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| author | Jan Hubicka <jh@suse.cz> | 2023-08-11 00:23:14 +0200 |
|---|---|---|
| committer | Jan Hubicka <jh@suse.cz> | 2023-08-11 00:23:14 +0200 |
| commit | 39204ae9ddbfca710880d7f5fda48234a1e85e4e (patch) | |
| tree | c5457d18279e722c9917a3380ad826e9e70658f7 /gcc | |
| parent | 0ac323238e91c6093709ce8f4176c0c8fb1a693d (diff) | |
| download | gcc-39204ae9ddbfca710880d7f5fda48234a1e85e4e.zip gcc-39204ae9ddbfca710880d7f5fda48234a1e85e4e.tar.gz gcc-39204ae9ddbfca710880d7f5fda48234a1e85e4e.tar.bz2 | |
Fix division by zero in loop splitting
Profile update I added to tree-ssa-loop-split can divide by zero in
situation that the conditional is predicted with 0 probability which
is triggered by jump threading update in the testcase.
gcc/ChangeLog:
PR middle-end/110923
* tree-ssa-loop-split.cc (split_loop): Watch for division by zero.
gcc/testsuite/ChangeLog:
PR middle-end/110923
* gcc.dg/tree-ssa/pr110923.c: New test.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/pr110923.c | 14 | ||||
| -rw-r--r-- | gcc/tree-ssa-loop-split.cc | 12 |
2 files changed, 22 insertions, 4 deletions
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr110923.c b/gcc/testsuite/gcc.dg/tree-ssa/pr110923.c new file mode 100644 index 0000000..8f5720a --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr110923.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-O3 -fdump-tree-lsplit-details-blocks" } */ +int a, b, c, d; +int main() { + for (a = 0; a < 2; a++) { + if (b > 2) + c = 0; + if (b > a) + d = 0; + } + return 0; +} +/* { dg-final { scan-tree-dump-times "loop split" 1 "lsplit" } } */ +/* { dg-final { scan-tree-dump-not "Invalid sum" "lsplit" } } */ diff --git a/gcc/tree-ssa-loop-split.cc b/gcc/tree-ssa-loop-split.cc index 2f7918c..6446480 100644 --- a/gcc/tree-ssa-loop-split.cc +++ b/gcc/tree-ssa-loop-split.cc @@ -703,7 +703,7 @@ split_loop (class loop *loop1) split between of the two new loops. Keep orignal estimate since it is likely better then completely dropping it. - TODO: If we know that onle of the new loops has constant + TODO: If we know that one of the new loops has constant number of iterations, we can do better. We could also update upper bounds. */ if (loop1->any_estimate @@ -713,11 +713,15 @@ split_loop (class loop *loop1) ? true_edge->probability.to_sreal () : (sreal)1; sreal scale2 = false_edge->probability.reliable_p () ? false_edge->probability.to_sreal () : (sreal)1; + sreal div1 = loop1_prob.to_sreal (); /* +1 to get header interations rather than latch iterations and then -1 to convert back. */ - loop1->nb_iterations_estimate - = MAX ((((sreal)loop1->nb_iterations_estimate.to_shwi () + 1) * scale - / loop1_prob.to_sreal ()).to_nearest_int () - 1, 0); + if (div1 != 0) + loop1->nb_iterations_estimate + = MAX ((((sreal)loop1->nb_iterations_estimate.to_shwi () + 1) + * scale / div1).to_nearest_int () - 1, 0); + else + loop1->any_estimate = false; loop2->nb_iterations_estimate = MAX ((((sreal)loop2->nb_iterations_estimate.to_shwi () + 1) * scale2 / profile_probability::very_likely ().to_sreal ()) |