for (j = 0; VEC_iterate (edge, exits, j, ex); j++)
{
tree niter = NULL;
+ HOST_WIDE_INT nitercst;
+ int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS);
+ int probability;
+ enum br_predictor predictor;
if (number_of_iterations_exit (loop, ex, &niter_desc, false))
niter = niter_desc.niter;
if (TREE_CODE (niter) == INTEGER_CST)
{
- int probability;
- int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS);
if (host_integerp (niter, 1)
&& compare_tree_int (niter, max-1) == -1)
- {
- HOST_WIDE_INT nitercst = tree_low_cst (niter, 1) + 1;
- probability = ((REG_BR_PROB_BASE + nitercst / 2)
- / nitercst);
- }
+ nitercst = tree_low_cst (niter, 1) + 1;
else
- probability = ((REG_BR_PROB_BASE + max / 2) / max);
+ nitercst = max;
+ predictor = PRED_LOOP_ITERATIONS;
+ }
+ /* If we have just one exit and we can derive some information about
+ the number of iterations of the loop from the statements inside
+ the loop, use it to predict this exit. */
+ else if (n_exits == 1)
+ {
+ nitercst = estimated_loop_iterations_int (loop, false);
+ if (nitercst < 0)
+ continue;
+ if (nitercst > max)
+ nitercst = max;
- predict_edge (ex, PRED_LOOP_ITERATIONS, probability);
+ predictor = PRED_LOOP_ITERATIONS_GUESSED;
}
+ else
+ continue;
+
+ probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst);
+ predict_edge (ex, predictor, probability);
}
VEC_free (edge, heap, exits);
/* Loop exit heuristics - predict an edge exiting the loop if the
conditional has no loop header successors as not taken. */
- if (!header_found)
+ if (!header_found
+ /* If we already used more reliable loop exit predictors, do not
+ bother with PRED_LOOP_EXIT. */
+ && !predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED)
+ && !predicted_by_p (bb, PRED_LOOP_ITERATIONS))
{
/* For loop with many exits we don't want to predict all exits
with the pretty large probability, because if all exits are
tree_bb_level_predictions ();
mark_irreducible_loops ();
+ record_loop_exits ();
if (current_loops)
predict_loops ();
fprintf (dump_file, ")\n");
}
-/* Get the real or estimated number of iterations for LOOPNUM, whichever is
- available. Return the number of iterations as a tree, or NULL_TREE if
- we don't know. */
+/* Sets NIT to the estimated number of executions of the statements in
+ LOOP. If CONSERVATIVE is true, we must be sure that NIT is at least as
+ large as the number of iterations. If we have no reliable estimate,
+ the function returns false, otherwise returns true. */
-static tree
-get_number_of_iters_for_loop (int loopnum)
+static bool
+estimated_loop_iterations (struct loop *loop, bool conservative,
+ double_int *nit)
{
- struct loop *loop = get_loop (loopnum);
tree numiter = number_of_exit_cond_executions (loop);
+ /* If we have an exact value, use it. */
if (TREE_CODE (numiter) == INTEGER_CST)
- return numiter;
+ {
+ *nit = tree_to_double_int (numiter);
+ return true;
+ }
+ /* If we have a measured profile and we do not ask for a conservative bound,
+ use it. */
+ if (!conservative && loop->header->count != 0)
+ {
+ *nit = uhwi_to_double_int (expected_loop_iterations (loop) + 1);
+ return true;
+ }
+
+ /* Finally, try using a reliable estimate on number of iterations according
+ to the size of the accessed data, if available. */
+ estimate_numbers_of_iterations_loop (loop);
if (loop->estimate_state == EST_AVAILABLE)
{
- tree type = lang_hooks.types.type_for_size (INT_TYPE_SIZE, true);
- if (double_int_fits_to_tree_p (type, loop->estimated_nb_iterations))
- return double_int_to_tree (type, loop->estimated_nb_iterations);
+ *nit = loop->estimated_nb_iterations;
+ return true;
}
- return NULL_TREE;
+ return false;
+}
+
+/* Similar to estimated_loop_iterations, but returns the estimate only
+ if it fits to HOST_WIDE_INT. If this is not the case, or the estimate
+ on the number of iterations of LOOP could not be derived, returns -1. */
+
+HOST_WIDE_INT
+estimated_loop_iterations_int (struct loop *loop, bool conservative)
+{
+ double_int nit;
+ HOST_WIDE_INT hwi_nit;
+
+ if (!estimated_loop_iterations (loop, conservative, &nit))
+ return -1;
+
+ if (!double_int_fits_in_shwi_p (nit))
+ return -1;
+ hwi_nit = double_int_to_shwi (nit);
+
+ return hwi_nit < 0 ? -1 : hwi_nit;
}
+/* Similar to estimated_loop_iterations, but returns the estimate as a tree,
+ and only if it fits to the int type. If this is not the case, or the
+ estimate on the number of iterations of LOOP could not be derived, returns
+ chrec_dont_know. */
+
+static tree
+estimated_loop_iterations_tree (struct loop *loop, bool conservative)
+{
+ double_int nit;
+ tree type;
+
+ if (!estimated_loop_iterations (loop, conservative, &nit))
+ return chrec_dont_know;
+
+ type = lang_hooks.types.type_for_size (INT_TYPE_SIZE, true);
+ if (!double_int_fits_to_tree_p (type, nit))
+ return chrec_dont_know;
+
+ return double_int_to_tree (type, nit);
+}
+
/* Analyze a SIV (Single Index Variable) subscript where CHREC_A is a
constant, and CHREC_B is an affine function. *OVERLAPS_A and
*OVERLAPS_B are initialized to the functions that describe the
if (tree_fold_divides_p (CHREC_RIGHT (chrec_b), difference))
{
- tree numiter;
- int loopnum = CHREC_VARIABLE (chrec_b);
+ HOST_WIDE_INT numiter;
+ struct loop *loop = get_chrec_loop (chrec_b);
*overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
tmp = fold_build2 (EXACT_DIV_EXPR, integer_type_node,
/* Perform weak-zero siv test to see if overlap is
outside the loop bounds. */
- numiter = get_number_of_iters_for_loop (loopnum);
+ numiter = estimated_loop_iterations_int (loop, true);
- if (numiter != NULL_TREE
- && TREE_CODE (tmp) == INTEGER_CST
- && tree_int_cst_lt (numiter, tmp))
+ if (numiter >= 0
+ && compare_tree_int (tmp, numiter) > 0)
{
free_conflict_function (*overlaps_a);
free_conflict_function (*overlaps_b);
*/
if (tree_fold_divides_p (CHREC_RIGHT (chrec_b), difference))
{
- tree numiter;
- int loopnum = CHREC_VARIABLE (chrec_b);
+ HOST_WIDE_INT numiter;
+ struct loop *loop = get_chrec_loop (chrec_b);
*overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
tmp = fold_build2 (EXACT_DIV_EXPR,
/* Perform weak-zero siv test to see if overlap is
outside the loop bounds. */
- numiter = get_number_of_iters_for_loop (loopnum);
+ numiter = estimated_loop_iterations_int (loop, true);
- if (numiter != NULL_TREE
- && TREE_CODE (tmp) == INTEGER_CST
- && tree_int_cst_lt (numiter, tmp))
+ if (numiter >= 0
+ && compare_tree_int (tmp, numiter) > 0)
{
free_conflict_function (*overlaps_a);
free_conflict_function (*overlaps_b);
{
bool xz_p, yz_p, xyz_p;
int step_x, step_y, step_z;
- int niter_x, niter_y, niter_z, niter;
- tree numiter_x, numiter_y, numiter_z;
+ HOST_WIDE_INT niter_x, niter_y, niter_z, niter;
affine_fn overlaps_a_xz, overlaps_b_xz;
affine_fn overlaps_a_yz, overlaps_b_yz;
affine_fn overlaps_a_xyz, overlaps_b_xyz;
step_y = int_cst_value (CHREC_RIGHT (chrec_a));
step_z = int_cst_value (CHREC_RIGHT (chrec_b));
- numiter_x = get_number_of_iters_for_loop (CHREC_VARIABLE (CHREC_LEFT (chrec_a)));
- numiter_y = get_number_of_iters_for_loop (CHREC_VARIABLE (chrec_a));
- numiter_z = get_number_of_iters_for_loop (CHREC_VARIABLE (chrec_b));
+ niter_x = estimated_loop_iterations_int
+ (get_chrec_loop (CHREC_LEFT (chrec_a)), true);
+ niter_y = estimated_loop_iterations_int (get_chrec_loop (chrec_a), true);
+ niter_z = estimated_loop_iterations_int (get_chrec_loop (chrec_b), true);
- if (numiter_x == NULL_TREE || numiter_y == NULL_TREE
- || numiter_z == NULL_TREE)
+ if (niter_x < 0 || niter_y < 0 || niter_z < 0)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "overlap steps test failed: no iteration counts.\n");
return;
}
- niter_x = int_cst_value (numiter_x);
- niter_y = int_cst_value (numiter_y);
- niter_z = int_cst_value (numiter_z);
-
niter = MIN (niter_x, niter_z);
compute_overlap_steps_for_affine_univar (niter, step_x, step_z,
&overlaps_a_xz,
if (nb_vars_a == 1 && nb_vars_b == 1)
{
int step_a, step_b;
- int niter, niter_a, niter_b;
- tree numiter_a, numiter_b;
+ HOST_WIDE_INT niter, niter_a, niter_b;
affine_fn ova, ovb;
- numiter_a = get_number_of_iters_for_loop (CHREC_VARIABLE (chrec_a));
- numiter_b = get_number_of_iters_for_loop (CHREC_VARIABLE (chrec_b));
- if (numiter_a == NULL_TREE || numiter_b == NULL_TREE)
+ niter_a = estimated_loop_iterations_int
+ (get_chrec_loop (chrec_a), true);
+ niter_b = estimated_loop_iterations_int
+ (get_chrec_loop (chrec_b), true);
+ if (niter_a < 0 || niter_b < 0)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "affine-affine test failed: missing iteration counts.\n");
goto end_analyze_subs_aa;
}
- niter_a = int_cst_value (numiter_a);
- niter_b = int_cst_value (numiter_b);
niter = MIN (niter_a, niter_b);
step_a = int_cst_value (CHREC_RIGHT (chrec_a));
equation: chrec_a (X0) = chrec_b (Y0). */
int x0, y0;
int niter, niter_a, niter_b;
- tree numiter_a, numiter_b;
- numiter_a = get_number_of_iters_for_loop (CHREC_VARIABLE (chrec_a));
- numiter_b = get_number_of_iters_for_loop (CHREC_VARIABLE (chrec_b));
+ niter_a = estimated_loop_iterations_int
+ (get_chrec_loop (chrec_a), true);
+ niter_b = estimated_loop_iterations_int
+ (get_chrec_loop (chrec_b), true);
- if (numiter_a == NULL_TREE || numiter_b == NULL_TREE)
+ if (niter_a < 0 || niter_b < 0)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "affine-affine test failed: missing iteration counts.\n");
goto end_analyze_subs_aa;
}
- niter_a = int_cst_value (numiter_a);
- niter_b = int_cst_value (numiter_b);
niter = MIN (niter_a, niter_b);
i0 = U[0][0] * gamma / gcd_alpha_beta;
in the same order. */
*overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
*overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node));
- *last_conflicts = get_number_of_iters_for_loop (CHREC_VARIABLE (chrec_a));
+ *last_conflicts = estimated_loop_iterations_tree
+ (get_chrec_loop (chrec_a), true);
dependence_stats.num_miv_dependent++;
}
compute_estimated_nb_iterations (struct loop *loop)
{
struct nb_iter_bound *bound;
+ double_int bnd_val, delta;
+ edge exit;
gcc_assert (loop->estimate_state == EST_NOT_AVAILABLE);
if (!bound->realistic)
continue;
+ bnd_val = bound->bound;
+ /* If bound->stmt is an exit, then every statement in the loop is
+ executed at most BND_VAL + 1 times. If it is not an exit, then
+ some of the statements before it could be executed BND_VAL + 2
+ times, if an exit of LOOP is before stmt. */
+ exit = single_exit (loop);
+
+ if (bound->is_exit
+ || (exit != NULL
+ && dominated_by_p (CDI_DOMINATORS,
+ exit->src, bb_for_stmt (bound->stmt))))
+ delta = double_int_one;
+ else
+ delta = double_int_two;
+ bnd_val = double_int_add (bnd_val, delta);
+
+ /* If an overflow occured, ignore the result. */
+ if (double_int_ucmp (bnd_val, delta) < 0)
+ continue;
+
/* Update only when there is no previous estimation, or when the current
estimation is smaller. */
if (loop->estimate_state == EST_NOT_AVAILABLE
- || double_int_ucmp (bound->bound, loop->estimated_nb_iterations) < 0)
+ || double_int_ucmp (bnd_val, loop->estimated_nb_iterations) < 0)
{
loop->estimate_state = EST_AVAILABLE;
- loop->estimated_nb_iterations = bound->bound;
+ loop->estimated_nb_iterations = bnd_val;
}
}
}
+/* Returns true if REF is a reference to an array at the end of a dynamically
+ allocated structure. If this is the case, the array may be allocated larger
+ than its upper bound implies. */
+
+static bool
+array_at_struct_end_p (tree ref)
+{
+ tree base = get_base_address (ref);
+ tree parent, field;
+
+ /* Unless the reference is through a pointer, the size of the array matches
+ its declaration. */
+ if (!base || !INDIRECT_REF_P (base))
+ return false;
+
+ for (;handled_component_p (ref); ref = parent)
+ {
+ parent = TREE_OPERAND (ref, 0);
+
+ if (TREE_CODE (ref) == COMPONENT_REF)
+ {
+ /* All fields of a union are at its end. */
+ if (TREE_CODE (TREE_TYPE (parent)) == UNION_TYPE)
+ continue;
+
+ /* Unless the field is at the end of the struct, we are done. */
+ field = TREE_OPERAND (ref, 1);
+ if (TREE_CHAIN (field))
+ return false;
+ }
+
+ /* The other options are ARRAY_REF, ARRAY_RANGE_REF, VIEW_CONVERT_EXPR.
+ In all these cases, we might be accessing the last element, and
+ although in practice this will probably never happen, it is legal for
+ the indices of this last element to exceed the bounds of the array.
+ Therefore, continue checking. */
+ }
+
+ gcc_assert (INDIRECT_REF_P (ref));
+ return true;
+}
+
/* Determine information about number of iterations a LOOP from the index
IDX of a data reference accessed in STMT. Callback for for_each_index. */
bool sign;
struct loop *loop = data->loop;
- if (TREE_CODE (base) != ARRAY_REF)
+ if (TREE_CODE (base) != ARRAY_REF
+ || array_at_struct_end_p (base))
return true;
ev = instantiate_parameters (loop, analyze_scalar_evolution (loop, *idx));
/* Records estimates on numbers of iterations of LOOP. */
-static void
+void
estimate_numbers_of_iterations_loop (struct loop *loop)
{
VEC (edge, heap) *exits;
projects / thirdparty / gcc.git / commitdiff
