Reland "Introduce intrinsics for double values in Javascript."

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 d263268b1634415c207f5e4fa622a013ccbdc5cb..8ca37d4eaf2e4e6c69454c327dfdbac544905cf6 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -2806,6 +2806,16 @@ void Assembler::movss(const Operand& src, XMMRegister dst) {
 }
 
 
+void Assembler::psllq(XMMRegister reg, byte imm8) {
+  EnsureSpace ensure_space(this);
+  emit(0x66);
+  emit(0x0F);
+  emit(0x73);
+  emit_sse_operand(rsi, reg);  // rsi == 6
+  emit(imm8);
+}
+
+
 void Assembler::cvttss2si(Register dst, const Operand& src) {
   EnsureSpace ensure_space(this);
   emit(0xF3);