This fixes a missed optimization where early phi-opt would
not work when there was predicates. The easiest fix is
to change empty_bb_or_one_feeding_into_p to ignore those
statements while checking for only feeding statement.
Note phi-opt-23.c and phi-opt-24.c still fail as we don't handle
diamond form in match_and_simplify phiopt yet.
OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
gcc/ChangeLog:
* tree-ssa-phiopt.cc (empty_bb_or_one_feeding_into_p):
Instead of calling last_and_only_stmt, look for the last statement
manually.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/ssa-ifcombine-13.c: Add -fno-ssa-phiopt.
---
.../gcc.dg/tree-ssa/ssa-ifcombine-13.c | 4 +++-
gcc/tree-ssa-phiopt.cc | 22 +++++++++++++++++--
2 files changed, 23 insertions(+), 3 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-13.c
b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-13.c
index 425eb3d6481..7976544c79b 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-13.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-13.c
@@ -1,5 +1,7 @@
/* { dg-do compile } */
-/* { dg-options "-O1 -fdump-tree-optimized-details-blocks --param
logical-op-non-short-circuit=1" } */
+/* Disable phi-opt as it is no longer confused by predicate which had allowed
ifcombine to work in the past.
+ Note this testcase is about ifcombine rather than phi-opt. */
+/* { dg-options "-O1 -fdump-tree-optimized-details-blocks --param
logical-op-non-short-circuit=1 -fno-ssa-phiopt" } */
_Bool f1(_Bool a, _Bool b)
{
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index cb4d8788b56..ffd6a4e6f35 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -962,9 +962,27 @@ empty_bb_or_one_feeding_into_p (basic_block bb,
if (!gimple_seq_empty_p (phi_nodes (bb)))
return false;
- stmt_to_move = last_and_only_stmt (bb);
+ gimple_stmt_iterator gsi;
+
+ gsi = gsi_start_nondebug_after_labels_bb (bb);
+ while (!gsi_end_p (gsi))
+ {
+ gimple *s = gsi_stmt (gsi);
+ gsi_next_nondebug (&gsi);
+ /* Skip over Predict and nop statements. */
+ if (gimple_code (s) == GIMPLE_PREDICT
+ || gimple_code (s) == GIMPLE_NOP)
+ continue;
+ /* If there is more one statement return false. */
+ if (stmt_to_move)
+ return false;
+ stmt_to_move = s;
+ }
+
+ /* The only statement here was a Predict or a nop statement
+ so return true. */
if (!stmt_to_move)
- return false;
+ return true;
if (gimple_vuse (stmt_to_move))
return false;
--
2.39.1
