On Wed, 4 May 2022, Jakub Jelinek wrote:
> Hi!
>
> Somebody complained on IRC that when writing a new backend one can get
> an error while compiling build/gencondmd.cc.
> The problem is that when host compiler is g++ 3 or later (or when
> bootstrapping), we compile it with g++ -std=c++11 -pedantic and
> the generated insn_conditions array contains pairs
> { "cond", __builtin_constant_p (cond) ? (int) (cond) : -1 },
> where cond is some non-trivial instruction condition. Now if a target
> uses "" for all the conditions (admittedly unlikely for non-trivial
> target), the initializer for insn_conditions[] is {} and that is
> pedantically rejected because C++ doesn't support zero-sized arrays.
>
> The following patch fixes that by adding an artificial termination
> element and skips that during the walk.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, no change in
> generated insn-conditions.md with it. Ok for trunk?
OK.
I wonder what the generated GCC_VERSION conditions are about ...
Richard.
> 2022-05-04 Jakub Jelinek <ja...@redhat.com>
>
> * genconditions.cc (write_conditions): Append a { nullptr, -1 }
> element at the end of insn_conditions.
> (write_writer): Use ARRAY_SIZE (insn_conditions) - 1 instead of
> ARRAY_SIZE (insn_conditions).
>
> --- gcc/genconditions.cc.jj 2022-01-18 11:58:59.586981999 +0100
> +++ gcc/genconditions.cc 2022-05-03 20:01:59.428065439 +0200
> @@ -175,7 +175,7 @@ static const struct c_test insn_conditio
>
> traverse_c_tests (write_one_condition, 0);
>
> - puts ("\n};\n#endif /* gcc >= 3.0.1 */\n");
> + puts (" { nullptr, -1 }\n};\n#endif /* gcc >= 3.0.1 */\n");
> }
>
> /* Emit code which will convert the C-format table to a
> @@ -192,7 +192,7 @@ write_writer (void)
> " const char *p;\n"
> " puts (\"(define_conditions [\");\n"
> "#if GCC_VERSION >= 3001\n"
> - " for (i = 0; i < ARRAY_SIZE (insn_conditions); i++)\n"
> + " for (i = 0; i < ARRAY_SIZE (insn_conditions) - 1; i++)\n"
> " {\n"
> " printf (\" (%d \\\"\", insn_conditions[i].value);\n"
> " for (p = insn_conditions[i].expr; *p; p++)\n"
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
