[simd] Disable Simd Scalar lowering for x64, enable tests for all other architectures.

test/cctest/wasm/test-run-wasm-simd-lowering.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/wasm/wasm-macro-gen.h"
 #include "src/wasm/wasm-module.h"
 
 #include "test/cctest/cctest.h"
 #include "test/cctest/compiler/value-helper.h"
 #include "test/cctest/wasm/wasm-run-utils.h"
 #include "test/common/wasm/test-signatures.h"
 
 using namespace v8::base;
 using namespace v8::internal;
 using namespace v8::internal::compiler;
 using namespace v8::internal::wasm;
 
+#if !V8_TARGET_ARCH_X64

[bbudge, 2016/11/18 19:30:59]

Rather than comment out the code here, don't include these tests in the build
files.

[gdeepti, 2016/11/21 19:30:03]

Done.

 WASM_EXEC_TEST(Simd_I32x4_Splat) {
   FLAG_wasm_simd_prototype = true;
   WasmRunner<int32_t> r(kExecuteCompiled, MachineType::Int32());
   BUILD(r,
         WASM_SIMD_I32x4_EXTRACT_LANE(0, WASM_SIMD_I32x4_SPLAT(WASM_I32V(5))));
   FOR_INT32_INPUTS(i) { CHECK_EQ(5, r.Call()); }
 }
 
 WASM_EXEC_TEST(Simd_I32x4_Add) {
   FLAG_wasm_simd_prototype = true;
@@ skipping 59 matching lines @@
         WASM_IF_ELSE(
             WASM_I32_EQ(WASM_SIMD_I32x4_EXTRACT_LANE(
                             0, WASM_SIMD_I32x4_ADD(
                                    WASM_SIMD_F32x4_SPLAT(WASM_F32(21.25)),
                                    WASM_SIMD_F32x4_SPLAT(WASM_F32(31.5)))),
                         WASM_I32_ADD(WASM_I32_REINTERPRET_F32(WASM_F32(21.25)),
                                      WASM_I32_REINTERPRET_F32(WASM_F32(31.5)))),
             WASM_RETURN1(WASM_I32V(1)), WASM_RETURN1(WASM_I32V(0))));
   FOR_INT32_INPUTS(i) { CHECK_EQ(1, r.Call()); }
 }
+#endif  // V8_TARGET_ARCH_X64