[MSan] Endianness should not matter while printing a byte

[mohit.bhakkad]

Summary

Print the hex digits of each byte in the most significant first order, and print different bytes in the memory order.

[eugenis]

Looks good, but it should be in the same commit as the test change, otherwise it would break the tests on little-endian targets.

[mohit.bhakkad]

In D17563#362157, @eugenis wrote:

Looks good, but it should be in the same commit as the test change, otherwise it would break the tests on little-endian targets.

Sure, I will commit both revisions together. Are you okay with new revision of D17264?

[eugenis]

yes

[mohit.bhakkad]

Commited in rL261982.

lib/msan/msan.cc

 
 void __msan_dump_shadow(const void *x, uptr size) {
   if (!MEM_IS_APP(x)) {
     Printf("Not a valid application address: %p\n", x);
     return;
   }
 
   unsigned char *s = (unsigned char*)MEM_TO_SHADOW(x);
-  for (uptr i = 0; i < size; i++) {
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-    Printf("%x%x ", s[i] & 0xf, s[i] >> 4);
-#else
+  for (uptr i = 0; i < size; i++)
     Printf("%x%x ", s[i] >> 4, s[i] & 0xf);
-#endif
-  }
   Printf("\n");
 }
 
 sptr __msan_test_shadow(const void *x, uptr size) {
   if (!MEM_IS_APP(x)) return -1;
   unsigned char *s = (unsigned char *)MEM_TO_SHADOW((uptr)x);
   for (uptr i = 0; i < size; ++i)
     if (s[i])

lib/msan/msan_report.cc

if (pos % 4 == 0) {
       last_quad_poisoned = false;
     }
     // Print shadow byte.
     if (s < start || s >= end) {
       Printf("..");
     } else {
       unsigned char v = *(unsigned char *)s;
       if (v) last_quad_poisoned = true;
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-      Printf("%x%x", v & 0xf, v >> 4);
-#else
       Printf("%x%x", v >> 4, v & 0xf);
-#endif
     }
     // Group end.
     if (pos % 4 == 3 && with_origins) {
       int id = OriginSet::MISSING;
       if (last_quad_poisoned) {
         u32 o = *(u32 *)SHADOW_TO_ORIGIN(s - 3);
         id = origin_set.insert(o);
       }