[wasm-simd][fuzzer] Add i8x16.popcnt to fuzzer

Also move it from post-mvp to mvp, since it is now in the proposal.

Bug: v8:11002
Change-Id: I711ee7a92e6937948c93e6028ef018188ea4c976
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2676937Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72643}

src/wasm/wasm-opcodes.h

@@ -392,6 +392,7 @@ bool V8_EXPORT_PRIVATE IsJSCompatibleSignature(const FunctionSig* sig,
   V(I8x16MaxS, 0xfd78, s_ss)                 \
   V(I8x16MaxU, 0xfd79, s_ss)                 \
   V(I8x16RoundingAverageU, 0xfd7b, s_ss)     \
+  V(I8x16Popcnt, 0xfd7c, s_s)                \
   V(I16x8Abs, 0xfd80, s_s)                   \
   V(I16x8Neg, 0xfd81, s_s)                   \
   V(V16x8AllTrue, 0xfd83, i_s)               \
@@ -510,7 +511,6 @@ bool V8_EXPORT_PRIVATE IsJSCompatibleSignature(const FunctionSig* sig,
 
 #define FOREACH_SIMD_POST_MVP_OPCODE(V)     \
   V(I8x16Mul, 0xfd75, s_ss)                 \
-  V(I8x16Popcnt, 0xfd7c, s_s)               \
   V(I8x16SignSelect, 0xfd7d, s_sss)         \
   V(I16x8SignSelect, 0xfd7e, s_sss)         \
   V(I32x4SignSelect, 0xfd7f, s_sss)         \

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

@@ -2742,7 +2742,6 @@ WASM_SIMD_TEST(I8x16Abs) {
 }
 
 WASM_SIMD_TEST_NO_LOWERING(I8x16Popcnt) {
-  FLAG_SCOPE(wasm_simd_post_mvp);
   WasmRunner<int32_t, int32_t> r(execution_tier, lower_simd);
   // Global to hold output.
   int8_t* g = r.builder().AddGlobal<int8_t>(kWasmS128);

test/fuzzer/wasm-compile.cc

@@ -1317,6 +1317,7 @@ void WasmGenerator::Generate<ValueType::kS128>(DataRange* data) {
                                      ValueType::kS128>,
       &WasmGenerator::op_with_prefix<kExprI8x16RoundingAverageU,
                                      ValueType::kS128, ValueType::kS128>,
+      &WasmGenerator::op_with_prefix<kExprI8x16Popcnt, ValueType::kS128>,
 
       &WasmGenerator::op_with_prefix<kExprI16x8Splat, ValueType::kI32>,
       &WasmGenerator::op_with_prefix<kExprI16x8Eq, ValueType::kS128,