--- a/src/hotspot/share/opto/loopTransform.cpp Thu Sep 26 10:00:07 2019 +0000
+++ b/src/hotspot/share/opto/loopTransform.cpp Thu Sep 12 11:44:51 2019 +0200
@@ -671,76 +671,50 @@
loop->record_for_igvn();
}
-// The Estimated Loop Unroll Size: UnrollFactor * (106% * 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. This is a simplified version of the loop clone
-// size calculation in est_loop_clone_sz(), defined for unroll factors larger
-// than one (>1), performing an overflow check and returning 'UINT_MAX' in
-// case of an overflow.
-static uint est_loop_unroll_sz(uint factor, uint size) {
- precond(0 < factor);
-
- uint const bc = 5;
- uint const cc = 7;
- uint const sz = size + (size + 15) / 16;
- uint estimate = factor * (sz + bc) + cc;
-
- return (estimate - cc) / factor == sz + bc ? estimate : UINT_MAX;
-}
-
-#define EMPTY_LOOP_SIZE 7 // Number of nodes in an empty loop.
-
//------------------------------policy_maximally_unroll------------------------
// Calculate the exact loop trip-count and return TRUE if loop can be fully,
// i.e. maximally, unrolled, otherwise return FALSE. When TRUE, the estimated
// node budget is also requested.
-bool IdealLoopTree::policy_maximally_unroll(PhaseIdealLoop *phase) const {
- CountedLoopNode *cl = _head->as_CountedLoop();
+bool IdealLoopTree::policy_maximally_unroll(PhaseIdealLoop* phase) const {
+ CountedLoopNode* cl = _head->as_CountedLoop();
assert(cl->is_normal_loop(), "");
if (!cl->is_valid_counted_loop()) {
- return false; // Malformed counted loop
+ return false; // Malformed counted loop.
}
if (!cl->has_exact_trip_count()) {
- // Trip count is not exact.
- return false;
+ return false; // Trip count is not exact.
}
uint trip_count = cl->trip_count();
// Note, max_juint is used to indicate unknown trip count.
assert(trip_count > 1, "one iteration loop should be optimized out already");
- assert(trip_count < max_juint, "exact trip_count should be less than max_uint.");
+ assert(trip_count < max_juint, "exact trip_count should be less than max_juint.");
// If nodes are depleted, some transform has miscalculated its needs.
assert(!phase->exceeding_node_budget(), "sanity");
- // Real policy: if we maximally unroll, does it get too big?
- // Allow the unrolled mess to get larger than standard loop
- // size. After all, it will no longer be a loop.
- uint body_size = _body.size();
+ // Allow the unrolled body to get larger than the standard loop size limit.
uint unroll_limit = (uint)LoopUnrollLimit * 4;
assert((intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
- if (trip_count > unroll_limit || body_size > unroll_limit) {
+ if (trip_count > unroll_limit || _body.size() > unroll_limit) {
return false;
}
- // Take into account that after unroll conjoined heads and tails will fold,
- // otherwise policy_unroll() may allow more unrolling than max unrolling.
- uint new_body_size = est_loop_unroll_sz(trip_count, body_size - EMPTY_LOOP_SIZE);
+ uint new_body_size = est_loop_unroll_sz(trip_count);
if (new_body_size == UINT_MAX) { // Check for bad estimate (overflow).
return false;
}
- // Fully unroll a loop with few iterations regardless next conditions since
- // following loop optimizations will split such loop anyway (pre-main-post).
+ // Fully unroll a loop with few iterations, regardless of other conditions,
+ // since the following (general) loop optimizations will split such loop in
+ // any case (into pre-main-post).
if (trip_count <= 3) {
return phase->may_require_nodes(new_body_size);
}
- if (new_body_size > unroll_limit ||
- // Unrolling can result in a large amount of node construction
- phase->exceeding_node_budget(new_body_size)) {
+ // Reject if unrolling will result in too much node construction.
+ if (new_body_size > unroll_limit || phase->exceeding_node_budget(new_body_size)) {
return false;
}
--- a/src/hotspot/share/opto/loopnode.cpp Thu Sep 26 10:00:07 2019 +0000
+++ b/src/hotspot/share/opto/loopnode.cpp Thu Sep 12 11:44:51 2019 +0200
@@ -2471,6 +2471,39 @@
assert((estimate - cc) / factor == sz + bc, "overflow");
+ return estimate + est_loop_flow_merge_sz();
+}
+
+// The Estimated Loop (full-) Unroll Size:
+// UnrollFactor * (~106% * BodySize) + CC + FanOutTerm,
+// where CC is a (totally) ad-hoc/magic "clone" constant, used to ensure that
+// node usage estimates made are on the safe side, for the most part. This is
+// a "light" version of the loop clone size calculation (above), based on the
+// assumption that most of the loop-construct overhead will be unraveled when
+// (fully) unrolled. Defined for unroll factors larger or equal to one (>=1),
+// including an overflow check and returning UINT_MAX in case of an overflow.
+uint IdealLoopTree::est_loop_unroll_sz(uint factor) const {
+
+ precond(factor > 0);
+
+ // Take into account that after unroll conjoined heads and tails will fold.
+ uint const b0 = _body.size() - EMPTY_LOOP_SIZE;
+ uint const cc = 7;
+ uint const sz = b0 + (b0 + 15) / 16;
+ uint estimate = factor * sz + cc;
+
+ if ((estimate - cc) / factor != sz) {
+ return UINT_MAX;
+ }
+
+ return estimate + est_loop_flow_merge_sz();
+}
+
+// Estimate the growth effect (in nodes) of merging control and data flow when
+// cloning a loop body, based on the amount of control and data flow reaching
+// outside of the (current) loop body.
+uint IdealLoopTree::est_loop_flow_merge_sz() const {
+
uint ctrl_edge_out_cnt = 0;
uint data_edge_out_cnt = 0;
@@ -2494,24 +2527,21 @@
}
}
}
- // Add data and control count (x2.0) to estimate iff both are > 0. This is
+ // Use data and control count (x2.0) in estimate iff both are > 0. This is
// a rather pessimistic estimate for the most part, in particular for some
// complex loops, but still not enough to capture all loops.
if (ctrl_edge_out_cnt > 0 && data_edge_out_cnt > 0) {
- estimate += 2 * (ctrl_edge_out_cnt + data_edge_out_cnt);
+ return 2 * (ctrl_edge_out_cnt + data_edge_out_cnt);
}
-
- return estimate;
+ return 0;
}
#ifndef PRODUCT
//------------------------------dump_head--------------------------------------
// Dump 1 liner for loop header info
void IdealLoopTree::dump_head() const {
- for (uint i = 0; i < _nest; i++) {
- tty->print(" ");
- }
- tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
+ tty->sp(2 * _nest);
+ tty->print("Loop: N%d/N%d ", _head->_idx, _tail->_idx);
if (_irreducible) tty->print(" IRREDUCIBLE");
Node* entry = _head->is_Loop() ? _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl) : _head->in(LoopNode::EntryControl);
Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
@@ -4501,69 +4531,67 @@
#ifndef PRODUCT
//------------------------------dump-------------------------------------------
-void PhaseIdealLoop::dump( ) const {
+void PhaseIdealLoop::dump() const {
ResourceMark rm;
Arena* arena = Thread::current()->resource_area();
Node_Stack stack(arena, C->live_nodes() >> 2);
Node_List rpo_list;
VectorSet visited(arena);
visited.set(C->top()->_idx);
- rpo( C->root(), stack, visited, rpo_list );
+ rpo(C->root(), stack, visited, rpo_list);
// Dump root loop indexed by last element in PO order
- dump( _ltree_root, rpo_list.size(), rpo_list );
+ dump(_ltree_root, rpo_list.size(), rpo_list);
}
-void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
+void PhaseIdealLoop::dump(IdealLoopTree* loop, uint idx, Node_List &rpo_list) const {
loop->dump_head();
// Now scan for CFG nodes in the same loop
- for( uint j=idx; j > 0; j-- ) {
- Node *n = rpo_list[j-1];
- if( !_nodes[n->_idx] ) // Skip dead nodes
+ for (uint j = idx; j > 0; j--) {
+ Node* n = rpo_list[j-1];
+ if (!_nodes[n->_idx]) // Skip dead nodes
continue;
- if( get_loop(n) != loop ) { // Wrong loop nest
- if( get_loop(n)->_head == n && // Found nested loop?
- get_loop(n)->_parent == loop )
- dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly
+
+ if (get_loop(n) != loop) { // Wrong loop nest
+ if (get_loop(n)->_head == n && // Found nested loop?
+ get_loop(n)->_parent == loop)
+ dump(get_loop(n), rpo_list.size(), rpo_list); // Print it nested-ly
continue;
}
// Dump controlling node
- for( uint x = 0; x < loop->_nest; x++ )
- tty->print(" ");
+ tty->sp(2 * loop->_nest);
tty->print("C");
- if( n == C->root() ) {
+ if (n == C->root()) {
n->dump();
} else {
Node* cached_idom = idom_no_update(n);
- Node *computed_idom = n->in(0);
- if( n->is_Region() ) {
+ Node* computed_idom = n->in(0);
+ if (n->is_Region()) {
computed_idom = compute_idom(n);
// computed_idom() will return n->in(0) when idom(n) is an IfNode (or
// any MultiBranch ctrl node), so apply a similar transform to
// the cached idom returned from idom_no_update.
cached_idom = find_non_split_ctrl(cached_idom);
}
- tty->print(" ID:%d",computed_idom->_idx);
+ tty->print(" ID:%d", computed_idom->_idx);
n->dump();
- if( cached_idom != computed_idom ) {
+ if (cached_idom != computed_idom) {
tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
computed_idom->_idx, cached_idom->_idx);
}
}
// Dump nodes it controls
- for( uint k = 0; k < _nodes.Size(); k++ ) {
+ for (uint k = 0; k < _nodes.Size(); k++) {
// (k < C->unique() && get_ctrl(find(k)) == n)
if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
- Node *m = C->root()->find(k);
- if( m && m->outcnt() > 0 ) {
+ Node* m = C->root()->find(k);
+ if (m && m->outcnt() > 0) {
if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
_nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
}
- for( uint j = 0; j < loop->_nest; j++ )
- tty->print(" ");
- tty->print(" ");
+ tty->sp(2 * loop->_nest + 1);
m->dump();
}
}
@@ -4574,7 +4602,7 @@
// Collect a R-P-O for the whole CFG.
// Result list is in post-order (scan backwards for RPO)
-void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
+void PhaseIdealLoop::rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const {
stk.push(start, 0);
visited.set(start->_idx);
@@ -4596,7 +4624,7 @@
//=============================================================================
-//------------------------------LoopTreeIterator-----------------------------------
+//------------------------------LoopTreeIterator-------------------------------
// Advance to next loop tree using a preorder, left-to-right traversal.
void LoopTreeIterator::next() {
--- a/src/hotspot/share/opto/loopnode.hpp Thu Sep 26 10:00:07 2019 +0000
+++ b/src/hotspot/share/opto/loopnode.hpp Thu Sep 12 11:44:51 2019 +0200
@@ -623,6 +623,8 @@
// Estimate the number of nodes required when cloning a loop (body).
uint est_loop_clone_sz(uint factor) const;
+ // Estimate the number of nodes required when unrolling a loop (body).
+ uint est_loop_unroll_sz(uint factor) const;
// Compute loop trip count if possible
void compute_trip_count(PhaseIdealLoop* phase);
@@ -654,11 +656,16 @@
void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
#ifndef PRODUCT
- void dump_head( ) const; // Dump loop head only
+ void dump_head() const; // Dump loop head only
void dump() const; // Dump this loop recursively
void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const;
#endif
+ private:
+ enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
+
+ // Estimate the number of nodes resulting from control and data flow merge.
+ uint est_loop_flow_merge_sz() const;
};
// -----------------------------PhaseIdealLoop---------------------------------
@@ -675,7 +682,7 @@
PhaseIterGVN &_igvn;
// Head of loop tree
- IdealLoopTree *_ltree_root;
+ IdealLoopTree* _ltree_root;
// Array of pre-order numbers, plus post-visited bit.
// ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
@@ -1017,9 +1024,9 @@
bool _has_irreducible_loops;
// Per-Node transform
- virtual Node *transform( Node *a_node ) { return 0; }
+ virtual Node* transform(Node* n) { return 0; }
- bool is_counted_loop(Node* x, IdealLoopTree*& loop);
+ bool is_counted_loop(Node* n, IdealLoopTree* &loop);
IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
IdealLoopTree* loop, float cl_prob, float le_fcnt,
Node*& entry_control, Node*& iffalse);
@@ -1034,7 +1041,7 @@
return (IdealLoopTree*)_nodes[n->_idx];
}
- IdealLoopTree *ltree_root() const { return _ltree_root; }
+ IdealLoopTree* ltree_root() const { return _ltree_root; }
// Is 'n' a (nested) member of 'loop'?
int is_member( const IdealLoopTree *loop, Node *n ) const {
@@ -1319,7 +1326,7 @@
// same block. Split thru the Region.
void do_split_if( Node *iff );
- // Conversion of fill/copy patterns into intrisic versions
+ // Conversion of fill/copy patterns into intrinsic versions
bool do_intrinsify_fill();
bool intrinsify_fill(IdealLoopTree* lpt);
bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
@@ -1419,18 +1426,18 @@
public:
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 );
+ void register_new_node(Node* n, Node* blk);
#ifdef ASSERT
void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
#endif
#ifndef PRODUCT
- void dump( ) const;
- void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const;
+ void dump() const;
+ void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
void verify() const; // Major slow :-)
- void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const;
- IdealLoopTree *get_loop_idx(Node* n) const {
+ void verify_compare(Node* n, const PhaseIdealLoop* loop_verify, VectorSet &visited) const;
+ IdealLoopTree* get_loop_idx(Node* n) const {
// Dead nodes have no loop, so return the top level loop instead
return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root;
}
@@ -1439,7 +1446,8 @@
static int _loop_invokes; // Count of PhaseIdealLoop invokes
static int _loop_work; // Sum of PhaseIdealLoop x _unique
#endif
- void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;
+
+ void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
};
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/compiler/loopopts/LoopUnrollBadNodeBudget.java Thu Sep 12 11:44:51 2019 +0200
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8229499
+ * @summary Node estimate for loop unrolling is not correct/sufficient:
+ * assert(delta <= 2 * required) failed: Bad node estimate ...
+ *
+ * @requires !vm.graal.enabled
+ *
+ * @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation
+ * LoopUnrollBadNodeBudget
+ *
+ */
+
+public class LoopUnrollBadNodeBudget {
+
+ int a;
+ long b;
+ int c;
+ int d(long e, short f, int g) {
+ int h, j = 2, k, l[][] = new int[a][];
+ for (h = 8; h < 58; ++h)
+ for (k = 1; 7 > k; ++k)
+ switch (h % 9 * 5 + 43) {
+ case 70:
+ case 65:
+ case 86:
+ case 81:
+ case 62:
+ case 69:
+ case 74:
+ g = j;
+ }
+ long m = u(l);
+ return (int)m;
+ }
+ void n(int p, int o) { d(b, (short)0, p); }
+ void r(String[] q) {
+ int i = 4;
+ n(i, c);
+ }
+ long u(int[][] a) {
+ long sum = 0;
+ return sum;
+ }
+ public static void main(String[] t) {
+ try {
+ LoopUnrollBadNodeBudget s = new LoopUnrollBadNodeBudget();
+ for (int i = 5000; i > 0; i--)
+ s.r(t);
+ } catch (Exception ex) {
+ }
+ }
+}