[wasm] Add native x64 implementations for I32x4Splat, I32x4ExtractLane

src/x64/macro-assembler-x64.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 3307 matching lines @@
   CHECK_EQ(end_position, pc_offset());
 #endif
 }
 
 
 void MacroAssembler::Pextrd(Register dst, XMMRegister src, int8_t imm8) {
   if (imm8 == 0) {
     Movd(dst, src);
     return;
   }
-  DCHECK_EQ(1, imm8);
   if (CpuFeatures::IsSupported(SSE4_1)) {
     CpuFeatureScope sse_scope(this, SSE4_1);
     pextrd(dst, src, imm8);
     return;
   }
+  DCHECK_EQ(1, imm8);
   movq(dst, src);
   shrq(dst, Immediate(32));
 }
 
 
 void MacroAssembler::Pinsrd(XMMRegister dst, Register src, int8_t imm8) {
   if (CpuFeatures::IsSupported(SSE4_1)) {
     CpuFeatureScope sse_scope(this, SSE4_1);
     pinsrd(dst, src, imm8);
     return;
@@ skipping 2479 matching lines @@
   movl(rax, dividend);
   shrl(rax, Immediate(31));
   addl(rdx, rax);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64