In this case, early phiopt would get rid of the user provided predicator
for hot/cold as it would remove the basic blocks. The easiest and best option is
for early phi-opt don't do phi-opt if the middle basic-block(s) have either
a hot or cold predict statement. Then after inlining, jump threading will most
likely
happen and that will keep around the predictor.
Note this only needs to be done for match_simplify_replacement and not the other
phi-opt functions because currently only match_simplify_replacement is able to
skip
middle bb with predicator statements in it.
OK? Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/117935
gcc/ChangeLog:
* tree-ssa-phiopt.cc (contains_hot_cold_predict): New function.
(match_simplify_replacement): Return early if early_p and one of
the middle bb(s) have a hot/cold predict statement.
gcc/testsuite/ChangeLog:
* gcc.dg/predict-24.c: New test.
Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
---
gcc/testsuite/gcc.dg/predict-24.c | 24 +++++++++++++++++++++
gcc/tree-ssa-phiopt.cc | 35 +++++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/predict-24.c
diff --git a/gcc/testsuite/gcc.dg/predict-24.c
b/gcc/testsuite/gcc.dg/predict-24.c
new file mode 100644
index 00000000000..b2c8a77c323
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/predict-24.c
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-profile_estimate" } */
+/* PR tree-optimization/117935 */
+
+static inline bool has_value(bool b)
+{
+ if (b)
+ {
+ [[gnu::hot, gnu::unused]] label1:
+ return true;
+ }
+ else
+ return false;
+}
+/* The hot label should last until it gets inlined into value_or and
jump_threaded. */
+int value_or(bool b, int def0, int def1)
+{
+ if (has_value(b))
+ return def0;
+ else
+ return def1;
+}
+/* { dg-final { scan-tree-dump-times "first match heuristics: 90.00%" 2
"profile_estimate"} } */
+/* { dg-final { scan-tree-dump-times "hot label heuristics of edge
\[0-9\]+->\[0-9]+: 90.00%" 2 "profile_estimate"} } */
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 64d3ba9e160..8fed3eadbb0 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -56,6 +56,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-ssa-dce.h"
#include "calls.h"
#include "tree-ssa-loop-niter.h"
+#include "gimple-predict.h"
/* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
@@ -916,6 +917,27 @@ auto_flow_sensitive::~auto_flow_sensitive ()
p.second.restore (p.first);
}
+/* Returns true if BB contains an user provided predictor
+ (PRED_HOT_LABEL/PRED_COLD_LABEL). */
+
+static bool
+contains_hot_cold_predict (basic_block bb)
+{
+ gimple_stmt_iterator gsi;
+ gsi = gsi_start_nondebug_after_labels_bb (bb);
+ for (; !gsi_end_p (gsi); gsi_next_nondebug (&gsi))
+ {
+ gimple *s = gsi_stmt (gsi);
+ if (gimple_code (s) != GIMPLE_PREDICT)
+ continue;
+ auto predict = gimple_predict_predictor (s);
+ if (predict == PRED_HOT_LABEL
+ || predict == PRED_COLD_LABEL)
+ return true;
+ }
+ return false;
+}
+
/* The function match_simplify_replacement does the main work of doing the
replacement using match and simplify. Return true if the replacement is
done.
Otherwise return false.
@@ -953,6 +975,19 @@ match_simplify_replacement (basic_block cond_bb,
basic_block middle_bb,
stmt_to_move_alt))
return false;
+ /* For early phiopt, we don't want to lose user generated predictors,
+ that is if either middle bb contains either a hot or cold label predict,
+ the phiopt should be skipped. */
+ if (early_p)
+ {
+ if (contains_hot_cold_predict (middle_bb))
+ return false;
+ if (threeway_p
+ && middle_bb != middle_bb_alt
+ && contains_hot_cold_predict (middle_bb_alt))
+ return false;
+ }
+
/* Do not make conditional undefs unconditional. */
if ((TREE_CODE (arg0) == SSA_NAME
&& ssa_name_maybe_undef_p (arg0))
--
2.43.0
