Re: gcc/amd64 head build error after r281316

On 08 Jul 2015, at 19:05, Luigi Rizzo <rizzo_at_iet.unipi.it> wrote:
> 
> the r281316 commit introduces the following lines
> which break compilation with gcc on amd64 (as far as i know
> immintrin.h is only available in our clang).
> If there are no objections I'd like to add a further check
> for the use of clang, see attached patch
> 
> Index: /home/luigi/FreeBSD/head/lib/liblzma/config.h
> ===================================================================
> --- /home/luigi/FreeBSD/head/lib/liblzma/config.h       (revision 285281)
> +++ /home/luigi/FreeBSD/head/lib/liblzma/config.h       (working copy)
> _at__at_ -150,7 +150,7 _at__at_
> #define HAVE_ICONV 1
> 
> /* Define to 1 if you have the <immintrin.h> header file. */
> -#if defined(__FreeBSD__) && defined(__amd64__)
> +#if defined(__clang__) && defined(__FreeBSD__) && defined(__amd64__)
> #define HAVE_IMMINTRIN_H 1
> #endif

Hi Luigi,

I just saw you already committed this, but can we change this so it also
detects gcc >= 4.4.0, where immintrin.h was introduced?  So then it
works nicely for external gcc's too.

E.g.:

Index: lib/liblzma/config.h
===================================================================
--- lib/liblzma/config.h        (revision 285287)
+++ lib/liblzma/config.h        (working copy)
_at__at_ -151,7 +151,9 _at__at_

 /* Define to 1 if you have the <immintrin.h> header file. */
 /* FreeBSD - only with clang because the base gcc does not support it */
-#if defined(__clang__) && defined(__FreeBSD__) && defined(__amd64__)
+#if (defined(__clang__) || \
+    __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR >= 4)) \
+    && defined(__FreeBSD__) && defined(__amd64__)
 #define HAVE_IMMINTRIN_H 1
 #endif

Additionally, why are we checking for __FreeBSD__ here?  This config
file is very specifically for use during buildworld, so I don't see the
use in checking it at all.

-Dimitry