Fix wrong endianness of wasm header in WasmModuleWriter on big-endian platforms

src/base/bits.h

 // Copyright 2014 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.
 
 #ifndef V8_BASE_BITS_H_
 #define V8_BASE_BITS_H_
 
 #include <stdint.h>
 #include "src/base/macros.h"
 #if V8_CC_MSVC
@@ skipping 113 matching lines @@
   return static_cast<unsigned>(result);
 #else
   if (value == 0) return 32;
   unsigned count = 0;
   for (value ^= value - 1; value >>= 1; ++count) {
   }
   return count;
 #endif
 }
 
+inline int16_t ChangeEndianness(int16_t value) {
+#if V8_HAS_BUILTIN_BSWAP16
+  return __builtin_bswap16(value);
+#else
+  return (value << 8) | ((value >> 8) & 0xFF);
+#endif
+}
+
+inline uint16_t ChangeEndianness(uint16_t value) {
+#if V8_HAS_BUILTIN_BSWAP16
+  return __builtin_bswap16(value);
+#else
+  return (value << 8) | (value >> 8);
+#endif
+}
+
+inline int32_t ChangeEndianness(int32_t value) {
+#if V8_HAS_BUILTIN_BSWAP32
+  return __builtin_bswap32(value);
+#else
+  int32_t tmp;
+  tmp = ((value << 8) & 0xFF00FF00) | ((value >> 8) & 0xFF00FF);
+  return (tmp << 16) | ((tmp >> 16) & 0xFFFF);
+#endif
+}
+
+inline uint32_t ChangeEndianness(uint32_t value) {
+#if V8_HAS_BUILTIN_BSWAP32
+  return __builtin_bswap32(value);
+#else
+  int32_t tmp;
+  tmp = ((value << 8) & 0xFF00FF00) | ((value >> 8) & 0xFF00FF);
+  return (tmp << 16) | (tmp >> 16);
+#endif
+}
+
+inline int64_t ChangeEndianness(int64_t value) {
+#if V8_HAS_BUILTIN_BSWAP64
+  return __builtin_bswap64(value);
+#else
+  int64_t tmp;
+  tmp = ((value << 8) & 0xFF00FF00FF00FF00ULL) |
+        ((value >> 8) & 0x00FF00FF00FF00FFULL);
+  tmp = ((tmp << 16) & 0xFFFF0000FFFF0000ULL) |
+        ((tmp >> 16) & 0x0000FFFF0000FFFFULL);
+  return (tmp << 32) | ((tmp >> 32) & 0xFFFFFFFFULL);
+#endif
+}
+
+inline int64_t ChangeEndianness(uint64_t value) {
+#if V8_HAS_BUILTIN_BSWAP64
+  return __builtin_bswap64(value);
+#else
+  int64_t tmp;
+  tmp = ((value << 8) & 0xFF00FF00FF00FF00ULL) |
+        ((value >> 8) & 0x00FF00FF00FF00FFULL);
+  tmp = ((tmp << 16) & 0xFFFF0000FFFF0000ULL) |
+        ((tmp >> 16) & 0x0000FFFF0000FFFFULL);
+  return (tmp << 32) | (tmp >> 32);
+#endif
+}
 
 // CountTrailingZeros64(value) returns the number of zero bits preceding the
 // least significant 1 bit in |value| if |value| is non-zero, otherwise it
 // returns 64.
 inline unsigned CountTrailingZeros64(uint64_t value) {
 #if V8_HAS_BUILTIN_CTZ
   return value ? __builtin_ctzll(value) : 64;
 #else
   if (value == 0) return 64;
   unsigned count = 0;
@@ skipping 171 matching lines @@
 // SignedSaturatedSub64(lhs, rhs) substracts |lhs| by |rhs|,
 // checks and returns the result.
 int64_t SignedSaturatedSub64(int64_t lhs, int64_t rhs);
 
 
 }  // namespace bits
 }  // namespace base
 }  // namespace v8
 
 #endif  // V8_BASE_BITS_H_