On Thu, 21 Nov 2019, Jakub Jelinek wrote:
> Hi!
>
> This patch doesn't fix the actual bug somewhere else, where inserting
> stmts on the edge between resx and corresponding landing pad confuses
> ehcleanup2, but attempts to restore previous behavior in the heuristics,
> which is IMHO desirable too (and makes the bug latent).
> r254698 changed:
> if (bb_loop_depth (best_bb) == bb_loop_depth (early_bb)
> - && best_bb->count.to_frequency (cfun)
> - < (early_bb->count.to_frequency (cfun) * threshold / 100.0))
> + /* If result of comparsion is unknown, preffer EARLY_BB.
> + Thus use !(...>=..) rather than (...<...) */
> + && !(best_bb->count.apply_scale (100, 1)
> + > (early_bb->count.apply_scale (threshold, 1))))
> return best_bb;
> I understand the difference between x < y and !(x >= y), profile_count
> comparisons are partial ordering, but the old x < y corresponds to
> !(x >= y) as the comment says, not to !(x > y) as the patch implemented.
> On the testcase, we have
> something;
> resx 4;
> and the count on the resx 4; bb is already zero, it is already something
> invoked after first throw, there is no advantage to sink statements across
> the resx 4; to the fallthru (across EH edge) bb, because both bbs will be
> executed exactly the same times.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
> 2019-11-21 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/91355
> * tree-ssa-sink.c (select_best_block): Use >= rather than >
> for early_bb scaled count with best_bb count comparison.
>
> * g++.dg/torture/pr91355.C: New test.
>
> --- gcc/tree-ssa-sink.c.jj 2019-11-20 14:25:19.081593017 +0100
> +++ gcc/tree-ssa-sink.c 2019-11-20 15:44:13.763686288 +0100
> @@ -228,7 +228,7 @@ select_best_block (basic_block early_bb,
> /* If result of comparsion is unknown, prefer EARLY_BB.
> Thus use !(...>=..) rather than (...<...) */
> && !(best_bb->count.apply_scale (100, 1)
> - > (early_bb->count.apply_scale (threshold, 1))))
> + >= early_bb->count.apply_scale (threshold, 1)))
> return best_bb;
>
> /* No better block found, so return EARLY_BB, which happens to be the
> --- gcc/testsuite/g++.dg/torture/pr91355.C.jj 2019-11-20 17:21:49.428962914
> +0100
> +++ gcc/testsuite/g++.dg/torture/pr91355.C 2019-11-20 17:23:46.370210313
> +0100
> @@ -0,0 +1,28 @@
> +// PR tree-optimization/91355
> +// { dg-do run }
> +// { dg-options "-std=c++14" }
> +
> +unsigned int d = 0;
> +
> +struct S {
> + S () { d++; }
> + S (const S &) { d++; }
> + ~S () { d--; }
> +};
> +
> +void
> +foo (int i) throw (int) // { dg-warning "dynamic exception specifications
> are deprecated" }
> +{
> + if (i == 0)
> + throw 3;
> + S d;
> + throw 3;
> +}
> +
> +int
> +main ()
> +{
> + try { foo (1); } catch (...) {}
> + if (d)
> + __builtin_abort ();
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
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