Bug compiling the C version of memset with gcc -O3

[Alexander Holler <holler at ahsoftware dot de>]

Hello,

I've stumbled over bug compiling newlib 2.0 for ARM with gcc and -O3.

I'm quoting from http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59420

----
The issue is there is a loop inside of memset that gets converted to a 
call to
memset; that is if I read the assembly code correctly.  if that is the case
then this is a bug in the newlib makefiles as they should be using
-fno-tree-loop-distribute-patterns or like what glibc does:
/* Add the compiler optimization to inhibit loop transformation to library
   calls.  This is used to avoid recursive calls in memset and memmove
   default implementations.  */
#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
# define inhibit_loop_to_libcall \
    __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
#else
# define inhibit_loop_to_libcall
#endif

So closing as invalid, please report this to newlib.

Note the work around is not to use -O3 or use -O3
-fno-tree-loop-distribute-patterns .

----

The bug was likely not discovered before, because most architectures 
except ARM are using optimized (assembler) versions for memset.

The C comment above (likely from glibc) sounds like memmove might be too 
a victim of that optimization of gcc, but I haven't tested it up to now.

Regards,

Alexander Holler