X64: Convert HeapNumbers that contain valid smi values to smis in binop-stub.

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 8086388b12854251d557cfff29d561be4514912f..4c177205b6be4f143933f751678641b9dbc14f52 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -323,6 +323,16 @@ class MacroAssembler: public Assembler {
                                            Register src,
                                            int power);
 
+  // Perform the logical or of two smi values and return a smi value.
+  // If either argument is not a smi, jump to on_not_smis and retain
+  // the original values of source registers. The destination register
+  // may be changed if it's not one of the source registers.
+  template <typename LabelType>
+  void SmiOrIfSmis(Register dst,
+                   Register src1,
+                   Register src2,
+                   LabelType* on_not_smis);
+
 
   // Simple comparison of smis.  Both sides must be known smis to use these,
   // otherwise use Cmp.
@@ -1790,6 +1800,24 @@ void MacroAssembler::JumpUnlessBothNonNegativeSmi(Register src1,
 
 
 template <typename LabelType>
+void MacroAssembler::SmiOrIfSmis(Register dst, Register src1, Register src2,
+                                 LabelType* on_not_smis) {
+  if (dst.is(src1) || dst.is(src2)) {
+    ASSERT(!src1.is(kScratchRegister));
+    ASSERT(!src2.is(kScratchRegister));
+    movq(kScratchRegister, src1);
+    or_(kScratchRegister, src2);
+    JumpIfNotSmi(kScratchRegister, on_not_smis);
+    movq(dst, kScratchRegister);
+  } else {
+    movq(dst, src1);
+    or_(dst, src2);
+    JumpIfNotSmi(dst, on_not_smis);
+  }
+}
+
+
+template <typename LabelType>
 void MacroAssembler::JumpIfNotString(Register object,
                                      Register object_map,
                                      LabelType* not_string) {