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.
(cherry picked from commit
90a8eab4a1292430467f68b65e5127f7760acc94)
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);
--- /dev/null
+/* { 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 ();
+ }
+}