[PATCH] sel-sched: fix zero-usefulness case in sel_rank_for_schedule (PR 83513)

[Alexander Monakov]

Hello,

we need the following follow-up fix for priority comparison in
sel_rank_for_schedule as demonstrated by PR 83513.  Checked on
x86_64 by running a bootstrap and also checking for no regressions in
make -k check-gcc 
RUNTESTFLAGS="--target_board=unix/-fselective-scheduling/-fschedule-insns"

OK to apply?

PR rtl-optimization/83513
* sel-sched.c (sel_rank_for_schedule): Order by non-zero usefulness
before priority comparison.

diff --git a/gcc/sel-sched.c b/gcc/sel-sched.c
index c1be0136551..be3813717ba 100644
--- a/gcc/sel-sched.c
+++ b/gcc/sel-sched.c
@@ -3396,17 +3396,22 @@ sel_rank_for_schedule (const void *x, const void *y)
   else if (control_flow_insn_p (tmp2_insn) && !control_flow_insn_p (tmp_insn))
 return 1;

+  /* Prefer an expr with non-zero usefulness.  */
+  int u1 = EXPR_USEFULNESS (tmp), u2 = EXPR_USEFULNESS (tmp2);
+
+  if (u1 == 0)
+{
+  if (u2 == 0)
+u1 = u2 = 1;
+  else
+return 1;
+}
+  else if (u2 == 0)
+return -1;
+
   /* Prefer an expr with greater priority.  */
-  if (EXPR_USEFULNESS (tmp) != 0 || EXPR_USEFULNESS (tmp2) != 0)
-{
-  int p2 = EXPR_PRIORITY (tmp2) + EXPR_PRIORITY_ADJ (tmp2),
-  p1 = EXPR_PRIORITY (tmp) + EXPR_PRIORITY_ADJ (tmp);
-
-  val = p2 * EXPR_USEFULNESS (tmp2) - p1 * EXPR_USEFULNESS (tmp);
-}
-  else
-val = EXPR_PRIORITY (tmp2) - EXPR_PRIORITY (tmp)
- + EXPR_PRIORITY_ADJ (tmp2) - EXPR_PRIORITY_ADJ (tmp);
+  val = (u2 * (EXPR_PRIORITY (tmp2) + EXPR_PRIORITY_ADJ (tmp2))
+ - u1 * (EXPR_PRIORITY (tmp) + EXPR_PRIORITY_ADJ (tmp)));
   if (val)
 return val;

Re: [PATCH] sel-sched: fix zero-usefulness case in sel_rank_for_schedule (PR 83513)

[Andrey Belevantsev]

On 25.12.2017 19:47, Alexander Monakov wrote:

Hello,

we need the following follow-up fix for priority comparison in
sel_rank_for_schedule as demonstrated by PR 83513.  Checked on
x86_64 by running a bootstrap and also checking for no regressions in
make -k check-gcc 
RUNTESTFLAGS="--target_board=unix/-fselective-scheduling/-fschedule-insns"

OK to apply?

Yes.

Andrey


PR rtl-optimization/83513
* sel-sched.c (sel_rank_for_schedule): Order by non-zero usefulness
before priority comparison.

diff --git a/gcc/sel-sched.c b/gcc/sel-sched.c
index c1be0136551..be3813717ba 100644
--- a/gcc/sel-sched.c
+++ b/gcc/sel-sched.c
@@ -3396,17 +3396,22 @@ sel_rank_for_schedule (const void *x, const void *y)
else if (control_flow_insn_p (tmp2_insn) && !control_flow_insn_p (tmp_insn))
  return 1;

+  /* Prefer an expr with non-zero usefulness.  */
+  int u1 = EXPR_USEFULNESS (tmp), u2 = EXPR_USEFULNESS (tmp2);
+
+  if (u1 == 0)
+{
+  if (u2 == 0)
+u1 = u2 = 1;
+  else
+return 1;
+}
+  else if (u2 == 0)
+return -1;
+
/* Prefer an expr with greater priority.  */
-  if (EXPR_USEFULNESS (tmp) != 0 || EXPR_USEFULNESS (tmp2) != 0)
-{
-  int p2 = EXPR_PRIORITY (tmp2) + EXPR_PRIORITY_ADJ (tmp2),
-  p1 = EXPR_PRIORITY (tmp) + EXPR_PRIORITY_ADJ (tmp);
-
-  val = p2 * EXPR_USEFULNESS (tmp2) - p1 * EXPR_USEFULNESS (tmp);
-}
-  else
-val = EXPR_PRIORITY (tmp2) - EXPR_PRIORITY (tmp)
- + EXPR_PRIORITY_ADJ (tmp2) - EXPR_PRIORITY_ADJ (tmp);
+  val = (u2 * (EXPR_PRIORITY (tmp2) + EXPR_PRIORITY_ADJ (tmp2))
+ - u1 * (EXPR_PRIORITY (tmp) + EXPR_PRIORITY_ADJ (tmp)));
if (val)
  return val;