Fix PR 83913

[Andrey Belevantsev]

Hello,

This issue ended up being fixed the way different from described in the PR.
 We do not want to walk away from the invariant "zero SCHED_TIMES -- insn
is not scheduled" even for bookkeeping copies (testing showed it trips over
asserts designed to catch this).  Rather we choose merging exprs in the way
the larger sched-times wins.

Best,
Andrey

2018-04-03  Andrey Belevantsev  <a...@ispras.ru>

        PR rtl-optimization/83913

        * sel-sched-ir.c (merge_expr_data): Choose the middle between two
different sched-times
        when merging exprs.

        * gcc.dg/pr83913.c: New test.

diff --git a/gcc/sel-sched-ir.c b/gcc/sel-sched-ir.c
index a965d2ec42f..f6de96a7f3d 100644
--- a/gcc/sel-sched-ir.c
+++ b/gcc/sel-sched-ir.c
@@ -1837,8 +1837,9 @@ merge_expr_data (expr_t to, expr_t from, insn_t
split_point)
   if (EXPR_PRIORITY (to) < EXPR_PRIORITY (from))
     EXPR_PRIORITY (to) = EXPR_PRIORITY (from);

-  if (EXPR_SCHED_TIMES (to) > EXPR_SCHED_TIMES (from))
-    EXPR_SCHED_TIMES (to) = EXPR_SCHED_TIMES (from);
+  if (EXPR_SCHED_TIMES (to) != EXPR_SCHED_TIMES (from))
+    EXPR_SCHED_TIMES (to) = ((EXPR_SCHED_TIMES (from) + EXPR_SCHED_TIMES (to)
+                             + 1) / 2);

   if (EXPR_ORIG_BB_INDEX (to) != EXPR_ORIG_BB_INDEX (from))
     EXPR_ORIG_BB_INDEX (to) = 0;
@@ -3293,11 +3294,22 @@ has_dependence_note_mem_dep (rtx mem ATTRIBUTE_UNUSED,

 /* Note a dependence.  */
 static void
diff --git a/gcc/testsuite/gcc.dg/pr83913.c b/gcc/testsuite/gcc.dg/pr83913.c
new file mode 100644
index 00000000000..c898d71a261
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr83913.c
@@ -0,0 +1,26 @@
+/* { dg-do compile { target powerpc*-*-* ia64-*-* i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 -funroll-all-loops -fselective-scheduling
-fsel-sched-pipelining -fschedule-insns -fno-dce -fno-forward-propagate
-fno-rerun-cse-after-loop -fno-web" } */
+
+int jo, z4;
+
+int
+be (long unsigned int l7, int nt)
+{
+  int en;
+
+  jo = l7;
+  for (en = 0; en < 24; ++en)
+    {
+      jo = (jo / z4) * (!!jo >= ((!!nt) & 2));
+      if (jo == 0)
+        nt = 0;
+      else
+        {
+          nt = z4;
+          ++z4;
+          nt = (long unsigned int) nt == (l7 + 1);
+        }
+    }
+
+  return nt;
+}