Re: Add .def file for public target instructions

[Richard Sandiford <richard.sandiford@arm.com>]

"H.J. Lu" <hjl.tools@gmail.com> writes:
> On Thu, Jun 25, 2015 at 4:37 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Thu, Jun 25, 2015 at 4:00 PM, Andrew Pinski <pinskia@gmail.com> wrote:
>>> On Thu, Jun 25, 2015 at 3:57 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>>> On Thu, Jun 25, 2015 at 1:09 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>>>> On Tue, Jun 23, 2015 at 11:41 AM, Richard Sandiford
>>>>> <rdsandiford@googlemail.com> wrote:
>>>>>> [A fair bit later than promised, sorry...]
>>>>>>
>>>>>> Mikhail posted a patch to make genflags generate the default HAVE_foo
>>>>>> and gen_foo definitions that have recently been added to defaults.h:
>>>>>>
>>>>>>   https://gcc.gnu.org/ml/gcc-patches/2015-06/msg00723.html
>>>>>>
>>>>>> I agree it'd be a good idea to generate this kind of thing automatically,
>>>>>> but I think we should take the opportunity to move the interface to the
>>>>>> target structure.  I.e.:
>>>>>>
>>>>>>   HAVE_foo -> targetm.have_foo ()
>>>>>>   gen_foo -> targetm.gen_foo ()
>>>>>>
>>>>>> This should move us closer to the pipedream goal of supporting multiple
>>>>>> targets at once.  It should also mean that only the target code depends
>>>>>> on insn-flags.h.
>>>>>>
>>>>>> The patch just moves return and simple_return as an example.  I have more
>>>>>> locally (in order to test other code paths), but they're just an obvious
>>>>>> extension of this one.
>>>>>>
>>>>>> The patch relies on the hashing changes in:
>>>>>>
>>>>>>   https://gcc.gnu.org/ml/gcc-patches/2015-06/msg01066.html
>>>>>>   https://gcc.gnu.org/ml/gcc-patches/2015-06/msg01564.html
>>>>>>
>>>>>> and on this trivial patch:
>>>>>>
>>>>>>   https://gcc.gnu.org/ml/gcc-patches/2015-06/msg01604.html
>>>>>>
>>>>>> It seems a bit heavyweight when you just look at these two instructions,
>>>>>> but I think it'll be a saving in the end.
>>>>>>
>>>>>> Bootstrapped & regression-tested on x86_64-linux-gnu.  Also tested
>>>>>> via config-list.mk.  OK to install?
>>>>>>
>>>>>> Thanks,
>>>>>> Richard
>>>>>>
>>>>>>
>>>>>> gcc/
>>>>>>         * Makefile.in (TARGET_DEF): Add target-insns.def.
>>>>>>         (.PRECIOUS, simple_rtl_generated_h): Add insn-target-def.h.
>>>>>>         (build/gentarget-def.o): New rule.
>>>>>>         (genprogrtl): Add target-def.
>>>>>>         * target-insns.def, gentarget-def.c: New files.
>>>>>>         * target.def: Add targetm.have_* and targetm.gen_* hooks,
>>>>>>         based on the contents of target-insns.def.
>>>>>>         * defaults.h (HAVE_simple_return, gen_simple_return): Delete.
>>>>>>         (HAVE_return, gen_return): Delete.
>>>>>>         * target-def.h: Include insn-target-def.h.
>>>>>>         * cfgrtl.c (force_nonfallthru_and_redirect): Use targetm interface
>>>>>>         instead of direct calls.  Rely on them to do the appropriate assertions.
>>>>>>         * function.c (gen_return_pattern): Likewise.  Return an rtx_insn *.
>>>>>>         (convert_jumps_to_returns): Use targetm interface instead of
>>>>>>         direct calls.
>>>>>>         (thread_prologue_and_epilogue_insns): Likewise.
>>>>>>         * reorg.c (find_end_label, dbr_schedule): Likewise.
>>>>>>         * shrink-wrap.h (SHRINK_WRAPPING_ENABLED): Likewise.
>>>>>>         * shrink-wrap.c (convert_to_simple_return): Likewise.
>>>>>>         (try_shrink_wrapping): Use SHRINK_WRAPPING_ENABLED.
>>>>>>
>>>>>
>>>>> This breaks bootstrap on Linux/ia32:
>>>>>
>>>>> https://gcc.gnu.org/ml/gcc-regression/2015-06/msg00649.html
>>>>>
>>>>> ../../src-trunk/gcc/gentarget-def.c: In function âvoid
>>>>> def_target_insn(const char*, const char*)â:
>>>>> ../../src-trunk/gcc/gentarget-def.c:88:34: error: comparison between
>>>>> signed and unsigned integer expressions [-Werror=sign-compare]
>>>>>   if (strtol (p + 1, &endptr, 10) != opno
>>>>>
>>>>
>>>> There are
>>>>
>>>>   unsigned int opno = 0;
>>>>   for (const char *p = prototype; *p; ++p)
>>>>     if (*p == 'x' && ISDIGIT (p[1]))
>>>>       {
>>>>         /* This should be a parameter name of the form "x<OPNO>".
>>>>            That doesn't contribute to the suffix, so skip ahead and
>>>>            process the following character.  */
>>>>         char *endptr;
>>>>         if (strtol (p + 1, &endptr, 10) != opno
>>>>             || (*endptr != ',' && *endptr != ')'))
>>>>
>>>> strtol returns long int.  Somehow, there is no warning on x86-64.
>>>
>>> Because on x86_64 (and all LP64 targets), the comparison gets promoted
>>> to long (which is 64bit) so the conversion from unsigned int to long
>>> does not lose precision.
>>>
>>
>> I am testing this.
>>
>>
>> --
>> H.J.
>> ---
>> diff --git a/gcc/gentarget-def.c b/gcc/gentarget-def.c
>> index d4839e8..3ca9cfd 100644
>> --- a/gcc/gentarget-def.c
>> +++ b/gcc/gentarget-def.c
>> @@ -77,7 +77,7 @@ def_target_insn (const char *name, const char *prototype)
>>       together to get a suffix.  */
>>    char *suffix = XALLOCAVEC (char, strlen (prototype) + 1);
>>    i = 0;
>> -  unsigned int opno = 0;
>> +  long opno = 0;
>>    for (const char *p = prototype; *p; ++p)
>>      if (*p == 'x' && ISDIGIT (p[1]))
>>        {
>
> It doesn't work.  I checked in this patch instead.

Thanks H.J., and sorry for the breakage.

Richard