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PR ipa/91089 - Setup predicate for switch default case in IPA 

2019-09-17  Feng Xue  <fxue@os.amperecomputing.com>

        PR ipa/91089
        * doc/invoke.texi (ipa-max-switch-predicate-bounds): Document new
        option.
        * params.def (PARAM_IPA_MAX_SWITCH_PREDICATE_BOUNDS): New.
        * ipa-fnsummary.c (set_switch_stmt_execution_predicate): Add predicate
        for switch default case using range analysis information.

2019-09-17  Feng Xue  <fxue@os.amperecomputing.com>

        PR ipa/91089
        * gcc.dg/ipa/pr91089.c: New test.

From-SVN: r275802
This commit is contained in:
Feng Xue 2019-09-17 12:30:08 +00:00 committed by Feng Xue
parent c4ccdc0e63
commit 351e7c3b5f
6 changed files with 204 additions and 7 deletions
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9
gcc/ChangeLog
View File

@ -1,3 +1,12 @@
2019-09-17 Feng Xue <fxue@os.amperecomputing.com>
PR ipa/91089
* doc/invoke.texi (ipa-max-switch-predicate-bounds): Document new
option.
* params.def (PARAM_IPA_MAX_SWITCH_PREDICATE_BOUNDS): New.
* ipa-fnsummary.c (set_switch_stmt_execution_predicate): Add predicate
for switch default case using range analysis information.
2019-09-17 Christophe Lyon <christophe.lyon@linaro.org>
PR target/91749

6
gcc/doc/invoke.texi
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@ -11937,6 +11937,12 @@ not spend too much time analyzing huge functions, it gives up and
consider all memory clobbered after examining
@option{ipa-max-aa-steps} statements modifying memory.
@item ipa-max-switch-predicate-bounds
Maximal number of boundary endpoints of case ranges of switch statement.
For switch exceeding this limit, IPA-CP will not construct cloning cost
predicate, which is used to estimate cloning benefit, for default case
of the switch statement.
@item lto-partitions
Specify desired number of partitions produced during WHOPR compilation.
The number of partitions should exceed the number of CPUs used for compilation.

123
gcc/ipa-fnsummary.c
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@ -1269,13 +1269,21 @@ set_switch_stmt_execution_predicate (struct ipa_func_body_info *fbi,
if (!unmodified_parm_or_parm_agg_item (fbi, last, op, &index, &size, &aggpos))
return;
auto_vec<std::pair<tree, tree> > ranges;
tree type = TREE_TYPE (op);
int bound_limit = PARAM_VALUE (PARAM_IPA_MAX_SWITCH_PREDICATE_BOUNDS);
int bound_count = 0;
wide_int vr_wmin, vr_wmax;
value_range_kind vr_type = get_range_info (op, &vr_wmin, &vr_wmax);
FOR_EACH_EDGE (e, ei, bb->succs)
{
e->aux = edge_predicate_pool.allocate ();
*(predicate *) e->aux = false;
}
n = gimple_switch_num_labels (last);
for (case_idx = 0; case_idx < n; ++case_idx)
for (case_idx = 1; case_idx < n; ++case_idx)
{
tree cl = gimple_switch_label (last, case_idx);
tree min, max;
@ -1285,12 +1293,7 @@ set_switch_stmt_execution_predicate (struct ipa_func_body_info *fbi,
min = CASE_LOW (cl);
max = CASE_HIGH (cl);
/* For default we might want to construct predicate that none
of cases is met, but it is bit hard to do not having negations
of conditionals handy. */
if (!min && !max)
p = true;
else if (!max)
if (!max)
p = add_condition (summary, index, size, &aggpos, EQ_EXPR,
unshare_expr_without_location (min));
else
@ -1304,7 +1307,113 @@ set_switch_stmt_execution_predicate (struct ipa_func_body_info *fbi,
}
*(class predicate *) e->aux
= p.or_with (summary->conds, *(class predicate *) e->aux);
/* If there are too many disjoint case ranges, predicate for default
case might become too complicated. So add a limit here. */
if (bound_count > bound_limit)
continue;
bool new_range = true;
if (!ranges.is_empty ())
{
wide_int curr_wmin = wi::to_wide (min);
wide_int last_wmax = wi::to_wide (ranges.last ().second);
/* Merge case ranges if they are continuous. */
if (curr_wmin == last_wmax + 1)
new_range = false;
else if (vr_type == VR_ANTI_RANGE)
{
/* If two disjoint case ranges can be connected by anti-range
of switch index, combine them to one range. */
if (wi::lt_p (vr_wmax, curr_wmin - 1, TYPE_SIGN (type)))
vr_type = VR_UNDEFINED;
else if (wi::le_p (vr_wmin, last_wmax + 1, TYPE_SIGN (type)))
new_range = false;
}
}
if (!max)
max = min;
/* Create/extend a case range. And we count endpoints of range set,
this number nearly equals to number of conditions that we will create
for predicate of default case. */
if (new_range)
{
bound_count += (min == max) ? 1 : 2;
ranges.safe_push (std::make_pair (min, max));
}
else
{
bound_count += (ranges.last ().first == ranges.last ().second);
ranges.last ().second = max;
}
}
e = gimple_switch_edge (cfun, last, 0);
if (bound_count > bound_limit)
{
*(class predicate *) e->aux = true;
return;
}
predicate p_seg = true;
predicate p_all = false;
if (vr_type != VR_RANGE)
{
vr_wmin = wi::to_wide (TYPE_MIN_VALUE (type));
vr_wmax = wi::to_wide (TYPE_MAX_VALUE (type));
}
/* Construct predicate to represent default range set that is negation of
all case ranges. Case range is classified as containing single/non-single
values. Suppose a piece of case ranges in the following.
[D1...D2] [S1] ... [Sn] [D3...D4]
To represent default case's range sets between two non-single value
case ranges (From D2 to D3), we construct predicate as:
D2 < x < D3 && x != S1 && ... && x != Sn
*/
for (size_t i = 0; i < ranges.length (); i++)
{
tree min = ranges[i].first;
tree max = ranges[i].second;
if (min == max)
p_seg &= add_condition (summary, index, size, &aggpos, NE_EXPR,
unshare_expr_without_location (min));
else
{
/* Do not create sub-predicate for range that is beyond low bound
of switch index. */
if (wi::lt_p (vr_wmin, wi::to_wide (min), TYPE_SIGN (type)))
{
p_seg &= add_condition (summary, index, size, &aggpos, LT_EXPR,
unshare_expr_without_location (min));
p_all = p_all.or_with (summary->conds, p_seg);
}
/* Do not create sub-predicate for range that is beyond up bound
of switch index. */
if (wi::le_p (vr_wmax, wi::to_wide (max), TYPE_SIGN (type)))
{
p_seg = false;
break;
}
p_seg = add_condition (summary, index, size, &aggpos, GT_EXPR,
unshare_expr_without_location (max));
}
}
p_all = p_all.or_with (summary->conds, p_seg);
*(class predicate *) e->aux
= p_all.or_with (summary->conds, *(class predicate *) e->aux);
}

6
gcc/params.def
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@ -1123,6 +1123,12 @@ DEFPARAM (PARAM_IPA_MAX_AA_STEPS,
"parameter analysis based on alias analysis in any given function.",
25000, 0, 0)
DEFPARAM (PARAM_IPA_MAX_SWITCH_PREDICATE_BOUNDS,
"ipa-max-switch-predicate-bounds",
"Maximal number of boundary endpoints of case ranges of switch "
"statement used during IPA functoin summary generation.",
5, 0, 0)
/* WHOPR partitioning configuration. */
DEFPARAM (PARAM_LTO_PARTITIONS,

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2019-09-17 Feng Xue <fxue@os.amperecomputing.com>
PR ipa/91089
* gcc.dg/ipa/pr91089.c: New test.
2019-09-17 Paul Thomas <pault@gcc.gnu.org>
PR fortran/91588

62
gcc/testsuite/gcc.dg/ipa/pr91089.c Normal file
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@ -0,0 +1,62 @@
/* { dg-do compile } */
/* { dg-options "-O3 -fdump-ipa-cp-details -fdump-ipa-fnsummary-details --param ipa-max-switch-predicate-bounds=10 -fno-inline" } */
int fn ();
int data;
int callee (int i)
{
switch (i)
{
case -126: return i + 13;
case -127: return i + 5;
case -8: return i * i;
case 0: return i % 9;
case 5:
case 7:
case 6: return 3;
default:
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
fn ();
}
return data += i;
}
int caller ()
{
return callee (-127) +
callee (-126) +
callee (-8) +
callee (0) +
callee (5) +
callee (6) +
callee (7) +
callee (100);
}
/* { dg-final { scan-ipa-dump-times "Creating a specialized node of callee" 7 "cp" } } */
/* { dg-final { scan-ipa-dump "op0 < -127" "fnsummary" } } */
/* { dg-final { scan-ipa-dump "op0 > -126" "fnsummary" } } */
/* { dg-final { scan-ipa-dump "op0 != -8" "fnsummary" } } */
/* { dg-final { scan-ipa-dump "op0 != 0" "fnsummary" } } */
/* { dg-final { scan-ipa-dump "op0 < 5" "fnsummary" } } */
/* { dg-final { scan-ipa-dump "op0 > 7" "fnsummary" } } */