X64 Win64: Reimplement fmod so that it works.

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index 7e09a416b562737bc8c75bd912856a0c7799f7ab..76d2a8dd1ba4da558c346790da3b73c7f3db657a 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -283,6 +283,25 @@ inline Hint NegateHint(Hint hint) {
 }
 
 
+// FPU status word bits
+
+enum FPUStatus {
+  kInvalidOperandException = 0x01,
+  kDenormalizedOperandException = 0x02,
+  kZeroDivideException = 0x04,
+  kOverflowException = 0x08,
+  kUnderflowException = 0x10,
+  kPrecisionException = 0x20,
+  kAnyExceptionMask = 0x3f,  // All of the above.
+  kStackFault = 0x40,
+  kErrorSummary = 0x80,
+  kCondition0 = 0x100,
+  kCondition1 = 0x200,
+  kCondition2 = 0x400,
+  kCondition3 = 0x4000
+};
+
+
 // -----------------------------------------------------------------------------
 // Machine instruction Immediates
 
@@ -327,12 +346,14 @@ class Operand BASE_EMBEDDED {
           ScaleFactor scale,
           int32_t disp);
 
+  // New operand based on previous operand and a fixed displacement.
+  Operand(const Operand& base, int32_t displacement);
+
  private:
   byte rex_;
   byte buf_[10];
   // The number of bytes in buf_.
   unsigned int len_;
-  RelocInfo::Mode rmode_;
 
   // Set the ModR/M byte without an encoded 'reg' register. The
   // register is encoded later as part of the emit_operand operation.
@@ -932,6 +953,10 @@ class Assembler : public Malloced {
     immediate_arithmetic_op(0x6, dst, src);
   }
 
+  void xorl(Register dst, Immediate src) {
+    immediate_arithmetic_op_32(0x6, dst, src);
+  }
+
   void xor_(const Operand& dst, Immediate src) {
     immediate_arithmetic_op(0x6, dst, src);
   }
@@ -1006,6 +1031,9 @@ class Assembler : public Malloced {
 
   void fstp_s(const Operand& adr);
   void fstp_d(const Operand& adr);
+  void fst_d(const Operand& adr);
+  void fstp(int stack_slot);
+  void fst(int stack_slot);
 
   void fild_s(const Operand& adr);
   void fild_d(const Operand& adr);
@@ -1040,12 +1068,14 @@ class Assembler : public Malloced {
   void ffree(int i = 0);
 
   void ftst();
+  void fucom(int i);
   void fucomp(int i);
   void fucompp();
   void fcompp();
   void fnstsw_ax();
   void fwait();
   void fnclex();
+  void fxam();
 
   void fsin();
   void fcos();