Re: Please revert the patches in bug #54040 and #59346 and special case x32
Hi,
Should I file a bug to get feedback on this issue? I know Ada is not the
most prioritized language for gcc, but anyway. The current
implementation is not POSIX-compliant.
On Mon, 2014-03-24 at 14:37 +0100, Svante Signell wrote:
> In reply to the thread ending with:
> http://gcc.gnu.org/ml/gcc-patches/2013-11/msg02069.html
>
> and bugs:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54040
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59346
>
> Changing s-osinte-posix.adb
>
> - tv_nsec => long (Long_Long_Integer (F * 10#1#E9)));
> + tv_nsec => time_t (Long_Long_Integer (F * 10#1#E9)));
>
> breaks the build for kFreeBSD and Hurd too (in addition to hpux and solaris).
>
> Note that POSIX specified tv_nsec to be long (i.e. 64 bit), see:
> http://pubs.opengroup.org/onlinepubs/009695299/basedefs/time.h.html
> The <time.h> header shall declare the structure timespec, which has at
> least the following members:
> time_t tv_sec Seconds.
> long tv_nsec Nanoseconds.
>
> Additionally Linux/kFreeBSD/Hurd all defines struct timespec in time.h as follows:
> /* POSIX.1b structure for a time value. This is like a `struct timeval'
> but
> has nanoseconds instead of microseconds. */
> struct timespec
> {
> __time_t tv_sec; /* Seconds. */
> __syscall_slong_t tv_nsec; /* Nanoseconds. */
> };
>
> So defining tv_nsec to be time_t is completely wrong. The problem seems
> to be present only for the x32 architecture, so why not make a special-case
> solution for that arch. Obviously x32 is non-POSIX compliant since long
> is 32 bits, resulting in tv_nsec being 32 bits where it needs to be 64
> bits. Isn't it possible to handle the differences for x32 with a
> s-osinte-linux-x32.ads file, even with s-osinte-posix.adb stays intact?
>
> Then ther changes would be limited to:
> * s-linux-x32.ads: New file.
> * s-osprim-x32.adb: Likewise.
> * gcc-interface/Makefile.in (LIBGNAT_TARGET_PAIRS): Replace
> s-linux.ads with s-linux-x32.ads, s-osprim-posix.adb with
> s-osprim-x32.adb for x32.
> and the rest would be obsolete:
> * s-linux.ads (time_t): New type.
> * s-linux-alpha.ads (time_t): Likewise.
> * s-linux-hppa.ads (time_t): Likewise.
> * s-linux-mipsel.ads (time_t): Likewise.
> * s-linux-sparc.ads (time_t): Likewise.
> * s-osinte-linux.ads (time_t): Mark it private. Replace long
> with System.Linux.time_t.
> (timespec): Replace long with time_t.
> * s-osinte-posix.adb (To_Timespec): Likewise.
> * s-taprop-linux.adb (timeval): Replace C.long with
> System.OS_Interface.time_t.
> and
> * s-osinte-hpux.ads (timespec): Change type of tv_nsec field to time_t.
> * s-osinte-kfreebsd-gnu.ads (timespec): Likewise.
> * s-osinte-solaris-posix.ads (timespec): Likewise.
>
> Possible content in s-osinte-linux-x32.ads would be:
> type tv_nsec_t is private;
> type tv_nsec_t is new Long_Long_Integer;
> type timespec is record
> tv_sec : time_t;
> tv_nsec : tv_nsec_t;
> end record;
> pragma Convention (C, timespec);
>
>
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