[wasm] Add native x64 implementations for I32x4Splat, I32x4ExtractLane

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 6dacc011df3be1672136a6d4f521c74a368a00d3..874fbae28b8e085058df95919e8e5bce9f33b234 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -3325,12 +3325,12 @@ void MacroAssembler::Pextrd(Register dst, XMMRegister src, int8_t imm8) {
     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));
 }