[x64] Fix invalid REX prefix for pslld, psrld and friends.

test/cctest/test-assembler-x64.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2278 matching lines @@
 #endif
 
   F1 f = FUNCTION_CAST<F1>(code->entry());
   for (int i = 0; i < kNumCases; ++i) {
     int res = f(i);
     PrintF("f(%d) = %d\n", i, res);
     CHECK_EQ(values[i], res);
   }
 }
 
+TEST(AssemblerX64PslldWithXmm15) {
+  CcTest::InitializeVM();
+  // Allocate an executable page of memory.
+  size_t actual_size;
+  byte* buffer = static_cast<byte*>(v8::base::OS::Allocate(
+      Assembler::kMinimalBufferSize, &actual_size, true));
+  CHECK(buffer);
+  Assembler assm(CcTest::i_isolate(), buffer, static_cast<int>(actual_size));
+
+  __ movq(xmm15, arg1);
+  __ pslld(xmm15, 1);
+  __ movq(rax, xmm15);
+  __ ret(0);
+
+  CodeDesc desc;
+  assm.GetCode(&desc);
+  uint64_t result = FUNCTION_CAST<F5>(buffer)(V8_UINT64_C(0x1122334455667788));
+  CHECK_EQ(V8_UINT64_C(0x22446688aaccef10), result);
+}
+
 #undef __