On Wed, Mar 16, 2022 at 1:31 PM Roger Sayle <ro...@nextmovesoftware.com> wrote:
>
>
> This patch is the second of two changes to genmatch that don't affect
> the executable code, but reduce the amount of debugging information
> generated in stage3 of a build, but adhering more closely to GNU style
> guidelines.
>
> This patch avoids generating "next_after_fail1:;" label statements
> in genmatch, if this label is unused/never referenced as the target
> of a goto. Because jumps to these labels are always forwards, we
> know at the point the label is emitted whether it is used or not.
> Because a debugger may set a breakpoint these labels, this increase
> the size of g{imple,eneric}-match.o in a stage3 build. To save a
> little extra space, I also shorten the label to "Lfail1:;" and only
> increment the counter when necessary. This reduces the size of
> gimple-match.o by 58K on x86_64-pc-linux-gnu.
>
> This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> and make -k check with no new failures. Ok for mainline?
I wonder if we could make this nicer by abstracting sth like
class fail_label
{
fail_label (unsigned num);
emit_goto () { fprintf (..., "goto L%u", num); used = true; }
emit_label () { fprintf ("L%u:;\n", num); }
unsigned num;
bool used;
};
or some better abstraction capturing all of the global state.
>
>
> 2022-03-16 Roger Sayle <ro...@nextmovesoftware.com>
>
> gcc/ChangeLog
> * gcc/genmatch.cc (fail_label_used): New global variable.
> (expr::gen_transform): Set fail_label_used whenever a goto
> FAIL_LABEL is generated.
> (dt_simplify::gen_1): Clear fail_label_used when generating
> a new (provisional) fail_label. Set fail_label used whenever
> a goto fail_label is generated. Avoid emitting fail_label:
> if fail_label_used is false, instead decrement fail_label_cnt.
>
>
> Thanks in advance,
> Roger
> --
>
