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re PR middle-end/45098 (Missed induction variable optimization)

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2011-05-19  Tom de Vries  <tom@codesourcery.com>

	PR target/45098
	* tree-ssa-loop-ivopts.c (get_expr_id): Factored new function out of
	get_loop_invariant_expr_id.
	(get_loop_invariant_expr_id): Use get_expr_id.
	(parm_decl_cost): New function.
	(determine_use_iv_cost_condition): Use get_expr_id and parm_decl_cost.
	Improve bound cost estimation.  Use different inv_expr_id for elim and
	express cases.

From-SVN: r173894
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Tom de Vries 2011-05-19 09:03:12 +00:00 committed by Tom de Vries
parent a53c50249f
commit bb8d292d39
2 changed files with 79 additions and 17 deletions
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11
gcc/ChangeLog
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@ -1,3 +1,14 @@
2011-05-19 Tom de Vries <tom@codesourcery.com>
PR target/45098
* tree-ssa-loop-ivopts.c (get_expr_id): Factored new function out of
get_loop_invariant_expr_id.
(get_loop_invariant_expr_id): Use get_expr_id.
(parm_decl_cost): New function.
(determine_use_iv_cost_condition): Use get_expr_id and parm_decl_cost.
Improve bound cost estimation. Use different inv_expr_id for elim and
express cases.
2011-05-19 Tom de Vries <tom@codesourcery.com>
PR target/45098

85
gcc/tree-ssa-loop-ivopts.c
View File

@ -3837,6 +3837,28 @@ compare_aff_trees (aff_tree *aff1, aff_tree *aff2)
return true;
}
/* Stores EXPR in DATA->inv_expr_tab, and assigns it an inv_expr_id. */
static int
get_expr_id (struct ivopts_data *data, tree expr)
{
struct iv_inv_expr_ent ent;
struct iv_inv_expr_ent **slot;
ent.expr = expr;
ent.hash = iterative_hash_expr (expr, 0);
slot = (struct iv_inv_expr_ent **) htab_find_slot (data->inv_expr_tab,
&ent, INSERT);
if (*slot)
return (*slot)->id;
*slot = XNEW (struct iv_inv_expr_ent);
(*slot)->expr = expr;
(*slot)->hash = ent.hash;
(*slot)->id = data->inv_expr_id++;
return (*slot)->id;
}
/* Returns the pseudo expr id if expression UBASE - RATIO * CBASE
requires a new compiler generated temporary. Returns -1 otherwise.
ADDRESS_P is a flag indicating if the expression is for address
@ -3849,8 +3871,6 @@ get_loop_invariant_expr_id (struct ivopts_data *data, tree ubase,
{
aff_tree ubase_aff, cbase_aff;
tree expr, ub, cb;
struct iv_inv_expr_ent ent;
struct iv_inv_expr_ent **slot;
STRIP_NOPS (ubase);
STRIP_NOPS (cbase);
@ -3938,18 +3958,7 @@ get_loop_invariant_expr_id (struct ivopts_data *data, tree ubase,
aff_combination_scale (&cbase_aff, shwi_to_double_int (-1 * ratio));
aff_combination_add (&ubase_aff, &cbase_aff);
expr = aff_combination_to_tree (&ubase_aff);
ent.expr = expr;
ent.hash = iterative_hash_expr (expr, 0);
slot = (struct iv_inv_expr_ent **) htab_find_slot (data->inv_expr_tab,
&ent, INSERT);
if (*slot)
return (*slot)->id;
*slot = XNEW (struct iv_inv_expr_ent);
(*slot)->expr = expr;
(*slot)->hash = ent.hash;
(*slot)->id = data->inv_expr_id++;
return (*slot)->id;
return get_expr_id (data, expr);
}
@ -4414,6 +4423,23 @@ may_eliminate_iv (struct ivopts_data *data,
return true;
}
/* Calculates the cost of BOUND, if it is a PARM_DECL. A PARM_DECL must
be copied, if is is used in the loop body and DATA->body_includes_call. */
static int
parm_decl_cost (struct ivopts_data *data, tree bound)
{
tree sbound = bound;
STRIP_NOPS (sbound);
if (TREE_CODE (sbound) == SSA_NAME
&& TREE_CODE (SSA_NAME_VAR (sbound)) == PARM_DECL
&& gimple_nop_p (SSA_NAME_DEF_STMT (sbound))
&& data->body_includes_call)
return COSTS_N_INSNS (1);
return 0;
}
/* Determines cost of basing replacement of USE on CAND in a condition. */
@ -4424,9 +4450,9 @@ determine_use_iv_cost_condition (struct ivopts_data *data,
tree bound = NULL_TREE;
struct iv *cmp_iv;
bitmap depends_on_elim = NULL, depends_on_express = NULL, depends_on;
comp_cost elim_cost, express_cost, cost;
comp_cost elim_cost, express_cost, cost, bound_cost;
bool ok;
int inv_expr_id = -1;
int elim_inv_expr_id = -1, express_inv_expr_id = -1, inv_expr_id;
tree *control_var, *bound_cst;
/* Only consider real candidates. */
@ -4440,6 +4466,21 @@ determine_use_iv_cost_condition (struct ivopts_data *data,
if (may_eliminate_iv (data, use, cand, &bound))
{
elim_cost = force_var_cost (data, bound, &depends_on_elim);
if (elim_cost.cost == 0)
elim_cost.cost = parm_decl_cost (data, bound);
else if (TREE_CODE (bound) == INTEGER_CST)
elim_cost.cost = 0;
/* If we replace a loop condition 'i < n' with 'p < base + n',
depends_on_elim will have 'base' and 'n' set, which implies
that both 'base' and 'n' will be live during the loop. More likely,
'base + n' will be loop invariant, resulting in only one live value
during the loop. So in that case we clear depends_on_elim and set
elim_inv_expr_id instead. */
if (depends_on_elim && bitmap_count_bits (depends_on_elim) > 1)
{
elim_inv_expr_id = get_expr_id (data, bound);
bitmap_clear (depends_on_elim);
}
/* The bound is a loop invariant, so it will be only computed
once. */
elim_cost.cost = adjust_setup_cost (data, elim_cost.cost);
@ -4467,16 +4508,25 @@ determine_use_iv_cost_condition (struct ivopts_data *data,
express_cost = get_computation_cost (data, use, cand, false,
&depends_on_express, NULL,
&inv_expr_id);
&express_inv_expr_id);
fd_ivopts_data = data;
walk_tree (&cmp_iv->base, find_depends, &depends_on_express, NULL);
/* Count the cost of the original bound as well. */
bound_cost = force_var_cost (data, *bound_cst, NULL);
if (bound_cost.cost == 0)
bound_cost.cost = parm_decl_cost (data, *bound_cst);
else if (TREE_CODE (*bound_cst) == INTEGER_CST)
bound_cost.cost = 0;
express_cost.cost += bound_cost.cost;
/* Choose the better approach, preferring the eliminated IV. */
if (compare_costs (elim_cost, express_cost) <= 0)
{
cost = elim_cost;
depends_on = depends_on_elim;
depends_on_elim = NULL;
inv_expr_id = elim_inv_expr_id;
}
else
{
@ -4484,6 +4534,7 @@ determine_use_iv_cost_condition (struct ivopts_data *data,
depends_on = depends_on_express;
depends_on_express = NULL;
bound = NULL_TREE;
inv_expr_id = express_inv_expr_id;
}
set_use_iv_cost (data, use, cand, cost, depends_on, bound, inv_expr_id);