Relax register constraints for LMathSqrt.

src/x64/assembler-x64.cc

Index: src/x64/assembler-x64.cc
diff --git a/src/x64/assembler-x64.cc b/src/x64/assembler-x64.cc
index 3d226b59f105b8346ee07e1dbbe101284ba4f8a4..64a5cc3ae631e7a018d03001d0e3aac3e8d0c3f5 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -2794,6 +2794,16 @@ void Assembler::sqrtsd(XMMRegister dst, XMMRegister src) {
 }
 
 
+void Assembler::sqrtsd(XMMRegister dst, const Operand& src) {
+  EnsureSpace ensure_space(this);
+  emit(0xF2);
+  emit_optional_rex_32(dst, src);
+  emit(0x0F);
+  emit(0x51);
+  emit_sse_operand(dst, src);
+}
+
+
 void Assembler::ucomisd(XMMRegister dst, XMMRegister src) {
   EnsureSpace ensure_space(this);
   emit(0x66);