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author | Alexandre Oliva <oliva@adacore.com> | 2022-05-11 04:27:42 -0300 |
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committer | Alexandre Oliva <oliva@gnu.org> | 2022-05-13 03:00:29 -0300 |
commit | 90a8eab4a1292430467f68b65e5127f7760acc94 (patch) | |
tree | 2c4f4a28c74683ba083cf0c6a2703ccc024b9112 | |
parent | 8ab4b484153031c407b7d8c760b6a2605da1199a (diff) | |
download | gcc-90a8eab4a1292430467f68b65e5127f7760acc94.zip gcc-90a8eab4a1292430467f68b65e5127f7760acc94.tar.gz gcc-90a8eab4a1292430467f68b65e5127f7760acc94.tar.bz2 |
[PR105455] Set edge probabilities when hardening conditionals
When turning unconditional edges into conditional, as in
gimple-harden-conditionals.cc:insert_check_and_trap, the newly-created
edge's probability comes out uninitialized, while the previously
unconditional edge's probability is presumably
profile_probability::always.
Mixing initialized and uninitialized probabilities before expand
breaks predict.cc:force_edge_cold: the initialized probability may end
up copied to a REG_BR_PROB note in a conditional branch insn, but if
force_edge_cold is called on that edge, it will find another edge with
uninitialized probability and assume the note is absent. Later on,
rtl_verify_edges complains that the note does not match the
probability modified by force_edge_cold in the edge.
This patch sets probabilities for edges affected by hardening of
conditionals, both the newly-created edges to trap blocks and the
previously-unconditional edges, so that the former are considered
never taken, while the latter are confirmed as always taken.
for gcc/ChangeLog
PR rtl-optimization/105455
* gimple-harden-conditionals.cc (insert_check_and_trap): Set
probabilities for newly-conditional edges.
for gcc/testsuite/ChangeLog
PR rtl-optimization/105455
* gcc.dg/pr105455.c: New.
-rw-r--r-- | gcc/gimple-harden-conditionals.cc | 2 | ||||
-rw-r--r-- | gcc/testsuite/gcc.dg/pr105455.c | 17 |
2 files changed, 19 insertions, 0 deletions
diff --git a/gcc/gimple-harden-conditionals.cc b/gcc/gimple-harden-conditionals.cc index c7e5e07..19ceb8a 100644 --- a/gcc/gimple-harden-conditionals.cc +++ b/gcc/gimple-harden-conditionals.cc @@ -254,8 +254,10 @@ insert_check_and_trap (location_t loc, gimple_stmt_iterator *gsip, equality. */ single_succ_edge (chk)->flags &= ~EDGE_FALLTHRU; single_succ_edge (chk)->flags |= neg_true_false_flag; + single_succ_edge (chk)->probability = profile_probability::always (); edge e = make_edge (chk, trp, true_false_flag); e->goto_locus = loc; + e->probability = profile_probability::never (); if (dom_info_available_p (CDI_DOMINATORS)) set_immediate_dominator (CDI_DOMINATORS, trp, chk); diff --git a/gcc/testsuite/gcc.dg/pr105455.c b/gcc/testsuite/gcc.dg/pr105455.c new file mode 100644 index 0000000..81e9154 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr105455.c @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O1 -fharden-conditional-branches -funroll-loops --param max-loop-header-insns=1" } */ + +__attribute__ ((cold)) void +bar (void); + +void +foo (int x) +{ + if (x) + { + int i; + + for (i = 0; i < 101; ++i) + bar (); + } +} |