1578,9 @@
   byte* last_pc_;
 
   PositionsRecorder positions_recorder_;
+
+  bool emit_debug_code_;
+
   friend class PositionsRecorder;
 };