Add packed add and subtract to IA32 and X64 assemblers

runtime/vm/assembler_ia32_test.cc

Index: runtime/vm/assembler_ia32_test.cc
diff --git a/runtime/vm/assembler_ia32_test.cc b/runtime/vm/assembler_ia32_test.cc
index 3a7d4a55df1e235e92c46db7c6ec0f945e7316d0..2f3087f7c48fe9db5386e062ee1e2fad87a41ba9 100644
--- a/runtime/vm/assembler_ia32_test.cc
+++ b/runtime/vm/assembler_ia32_test.cc
@@ -874,6 +874,31 @@ ASSEMBLER_TEST_RUN(PackedFPOperations, test) {
 }
 
 
+ASSEMBLER_TEST_GENERATE(PackedIntOperations, assembler) {
+  __ movl(EAX, Immediate(0x2));
+  __ movd(XMM0, EAX);
+  __ shufps(XMM0, XMM0, Immediate(0x0));
+  __ movl(EAX, Immediate(0x1));
+  __ movd(XMM1, EAX);
+  __ shufps(XMM1, XMM1, Immediate(0x0));
+  __ addpl(XMM0, XMM1);  // 0x3
+  __ addpl(XMM0, XMM0);  // 0x6
+  __ subpl(XMM0, XMM1);  // 0x5
+  // Copy the low lane at ESP.
+  __ pushl(EAX);
+  __ movss(Address(ESP, 0), XMM0);
+  __ popl(EAX);
+  __ ret();
+}
+
+
+ASSEMBLER_TEST_RUN(PackedIntOperations, test) {
+  typedef uint32_t (*PackedIntOperationsCode)();
+  uint32_t res = reinterpret_cast<PackedIntOperationsCode>(test->entry())();
+  EXPECT_EQ(static_cast<uword>(0x5), res);
+}
+
+
 ASSEMBLER_TEST_GENERATE(PackedFPOperations2, assembler) {
   __ movl(EAX, Immediate(bit_cast<int32_t, float>(4.0f)));
   __ movd(XMM0, EAX);