struct gmon_cg_arc_record

[Jes Sorensen]

64 bit port maintainers please read!

>>>>> "Ulrich" == Ulrich Drepper <drepper@redhat.com> writes:

Ulrich> Hum, for new 64-bit architecture I'd suggest changing the
Ulrich> on-disk format.  There is no reason to make things slower than
Ulrich> necessary.

Ok

Ulrich> For Alpha, I'd also go with a new format if rth thinks this is
Ulrich> OK.

Ulrich> The [4] in the data structure definition clearly is motivated
Ulrich> by the use in 32-bit architecture.

Hmmm something is certainly fishy here, comparing glibc-2.2 with the
difinitions found in gprof it looks like we should update glibc to
match gprof.

Ie. the arc structure in gprof looks like this:

struct raw_arc
  {
    /* FIXME: Checking a host compiler define means that we can't use
       a cross gprof to the alpha.  */
#ifdef __alpha__
    char from_pc[8];
    char self_pc[8];
    char count[8];
#else
    char from_pc[4];
    char self_pc[4];
    char count[4];
#endif
  };

We also have a mismatch in gmon_list_hdr: in glibc it looks like this:

struct gmon_hist_hdr
  {
    char low_pc[sizeof (char *)];       /* base pc address of sample buffer */
    char high_pc[sizeof (char *)];      /* max pc address of sampled buffer */
    char hist_size[4];                  /* size of sample buffer */
    char prof_rate[4];                  /* profiling clock rate */
    char dimen[15];                     /* phys. dim., usually "seconds" */
    char dimen_abbrev;                  /* usually 's' for "seconds" */
  };

For gprof it looks like this - note the extra version field:

struct raw_phdr
  {
    /* FIXME: Checking a host compiler define means that we can't use
       a cross gprof to the alpha.  */
#ifdef __alpha__
    char low_pc[8];             /* base pc address of sample buffer */
    char high_pc[8];            /* max pc address of sampled buffer */
#else
    char low_pc[4];             /* base pc address of sample buffer */
    char high_pc[4];            /* max pc address of sampled buffer */
#endif
    char ncnt[4];               /* size of sample buffer (plus this header) */

    char version[4];            /* version number */
    char profrate[4];           /* profiling clock rate */
    char spare[3*4];            /* reserved */
  };

My suggestion would be that we change count in gmon_cg_arc_record to
sizeof(char *) like it is in gprof and introduce the version field as
well.

Two questions, how will the latter affect architectures like the x86?
Second what about Sparc64/MIPS64/PPC64? Do you guys have profile
support running already that will break from this?

Jes