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| author | Richard Henderson <rth@gcc.gnu.org> | 2000-05-08 23:15:18 -0700 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 2000-05-08 23:15:18 -0700 |
| commit | c66f079e8d2c33f5996fc0b7383153336a957efd (patch) | |
| tree | 4e267c18c32a4fdd44a7212340170c2318268bd3 | |
| parent | 2ff00dd433d9ad9b342bbaa2eb90ced859a02874 (diff) | |
| download | gcc-c66f079e8d2c33f5996fc0b7383153336a957efd.zip gcc-c66f079e8d2c33f5996fc0b7383153336a957efd.tar.gz gcc-c66f079e8d2c33f5996fc0b7383153336a957efd.tar.bz2 | |
predict.c (PROB_NEVER, [...]): New.
* 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.
From-SVN: r33792
| -rw-r--r-- | gcc/predict.c | 36 |
1 files changed, 23 insertions, 13 deletions
diff --git a/gcc/predict.c b/gcc/predict.c index b957e5f6..85f3ea1 100644 --- 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)); } |