From: Mike Hommey <mh@glandium.org>
Date: Wed, 15 Feb 2023 08:44:19 +0900
Subject: Use compiler macros to detect big endian

Both clang and GCC define endianness as builtin defines.
---
 third_party/wasm2c/src/common.h                  | 8 ++++++++
 third_party/wasm2c/src/prebuilt/wasm2c.include.c | 8 ++++++++
 third_party/wasm2c/src/wasm2c.c.tmpl             | 8 ++++++++
 3 files changed, 24 insertions(+)

diff --git a/third_party/wasm2c/src/common.h b/third_party/wasm2c/src/common.h
index de5e44a..c4eb760 100644
--- a/third_party/wasm2c/src/common.h
+++ b/third_party/wasm2c/src/common.h
@@ -103,6 +103,14 @@
 #define PRIaddress PRIu64
 #define PRIoffset PRIzx
 
+#ifndef WABT_BIG_ENDIAN
+#  if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#    define WABT_BIG_ENDIAN 1
+#  elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#    define WABT_BIG_ENDIAN 0
+#  endif
+#endif
+
 namespace wabt {
 #if WABT_BIG_ENDIAN
   inline void MemcpyEndianAware(void *dst, const void *src, size_t dsize, size_t ssize, size_t doff, size_t soff, size_t len) {
diff --git a/third_party/wasm2c/src/prebuilt/wasm2c.include.c b/third_party/wasm2c/src/prebuilt/wasm2c.include.c
index de62978..5040afa 100644
--- a/third_party/wasm2c/src/prebuilt/wasm2c.include.c
+++ b/third_party/wasm2c/src/prebuilt/wasm2c.include.c
@@ -113,6 +113,14 @@ const char SECTION_NAME(declarations)[] =
 "#define wasm_asm(X)\n"
 "#endif\n"
 "\n"
+"#ifndef WABT_BIG_ENDIAN\n"
+"#  if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__\n"
+"#    define WABT_BIG_ENDIAN 1\n"
+"#  elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__\n"
+"#    define WABT_BIG_ENDIAN 0\n"
+"#  endif\n"
+"#endif\n"
+"\n"
 "#if WABT_BIG_ENDIAN\n"
 "static inline void load_data(void *dest, const void *src, size_t n) {\n"
 "  size_t i = 0;\n"
diff --git a/third_party/wasm2c/src/wasm2c.c.tmpl b/third_party/wasm2c/src/wasm2c.c.tmpl
index 6539ddc..990bb2f 100644
--- a/third_party/wasm2c/src/wasm2c.c.tmpl
+++ b/third_party/wasm2c/src/wasm2c.c.tmpl
@@ -110,6 +110,14 @@ void WASM2C_MALLOC_FAIL_CALLBACK(u32 ptr_size);
 #define wasm_asm(X)
 #endif
 
+#ifndef WABT_BIG_ENDIAN
+#  if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#    define WABT_BIG_ENDIAN 1
+#  elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#    define WABT_BIG_ENDIAN 0
+#  endif
+#endif
+
 #if WABT_BIG_ENDIAN
 static inline void load_data(void *dest, const void *src, size_t n) {
   size_t i = 0;