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predict.c (last_basic_block_p): Remove. 

* predict.c (last_basic_block_p): Remove.
	(tree_estimate_probability): Update return heuristic for commonized
	return blocks.

From-SVN: r122367
This commit is contained in:
Jan Hubicka 2007-02-27 11:21:55 +01:00 committed by Jan Hubicka
parent e5fc6da81a
commit dcb995f769
2 changed files with 37 additions and 25 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2007-02-27 Jan Hubicka <jh@suse.cz>
* predict.c (last_basic_block_p): Remove.
(tree_estimate_probability): Update return heuristic for commonized
return blocks.
2007-02-26 Brooks Moses <brooks.moses@codesourcery.com>
* Makefile.in (TEXI_GCCINSTALL_FILES): Add gcc-vers.texi dependency.

56
gcc/predict.c
View File

@ -75,7 +75,6 @@ static sreal real_zero, real_one, real_almost_one, real_br_prob_base,
static void combine_predictions_for_insn (rtx, basic_block);
static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int);
static void predict_paths_leading_to (basic_block, int *, enum br_predictor, enum prediction);
static bool last_basic_block_p (basic_block);
static void compute_function_frequency (void);
static void choose_function_section (void);
static bool can_predict_insn_p (rtx);
@ -1290,20 +1289,41 @@ tree_estimate_probability (void)
{
/* Predict early returns to be probable, as we've already taken
care for error returns and other cases are often used for
fast paths through function. */
if (e->dest == EXIT_BLOCK_PTR
&& TREE_CODE (last_stmt (bb)) == RETURN_EXPR
&& !single_pred_p (bb))
fast paths through function.
Since we've already removed the return statments, we are
looking for CFG like:
if (conditoinal)
{
..
goto return_block
}
some other blocks
return_block:
return_stmt. */
if (e->dest != bb->next_bb
&& e->dest != EXIT_BLOCK_PTR
&& single_succ_p (e->dest)
&& single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR
&& TREE_CODE (last_stmt (e->dest)) == RETURN_EXPR)
{
edge e1;
edge_iterator ei1;
FOR_EACH_EDGE (e1, ei1, bb->preds)
if (!predicted_by_p (e1->src, PRED_NULL_RETURN)
&& !predicted_by_p (e1->src, PRED_CONST_RETURN)
&& !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN)
&& !last_basic_block_p (e1->src))
predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN);
if (single_succ_p (bb))
{
FOR_EACH_EDGE (e1, ei1, bb->preds)
if (!predicted_by_p (e1->src, PRED_NULL_RETURN)
&& !predicted_by_p (e1->src, PRED_CONST_RETURN)
&& !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN))
predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN);
}
else
if (!predicted_by_p (e->src, PRED_NULL_RETURN)
&& !predicted_by_p (e->src, PRED_CONST_RETURN)
&& !predicted_by_p (e->src, PRED_NEGATIVE_RETURN))
predict_edge_def (e, PRED_TREE_EARLY_RETURN, NOT_TAKEN);
}
/* Look for block we are guarding (ie we dominate it,
@ -1353,20 +1373,6 @@ tree_estimate_probability (void)
return 0;
}
/* Check whether this is the last basic block of function. Commonly
there is one extra common cleanup block. */
static bool
last_basic_block_p (basic_block bb)
{
if (bb == EXIT_BLOCK_PTR)
return false;
return (bb->next_bb == EXIT_BLOCK_PTR
|| (bb->next_bb->next_bb == EXIT_BLOCK_PTR
&& single_succ_p (bb)
&& single_succ (bb)->next_bb == EXIT_BLOCK_PTR));
}
/* Sets branch probabilities according to PREDiction and
FLAGS. HEADS[bb->index] should be index of basic block in that we
need to alter branch predictions (i.e. the first of our dominators