[PATCH] sel-sched: Don't clone CALLs (PR48273)

[Alexander Monakov]

Hi,

Selective scheduler does not explicitly forbid creating bookkeeping copies of
CALLs, but an assert in create_copy_of_insn_rtx does not expect a CALL.  Since
there's little benefit from aggressive scheduling of CALLs, it makes sense to
restrict it so that CALLs cannot be duplicated.

This patch makes CALLs non-clonable by adding an explicit check in additional
to other non-clonable insns (ASMs, instructions that are a part of
SCHED_GROUPs, etc.).  We also need to forbid pipelining of loops that have no
exit edges, since our check for whether a motion would create bookkeeping does
not work in that case (it's one of the solutions; the other is to fixup
remove_insns_that_need_bookkeeping function, but this one is simpler and
faster).


        PR target/48273
        * cfgloop.h (loop_has_exit_edges): New helper.
        * sel-sched-ir.c (init_global_and_expr_for_insn): Make CALLs
        non-clonable.
        (sel_setup_region_sched_flags): Don't pipeline loops that have no
        exit edges.

testsuite:
        * g++.dg/opt/pr48273.C: New.

diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index f7bb134..0ff44de 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -443,6 +443,14 @@ loop_outer (const struct loop *loop)
   return VEC_index (loop_p, loop->superloops, n - 1);
 }
 
+/* Returns true if LOOP has at least one exit edge.  */
+
+static inline bool
+loop_has_exit_edges (const struct loop *loop)
+{
+  return loop->exits->next->e != NULL;
+}
+
 /* Returns the list of loops in current_loops.  */
 
 static inline VEC (loop_p, gc) *
diff --git a/gcc/sel-sched-ir.c b/gcc/sel-sched-ir.c
index 67484dd..95c1431 100644
--- a/gcc/sel-sched-ir.c
+++ b/gcc/sel-sched-ir.c
@@ -2905,6 +2905,7 @@ init_global_and_expr_for_insn (insn_t insn)
       if (CANT_MOVE (insn)
           || INSN_ASM_P (insn)
           || SCHED_GROUP_P (insn)
+         || CALL_P (insn)
           /* Exception handling insns are always unique.  */
           || (cfun->can_throw_non_call_exceptions && can_throw_internal (insn))
           /* TRAP_IF though have an INSN code is control_flow_insn_p ().  */
diff --git a/gcc/sel-sched.c b/gcc/sel-sched.c
index 0e8173b..fb1a026 100644
--- a/gcc/sel-sched.c
+++ b/gcc/sel-sched.c
@@ -6781,7 +6781,8 @@ sel_setup_region_sched_flags (void)
   bookkeeping_p = 1;
   pipelining_p = (bookkeeping_p
                   && (flag_sel_sched_pipelining != 0)
-                 && current_loop_nest != NULL);
+                 && current_loop_nest != NULL
+                 && loop_has_exit_edges (current_loop_nest));
   max_insns_to_rename = PARAM_VALUE (PARAM_SELSCHED_INSNS_TO_RENAME);
   max_ws = MAX_WS;
 }
diff --git a/gcc/testsuite/g++.dg/opt/pr48273.C 
b/gcc/testsuite/g++.dg/opt/pr48273.C
new file mode 100644
index 0000000..4c5108b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/pr48273.C
@@ -0,0 +1,10 @@
+// { dg-do compile { target x86_64-*-* } }
+// { dg-options "-fschedule-insns2 -fsel-sched-pipelining 
-fselective-scheduling2 -funroll-all-loops -march=core2" }
+
+void bar ();
+
+void foo ()
+{
+  for (;;)
+    bar ();
+}