A64: Introduce a DeoptimizeIfMinusZero() helper.

src/a64/macro-assembler-a64.cc

Index: src/a64/macro-assembler-a64.cc
diff --git a/src/a64/macro-assembler-a64.cc b/src/a64/macro-assembler-a64.cc
index 25edc06161dc533d02e718cc09d9fe4fc4312cda..3f9905dfd4c908e133144c3d6745220579e07f40 100644
--- a/src/a64/macro-assembler-a64.cc
+++ b/src/a64/macro-assembler-a64.cc
@@ -2225,14 +2225,19 @@ void MacroAssembler::TryConvertDoubleToInt(Register as_int,
 }
 
 
-void MacroAssembler::JumpIfMinusZero(DoubleRegister input,
-                                     Label* on_negative_zero) {
+void MacroAssembler::TestForMinusZero(DoubleRegister input) {
   UseScratchRegisterScope temps(this);
   Register temp = temps.AcquireX();
   // Floating point -0.0 is kMinInt as an integer, so subtracting 1 (cmp) will
   // cause overflow.
   Fmov(temp, input);
   Cmp(temp, 1);
+}
+
+
+void MacroAssembler::JumpIfMinusZero(DoubleRegister input,
+                                     Label* on_negative_zero) {
+  TestForMinusZero(input);
   B(vs, on_negative_zero);
 }