Re: Update probabilities in predict.def to match reality

[Martin Liška]

On 06/08/2016 12:21 PM, Andreas Schwab wrote:
> Jan Hubicka <hubi...@ucw.cz> writes:
> 
>> Bootstrapped/regtested x86_64-linux, will commit it later today.
> 
> FAIL: gcc.dg/tree-ssa/slsr-8.c scan-tree-dump-times optimized " w?\\\\* " 7
> 
> Andreas.
> 

Hi.

It's caused by a different probabilities for BB 2:

@@ -11,11 +11,11 @@
 ;; 3 succs { 4 }
 ;; 4 succs { 1 }
 Predictions for bb 2
-  DS theory heuristics: 78.4%
-  first match heuristics (ignored): 85.0%
-  combined heuristics: 78.4%
-  pointer (on trees) heuristics: 85.0%
-  early return (on trees) heuristics: 39.0%
+  DS theory heuristics: 66.5%
+  first match heuristics (ignored): 70.0%
+  combined heuristics: 66.5%
+  pointer (on trees) heuristics: 70.0%
+  early return (on trees) heuristics: 46.0%

Which leads to a different decision made by tree-ssa-sink:

+++ /tmp/sl-new/slsr-8.c.127t.sink      2016-06-08 14:07:59.747958332 +0200
@@ -21,6 +21,16 @@
  from bb 2 to bb 3
 Sinking a3_17 = s_11(D) * 6;
  from bb 2 to bb 3
+Sinking x2_16 = c_13(D) + _6;
+ from bb 2 to bb 5
+Sinking _6 = -_5;
+ from bb 2 to bb 5
+Sinking _5 = _4 * 4;
+ from bb 2 to bb 5
+Sinking _4 = (long unsigned int) a2_15;
+ from bb 2 to bb 5
+Sinking a2_15 = s_11(D) * 4;
+ from bb 2 to bb 5
 f (int s, int * c)
 {
   int * x3;
@@ -46,17 +56,17 @@
   _2 = _1 * 4;
   _3 = -_2;
   x1_14 = c_13(D) + _3;
-  a2_15 = s_11(D) * 4;
-  _4 = (long unsigned int) a2_15;
-  _5 = _4 * 4;
-  _6 = -_5;
-  x2_16 = c_13(D) + _6;
   if (x1_14 != 0B)
     goto <bb 5>;
   else
     goto <bb 3>;
 
   <bb 5>:
+  a2_15 = s_11(D) * 4;
+  _4 = (long unsigned int) a2_15;
+  _5 = _4 * 4;
+  _6 = -_5;
+  x2_16 = c_13(D) + _6;
   goto <bb 4>;
 
   <bb 3>:

That eventually leads to 9 occurrences of the scanned pattern. However, I'm not 
sure if the test-case makes
sense any longer?

Thanks,
Martin

;; Function f (f, funcdef_no=0, decl_uid=1747, cgraph_uid=0, symbol_order=0)

;; 1 loops found
;;
;; Loop 0
;;  header 0, latch 1
;;  depth 0, outer -1
;;  nodes: 0 1 2 5 3 4
;; 2 succs { 5 3 }
;; 5 succs { 4 }
;; 3 succs { 4 }
;; 4 succs { 1 }
Sinking x3_18 = c_13(D) + _9;
 from bb 2 to bb 3
Sinking _9 = -_8;
 from bb 2 to bb 3
Sinking _8 = _7 * 4;
 from bb 2 to bb 3
Sinking _7 = (long unsigned int) a3_17;
 from bb 2 to bb 3
Sinking a3_17 = s_11(D) * 6;
 from bb 2 to bb 3
Sinking x2_16 = c_13(D) + _6;
 from bb 2 to bb 5
Sinking _6 = -_5;
 from bb 2 to bb 5
Sinking _5 = _4 * 4;
 from bb 2 to bb 5
Sinking _4 = (long unsigned int) a2_15;
 from bb 2 to bb 5
Sinking a2_15 = s_11(D) * 4;
 from bb 2 to bb 5
f (int s, int * c)
{
  int * x3;
  int * x2;
  int * x1;
  int a3;
  int a2;
  int a1;
  long unsigned int _1;
  long unsigned int _2;
  sizetype _3;
  long unsigned int _4;
  long unsigned int _5;
  sizetype _6;
  long unsigned int _7;
  long unsigned int _8;
  sizetype _9;
  int * iftmp.0_10;

  <bb 2>:
  a1_12 = s_11(D) * 2;
  _1 = (long unsigned int) a1_12;
  _2 = _1 * 4;
  _3 = -_2;
  x1_14 = c_13(D) + _3;
  if (x1_14 != 0B)
    goto <bb 5>;
  else
    goto <bb 3>;

  <bb 5>:
  a2_15 = s_11(D) * 4;
  _4 = (long unsigned int) a2_15;
  _5 = _4 * 4;
  _6 = -_5;
  x2_16 = c_13(D) + _6;
  goto <bb 4>;

  <bb 3>:
  a3_17 = s_11(D) * 6;
  _7 = (long unsigned int) a3_17;
  _8 = _7 * 4;
  _9 = -_8;
  x3_18 = c_13(D) + _9;

  <bb 4>:
  # iftmp.0_10 = PHI <x2_16(5), x3_18(3)>
  return iftmp.0_10;

}