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?
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
