--- a/src/hotspot/share/opto/loopnode.hpp Mon Jun 03 10:51:28 2019 +0200
+++ b/src/hotspot/share/opto/loopnode.hpp Tue May 28 14:56:58 2019 +0200
@@ -589,17 +589,18 @@
// Convert one iteration loop into normal code.
bool do_one_iteration_loop( PhaseIdealLoop *phase );
- // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
- // make some loop-invariant test (usually a null-check) happen before the
- // loop.
- bool policy_peeling( PhaseIdealLoop *phase ) const;
+ // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
+ // move some loop-invariant test (usually a null-check) before the loop.
+ bool policy_peeling(PhaseIdealLoop *phase);
+
+ uint estimate_peeling(PhaseIdealLoop *phase);
// Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
// known trip count in the counted loop node.
- bool policy_maximally_unroll( PhaseIdealLoop *phase ) const;
+ bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
- // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
- // the loop is a CountedLoop and the body is small enough.
+ // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
+ // if the loop is a counted loop and the loop body is small enough.
bool policy_unroll(PhaseIdealLoop *phase);
// Loop analyses to map to a maximal superword unrolling for vectorization.
@@ -620,6 +621,9 @@
// Return TRUE if "iff" is a range check.
bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const;
+ // Estimate the number of nodes required when cloning a loop (body).
+ uint est_loop_clone_sz(uint factor) const;
+
// Compute loop trip count if possible
void compute_trip_count(PhaseIdealLoop* phase);
@@ -1356,50 +1360,66 @@
// < UINT_MAX Nodes currently requested (estimate).
uint _nodes_required;
+ enum { REQUIRE_MIN = 70 };
+
+ uint nodes_required() const { return _nodes_required; }
+
+ // Given the _currently_ available number of nodes, check whether there is
+ // "room" for an additional request or not, considering the already required
+ // number of nodes. Return TRUE if the new request is exceeding the node
+ // budget limit, otherwise return FALSE. Note that this interpretation will
+ // act pessimistic on additional requests when new nodes have already been
+ // generated since the 'begin'. This behaviour fits with the intention that
+ // node estimates/requests should be made upfront.
bool exceeding_node_budget(uint required = 0) {
assert(C->live_nodes() < C->max_node_limit(), "sanity");
uint available = C->max_node_limit() - C->live_nodes();
return available < required + _nodes_required;
}
- uint require_nodes(uint require) {
+ uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
precond(require > 0);
- _nodes_required += MAX2(100u, require); // Keep requests at minimum 100.
+ _nodes_required += MAX2(require, minreq);
return _nodes_required;
}
- bool may_require_nodes(uint require) {
- return !exceeding_node_budget(require) && require_nodes(require) > 0;
+ bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
+ return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
}
- void require_nodes_begin() {
+ uint require_nodes_begin() {
assert(_nodes_required == UINT_MAX, "Bad state (begin).");
_nodes_required = 0;
+ return C->live_nodes();
}
- // Final check that the requested nodes did not exceed the limit and that
- // the request was reasonably correct with respect to the number of new
- // nodes introduced by any transform since the last 'begin'.
- void require_nodes_final_check(uint live_at_begin) {
- uint required = _nodes_required;
- require_nodes_final();
- uint delta = C->live_nodes() - live_at_begin;
- // Assert is disabled, see JDK-8223911 and related issues.
- assert(true || delta <= 2 * required, "Bad node estimate (actual: %d, request: %d)",
- delta, required);
- }
+ // When a node request is final, optionally check that the requested number
+ // of nodes was reasonably correct with respect to the number of new nodes
+ // introduced since the last 'begin'. Always check that we have not exceeded
+ // the maximum node limit.
+ void require_nodes_final(uint live_at_begin, bool check_estimate) {
+ assert(_nodes_required < UINT_MAX, "Bad state (final).");
- void require_nodes_final() {
- assert(_nodes_required < UINT_MAX, "Bad state (final).");
- assert(!exceeding_node_budget(), "Too many NODES required!");
+ if (check_estimate) {
+ // Assert that the node budget request was not off by too much (x2).
+ // Should this be the case we _surely_ need to improve the estimates
+ // used in our budget calculations.
+ assert(C->live_nodes() - live_at_begin <= 2 * _nodes_required,
+ "Bad node estimate: actual = %d >> request = %d",
+ C->live_nodes() - live_at_begin, _nodes_required);
+ }
+ // Assert that we have stayed within the node budget limit.
+ assert(C->live_nodes() < C->max_node_limit(),
+ "Exceeding node budget limit: %d + %d > %d (request = %d)",
+ C->live_nodes() - live_at_begin, live_at_begin,
+ C->max_node_limit(), _nodes_required);
+
_nodes_required = UINT_MAX;
}
bool _created_loop_node;
public:
- uint nodes_required() const { return _nodes_required; }
-
void set_created_loop_node() { _created_loop_node = true; }
bool created_loop_node() { return _created_loop_node; }
void register_new_node( Node *n, Node *blk );
@@ -1438,29 +1458,30 @@
{
precond(_phase != NULL);
- _nodes_at_begin = _phase->C->live_nodes();
- _phase->require_nodes_begin();
+ _nodes_at_begin = _phase->require_nodes_begin();
}
~AutoNodeBudget() {
- if (_check_at_final) {
#ifndef PRODUCT
- if (TraceLoopOpts) {
- uint request = _phase->nodes_required();
+ if (TraceLoopOpts) {
+ uint request = _phase->nodes_required();
+ uint delta = _phase->C->live_nodes() - _nodes_at_begin;
- if (request > 0) {
- uint delta = _phase->C->live_nodes() - _nodes_at_begin;
-
- if (request < delta) {
- tty->print_cr("Exceeding node budget: %d < %d", request, delta);
+ if (request < delta) {
+ tty->print_cr("Exceeding node budget: %d < %d", request, delta);
+ } else {
+ uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
+ // Identify the worst estimates as "poor" ones.
+ if (request > REQUIRE_MIN && delta > 0) {
+ if ((delta > REQUIRE_MIN && request > 3 * delta) ||
+ (delta <= REQUIRE_MIN && request > 10 * delta)) {
+ tty->print_cr("Poor node estimate: %d >> %d", request, delta);
}
}
}
-#endif
- _phase->require_nodes_final_check(_nodes_at_begin);
- } else {
- _phase->require_nodes_final();
}
+#endif // PRODUCT
+ _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
}
private:
@@ -1469,17 +1490,6 @@
uint _nodes_at_begin;
};
-// The Estimated Loop Clone Size: CloneFactor * (BodySize + BC) + CC, where BC
-// and CC are totally ad-hoc/magic "body" and "clone" constants, respectively,
-// used to ensure that node usage estimates made are on the safe side, for the
-// most part.
-static inline uint est_loop_clone_sz(uint fact, uint size) {
- uint const bc = 31;
- uint const cc = 41;
- uint estimate = fact * (size + bc) + cc;
- return (estimate - cc) / fact == size + bc ? estimate : UINT_MAX;
-}
-
// This kit may be used for making of a reserved copy of a loop before this loop
// goes under non-reversible changes.