Fix use of uninitialized value in WastParser::ParseSimdV128Const.

Author: wffurr

src/wast-parser.cc

@@ -2873,24 +2873,28 @@ Result WastParser::ParseSimdV128Const(Const* const_,
         case 16: {
           uint8_t value = 0;
           result = ParseInt8(sv, &value, ParseIntType::SignedAndUnsigned);
+          if (Failed(result)) break;
           const_->set_v128_u8(lane, value);
           break;
         }
         case 8: {
           uint16_t value = 0;
           result = ParseInt16(sv, &value, ParseIntType::SignedAndUnsigned);
+          if (Failed(result)) break;
           const_->set_v128_u16(lane, value);
           break;
         }
         case 4: {
           uint32_t value = 0;
           result = ParseInt32(sv, &value, ParseIntType::SignedAndUnsigned);
+          if (Failed(result)) break;
           const_->set_v128_u32(lane, value);
           break;
         }
         case 2: {
           uint64_t value = 0;
           result = ParseInt64(sv, &value, ParseIntType::SignedAndUnsigned);
+          if (Failed(result)) break;
           const_->set_v128_u64(lane, value);
           break;
         }
@@ -2900,16 +2904,20 @@ Result WastParser::ParseSimdV128Const(Const* const_,
       switch (lane_count) {
         case 4:
           result = ParseF32(&lane_const_, const_type);
+          if (Failed(result)) break;
           const_->set_v128_f32(lane, lane_const_.f32_bits());
           break;
 
         case 2:
           result = ParseF64(&lane_const_, const_type);
+          if (Failed(result)) break;
           const_->set_v128_f64(lane, lane_const_.f64_bits());
           break;
       }
 
-      const_->set_expected_nan(lane, lane_const_.expected_nan());
+      if (Succeeded(result)) {
+        const_->set_expected_nan(lane, lane_const_.expected_nan());
+      }
     }
 
     if (Failed(result)) {