* predict.c (PROB_NEVER, PROB_VERY_UNLIKELY): New.

        (PROB_UNLIKELY, PROB_EVEN, PROB_LIKELY): New.
        (PROB_VERY_LIKELY, PROB_ALWAYS): New.
        (estimate_probability, expected_value_to_br_prob): Use them.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@33792 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/predict.c b/gcc/predict.c
index b957e5f..85f3ea1 100644 (file)
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -48,6 +48,14 @@
 #include "expr.h"
 
 
+/* Random guesstimation given names.  */
+#define PROB_NEVER             (0)
+#define PROB_VERY_UNLIKELY     (REG_BR_PROB_BASE / 10 - 1)
+#define PROB_UNLIKELY          (REG_BR_PROB_BASE * 4 / 10 - 1)
+#define PROB_EVEN              (REG_BR_PROB_BASE / 2)
+#define PROB_LIKELY            (REG_BR_PROB_BASE - PROB_UNLIKELY)
+#define PROB_VERY_LIKELY       (REG_BR_PROB_BASE - PROB_VERY_UNLIKELY)
+#define PROB_ALWAYS            (REG_BR_PROB_BASE)
 
 /* Statically estimate the probability that a branch will be taken.
    ??? In the next revision there will be a number of other predictors added
@@ -89,7 +97,7 @@ estimate_probability (loops_info)
                  if (! find_reg_note (last_insn, REG_BR_PROB, 0))
                    REG_NOTES (last_insn)
                      = gen_rtx_EXPR_LIST (REG_BR_PROB,
-                                          GEN_INT (REG_BR_PROB_BASE),
+                                          GEN_INT (PROB_VERY_LIKELY),
                                           REG_NOTES (last_insn));
                }
        }
@@ -124,9 +132,9 @@ estimate_probability (loops_info)
        if (e->dest->succ == NULL)
          {
            if (e->flags & EDGE_FALLTHRU)
-             prob = REG_BR_PROB_BASE;
+             prob = PROB_ALWAYS;
            else
-             prob = 0;
+             prob = PROB_NEVER;
            goto emitnote;
          }
 
@@ -142,7 +150,7 @@ estimate_probability (loops_info)
                  || (GET_CODE (XEXP (cond, 1)) == REG
                      && REGNO_POINTER_FLAG (REGNO (XEXP (cond, 1))))))
            {
-             prob = REG_BR_PROB_BASE / 10;
+             prob = PROB_UNLIKELY;
              goto emitnote;
            }
          break;
@@ -153,7 +161,7 @@ estimate_probability (loops_info)
                  || (GET_CODE (XEXP (cond, 1)) == REG
                      && REGNO_POINTER_FLAG (REGNO (XEXP (cond, 1))))))
            {
-             prob = REG_BR_PROB_BASE - (REG_BR_PROB_BASE / 10);
+             prob = PROB_LIKELY;
              goto emitnote;
            }
          break;
@@ -170,20 +178,20 @@ estimate_probability (loops_info)
        {
        case CONST_INT:
          /* Unconditional branch.  */
-         prob = (cond == const0_rtx ? 0 : REG_BR_PROB_BASE);
+         prob = (cond == const0_rtx ? PROB_NEVER : PROB_ALWAYS);
          goto emitnote;
 
        case EQ:
-         prob = REG_BR_PROB_BASE / 10;
+         prob = PROB_UNLIKELY;
          goto emitnote;
        case NE:
-         prob = REG_BR_PROB_BASE - (REG_BR_PROB_BASE / 10);
+         prob = PROB_LIKELY;
          goto emitnote;
        case LE:
        case LT:
          if (XEXP (cond, 1) == const0_rtx)
            {
-             prob = REG_BR_PROB_BASE / 10;
+             prob = PROB_UNLIKELY;
              goto emitnote;
            }
          break;
@@ -193,7 +201,7 @@ estimate_probability (loops_info)
              || (GET_CODE (XEXP (cond, 1)) == CONST_INT
                  && INTVAL (XEXP (cond, 1)) == -1))
            {
-             prob = REG_BR_PROB_BASE - (REG_BR_PROB_BASE / 10);
+             prob = PROB_LIKELY;
              goto emitnote;
            }
          break;
@@ -203,7 +211,7 @@ estimate_probability (loops_info)
        }
 
       /* If we havn't chosen something by now, predict 50-50.  */
-      prob = REG_BR_PROB_BASE / 2;
+      prob = PROB_EVEN;
 
     emitnote:
       REG_NOTES (last_insn)
@@ -280,8 +288,10 @@ expected_value_to_br_prob ()
 
       /* Turn the condition into a scaled branch probability.  */
       if (cond == const1_rtx)
-       cond = GEN_INT (REG_BR_PROB_BASE);
-      else if (cond != const0_rtx)
+       cond = GEN_INT (PROB_VERY_LIKELY);
+      else if (cond == const0_rtx)
+       cond = GEN_INT (PROB_VERY_UNLIKELY);
+      else
        abort ();
       REG_NOTES (insn) = alloc_EXPR_LIST (REG_BR_PROB, cond, REG_NOTES (insn));
     }