[Patch, libfortran] Improve performance of byte swapped IO

[Andreas Schwab]

Janne Blomqvist <blomqvist.janne@gmail.com> writes:

> diff --git a/libgfortran/io/file_pos.c b/libgfortran/io/file_pos.c
> index c8ecc3a..bf2250a 100644
> --- a/libgfortran/io/file_pos.c
> +++ b/libgfortran/io/file_pos.c
> @@ -140,15 +140,21 @@ unformatted_backspace (st_parameter_filepos *fpp, gfc_unit *u)
>  	}
>        else
>  	{
> +	  uint32_t u32;
> +	  uint64_t u64;
>  	  switch (length)
>  	    {
>  	    case sizeof(GFC_INTEGER_4):
> -	      reverse_memcpy (&m4, p, sizeof (m4));
> +	      memcpy (&u32, p, sizeof (u32));
> +	      u32 = __builtin_bswap32 (u32);
> +	      m4 = *(GFC_INTEGER_4*)&u32;

Isn't that an aliasing violation?

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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