Increase precision of static profiles

[Jan Hubicka]

Hi,
this patch makes static profile to be in range 0...2^30 rather than
0...10000.  This is safe now as profile-counts are taking care of
possible overflow when the profile ends up cummulating too high after
inlining.
MThere are two testcases that needs adusting. dump-2.c simply checks
for specific value of counter that is now different. pr77445-2
now gets one extra mismatch reported. The mismatch was present before
too but due to low precision it was not visible.

Bootstrapped/regtested x86_64-linux, comitted.

Honza

	* predict.c (determine_unlikely_bbs): Set cgraph node count to 0
	when entry block was promoted unlikely.
	(estimate_bb_frequencies): Increase frequency scale.
	* profile-count.h (profile_count): Export precision info.
	* gcc.dg/tree-ssa/dump-2.c: Fixup template for profile precision
	changes.
	* gcc.dg/tree-ssa/pr77445-2.c: Fixup template for profile precision
	changes.
Index: predict.c
===================================================================
--- predict.c	(revision 254884)
+++ predict.c	(working copy)
@@ -3542,6 +3542,8 @@ determine_unlikely_bbs ()
 			bb->index, e->dest->index);
 	     e->probability = profile_probability::never ();
 	   }
+  if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count == profile_count::zero ())
+    cgraph_node::get (current_function_decl)->count = profile_count::zero ();
 }
 
 /* Estimate and propagate basic block frequencies using the given branch
@@ -3565,7 +3567,11 @@ estimate_bb_frequencies (bool force)
         {
 	  real_values_initialized = 1;
 	  real_br_prob_base = REG_BR_PROB_BASE;
-	  real_bb_freq_max = BB_FREQ_MAX;
+	  /* Scaling frequencies up to maximal profile count may result in
+	     frequent overflows especially when inlining loops.
+	     Small scalling results in unnecesary precision loss.  Stay in
+	     the half of the (exponential) range.  */
+	  real_bb_freq_max = (uint64_t)1 << (profile_count::n_bits / 2);
 	  real_one_half = sreal (1, -1);
 	  real_inv_br_prob_base = sreal (1) / real_br_prob_base;
 	  real_almost_one = sreal (1) - real_inv_br_prob_base;
@@ -3610,6 +3616,8 @@ estimate_bb_frequencies (bool force)
 	  freq_max = BLOCK_INFO (bb)->frequency;
 
       freq_max = real_bb_freq_max / freq_max;
+      if (freq_max < 16)
+	freq_max = 16;
       cfun->cfg->count_max = profile_count::uninitialized ();
       FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
 	{
Index: profile-count.h
===================================================================
--- profile-count.h	(revision 254884)
+++ profile-count.h	(working copy)
@@ -605,11 +605,13 @@ class sreal;
 
 class GTY(()) profile_count
 {
+public:
   /* Use 62bit to hold basic block counters.  Should be at least
      64bit.  Although a counter cannot be negative, we use a signed
      type to hold various extra stages.  */
 
   static const int n_bits = 61;
+private:
   static const uint64_t max_count = ((uint64_t) 1 << n_bits) - 2;
   static const uint64_t uninitialized_count = ((uint64_t) 1 << n_bits) - 1;
 
Index: testsuite/gcc.dg/tree-ssa/dump-2.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/dump-2.c	(revision 254884)
+++ testsuite/gcc.dg/tree-ssa/dump-2.c	(working copy)
@@ -6,4 +6,4 @@ int f(void)
   return 0;
 }
 
-/* { dg-final { scan-tree-dump "<bb \[0-9\]> \\\[local count: 10000\\\]:" "optimized" } } */
+/* { dg-final { scan-tree-dump "<bb \[0-9\]> \\\[local count: " "optimized" } } */
Index: testsuite/gcc.dg/tree-ssa/pr77445-2.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/pr77445-2.c	(revision 254884)
+++ testsuite/gcc.dg/tree-ssa/pr77445-2.c	(working copy)
@@ -120,7 +120,7 @@ enum STATES FMS( u8 **in , u32 *transiti
    profile estimation stage. But the number of inconsistencies should not
    increase much.  */
 /* { dg-final { scan-tree-dump "Jumps threaded: 1\[1-9\]" "thread1" } } */
-/* { dg-final { scan-tree-dump-times "Invalid sum" 2 "thread1" } } */
+/* { dg-final { scan-tree-dump-times "Invalid sum" 3 "thread1" } } */
 /* { dg-final { scan-tree-dump-not "not considered" "thread1" } } */
 /* { dg-final { scan-tree-dump-not "not considered" "thread2" } } */
 /* { dg-final { scan-tree-dump-not "not considered" "thread3" } } */