Use three-address form of imul

src/IceAssemblerX86Base.h

Index: src/IceAssemblerX86Base.h
diff --git a/src/IceAssemblerX86Base.h b/src/IceAssemblerX86Base.h
index 7c4be6f76d61283379271005c4e426e39068d41a..f9de5a525b37aace2f77973ac1742654427c0a1f 100644
--- a/src/IceAssemblerX86Base.h
+++ b/src/IceAssemblerX86Base.h
@@ -751,6 +751,11 @@ public:
   void imul(Type Ty, typename Traits::GPRRegister reg);
   void imul(Type Ty, const typename Traits::Address &address);
 
+  void imul(Type Ty, typename Traits::GPRRegister dst,
+            typename Traits::GPRRegister src, const Immediate &imm);
+  void imul(Type Ty, typename Traits::GPRRegister dst,
+            const typename Traits::Address &address, const Immediate &imm);
+
   void mul(Type Ty, typename Traits::GPRRegister reg);
   void mul(Type Ty, const typename Traits::Address &address);