score: Optimize scheduler priority updates

Thread priority changes may append or prepend the thread to its priority
group on the scheduler ready queue.  Previously, a separate priority
value and a prepend-it flag in the scheduler node were used to propagate
a priority change to the scheduler.

Now, use an append-it bit in the priority control and reduce the plain
priority value to 63 bits.

This change leads to a significant code size reduction (about 25%) of
the SMP schedulers.  The negligible increase of the standard priority
scheduler is due to some additional shift operations
(SCHEDULER_PRIORITY_MAP() and SCHEDULER_PRIORITY_UNMAP()).

Before:

   text filename
    136 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleblock.o
    464 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimplechangepriority.o
     24 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimple.o
    108 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleschedule.o
    292 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleunblock.o
    264 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleyield.o

   text filename
    280 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityblock.o
    488 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerprioritychangepriority.o
    200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriority.o
    164 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityschedule.o
    328 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityunblock.o
    200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityyield.o

   text filename
  24112 arm-rtems5/c/imx7/cpukit/score/src/libscore_a-scheduleredfsmp.o

   text filename
  37204 sparc-rtems5/c/gr740/cpukit/score/src/libscore_a-scheduleredfsmp.o

   text filename
  42236 powerpc-rtems5/c/qoriq_e6500_32/cpukit/score/src/libscore_a-scheduleredfsmp.o

After:

   text filename
    136 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleblock.o
    272 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimplechangepriority.o
     24 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimple.o
    108 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleschedule.o
    292 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleunblock.o
    264 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleyield.o

   text filename
    280 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityblock.o
    488 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerprioritychangepriority.o
    208 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriority.o
    164 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityschedule.o
    332 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityunblock.o
    200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityyield.o

   text filename
  18860 arm-rtems5/c/imx7/cpukit/score/src/libscore_a-scheduleredfsmp.o

   text filename
  28520 sparc-rtems5/c/gr740/cpukit/score/src/libscore_a-scheduleredfsmp.o

   text filename
  32664 powerpc-rtems5/c/qoriq_e6500_32/cpukit/score/src/libscore_a-scheduleredfsmp.o

2 files changed, 11 insertions, 6 deletions

diff --git a/testsuites/smptests/smpscheduler01/smpscheduler01.doc b/testsuites/smptests/smpscheduler01/smpscheduler01.doc
index def7dac128..a881fc0fc4 100644
--- a/testsuites/smptests/smpscheduler01/smpscheduler01.doc
+++ b/testsuites/smptests/smpscheduler01/smpscheduler01.doc
@@ -4,7 +4,7 @@ test set name: smpscheduler01
 
 directives:
 
-  - _Scheduler_SMP_Enqueue_ordered()
+  - _Scheduler_SMP_Enqueue()
   - _Scheduler_SMP_Block()
 
 concepts:
diff --git a/testsuites/sptests/spintrcritical23/init.c b/testsuites/sptests/spintrcritical23/init.c
index c0a159471c..02c8a7ef37 100644
--- a/testsuites/sptests/spintrcritical23/init.c
+++ b/testsuites/sptests/spintrcritical23/init.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016 embedded brains GmbH.  All rights reserved.
+ * Copyright (c) 2015, 2017 embedded brains GmbH.  All rights reserved.
  *
  *  embedded brains GmbH
  *  Dornierstr. 4
@@ -43,12 +43,15 @@ static void change_priority(rtems_id timer, void *arg)
   /* The arg is NULL */
   test_context *ctx = &ctx_instance;
   rtems_interrupt_lock_context lock_context;
+  unsigned int next_priority;
 
   rtems_interrupt_lock_acquire(&ctx->lock, &lock_context);
-  if (
-    ctx->scheduler_node->Ready_queue.current_priority
-      != ctx->scheduler_node->Base.Priority.value
-  ) {
+
+  next_priority = SCHEDULER_PRIORITY_UNMAP(
+    (unsigned int) ctx->scheduler_node->Base.Priority.value
+  );
+
+  if ( ctx->scheduler_node->Ready_queue.current_priority != next_priority ) {
     rtems_task_priority priority_interrupt;
     rtems_task_priority priority_task;
     rtems_task_priority previous;
@@ -84,11 +87,13 @@ static bool test_body(void *arg)
   rtems_task_priority previous;
 
   rtems_interrupt_lock_acquire(&ctx->lock, &lock_context);
+
   priority_last = ctx->priority_task;
   priority_task = 1 + (priority_last + 1) % 3;
   priority_interrupt = 1 + (priority_task + 1) % 3;
   ctx->priority_task = priority_task;
   ctx->priority_interrupt = priority_interrupt;
+
   rtems_interrupt_lock_release(&ctx->lock, &lock_context);
 
   sc = rtems_task_set_priority(