Optionally use 31-bits SMI value for 64-bit system

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 9d5d2a31c5ceee61652cd923ca83e8a13d1388ca..faf30f1b249d4f237870d358572388ab64c2815e 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -484,10 +484,17 @@ class MacroAssembler: public Assembler {
   // Jump if the value cannot be represented by a smi.
   void JumpIfNotValidSmiValue(Register src, Label* on_invalid,
                               Label::Distance near_jump = Label::kFar);
+  // Jump if the value can be represented by a smi.
+  void JumpIfValidSmiValue(Register src, Label* on_valid,
+                           Label::Distance near_jump = Label::kFar);
 
   // Jump if the unsigned integer value cannot be represented by a smi.
   void JumpIfUIntNotValidSmiValue(Register src, Label* on_invalid,
                                   Label::Distance near_jump = Label::kFar);
+  // Jump if the unsigned integer value can be represented by a smi.
+  void JumpIfUIntValidSmiValue(Register src, Label* on_valid,
+                               Label::Distance near_jump = Label::kFar);
+
 
   // Jump to label if the value is a tagged smi.
   void JumpIfSmi(Register src,
@@ -650,7 +657,8 @@ class MacroAssembler: public Assembler {
 
   void SmiShiftLeftConstant(Register dst,
                             Register src,
-                            int shift_value);
+                            int shift_value,
+                            Label* on_not_smi_result);
   void SmiShiftLogicalRightConstant(Register dst,
                                   Register src,
                                   int shift_value,
@@ -664,7 +672,8 @@ class MacroAssembler: public Assembler {
   // Uses and clobbers rcx, so dst may not be rcx.
   void SmiShiftLeft(Register dst,
                     Register src1,
-                    Register src2);
+                    Register src2,
+                    Label* on_not_smi_result);
   // Shifts a smi value to the right, shifting in zero bits at the top, and
   // returns the unsigned intepretation of the result if that is a smi.
   // Uses and clobbers rcx, so dst may not be rcx.