Re: Three weeks to branching (gdb 7.5 release)

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Sun, May 20, 2012 at 1:43 PM, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
>> Date: Sun, 20 May 2012 08:40:26 -0700
>> From: "H.J. Lu" <hjl.tools@gmail.com>
>>
>> On Fri, May 11, 2012 at 11:43 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> > On Fri, May 11, 2012 at 11:17 AM, Joel Brobecker <brobecker@adacore.com> wrote:
>> >> Hello,
>> >>
>> >> Just a quick heads up: The current tentative date for branching
>> >> GDB (7.5 release) is Mon Jun 4th, which is a little over three weeks
>> >> away.
>> >>
>> >> I've created a wiki page for known issues that need to be fixed
>> >> before then:
>> >>
>> >> ? ?http://sourceware.org/gdb/wiki/GDB_7.5_Release
>> >>
>> >> When you add an issue, please make sure you add a name so we know
>> >> who is coordinating the effort. ?If you don't know who can work
>> >> on it, please just post the issue here, and we'll try to find some
>> >> help.
>> >>
>> >> I only know of one issue, which is a noticeable performance degradation
>> >> that was reported a while ago:
>> >>
>> >
>> > I'd like to merge x32 into GDB 7.5. ?My x32 change is on hjl/x32/master
>> > branch at
>> >
>> > http://sourceware.org/git/?p=gdb.git;a=summary
>> >
>> > The current diff only has 864 lines. ?One patch:
>> >
>> > http://sourceware.org/ml/gdb-patches/2012-05/msg00097.html
>> >
>> > isn't reviewed yet. ?I will open a meta bug for x32 integration.
>> >
>>
>> I opened:
>>
>> http://sourceware.org/bugzilla/show_bug.cgi?id=14099
>>
>> Thanks for help from everyone. ?The full GDBserver x32 support
>> as well as partial GDB x32 support have been checked in. ?The
>> remaining patches are:
>>
>> http://sourceware.org/ml/gdb-patches/2012-04/msg00195.html
>> http://sourceware.org/ml/gdb-patches/2012-04/msg00191.html
>> http://sourceware.org/ml/gdb-patches/2012-05/msg00744.html
>> http://sourceware.org/ml/gdb-patches/2012-05/msg00531.html
>> http://sourceware.org/ml/gdb-patches/2012-05/msg00533.html
>> http://sourceware.org/ml/gdb-patches/2012-05/msg00489.html
>> http://sourceware.org/ml/gdb-patches/2012-05/msg00438.html
>> http://sourceware.org/ml/gdb-patches/2012-05/msg00097.html
>>
>> I would appreciate help to get them reviewed and approved.
>
> As I wrote before, I don't think adding lots if if-statements is the
> proper way to add a new ABI to GDB. ?The proper way is to do it like
> the diff below. ?In that diff, I'm not entirely confident that calling
> amd64_linux_init_abi() from amd64_x32_linux_init_abi() makes all that
> much sense. ?For example the amd64_linux_record_tdep stuff probably
> isn't right for the x32 ABI. ?But at least this will give us a
> starting point where we won't end up adding
>
> ?if (gdbarch_ptr_bit (gdbarch) == 32)
> ? ?{
> ? ? ?...
> ? ?}

Please take a look at

http://sourceware.org/ml/gdb-patches/2012-04/msg00195.html

It doesn't add any  (gdbarch_ptr_bit (gdbarch) == 32).  It just changes
it to bits_per_word.  I add one  "gdbarch_ptr_bit (gdbarch) == 32" in
amd64_linux_sigtramp_start and I will remove them from

http://sourceware.org/ml/gdb-patches/2012-05/msg00744.html

> ?else
> ? ?{
> ? ?}
>
> blocks all over the place.
>
>
>
> Index: amd64-linux-tdep.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/amd64-linux-tdep.c,v
> retrieving revision 1.50
> diff -u -p -r1.50 amd64-linux-tdep.c
> --- amd64-linux-tdep.c ?12 May 2012 08:54:03 -0000 ? ? ?1.50
> +++ amd64-linux-tdep.c ?20 May 2012 20:31:53 -0000
> @@ -1543,6 +1543,24 @@ amd64_linux_init_abi (struct gdbarch_inf
>
> ? tdep->i386_syscall_record = amd64_linux_syscall_record;
> ?}
> +
> +static void
> +amd64_x32_linux_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)
> +{
> + ?struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
> + ?const struct target_desc *tdesc = info.target_desc;
> +
> + ?amd64_linux_init_abi (info, gdbarch);
> + ?amd64_x32_init_abi (info, gdbarch);
> +
> + ?if (! tdesc_has_registers (tdesc))
> + ? ?tdesc = tdesc_amd64_linux;

I assume you meant tdesc_x32_linux here.  The problem is
when we reach here, if (! tdesc_has_registers (tdesc)) will always
be false since tdep->tdesc has been set by amd64_linux_init_abi.

> + ?tdep->tdesc = tdesc;
> +
> + ?/* GNU/Linux uses SVR4-style shared libraries. ?*/
> + ?set_solib_svr4_fetch_link_map_offsets
> + ? ?(gdbarch, svr4_ilp32_fetch_link_map_offsets);
> +}
>
>
> ?/* Provide a prototype to silence -Wmissing-prototypes. ?*/
> @@ -1553,6 +1571,8 @@ _initialize_amd64_linux_tdep (void)
> ?{
> ? gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
> ? ? ? ? ? ? ? ? ? ? ? ? ?GDB_OSABI_LINUX, amd64_linux_init_abi);
> + ?gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x64_32,
> + ? ? ? ? ? ? ? ? ? ? ? ? GDB_OSABI_LINUX, amd64_x32_linux_init_abi);
>
> ? /* Initialize the Linux target description. ?*/
> ? initialize_tdesc_amd64_linux ();
> Index: amd64-tdep.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/amd64-tdep.c,v
> retrieving revision 1.104
> diff -u -p -r1.104 amd64-tdep.c
> --- amd64-tdep.c ? ? ? ?14 May 2012 18:56:40 -0000 ? ? ?1.104
> +++ amd64-tdep.c ? ? ? ?20 May 2012 20:31:54 -0000
> @@ -258,7 +258,8 @@ static const char *amd64_word_names[] =
> ?static const char *amd64_dword_names[] =
> ?{
> ? "eax", "ebx", "ecx", "edx", "esi", "edi", "ebp", "esp",
> - ?"r8d", "r9d", "r10d", "r11d", "r12d", "r13d", "r14d", "r15d"
> + ?"r8d", "r9d", "r10d", "r11d", "r12d", "r13d", "r14d", "r15d",
> + ?"eip"
> ?};
>
> ?/* Return the name of register REGNUM. ?*/
> @@ -2729,6 +2730,43 @@ amd64_init_abi (struct gdbarch_info info
> ? set_gdbarch_stap_parse_special_token (gdbarch,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?i386_stap_parse_special_token);
> ?}
> +
> +
> +static struct type *
> +amd64_x32_pseudo_register_type (struct gdbarch *gdbarch, int regnum)
> +{
> + ?struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
> +
> + ?switch (regnum - tdep->eax_regnum)
> + ? ?{
> + ? ?case AMD64_RBP_REGNUM: ? ? /* %ebp */
> + ? ?case AMD64_RSP_REGNUM: ? ? /* %esp */
> + ? ? ?return builtin_type (gdbarch)->builtin_data_ptr;
> + ? ?case AMD64_RIP_REGNUM: ? ? /* %eip */
> + ? ? ?return builtin_type (gdbarch)->builtin_func_ptr;
> + ? ?}
> +
> + ?return i386_pseudo_register_type (gdbarch, regnum);
> +}
> +
> +void
> +amd64_x32_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
> +{
> + ?struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
> + ?const struct target_desc *tdesc = info.target_desc;
> +
> + ?amd64_init_abi (info, gdbarch);
> +
> + ?if (! tdesc_has_registers (tdesc))
> + ? ?tdesc = tdesc_x32;

Again, " if (! tdesc_has_registers (tdesc))" will always false
since tdep->tdesc has been set in amd64_init_abi.  How
do we solve it?  My suggestion is to add a new function
which is similar to amd64_init_abi, but takes a new argument,
const struct target_desc *, as the default tdesc. Both
amd64_init_abi and amd64_x32_init_abi will call this
function.  Will it work for you?

Thanks.


-- 
H.J.