--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/opto/loopnode.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,2886 @@
+/*
+ * Copyright 1998-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+#include "incls/_precompiled.incl"
+#include "incls/_loopnode.cpp.incl"
+
+//=============================================================================
+//------------------------------is_loop_iv-------------------------------------
+// Determine if a node is Counted loop induction variable.
+// The method is declared in node.hpp.
+const Node* Node::is_loop_iv() const {
+ if (this->is_Phi() && !this->as_Phi()->is_copy() &&
+ this->as_Phi()->region()->is_CountedLoop() &&
+ this->as_Phi()->region()->as_CountedLoop()->phi() == this) {
+ return this;
+ } else {
+ return NULL;
+ }
+}
+
+//=============================================================================
+//------------------------------dump_spec--------------------------------------
+// Dump special per-node info
+#ifndef PRODUCT
+void LoopNode::dump_spec(outputStream *st) const {
+ if( is_inner_loop () ) st->print( "inner " );
+ if( is_partial_peel_loop () ) st->print( "partial_peel " );
+ if( partial_peel_has_failed () ) st->print( "partial_peel_failed " );
+}
+#endif
+
+//------------------------------get_early_ctrl---------------------------------
+// Compute earliest legal control
+Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
+ assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
+ uint i;
+ Node *early;
+ if( n->in(0) ) {
+ early = n->in(0);
+ if( !early->is_CFG() ) // Might be a non-CFG multi-def
+ early = get_ctrl(early); // So treat input as a straight data input
+ i = 1;
+ } else {
+ early = get_ctrl(n->in(1));
+ i = 2;
+ }
+ uint e_d = dom_depth(early);
+ assert( early, "" );
+ for( ; i < n->req(); i++ ) {
+ Node *cin = get_ctrl(n->in(i));
+ assert( cin, "" );
+ // Keep deepest dominator depth
+ uint c_d = dom_depth(cin);
+ if( c_d > e_d ) { // Deeper guy?
+ early = cin; // Keep deepest found so far
+ e_d = c_d;
+ } else if( c_d == e_d && // Same depth?
+ early != cin ) { // If not equal, must use slower algorithm
+ // If same depth but not equal, one _must_ dominate the other
+ // and we want the deeper (i.e., dominated) guy.
+ Node *n1 = early;
+ Node *n2 = cin;
+ while( 1 ) {
+ n1 = idom(n1); // Walk up until break cycle
+ n2 = idom(n2);
+ if( n1 == cin || // Walked early up to cin
+ dom_depth(n2) < c_d )
+ break; // early is deeper; keep him
+ if( n2 == early || // Walked cin up to early
+ dom_depth(n1) < c_d ) {
+ early = cin; // cin is deeper; keep him
+ break;
+ }
+ }
+ e_d = dom_depth(early); // Reset depth register cache
+ }
+ }
+
+ // Return earliest legal location
+ assert(early == find_non_split_ctrl(early), "unexpected early control");
+
+ return early;
+}
+
+//------------------------------set_early_ctrl---------------------------------
+// Set earliest legal control
+void PhaseIdealLoop::set_early_ctrl( Node *n ) {
+ Node *early = get_early_ctrl(n);
+
+ // Record earliest legal location
+ set_ctrl(n, early);
+}
+
+//------------------------------set_subtree_ctrl-------------------------------
+// set missing _ctrl entries on new nodes
+void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
+ // Already set? Get out.
+ if( _nodes[n->_idx] ) return;
+ // Recursively set _nodes array to indicate where the Node goes
+ uint i;
+ for( i = 0; i < n->req(); ++i ) {
+ Node *m = n->in(i);
+ if( m && m != C->root() )
+ set_subtree_ctrl( m );
+ }
+
+ // Fixup self
+ set_early_ctrl( n );
+}
+
+//------------------------------is_counted_loop--------------------------------
+Node *PhaseIdealLoop::is_counted_loop( Node *x, IdealLoopTree *loop ) {
+ PhaseGVN *gvn = &_igvn;
+
+ // Counted loop head must be a good RegionNode with only 3 not NULL
+ // control input edges: Self, Entry, LoopBack.
+ if ( x->in(LoopNode::Self) == NULL || x->req() != 3 )
+ return NULL;
+
+ Node *init_control = x->in(LoopNode::EntryControl);
+ Node *back_control = x->in(LoopNode::LoopBackControl);
+ if( init_control == NULL || back_control == NULL ) // Partially dead
+ return NULL;
+ // Must also check for TOP when looking for a dead loop
+ if( init_control->is_top() || back_control->is_top() )
+ return NULL;
+
+ // Allow funny placement of Safepoint
+ if( back_control->Opcode() == Op_SafePoint )
+ back_control = back_control->in(TypeFunc::Control);
+
+ // Controlling test for loop
+ Node *iftrue = back_control;
+ uint iftrue_op = iftrue->Opcode();
+ if( iftrue_op != Op_IfTrue &&
+ iftrue_op != Op_IfFalse )
+ // I have a weird back-control. Probably the loop-exit test is in
+ // the middle of the loop and I am looking at some trailing control-flow
+ // merge point. To fix this I would have to partially peel the loop.
+ return NULL; // Obscure back-control
+
+ // Get boolean guarding loop-back test
+ Node *iff = iftrue->in(0);
+ if( get_loop(iff) != loop || !iff->in(1)->is_Bool() ) return NULL;
+ BoolNode *test = iff->in(1)->as_Bool();
+ BoolTest::mask bt = test->_test._test;
+ float cl_prob = iff->as_If()->_prob;
+ if( iftrue_op == Op_IfFalse ) {
+ bt = BoolTest(bt).negate();
+ cl_prob = 1.0 - cl_prob;
+ }
+ // Get backedge compare
+ Node *cmp = test->in(1);
+ int cmp_op = cmp->Opcode();
+ if( cmp_op != Op_CmpI )
+ return NULL; // Avoid pointer & float compares
+
+ // Find the trip-counter increment & limit. Limit must be loop invariant.
+ Node *incr = cmp->in(1);
+ Node *limit = cmp->in(2);
+
+ // ---------
+ // need 'loop()' test to tell if limit is loop invariant
+ // ---------
+
+ if( !is_member( loop, get_ctrl(incr) ) ) { // Swapped trip counter and limit?
+ Node *tmp = incr; // Then reverse order into the CmpI
+ incr = limit;
+ limit = tmp;
+ bt = BoolTest(bt).commute(); // And commute the exit test
+ }
+ if( is_member( loop, get_ctrl(limit) ) ) // Limit must loop-invariant
+ return NULL;
+
+ // Trip-counter increment must be commutative & associative.
+ uint incr_op = incr->Opcode();
+ if( incr_op == Op_Phi && incr->req() == 3 ) {
+ incr = incr->in(2); // Assume incr is on backedge of Phi
+ incr_op = incr->Opcode();
+ }
+ Node* trunc1 = NULL;
+ Node* trunc2 = NULL;
+ const TypeInt* iv_trunc_t = NULL;
+ if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
+ return NULL; // Funny increment opcode
+ }
+
+ // Get merge point
+ Node *xphi = incr->in(1);
+ Node *stride = incr->in(2);
+ if( !stride->is_Con() ) { // Oops, swap these
+ if( !xphi->is_Con() ) // Is the other guy a constant?
+ return NULL; // Nope, unknown stride, bail out
+ Node *tmp = xphi; // 'incr' is commutative, so ok to swap
+ xphi = stride;
+ stride = tmp;
+ }
+ //if( loop(xphi) != l) return NULL;// Merge point is in inner loop??
+ if( !xphi->is_Phi() ) return NULL; // Too much math on the trip counter
+ PhiNode *phi = xphi->as_Phi();
+
+ // Stride must be constant
+ const Type *stride_t = stride->bottom_type();
+ int stride_con = stride_t->is_int()->get_con();
+ assert( stride_con, "missed some peephole opt" );
+
+ // Phi must be of loop header; backedge must wrap to increment
+ if( phi->region() != x ) return NULL;
+ if( trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr ||
+ trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1 ) {
+ return NULL;
+ }
+ Node *init_trip = phi->in(LoopNode::EntryControl);
+ //if (!init_trip->is_Con()) return NULL; // avoid rolling over MAXINT/MININT
+
+ // If iv trunc type is smaller than int, check for possible wrap.
+ if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
+ assert(trunc1 != NULL, "must have found some truncation");
+
+ // Get a better type for the phi (filtered thru if's)
+ const TypeInt* phi_ft = filtered_type(phi);
+
+ // Can iv take on a value that will wrap?
+ //
+ // Ensure iv's limit is not within "stride" of the wrap value.
+ //
+ // Example for "short" type
+ // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
+ // If the stride is +10, then the last value of the induction
+ // variable before the increment (phi_ft->_hi) must be
+ // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
+ // ensure no truncation occurs after the increment.
+
+ if (stride_con > 0) {
+ if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
+ iv_trunc_t->_lo > phi_ft->_lo) {
+ return NULL; // truncation may occur
+ }
+ } else if (stride_con < 0) {
+ if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
+ iv_trunc_t->_hi < phi_ft->_hi) {
+ return NULL; // truncation may occur
+ }
+ }
+ // No possibility of wrap so truncation can be discarded
+ // Promote iv type to Int
+ } else {
+ assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
+ }
+
+ // =================================================
+ // ---- SUCCESS! Found A Trip-Counted Loop! -----
+ //
+ // Canonicalize the condition on the test. If we can exactly determine
+ // the trip-counter exit value, then set limit to that value and use
+ // a '!=' test. Otherwise use conditon '<' for count-up loops and
+ // '>' for count-down loops. If the condition is inverted and we will
+ // be rolling through MININT to MAXINT, then bail out.
+
+ C->print_method("Before CountedLoop", 3);
+
+ // Check for SafePoint on backedge and remove
+ Node *sfpt = x->in(LoopNode::LoopBackControl);
+ if( sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
+ lazy_replace( sfpt, iftrue );
+ loop->_tail = iftrue;
+ }
+
+
+ // If compare points to incr, we are ok. Otherwise the compare
+ // can directly point to the phi; in this case adjust the compare so that
+ // it points to the incr by adusting the limit.
+ if( cmp->in(1) == phi || cmp->in(2) == phi )
+ limit = gvn->transform(new (C, 3) AddINode(limit,stride));
+
+ // trip-count for +-tive stride should be: (limit - init_trip + stride - 1)/stride.
+ // Final value for iterator should be: trip_count * stride + init_trip.
+ const Type *limit_t = limit->bottom_type();
+ const Type *init_t = init_trip->bottom_type();
+ Node *one_p = gvn->intcon( 1);
+ Node *one_m = gvn->intcon(-1);
+
+ Node *trip_count = NULL;
+ Node *hook = new (C, 6) Node(6);
+ switch( bt ) {
+ case BoolTest::eq:
+ return NULL; // Bail out, but this loop trips at most twice!
+ case BoolTest::ne: // Ahh, the case we desire
+ if( stride_con == 1 )
+ trip_count = gvn->transform(new (C, 3) SubINode(limit,init_trip));
+ else if( stride_con == -1 )
+ trip_count = gvn->transform(new (C, 3) SubINode(init_trip,limit));
+ else
+ return NULL; // Odd stride; must prove we hit limit exactly
+ set_subtree_ctrl( trip_count );
+ //_loop.map(trip_count->_idx,loop(limit));
+ break;
+ case BoolTest::le: // Maybe convert to '<' case
+ limit = gvn->transform(new (C, 3) AddINode(limit,one_p));
+ set_subtree_ctrl( limit );
+ hook->init_req(4, limit);
+
+ bt = BoolTest::lt;
+ // Make the new limit be in the same loop nest as the old limit
+ //_loop.map(limit->_idx,limit_loop);
+ // Fall into next case
+ case BoolTest::lt: { // Maybe convert to '!=' case
+ if( stride_con < 0 ) return NULL; // Count down loop rolls through MAXINT
+ Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip));
+ set_subtree_ctrl( range );
+ hook->init_req(0, range);
+
+ Node *bias = gvn->transform(new (C, 3) AddINode(range,stride));
+ set_subtree_ctrl( bias );
+ hook->init_req(1, bias);
+
+ Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_m));
+ set_subtree_ctrl( bias1 );
+ hook->init_req(2, bias1);
+
+ trip_count = gvn->transform(new (C, 3) DivINode(0,bias1,stride));
+ set_subtree_ctrl( trip_count );
+ hook->init_req(3, trip_count);
+ break;
+ }
+
+ case BoolTest::ge: // Maybe convert to '>' case
+ limit = gvn->transform(new (C, 3) AddINode(limit,one_m));
+ set_subtree_ctrl( limit );
+ hook->init_req(4 ,limit);
+
+ bt = BoolTest::gt;
+ // Make the new limit be in the same loop nest as the old limit
+ //_loop.map(limit->_idx,limit_loop);
+ // Fall into next case
+ case BoolTest::gt: { // Maybe convert to '!=' case
+ if( stride_con > 0 ) return NULL; // count up loop rolls through MININT
+ Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip));
+ set_subtree_ctrl( range );
+ hook->init_req(0, range);
+
+ Node *bias = gvn->transform(new (C, 3) AddINode(range,stride));
+ set_subtree_ctrl( bias );
+ hook->init_req(1, bias);
+
+ Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_p));
+ set_subtree_ctrl( bias1 );
+ hook->init_req(2, bias1);
+
+ trip_count = gvn->transform(new (C, 3) DivINode(0,bias1,stride));
+ set_subtree_ctrl( trip_count );
+ hook->init_req(3, trip_count);
+ break;
+ }
+ }
+
+ Node *span = gvn->transform(new (C, 3) MulINode(trip_count,stride));
+ set_subtree_ctrl( span );
+ hook->init_req(5, span);
+
+ limit = gvn->transform(new (C, 3) AddINode(span,init_trip));
+ set_subtree_ctrl( limit );
+
+ // Build a canonical trip test.
+ // Clone code, as old values may be in use.
+ incr = incr->clone();
+ incr->set_req(1,phi);
+ incr->set_req(2,stride);
+ incr = _igvn.register_new_node_with_optimizer(incr);
+ set_early_ctrl( incr );
+ _igvn.hash_delete(phi);
+ phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
+
+ // If phi type is more restrictive than Int, raise to
+ // Int to prevent (almost) infinite recursion in igvn
+ // which can only handle integer types for constants or minint..maxint.
+ if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
+ Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
+ nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
+ nphi = _igvn.register_new_node_with_optimizer(nphi);
+ set_ctrl(nphi, get_ctrl(phi));
+ _igvn.subsume_node(phi, nphi);
+ phi = nphi->as_Phi();
+ }
+ cmp = cmp->clone();
+ cmp->set_req(1,incr);
+ cmp->set_req(2,limit);
+ cmp = _igvn.register_new_node_with_optimizer(cmp);
+ set_ctrl(cmp, iff->in(0));
+
+ Node *tmp = test->clone();
+ assert( tmp->is_Bool(), "" );
+ test = (BoolNode*)tmp;
+ (*(BoolTest*)&test->_test)._test = bt; //BoolTest::ne;
+ test->set_req(1,cmp);
+ _igvn.register_new_node_with_optimizer(test);
+ set_ctrl(test, iff->in(0));
+ // If the exit test is dead, STOP!
+ if( test == NULL ) return NULL;
+ _igvn.hash_delete(iff);
+ iff->set_req_X( 1, test, &_igvn );
+
+ // Replace the old IfNode with a new LoopEndNode
+ Node *lex = _igvn.register_new_node_with_optimizer(new (C, 2) CountedLoopEndNode( iff->in(0), iff->in(1), cl_prob, iff->as_If()->_fcnt ));
+ IfNode *le = lex->as_If();
+ uint dd = dom_depth(iff);
+ set_idom(le, le->in(0), dd); // Update dominance for loop exit
+ set_loop(le, loop);
+
+ // Get the loop-exit control
+ Node *if_f = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
+
+ // Need to swap loop-exit and loop-back control?
+ if( iftrue_op == Op_IfFalse ) {
+ Node *ift2=_igvn.register_new_node_with_optimizer(new (C, 1) IfTrueNode (le));
+ Node *iff2=_igvn.register_new_node_with_optimizer(new (C, 1) IfFalseNode(le));
+
+ loop->_tail = back_control = ift2;
+ set_loop(ift2, loop);
+ set_loop(iff2, get_loop(if_f));
+
+ // Lazy update of 'get_ctrl' mechanism.
+ lazy_replace_proj( if_f , iff2 );
+ lazy_replace_proj( iftrue, ift2 );
+
+ // Swap names
+ if_f = iff2;
+ iftrue = ift2;
+ } else {
+ _igvn.hash_delete(if_f );
+ _igvn.hash_delete(iftrue);
+ if_f ->set_req_X( 0, le, &_igvn );
+ iftrue->set_req_X( 0, le, &_igvn );
+ }
+
+ set_idom(iftrue, le, dd+1);
+ set_idom(if_f, le, dd+1);
+
+ // Now setup a new CountedLoopNode to replace the existing LoopNode
+ CountedLoopNode *l = new (C, 3) CountedLoopNode(init_control, back_control);
+ // The following assert is approximately true, and defines the intention
+ // of can_be_counted_loop. It fails, however, because phase->type
+ // is not yet initialized for this loop and its parts.
+ //assert(l->can_be_counted_loop(this), "sanity");
+ _igvn.register_new_node_with_optimizer(l);
+ set_loop(l, loop);
+ loop->_head = l;
+ // Fix all data nodes placed at the old loop head.
+ // Uses the lazy-update mechanism of 'get_ctrl'.
+ lazy_replace( x, l );
+ set_idom(l, init_control, dom_depth(x));
+
+ // Check for immediately preceeding SafePoint and remove
+ Node *sfpt2 = le->in(0);
+ if( sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2))
+ lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
+
+ // Free up intermediate goo
+ _igvn.remove_dead_node(hook);
+
+ C->print_method("After CountedLoop", 3);
+
+ // Return trip counter
+ return trip_count;
+}
+
+
+//------------------------------Ideal------------------------------------------
+// Return a node which is more "ideal" than the current node.
+// Attempt to convert into a counted-loop.
+Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
+ if (!can_be_counted_loop(phase)) {
+ phase->C->set_major_progress();
+ }
+ return RegionNode::Ideal(phase, can_reshape);
+}
+
+
+//=============================================================================
+//------------------------------Ideal------------------------------------------
+// Return a node which is more "ideal" than the current node.
+// Attempt to convert into a counted-loop.
+Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
+ return RegionNode::Ideal(phase, can_reshape);
+}
+
+//------------------------------dump_spec--------------------------------------
+// Dump special per-node info
+#ifndef PRODUCT
+void CountedLoopNode::dump_spec(outputStream *st) const {
+ LoopNode::dump_spec(st);
+ if( stride_is_con() ) {
+ st->print("stride: %d ",stride_con());
+ } else {
+ st->print("stride: not constant ");
+ }
+ if( is_pre_loop () ) st->print("pre of N%d" , _main_idx );
+ if( is_main_loop() ) st->print("main of N%d", _idx );
+ if( is_post_loop() ) st->print("post of N%d", _main_idx );
+}
+#endif
+
+//=============================================================================
+int CountedLoopEndNode::stride_con() const {
+ return stride()->bottom_type()->is_int()->get_con();
+}
+
+
+//----------------------match_incr_with_optional_truncation--------------------
+// Match increment with optional truncation:
+// CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
+// Return NULL for failure. Success returns the increment node.
+Node* CountedLoopNode::match_incr_with_optional_truncation(
+ Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
+ // Quick cutouts:
+ if (expr == NULL || expr->req() != 3) return false;
+
+ Node *t1 = NULL;
+ Node *t2 = NULL;
+ const TypeInt* trunc_t = TypeInt::INT;
+ Node* n1 = expr;
+ int n1op = n1->Opcode();
+
+ // Try to strip (n1 & M) or (n1 << N >> N) from n1.
+ if (n1op == Op_AndI &&
+ n1->in(2)->is_Con() &&
+ n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
+ // %%% This check should match any mask of 2**K-1.
+ t1 = n1;
+ n1 = t1->in(1);
+ n1op = n1->Opcode();
+ trunc_t = TypeInt::CHAR;
+ } else if (n1op == Op_RShiftI &&
+ n1->in(1) != NULL &&
+ n1->in(1)->Opcode() == Op_LShiftI &&
+ n1->in(2) == n1->in(1)->in(2) &&
+ n1->in(2)->is_Con()) {
+ jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
+ // %%% This check should match any shift in [1..31].
+ if (shift == 16 || shift == 8) {
+ t1 = n1;
+ t2 = t1->in(1);
+ n1 = t2->in(1);
+ n1op = n1->Opcode();
+ if (shift == 16) {
+ trunc_t = TypeInt::SHORT;
+ } else if (shift == 8) {
+ trunc_t = TypeInt::BYTE;
+ }
+ }
+ }
+
+ // If (maybe after stripping) it is an AddI, we won:
+ if (n1op == Op_AddI) {
+ *trunc1 = t1;
+ *trunc2 = t2;
+ *trunc_type = trunc_t;
+ return n1;
+ }
+
+ // failed
+ return NULL;
+}
+
+
+//------------------------------filtered_type--------------------------------
+// Return a type based on condition control flow
+// A successful return will be a type that is restricted due
+// to a series of dominating if-tests, such as:
+// if (i < 10) {
+// if (i > 0) {
+// here: "i" type is [1..10)
+// }
+// }
+// or a control flow merge
+// if (i < 10) {
+// do {
+// phi( , ) -- at top of loop type is [min_int..10)
+// i = ?
+// } while ( i < 10)
+//
+const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
+ assert(n && n->bottom_type()->is_int(), "must be int");
+ const TypeInt* filtered_t = NULL;
+ if (!n->is_Phi()) {
+ assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
+ filtered_t = filtered_type_from_dominators(n, n_ctrl);
+
+ } else {
+ Node* phi = n->as_Phi();
+ Node* region = phi->in(0);
+ assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
+ if (region && region != C->top()) {
+ for (uint i = 1; i < phi->req(); i++) {
+ Node* val = phi->in(i);
+ Node* use_c = region->in(i);
+ const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
+ if (val_t != NULL) {
+ if (filtered_t == NULL) {
+ filtered_t = val_t;
+ } else {
+ filtered_t = filtered_t->meet(val_t)->is_int();
+ }
+ }
+ }
+ }
+ }
+ const TypeInt* n_t = _igvn.type(n)->is_int();
+ if (filtered_t != NULL) {
+ n_t = n_t->join(filtered_t)->is_int();
+ }
+ return n_t;
+}
+
+
+//------------------------------filtered_type_from_dominators--------------------------------
+// Return a possibly more restrictive type for val based on condition control flow of dominators
+const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
+ if (val->is_Con()) {
+ return val->bottom_type()->is_int();
+ }
+ uint if_limit = 10; // Max number of dominating if's visited
+ const TypeInt* rtn_t = NULL;
+
+ if (use_ctrl && use_ctrl != C->top()) {
+ Node* val_ctrl = get_ctrl(val);
+ uint val_dom_depth = dom_depth(val_ctrl);
+ Node* pred = use_ctrl;
+ uint if_cnt = 0;
+ while (if_cnt < if_limit) {
+ if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
+ if_cnt++;
+ const TypeInt* if_t = filtered_type_at_if(val, pred);
+ if (if_t != NULL) {
+ if (rtn_t == NULL) {
+ rtn_t = if_t;
+ } else {
+ rtn_t = rtn_t->join(if_t)->is_int();
+ }
+ }
+ }
+ pred = idom(pred);
+ if (pred == NULL || pred == C->top()) {
+ break;
+ }
+ // Stop if going beyond definition block of val
+ if (dom_depth(pred) < val_dom_depth) {
+ break;
+ }
+ }
+ }
+ return rtn_t;
+}
+
+
+//------------------------------filtered_type_at_if--------------------------------
+// Return a possibly more restrictive type for val based on condition control flow for an if
+const TypeInt* PhaseIdealLoop::filtered_type_at_if( Node* val, Node *if_proj) {
+ assert(if_proj &&
+ (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
+ if (if_proj->in(0) && if_proj->in(0)->is_If()) {
+ IfNode* iff = if_proj->in(0)->as_If();
+ if (iff->in(1) && iff->in(1)->is_Bool()) {
+ BoolNode* bol = iff->in(1)->as_Bool();
+ if (bol->in(1) && bol->in(1)->is_Cmp()) {
+ const CmpNode* cmp = bol->in(1)->as_Cmp();
+ if (cmp->in(1) == val) {
+ const TypeInt* cmp2_t = _igvn.type(cmp->in(2))->isa_int();
+ if (cmp2_t != NULL) {
+ jint lo = cmp2_t->_lo;
+ jint hi = cmp2_t->_hi;
+ BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
+ switch (msk) {
+ case BoolTest::ne:
+ // Can't refine type
+ return NULL;
+ case BoolTest::eq:
+ return cmp2_t;
+ case BoolTest::lt:
+ lo = TypeInt::INT->_lo;
+ if (hi - 1 < hi) {
+ hi = hi - 1;
+ }
+ break;
+ case BoolTest::le:
+ lo = TypeInt::INT->_lo;
+ break;
+ case BoolTest::gt:
+ if (lo + 1 > lo) {
+ lo = lo + 1;
+ }
+ hi = TypeInt::INT->_hi;
+ break;
+ case BoolTest::ge:
+ // lo unchanged
+ hi = TypeInt::INT->_hi;
+ break;
+ }
+ const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
+ return rtn_t;
+ }
+ }
+ }
+ }
+ }
+ return NULL;
+}
+
+//------------------------------dump_spec--------------------------------------
+// Dump special per-node info
+#ifndef PRODUCT
+void CountedLoopEndNode::dump_spec(outputStream *st) const {
+ if( in(TestValue)->is_Bool() ) {
+ BoolTest bt( test_trip()); // Added this for g++.
+
+ st->print("[");
+ bt.dump_on(st);
+ st->print("]");
+ }
+ st->print(" ");
+ IfNode::dump_spec(st);
+}
+#endif
+
+//=============================================================================
+//------------------------------is_member--------------------------------------
+// Is 'l' a member of 'this'?
+int IdealLoopTree::is_member( const IdealLoopTree *l ) const {
+ while( l->_nest > _nest ) l = l->_parent;
+ return l == this;
+}
+
+//------------------------------set_nest---------------------------------------
+// Set loop tree nesting depth. Accumulate _has_call bits.
+int IdealLoopTree::set_nest( uint depth ) {
+ _nest = depth;
+ int bits = _has_call;
+ if( _child ) bits |= _child->set_nest(depth+1);
+ if( bits ) _has_call = 1;
+ if( _next ) bits |= _next ->set_nest(depth );
+ return bits;
+}
+
+//------------------------------split_fall_in----------------------------------
+// Split out multiple fall-in edges from the loop header. Move them to a
+// private RegionNode before the loop. This becomes the loop landing pad.
+void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
+ PhaseIterGVN &igvn = phase->_igvn;
+ uint i;
+
+ // Make a new RegionNode to be the landing pad.
+ Node *landing_pad = new (phase->C, fall_in_cnt+1) RegionNode( fall_in_cnt+1 );
+ phase->set_loop(landing_pad,_parent);
+ // Gather all the fall-in control paths into the landing pad
+ uint icnt = fall_in_cnt;
+ uint oreq = _head->req();
+ for( i = oreq-1; i>0; i-- )
+ if( !phase->is_member( this, _head->in(i) ) )
+ landing_pad->set_req(icnt--,_head->in(i));
+
+ // Peel off PhiNode edges as well
+ for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
+ Node *oj = _head->fast_out(j);
+ if( oj->is_Phi() ) {
+ PhiNode* old_phi = oj->as_Phi();
+ assert( old_phi->region() == _head, "" );
+ igvn.hash_delete(old_phi); // Yank from hash before hacking edges
+ Node *p = PhiNode::make_blank(landing_pad, old_phi);
+ uint icnt = fall_in_cnt;
+ for( i = oreq-1; i>0; i-- ) {
+ if( !phase->is_member( this, _head->in(i) ) ) {
+ p->init_req(icnt--, old_phi->in(i));
+ // Go ahead and clean out old edges from old phi
+ old_phi->del_req(i);
+ }
+ }
+ // Search for CSE's here, because ZKM.jar does a lot of
+ // loop hackery and we need to be a little incremental
+ // with the CSE to avoid O(N^2) node blow-up.
+ Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
+ if( p2 ) { // Found CSE
+ p->destruct(); // Recover useless new node
+ p = p2; // Use old node
+ } else {
+ igvn.register_new_node_with_optimizer(p, old_phi);
+ }
+ // Make old Phi refer to new Phi.
+ old_phi->add_req(p);
+ // Check for the special case of making the old phi useless and
+ // disappear it. In JavaGrande I have a case where this useless
+ // Phi is the loop limit and prevents recognizing a CountedLoop
+ // which in turn prevents removing an empty loop.
+ Node *id_old_phi = old_phi->Identity( &igvn );
+ if( id_old_phi != old_phi ) { // Found a simple identity?
+ // Note that I cannot call 'subsume_node' here, because
+ // that will yank the edge from old_phi to the Region and
+ // I'm mid-iteration over the Region's uses.
+ for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
+ Node* use = old_phi->last_out(i);
+ igvn.hash_delete(use);
+ igvn._worklist.push(use);
+ uint uses_found = 0;
+ for (uint j = 0; j < use->len(); j++) {
+ if (use->in(j) == old_phi) {
+ if (j < use->req()) use->set_req (j, id_old_phi);
+ else use->set_prec(j, id_old_phi);
+ uses_found++;
+ }
+ }
+ i -= uses_found; // we deleted 1 or more copies of this edge
+ }
+ }
+ igvn._worklist.push(old_phi);
+ }
+ }
+ // Finally clean out the fall-in edges from the RegionNode
+ for( i = oreq-1; i>0; i-- ) {
+ if( !phase->is_member( this, _head->in(i) ) ) {
+ _head->del_req(i);
+ }
+ }
+ // Transform landing pad
+ igvn.register_new_node_with_optimizer(landing_pad, _head);
+ // Insert landing pad into the header
+ _head->add_req(landing_pad);
+}
+
+//------------------------------split_outer_loop-------------------------------
+// Split out the outermost loop from this shared header.
+void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
+ PhaseIterGVN &igvn = phase->_igvn;
+
+ // Find index of outermost loop; it should also be my tail.
+ uint outer_idx = 1;
+ while( _head->in(outer_idx) != _tail ) outer_idx++;
+
+ // Make a LoopNode for the outermost loop.
+ Node *ctl = _head->in(LoopNode::EntryControl);
+ Node *outer = new (phase->C, 3) LoopNode( ctl, _head->in(outer_idx) );
+ outer = igvn.register_new_node_with_optimizer(outer, _head);
+ phase->set_created_loop_node();
+ // Outermost loop falls into '_head' loop
+ _head->set_req(LoopNode::EntryControl, outer);
+ _head->del_req(outer_idx);
+ // Split all the Phis up between '_head' loop and 'outer' loop.
+ for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
+ Node *out = _head->fast_out(j);
+ if( out->is_Phi() ) {
+ PhiNode *old_phi = out->as_Phi();
+ assert( old_phi->region() == _head, "" );
+ Node *phi = PhiNode::make_blank(outer, old_phi);
+ phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
+ phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
+ phi = igvn.register_new_node_with_optimizer(phi, old_phi);
+ // Make old Phi point to new Phi on the fall-in path
+ igvn.hash_delete(old_phi);
+ old_phi->set_req(LoopNode::EntryControl, phi);
+ old_phi->del_req(outer_idx);
+ igvn._worklist.push(old_phi);
+ }
+ }
+
+ // Use the new loop head instead of the old shared one
+ _head = outer;
+ phase->set_loop(_head, this);
+}
+
+//------------------------------fix_parent-------------------------------------
+static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
+ loop->_parent = parent;
+ if( loop->_child ) fix_parent( loop->_child, loop );
+ if( loop->_next ) fix_parent( loop->_next , parent );
+}
+
+//------------------------------estimate_path_freq-----------------------------
+static float estimate_path_freq( Node *n ) {
+ // Try to extract some path frequency info
+ IfNode *iff;
+ for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
+ uint nop = n->Opcode();
+ if( nop == Op_SafePoint ) { // Skip any safepoint
+ n = n->in(0);
+ continue;
+ }
+ if( nop == Op_CatchProj ) { // Get count from a prior call
+ // Assume call does not always throw exceptions: means the call-site
+ // count is also the frequency of the fall-through path.
+ assert( n->is_CatchProj(), "" );
+ if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
+ return 0.0f; // Assume call exception path is rare
+ Node *call = n->in(0)->in(0)->in(0);
+ assert( call->is_Call(), "expect a call here" );
+ const JVMState *jvms = ((CallNode*)call)->jvms();
+ ciMethodData* methodData = jvms->method()->method_data();
+ if (!methodData->is_mature()) return 0.0f; // No call-site data
+ ciProfileData* data = methodData->bci_to_data(jvms->bci());
+ if ((data == NULL) || !data->is_CounterData()) {
+ // no call profile available, try call's control input
+ n = n->in(0);
+ continue;
+ }
+ return data->as_CounterData()->count()/FreqCountInvocations;
+ }
+ // See if there's a gating IF test
+ Node *n_c = n->in(0);
+ if( !n_c->is_If() ) break; // No estimate available
+ iff = n_c->as_If();
+ if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
+ // Compute how much count comes on this path
+ return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
+ // Have no count info. Skip dull uncommon-trap like branches.
+ if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
+ (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
+ break;
+ // Skip through never-taken branch; look for a real loop exit.
+ n = iff->in(0);
+ }
+ return 0.0f; // No estimate available
+}
+
+//------------------------------merge_many_backedges---------------------------
+// Merge all the backedges from the shared header into a private Region.
+// Feed that region as the one backedge to this loop.
+void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
+ uint i;
+
+ // Scan for the top 2 hottest backedges
+ float hotcnt = 0.0f;
+ float warmcnt = 0.0f;
+ uint hot_idx = 0;
+ // Loop starts at 2 because slot 1 is the fall-in path
+ for( i = 2; i < _head->req(); i++ ) {
+ float cnt = estimate_path_freq(_head->in(i));
+ if( cnt > hotcnt ) { // Grab hottest path
+ warmcnt = hotcnt;
+ hotcnt = cnt;
+ hot_idx = i;
+ } else if( cnt > warmcnt ) { // And 2nd hottest path
+ warmcnt = cnt;
+ }
+ }
+
+ // See if the hottest backedge is worthy of being an inner loop
+ // by being much hotter than the next hottest backedge.
+ if( hotcnt <= 0.0001 ||
+ hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
+
+ // Peel out the backedges into a private merge point; peel
+ // them all except optionally hot_idx.
+ PhaseIterGVN &igvn = phase->_igvn;
+
+ Node *hot_tail = NULL;
+ // Make a Region for the merge point
+ Node *r = new (phase->C, 1) RegionNode(1);
+ for( i = 2; i < _head->req(); i++ ) {
+ if( i != hot_idx )
+ r->add_req( _head->in(i) );
+ else hot_tail = _head->in(i);
+ }
+ igvn.register_new_node_with_optimizer(r, _head);
+ // Plug region into end of loop _head, followed by hot_tail
+ while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
+ _head->set_req(2, r);
+ if( hot_idx ) _head->add_req(hot_tail);
+
+ // Split all the Phis up between '_head' loop and the Region 'r'
+ for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
+ Node *out = _head->fast_out(j);
+ if( out->is_Phi() ) {
+ PhiNode* n = out->as_Phi();
+ igvn.hash_delete(n); // Delete from hash before hacking edges
+ Node *hot_phi = NULL;
+ Node *phi = new (phase->C, r->req()) PhiNode(r, n->type(), n->adr_type());
+ // Check all inputs for the ones to peel out
+ uint j = 1;
+ for( uint i = 2; i < n->req(); i++ ) {
+ if( i != hot_idx )
+ phi->set_req( j++, n->in(i) );
+ else hot_phi = n->in(i);
+ }
+ // Register the phi but do not transform until whole place transforms
+ igvn.register_new_node_with_optimizer(phi, n);
+ // Add the merge phi to the old Phi
+ while( n->req() > 3 ) n->del_req( n->req()-1 );
+ n->set_req(2, phi);
+ if( hot_idx ) n->add_req(hot_phi);
+ }
+ }
+
+
+ // Insert a new IdealLoopTree inserted below me. Turn it into a clone
+ // of self loop tree. Turn self into a loop headed by _head and with
+ // tail being the new merge point.
+ IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
+ phase->set_loop(_tail,ilt); // Adjust tail
+ _tail = r; // Self's tail is new merge point
+ phase->set_loop(r,this);
+ ilt->_child = _child; // New guy has my children
+ _child = ilt; // Self has new guy as only child
+ ilt->_parent = this; // new guy has self for parent
+ ilt->_nest = _nest; // Same nesting depth (for now)
+
+ // Starting with 'ilt', look for child loop trees using the same shared
+ // header. Flatten these out; they will no longer be loops in the end.
+ IdealLoopTree **pilt = &_child;
+ while( ilt ) {
+ if( ilt->_head == _head ) {
+ uint i;
+ for( i = 2; i < _head->req(); i++ )
+ if( _head->in(i) == ilt->_tail )
+ break; // Still a loop
+ if( i == _head->req() ) { // No longer a loop
+ // Flatten ilt. Hang ilt's "_next" list from the end of
+ // ilt's '_child' list. Move the ilt's _child up to replace ilt.
+ IdealLoopTree **cp = &ilt->_child;
+ while( *cp ) cp = &(*cp)->_next; // Find end of child list
+ *cp = ilt->_next; // Hang next list at end of child list
+ *pilt = ilt->_child; // Move child up to replace ilt
+ ilt->_head = NULL; // Flag as a loop UNIONED into parent
+ ilt = ilt->_child; // Repeat using new ilt
+ continue; // do not advance over ilt->_child
+ }
+ assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
+ phase->set_loop(_head,ilt);
+ }
+ pilt = &ilt->_child; // Advance to next
+ ilt = *pilt;
+ }
+
+ if( _child ) fix_parent( _child, this );
+}
+
+//------------------------------beautify_loops---------------------------------
+// Split shared headers and insert loop landing pads.
+// Insert a LoopNode to replace the RegionNode.
+// Return TRUE if loop tree is structurally changed.
+bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
+ bool result = false;
+ // Cache parts in locals for easy
+ PhaseIterGVN &igvn = phase->_igvn;
+
+ phase->C->print_method("Before beautify loops", 3);
+
+ igvn.hash_delete(_head); // Yank from hash before hacking edges
+
+ // Check for multiple fall-in paths. Peel off a landing pad if need be.
+ int fall_in_cnt = 0;
+ for( uint i = 1; i < _head->req(); i++ )
+ if( !phase->is_member( this, _head->in(i) ) )
+ fall_in_cnt++;
+ assert( fall_in_cnt, "at least 1 fall-in path" );
+ if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
+ split_fall_in( phase, fall_in_cnt );
+
+ // Swap inputs to the _head and all Phis to move the fall-in edge to
+ // the left.
+ fall_in_cnt = 1;
+ while( phase->is_member( this, _head->in(fall_in_cnt) ) )
+ fall_in_cnt++;
+ if( fall_in_cnt > 1 ) {
+ // Since I am just swapping inputs I do not need to update def-use info
+ Node *tmp = _head->in(1);
+ _head->set_req( 1, _head->in(fall_in_cnt) );
+ _head->set_req( fall_in_cnt, tmp );
+ // Swap also all Phis
+ for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
+ Node* phi = _head->fast_out(i);
+ if( phi->is_Phi() ) {
+ igvn.hash_delete(phi); // Yank from hash before hacking edges
+ tmp = phi->in(1);
+ phi->set_req( 1, phi->in(fall_in_cnt) );
+ phi->set_req( fall_in_cnt, tmp );
+ }
+ }
+ }
+ assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
+ assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
+
+ // If I am a shared header (multiple backedges), peel off the many
+ // backedges into a private merge point and use the merge point as
+ // the one true backedge.
+ if( _head->req() > 3 ) {
+ // Merge the many backedges into a single backedge.
+ merge_many_backedges( phase );
+ result = true;
+ }
+
+ // If I am a shared header (multiple backedges), peel off myself loop.
+ // I better be the outermost loop.
+ if( _head->req() > 3 ) {
+ split_outer_loop( phase );
+ result = true;
+
+ } else if( !_head->is_Loop() && !_irreducible ) {
+ // Make a new LoopNode to replace the old loop head
+ Node *l = new (phase->C, 3) LoopNode( _head->in(1), _head->in(2) );
+ l = igvn.register_new_node_with_optimizer(l, _head);
+ phase->set_created_loop_node();
+ // Go ahead and replace _head
+ phase->_igvn.subsume_node( _head, l );
+ _head = l;
+ phase->set_loop(_head, this);
+ for (DUIterator_Fast imax, i = l->fast_outs(imax); i < imax; i++)
+ phase->_igvn.add_users_to_worklist(l->fast_out(i));
+ }
+
+ phase->C->print_method("After beautify loops", 3);
+
+ // Now recursively beautify nested loops
+ if( _child ) result |= _child->beautify_loops( phase );
+ if( _next ) result |= _next ->beautify_loops( phase );
+ return result;
+}
+
+//------------------------------allpaths_check_safepts----------------------------
+// Allpaths backwards scan from loop tail, terminating each path at first safepoint
+// encountered. Helper for check_safepts.
+void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
+ assert(stack.size() == 0, "empty stack");
+ stack.push(_tail);
+ visited.Clear();
+ visited.set(_tail->_idx);
+ while (stack.size() > 0) {
+ Node* n = stack.pop();
+ if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
+ // Terminate this path
+ } else if (n->Opcode() == Op_SafePoint) {
+ if (_phase->get_loop(n) != this) {
+ if (_required_safept == NULL) _required_safept = new Node_List();
+ _required_safept->push(n); // save the one closest to the tail
+ }
+ // Terminate this path
+ } else {
+ uint start = n->is_Region() ? 1 : 0;
+ uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
+ for (uint i = start; i < end; i++) {
+ Node* in = n->in(i);
+ assert(in->is_CFG(), "must be");
+ if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
+ stack.push(in);
+ }
+ }
+ }
+ }
+}
+
+//------------------------------check_safepts----------------------------
+// Given dominators, try to find loops with calls that must always be
+// executed (call dominates loop tail). These loops do not need non-call
+// safepoints (ncsfpt).
+//
+// A complication is that a safepoint in a inner loop may be needed
+// by an outer loop. In the following, the inner loop sees it has a
+// call (block 3) on every path from the head (block 2) to the
+// backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
+// in block 2, _but_ this leaves the outer loop without a safepoint.
+//
+// entry 0
+// |
+// v
+// outer 1,2 +->1
+// | |
+// | v
+// | 2<---+ ncsfpt in 2
+// |_/|\ |
+// | v |
+// inner 2,3 / 3 | call in 3
+// / | |
+// v +--+
+// exit 4
+//
+//
+// This method creates a list (_required_safept) of ncsfpt nodes that must
+// be protected is created for each loop. When a ncsfpt maybe deleted, it
+// is first looked for in the lists for the outer loops of the current loop.
+//
+// The insights into the problem:
+// A) counted loops are okay
+// B) innermost loops are okay (only an inner loop can delete
+// a ncsfpt needed by an outer loop)
+// C) a loop is immune from an inner loop deleting a safepoint
+// if the loop has a call on the idom-path
+// D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
+// idom-path that is not in a nested loop
+// E) otherwise, an ncsfpt on the idom-path that is nested in an inner
+// loop needs to be prevented from deletion by an inner loop
+//
+// There are two analyses:
+// 1) The first, and cheaper one, scans the loop body from
+// tail to head following the idom (immediate dominator)
+// chain, looking for the cases (C,D,E) above.
+// Since inner loops are scanned before outer loops, there is summary
+// information about inner loops. Inner loops can be skipped over
+// when the tail of an inner loop is encountered.
+//
+// 2) The second, invoked if the first fails to find a call or ncsfpt on
+// the idom path (which is rare), scans all predecessor control paths
+// from the tail to the head, terminating a path when a call or sfpt
+// is encountered, to find the ncsfpt's that are closest to the tail.
+//
+void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
+ // Bottom up traversal
+ IdealLoopTree* ch = _child;
+ while (ch != NULL) {
+ ch->check_safepts(visited, stack);
+ ch = ch->_next;
+ }
+
+ if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
+ bool has_call = false; // call on dom-path
+ bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
+ Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
+ // Scan the dom-path nodes from tail to head
+ for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
+ if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
+ has_call = true;
+ _has_sfpt = 1; // Then no need for a safept!
+ break;
+ } else if (n->Opcode() == Op_SafePoint) {
+ if (_phase->get_loop(n) == this) {
+ has_local_ncsfpt = true;
+ break;
+ }
+ if (nonlocal_ncsfpt == NULL) {
+ nonlocal_ncsfpt = n; // save the one closest to the tail
+ }
+ } else {
+ IdealLoopTree* nlpt = _phase->get_loop(n);
+ if (this != nlpt) {
+ // If at an inner loop tail, see if the inner loop has already
+ // recorded seeing a call on the dom-path (and stop.) If not,
+ // jump to the head of the inner loop.
+ assert(is_member(nlpt), "nested loop");
+ Node* tail = nlpt->_tail;
+ if (tail->in(0)->is_If()) tail = tail->in(0);
+ if (n == tail) {
+ // If inner loop has call on dom-path, so does outer loop
+ if (nlpt->_has_sfpt) {
+ has_call = true;
+ _has_sfpt = 1;
+ break;
+ }
+ // Skip to head of inner loop
+ assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
+ n = nlpt->_head;
+ }
+ }
+ }
+ }
+ // Record safept's that this loop needs preserved when an
+ // inner loop attempts to delete it's safepoints.
+ if (_child != NULL && !has_call && !has_local_ncsfpt) {
+ if (nonlocal_ncsfpt != NULL) {
+ if (_required_safept == NULL) _required_safept = new Node_List();
+ _required_safept->push(nonlocal_ncsfpt);
+ } else {
+ // Failed to find a suitable safept on the dom-path. Now use
+ // an all paths walk from tail to head, looking for safepoints to preserve.
+ allpaths_check_safepts(visited, stack);
+ }
+ }
+ }
+}
+
+//---------------------------is_deleteable_safept----------------------------
+// Is safept not required by an outer loop?
+bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
+ assert(sfpt->Opcode() == Op_SafePoint, "");
+ IdealLoopTree* lp = get_loop(sfpt)->_parent;
+ while (lp != NULL) {
+ Node_List* sfpts = lp->_required_safept;
+ if (sfpts != NULL) {
+ for (uint i = 0; i < sfpts->size(); i++) {
+ if (sfpt == sfpts->at(i))
+ return false;
+ }
+ }
+ lp = lp->_parent;
+ }
+ return true;
+}
+
+//------------------------------counted_loop-----------------------------------
+// Convert to counted loops where possible
+void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
+
+ // For grins, set the inner-loop flag here
+ if( !_child ) {
+ if( _head->is_Loop() ) _head->as_Loop()->set_inner_loop();
+ }
+
+ if( _head->is_CountedLoop() ||
+ phase->is_counted_loop( _head, this ) ) {
+ _has_sfpt = 1; // Indicate we do not need a safepoint here
+
+ // Look for a safepoint to remove
+ for (Node* n = tail(); n != _head; n = phase->idom(n))
+ if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this &&
+ phase->is_deleteable_safept(n))
+ phase->lazy_replace(n,n->in(TypeFunc::Control));
+
+ CountedLoopNode *cl = _head->as_CountedLoop();
+ Node *incr = cl->incr();
+ if( !incr ) return; // Dead loop?
+ Node *init = cl->init_trip();
+ Node *phi = cl->phi();
+ // protect against stride not being a constant
+ if( !cl->stride_is_con() ) return;
+ int stride_con = cl->stride_con();
+
+ // Look for induction variables
+
+ // Visit all children, looking for Phis
+ for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
+ Node *out = cl->out(i);
+ if (!out->is_Phi()) continue; // Looking for phis
+ PhiNode* phi2 = out->as_Phi();
+ Node *incr2 = phi2->in( LoopNode::LoopBackControl );
+ // Look for induction variables of the form: X += constant
+ if( phi2->region() != _head ||
+ incr2->req() != 3 ||
+ incr2->in(1) != phi2 ||
+ incr2 == incr ||
+ incr2->Opcode() != Op_AddI ||
+ !incr2->in(2)->is_Con() )
+ continue;
+
+ // Check for parallel induction variable (parallel to trip counter)
+ // via an affine function. In particular, count-down loops with
+ // count-up array indices are common. We only RCE references off
+ // the trip-counter, so we need to convert all these to trip-counter
+ // expressions.
+ Node *init2 = phi2->in( LoopNode::EntryControl );
+ int stride_con2 = incr2->in(2)->get_int();
+
+ // The general case here gets a little tricky. We want to find the
+ // GCD of all possible parallel IV's and make a new IV using this
+ // GCD for the loop. Then all possible IVs are simple multiples of
+ // the GCD. In practice, this will cover very few extra loops.
+ // Instead we require 'stride_con2' to be a multiple of 'stride_con',
+ // where +/-1 is the common case, but other integer multiples are
+ // also easy to handle.
+ int ratio_con = stride_con2/stride_con;
+
+ if( ratio_con * stride_con == stride_con2 ) { // Check for exact
+ // Convert to using the trip counter. The parallel induction
+ // variable differs from the trip counter by a loop-invariant
+ // amount, the difference between their respective initial values.
+ // It is scaled by the 'ratio_con'.
+ Compile* C = phase->C;
+ Node* ratio = phase->_igvn.intcon(ratio_con);
+ phase->set_ctrl(ratio, C->root());
+ Node* ratio_init = new (C, 3) MulINode(init, ratio);
+ phase->_igvn.register_new_node_with_optimizer(ratio_init, init);
+ phase->set_early_ctrl(ratio_init);
+ Node* diff = new (C, 3) SubINode(init2, ratio_init);
+ phase->_igvn.register_new_node_with_optimizer(diff, init2);
+ phase->set_early_ctrl(diff);
+ Node* ratio_idx = new (C, 3) MulINode(phi, ratio);
+ phase->_igvn.register_new_node_with_optimizer(ratio_idx, phi);
+ phase->set_ctrl(ratio_idx, cl);
+ Node* add = new (C, 3) AddINode(ratio_idx, diff);
+ phase->_igvn.register_new_node_with_optimizer(add);
+ phase->set_ctrl(add, cl);
+ phase->_igvn.hash_delete( phi2 );
+ phase->_igvn.subsume_node( phi2, add );
+ // Sometimes an induction variable is unused
+ if (add->outcnt() == 0) {
+ phase->_igvn.remove_dead_node(add);
+ }
+ --i; // deleted this phi; rescan starting with next position
+ continue;
+ }
+ }
+ } else if (_parent != NULL && !_irreducible) {
+ // Not a counted loop.
+ // Look for a safepoint on the idom-path to remove, preserving the first one
+ bool found = false;
+ Node* n = tail();
+ for (; n != _head && !found; n = phase->idom(n)) {
+ if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this)
+ found = true; // Found one
+ }
+ // Skip past it and delete the others
+ for (; n != _head; n = phase->idom(n)) {
+ if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this &&
+ phase->is_deleteable_safept(n))
+ phase->lazy_replace(n,n->in(TypeFunc::Control));
+ }
+ }
+
+ // Recursively
+ if( _child ) _child->counted_loop( phase );
+ if( _next ) _next ->counted_loop( phase );
+}
+
+#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);
+ if( _irreducible ) tty->print(" IRREDUCIBLE");
+ if( _head->is_CountedLoop() ) {
+ CountedLoopNode *cl = _head->as_CountedLoop();
+ tty->print(" counted");
+ if( cl->is_pre_loop () ) tty->print(" pre" );
+ if( cl->is_main_loop() ) tty->print(" main");
+ if( cl->is_post_loop() ) tty->print(" post");
+ }
+ tty->cr();
+}
+
+//------------------------------dump-------------------------------------------
+// Dump loops by loop tree
+void IdealLoopTree::dump( ) const {
+ dump_head();
+ if( _child ) _child->dump();
+ if( _next ) _next ->dump();
+}
+
+#endif
+
+//=============================================================================
+//------------------------------PhaseIdealLoop---------------------------------
+// Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
+// its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
+PhaseIdealLoop::PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me, bool do_split_ifs )
+ : PhaseTransform(Ideal_Loop),
+ _igvn(igvn),
+ _dom_lca_tags(C->comp_arena()) {
+ // Reset major-progress flag for the driver's heuristics
+ C->clear_major_progress();
+
+#ifndef PRODUCT
+ // Capture for later assert
+ uint unique = C->unique();
+ _loop_invokes++;
+ _loop_work += unique;
+#endif
+
+ // True if the method has at least 1 irreducible loop
+ _has_irreducible_loops = false;
+
+ _created_loop_node = false;
+
+ Arena *a = Thread::current()->resource_area();
+ VectorSet visited(a);
+ // Pre-grow the mapping from Nodes to IdealLoopTrees.
+ _nodes.map(C->unique(), NULL);
+ memset(_nodes.adr(), 0, wordSize * C->unique());
+
+ // Pre-build the top-level outermost loop tree entry
+ _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
+ // Do not need a safepoint at the top level
+ _ltree_root->_has_sfpt = 1;
+
+ // Empty pre-order array
+ allocate_preorders();
+
+ // Build a loop tree on the fly. Build a mapping from CFG nodes to
+ // IdealLoopTree entries. Data nodes are NOT walked.
+ build_loop_tree();
+ // Check for bailout, and return
+ if (C->failing()) {
+ return;
+ }
+
+ // No loops after all
+ if( !_ltree_root->_child ) C->set_has_loops(false);
+
+ // There should always be an outer loop containing the Root and Return nodes.
+ // If not, we have a degenerate empty program. Bail out in this case.
+ if (!has_node(C->root())) {
+ C->clear_major_progress();
+ C->record_method_not_compilable("empty program detected during loop optimization");
+ return;
+ }
+
+ // Nothing to do, so get out
+ if( !C->has_loops() && !do_split_ifs && !verify_me) {
+ _igvn.optimize(); // Cleanup NeverBranches
+ return;
+ }
+
+ // Set loop nesting depth
+ _ltree_root->set_nest( 0 );
+
+ // Split shared headers and insert loop landing pads.
+ // Do not bother doing this on the Root loop of course.
+ if( !verify_me && _ltree_root->_child ) {
+ if( _ltree_root->_child->beautify_loops( this ) ) {
+ // Re-build loop tree!
+ _ltree_root->_child = NULL;
+ _nodes.clear();
+ reallocate_preorders();
+ build_loop_tree();
+ // Check for bailout, and return
+ if (C->failing()) {
+ return;
+ }
+ // Reset loop nesting depth
+ _ltree_root->set_nest( 0 );
+ }
+ }
+
+ // Build Dominators for elision of NULL checks & loop finding.
+ // Since nodes do not have a slot for immediate dominator, make
+ // a persistant side array for that info indexed on node->_idx.
+ _idom_size = C->unique();
+ _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
+ _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
+ _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
+ memset( _dom_depth, 0, _idom_size * sizeof(uint) );
+
+ Dominators();
+
+ // As a side effect, Dominators removed any unreachable CFG paths
+ // into RegionNodes. It doesn't do this test against Root, so
+ // we do it here.
+ for( uint i = 1; i < C->root()->req(); i++ ) {
+ if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
+ _igvn.hash_delete(C->root());
+ C->root()->del_req(i);
+ _igvn._worklist.push(C->root());
+ i--; // Rerun same iteration on compressed edges
+ }
+ }
+
+ // Given dominators, try to find inner loops with calls that must
+ // always be executed (call dominates loop tail). These loops do
+ // not need a seperate safepoint.
+ Node_List cisstack(a);
+ _ltree_root->check_safepts(visited, cisstack);
+
+ // Walk the DATA nodes and place into loops. Find earliest control
+ // node. For CFG nodes, the _nodes array starts out and remains
+ // holding the associated IdealLoopTree pointer. For DATA nodes, the
+ // _nodes array holds the earliest legal controlling CFG node.
+
+ // Allocate stack with enough space to avoid frequent realloc
+ int stack_size = (C->unique() >> 1) + 16; // (unique>>1)+16 from Java2D stats
+ Node_Stack nstack( a, stack_size );
+
+ visited.Clear();
+ Node_List worklist(a);
+ // Don't need C->root() on worklist since
+ // it will be processed among C->top() inputs
+ worklist.push( C->top() );
+ visited.set( C->top()->_idx ); // Set C->top() as visited now
+ build_loop_early( visited, worklist, nstack, verify_me );
+
+ // Given early legal placement, try finding counted loops. This placement
+ // is good enough to discover most loop invariants.
+ if( !verify_me )
+ _ltree_root->counted_loop( this );
+
+ // Find latest loop placement. Find ideal loop placement.
+ visited.Clear();
+ init_dom_lca_tags();
+ // Need C->root() on worklist when processing outs
+ worklist.push( C->root() );
+ NOT_PRODUCT( C->verify_graph_edges(); )
+ worklist.push( C->top() );
+ build_loop_late( visited, worklist, nstack, verify_me );
+
+ // clear out the dead code
+ while(_deadlist.size()) {
+ igvn.remove_globally_dead_node(_deadlist.pop());
+ }
+
+#ifndef PRODUCT
+ C->verify_graph_edges();
+ if( verify_me ) { // Nested verify pass?
+ // Check to see if the verify mode is broken
+ assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
+ return;
+ }
+ if( VerifyLoopOptimizations ) verify();
+#endif
+
+ if (ReassociateInvariants) {
+ // Reassociate invariants and prep for split_thru_phi
+ for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
+ IdealLoopTree* lpt = iter.current();
+ if (!lpt->is_counted() || !lpt->is_inner()) continue;
+
+ lpt->reassociate_invariants(this);
+
+ // Because RCE opportunities can be masked by split_thru_phi,
+ // look for RCE candidates and inhibit split_thru_phi
+ // on just their loop-phi's for this pass of loop opts
+ if( SplitIfBlocks && do_split_ifs ) {
+ if (lpt->policy_range_check(this)) {
+ lpt->_rce_candidate = true;
+ }
+ }
+ }
+ }
+
+ // Check for aggressive application of split-if and other transforms
+ // that require basic-block info (like cloning through Phi's)
+ if( SplitIfBlocks && do_split_ifs ) {
+ visited.Clear();
+ split_if_with_blocks( visited, nstack );
+ NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
+ }
+
+ // Perform iteration-splitting on inner loops. Split iterations to avoid
+ // range checks or one-shot null checks.
+
+ // If split-if's didn't hack the graph too bad (no CFG changes)
+ // then do loop opts.
+ if( C->has_loops() && !C->major_progress() ) {
+ memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
+ _ltree_root->_child->iteration_split( this, worklist );
+ // No verify after peeling! GCM has hoisted code out of the loop.
+ // After peeling, the hoisted code could sink inside the peeled area.
+ // The peeling code does not try to recompute the best location for
+ // all the code before the peeled area, so the verify pass will always
+ // complain about it.
+ }
+ // Do verify graph edges in any case
+ NOT_PRODUCT( C->verify_graph_edges(); );
+
+ if( !do_split_ifs ) {
+ // We saw major progress in Split-If to get here. We forced a
+ // pass with unrolling and not split-if, however more split-if's
+ // might make progress. If the unrolling didn't make progress
+ // then the major-progress flag got cleared and we won't try
+ // another round of Split-If. In particular the ever-common
+ // instance-of/check-cast pattern requires at least 2 rounds of
+ // Split-If to clear out.
+ C->set_major_progress();
+ }
+
+ // Repeat loop optimizations if new loops were seen
+ if (created_loop_node()) {
+ C->set_major_progress();
+ }
+
+ // Convert scalar to superword operations
+
+ if (UseSuperWord && C->has_loops() && !C->major_progress()) {
+ // SuperWord transform
+ SuperWord sw(this);
+ for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
+ IdealLoopTree* lpt = iter.current();
+ if (lpt->is_counted()) {
+ sw.transform_loop(lpt);
+ }
+ }
+ }
+
+ // Cleanup any modified bits
+ _igvn.optimize();
+
+ // Do not repeat loop optimizations if irreducible loops are present
+ // by claiming no-progress.
+ if( _has_irreducible_loops )
+ C->clear_major_progress();
+}
+
+#ifndef PRODUCT
+//------------------------------print_statistics-------------------------------
+int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
+int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
+void PhaseIdealLoop::print_statistics() {
+ tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
+}
+
+//------------------------------verify-----------------------------------------
+// Build a verify-only PhaseIdealLoop, and see that it agrees with me.
+static int fail; // debug only, so its multi-thread dont care
+void PhaseIdealLoop::verify() const {
+ int old_progress = C->major_progress();
+ ResourceMark rm;
+ PhaseIdealLoop loop_verify( _igvn, this, false );
+ VectorSet visited(Thread::current()->resource_area());
+
+ fail = 0;
+ verify_compare( C->root(), &loop_verify, visited );
+ assert( fail == 0, "verify loops failed" );
+ // Verify loop structure is the same
+ _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
+ // Reset major-progress. It was cleared by creating a verify version of
+ // PhaseIdealLoop.
+ for( int i=0; i<old_progress; i++ )
+ C->set_major_progress();
+}
+
+//------------------------------verify_compare---------------------------------
+// Make sure me and the given PhaseIdealLoop agree on key data structures
+void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
+ if( !n ) return;
+ if( visited.test_set( n->_idx ) ) return;
+ if( !_nodes[n->_idx] ) { // Unreachable
+ assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
+ return;
+ }
+
+ uint i;
+ for( i = 0; i < n->req(); i++ )
+ verify_compare( n->in(i), loop_verify, visited );
+
+ // Check the '_nodes' block/loop structure
+ i = n->_idx;
+ if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
+ if( _nodes[i] != loop_verify->_nodes[i] &&
+ get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
+ tty->print("Mismatched control setting for: ");
+ n->dump();
+ if( fail++ > 10 ) return;
+ Node *c = get_ctrl_no_update(n);
+ tty->print("We have it as: ");
+ if( c->in(0) ) c->dump();
+ else tty->print_cr("N%d",c->_idx);
+ tty->print("Verify thinks: ");
+ if( loop_verify->has_ctrl(n) )
+ loop_verify->get_ctrl_no_update(n)->dump();
+ else
+ loop_verify->get_loop_idx(n)->dump();
+ tty->cr();
+ }
+ } else { // We have a loop
+ IdealLoopTree *us = get_loop_idx(n);
+ if( loop_verify->has_ctrl(n) ) {
+ tty->print("Mismatched loop setting for: ");
+ n->dump();
+ if( fail++ > 10 ) return;
+ tty->print("We have it as: ");
+ us->dump();
+ tty->print("Verify thinks: ");
+ loop_verify->get_ctrl_no_update(n)->dump();
+ tty->cr();
+ } else if (!C->major_progress()) {
+ // Loop selection can be messed up if we did a major progress
+ // operation, like split-if. Do not verify in that case.
+ IdealLoopTree *them = loop_verify->get_loop_idx(n);
+ if( us->_head != them->_head || us->_tail != them->_tail ) {
+ tty->print("Unequals loops for: ");
+ n->dump();
+ if( fail++ > 10 ) return;
+ tty->print("We have it as: ");
+ us->dump();
+ tty->print("Verify thinks: ");
+ them->dump();
+ tty->cr();
+ }
+ }
+ }
+
+ // Check for immediate dominators being equal
+ if( i >= _idom_size ) {
+ if( !n->is_CFG() ) return;
+ tty->print("CFG Node with no idom: ");
+ n->dump();
+ return;
+ }
+ if( !n->is_CFG() ) return;
+ if( n == C->root() ) return; // No IDOM here
+
+ assert(n->_idx == i, "sanity");
+ Node *id = idom_no_update(n);
+ if( id != loop_verify->idom_no_update(n) ) {
+ tty->print("Unequals idoms for: ");
+ n->dump();
+ if( fail++ > 10 ) return;
+ tty->print("We have it as: ");
+ id->dump();
+ tty->print("Verify thinks: ");
+ loop_verify->idom_no_update(n)->dump();
+ tty->cr();
+ }
+
+}
+
+//------------------------------verify_tree------------------------------------
+// Verify that tree structures match. Because the CFG can change, siblings
+// within the loop tree can be reordered. We attempt to deal with that by
+// reordering the verify's loop tree if possible.
+void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
+ assert( _parent == parent, "Badly formed loop tree" );
+
+ // Siblings not in same order? Attempt to re-order.
+ if( _head != loop->_head ) {
+ // Find _next pointer to update
+ IdealLoopTree **pp = &loop->_parent->_child;
+ while( *pp != loop )
+ pp = &((*pp)->_next);
+ // Find proper sibling to be next
+ IdealLoopTree **nn = &loop->_next;
+ while( (*nn) && (*nn)->_head != _head )
+ nn = &((*nn)->_next);
+
+ // Check for no match.
+ if( !(*nn) ) {
+ // Annoyingly, irreducible loops can pick different headers
+ // after a major_progress operation, so the rest of the loop
+ // tree cannot be matched.
+ if (_irreducible && Compile::current()->major_progress()) return;
+ assert( 0, "failed to match loop tree" );
+ }
+
+ // Move (*nn) to (*pp)
+ IdealLoopTree *hit = *nn;
+ *nn = hit->_next;
+ hit->_next = loop;
+ *pp = loop;
+ loop = hit;
+ // Now try again to verify
+ }
+
+ assert( _head == loop->_head , "mismatched loop head" );
+ Node *tail = _tail; // Inline a non-updating version of
+ while( !tail->in(0) ) // the 'tail()' call.
+ tail = tail->in(1);
+ assert( tail == loop->_tail, "mismatched loop tail" );
+
+ // Counted loops that are guarded should be able to find their guards
+ if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
+ CountedLoopNode *cl = _head->as_CountedLoop();
+ Node *init = cl->init_trip();
+ Node *ctrl = cl->in(LoopNode::EntryControl);
+ assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
+ Node *iff = ctrl->in(0);
+ assert( iff->Opcode() == Op_If, "" );
+ Node *bol = iff->in(1);
+ assert( bol->Opcode() == Op_Bool, "" );
+ Node *cmp = bol->in(1);
+ assert( cmp->Opcode() == Op_CmpI, "" );
+ Node *add = cmp->in(1);
+ Node *opaq;
+ if( add->Opcode() == Op_Opaque1 ) {
+ opaq = add;
+ } else {
+ assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
+ assert( add == init, "" );
+ opaq = cmp->in(2);
+ }
+ assert( opaq->Opcode() == Op_Opaque1, "" );
+
+ }
+
+ if (_child != NULL) _child->verify_tree(loop->_child, this);
+ if (_next != NULL) _next ->verify_tree(loop->_next, parent);
+ // Innermost loops need to verify loop bodies,
+ // but only if no 'major_progress'
+ int fail = 0;
+ if (!Compile::current()->major_progress() && _child == NULL) {
+ for( uint i = 0; i < _body.size(); i++ ) {
+ Node *n = _body.at(i);
+ if (n->outcnt() == 0) continue; // Ignore dead
+ uint j;
+ for( j = 0; j < loop->_body.size(); j++ )
+ if( loop->_body.at(j) == n )
+ break;
+ if( j == loop->_body.size() ) { // Not found in loop body
+ // Last ditch effort to avoid assertion: Its possible that we
+ // have some users (so outcnt not zero) but are still dead.
+ // Try to find from root.
+ if (Compile::current()->root()->find(n->_idx)) {
+ fail++;
+ tty->print("We have that verify does not: ");
+ n->dump();
+ }
+ }
+ }
+ for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
+ Node *n = loop->_body.at(i2);
+ if (n->outcnt() == 0) continue; // Ignore dead
+ uint j;
+ for( j = 0; j < _body.size(); j++ )
+ if( _body.at(j) == n )
+ break;
+ if( j == _body.size() ) { // Not found in loop body
+ // Last ditch effort to avoid assertion: Its possible that we
+ // have some users (so outcnt not zero) but are still dead.
+ // Try to find from root.
+ if (Compile::current()->root()->find(n->_idx)) {
+ fail++;
+ tty->print("Verify has that we do not: ");
+ n->dump();
+ }
+ }
+ }
+ assert( !fail, "loop body mismatch" );
+ }
+}
+
+#endif
+
+//------------------------------set_idom---------------------------------------
+void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
+ uint idx = d->_idx;
+ if (idx >= _idom_size) {
+ uint newsize = _idom_size<<1;
+ while( idx >= newsize ) {
+ newsize <<= 1;
+ }
+ _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
+ _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
+ memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
+ _idom_size = newsize;
+ }
+ _idom[idx] = n;
+ _dom_depth[idx] = dom_depth;
+}
+
+//------------------------------recompute_dom_depth---------------------------------------
+// The dominator tree is constructed with only parent pointers.
+// This recomputes the depth in the tree by first tagging all
+// nodes as "no depth yet" marker. The next pass then runs up
+// the dom tree from each node marked "no depth yet", and computes
+// the depth on the way back down.
+void PhaseIdealLoop::recompute_dom_depth() {
+ uint no_depth_marker = C->unique();
+ uint i;
+ // Initialize depth to "no depth yet"
+ for (i = 0; i < _idom_size; i++) {
+ if (_dom_depth[i] > 0 && _idom[i] != NULL) {
+ _dom_depth[i] = no_depth_marker;
+ }
+ }
+ if (_dom_stk == NULL) {
+ uint init_size = C->unique() / 100; // Guess that 1/100 is a reasonable initial size.
+ if (init_size < 10) init_size = 10;
+ _dom_stk = new (C->node_arena()) GrowableArray<uint>(C->node_arena(), init_size, 0, 0);
+ }
+ // Compute new depth for each node.
+ for (i = 0; i < _idom_size; i++) {
+ uint j = i;
+ // Run up the dom tree to find a node with a depth
+ while (_dom_depth[j] == no_depth_marker) {
+ _dom_stk->push(j);
+ j = _idom[j]->_idx;
+ }
+ // Compute the depth on the way back down this tree branch
+ uint dd = _dom_depth[j] + 1;
+ while (_dom_stk->length() > 0) {
+ uint j = _dom_stk->pop();
+ _dom_depth[j] = dd;
+ dd++;
+ }
+ }
+}
+
+//------------------------------sort-------------------------------------------
+// Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
+// loop tree, not the root.
+IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
+ if( !innermost ) return loop; // New innermost loop
+
+ int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
+ assert( loop_preorder, "not yet post-walked loop" );
+ IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
+ IdealLoopTree *l = *pp; // Do I go before or after 'l'?
+
+ // Insert at start of list
+ while( l ) { // Insertion sort based on pre-order
+ if( l == loop ) return innermost; // Already on list!
+ int l_preorder = get_preorder(l->_head); // Cache pre-order number
+ assert( l_preorder, "not yet post-walked l" );
+ // Check header pre-order number to figure proper nesting
+ if( loop_preorder > l_preorder )
+ break; // End of insertion
+ // If headers tie (e.g., shared headers) check tail pre-order numbers.
+ // Since I split shared headers, you'd think this could not happen.
+ // BUT: I must first do the preorder numbering before I can discover I
+ // have shared headers, so the split headers all get the same preorder
+ // number as the RegionNode they split from.
+ if( loop_preorder == l_preorder &&
+ get_preorder(loop->_tail) < get_preorder(l->_tail) )
+ break; // Also check for shared headers (same pre#)
+ pp = &l->_parent; // Chain up list
+ l = *pp;
+ }
+ // Link into list
+ // Point predecessor to me
+ *pp = loop;
+ // Point me to successor
+ IdealLoopTree *p = loop->_parent;
+ loop->_parent = l; // Point me to successor
+ if( p ) sort( p, innermost ); // Insert my parents into list as well
+ return innermost;
+}
+
+//------------------------------build_loop_tree--------------------------------
+// I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
+// bits. The _nodes[] array is mapped by Node index and holds a NULL for
+// not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
+// tightest enclosing IdealLoopTree for post-walked.
+//
+// During my forward walk I do a short 1-layer lookahead to see if I can find
+// a loop backedge with that doesn't have any work on the backedge. This
+// helps me construct nested loops with shared headers better.
+//
+// Once I've done the forward recursion, I do the post-work. For each child
+// I check to see if there is a backedge. Backedges define a loop! I
+// insert an IdealLoopTree at the target of the backedge.
+//
+// During the post-work I also check to see if I have several children
+// belonging to different loops. If so, then this Node is a decision point
+// where control flow can choose to change loop nests. It is at this
+// decision point where I can figure out how loops are nested. At this
+// time I can properly order the different loop nests from my children.
+// Note that there may not be any backedges at the decision point!
+//
+// Since the decision point can be far removed from the backedges, I can't
+// order my loops at the time I discover them. Thus at the decision point
+// I need to inspect loop header pre-order numbers to properly nest my
+// loops. This means I need to sort my childrens' loops by pre-order.
+// The sort is of size number-of-control-children, which generally limits
+// it to size 2 (i.e., I just choose between my 2 target loops).
+void PhaseIdealLoop::build_loop_tree() {
+ // Allocate stack of size C->unique()/2 to avoid frequent realloc
+ GrowableArray <Node *> bltstack(C->unique() >> 1);
+ Node *n = C->root();
+ bltstack.push(n);
+ int pre_order = 1;
+ int stack_size;
+
+ while ( ( stack_size = bltstack.length() ) != 0 ) {
+ n = bltstack.top(); // Leave node on stack
+ if ( !is_visited(n) ) {
+ // ---- Pre-pass Work ----
+ // Pre-walked but not post-walked nodes need a pre_order number.
+
+ set_preorder_visited( n, pre_order ); // set as visited
+
+ // ---- Scan over children ----
+ // Scan first over control projections that lead to loop headers.
+ // This helps us find inner-to-outer loops with shared headers better.
+
+ // Scan children's children for loop headers.
+ for ( int i = n->outcnt() - 1; i >= 0; --i ) {
+ Node* m = n->raw_out(i); // Child
+ if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
+ // Scan over children's children to find loop
+ for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
+ Node* l = m->fast_out(j);
+ if( is_visited(l) && // Been visited?
+ !is_postvisited(l) && // But not post-visited
+ get_preorder(l) < pre_order ) { // And smaller pre-order
+ // Found! Scan the DFS down this path before doing other paths
+ bltstack.push(m);
+ break;
+ }
+ }
+ }
+ }
+ pre_order++;
+ }
+ else if ( !is_postvisited(n) ) {
+ // Note: build_loop_tree_impl() adds out edges on rare occasions,
+ // such as com.sun.rsasign.am::a.
+ // For non-recursive version, first, process current children.
+ // On next iteration, check if additional children were added.
+ for ( int k = n->outcnt() - 1; k >= 0; --k ) {
+ Node* u = n->raw_out(k);
+ if ( u->is_CFG() && !is_visited(u) ) {
+ bltstack.push(u);
+ }
+ }
+ if ( bltstack.length() == stack_size ) {
+ // There were no additional children, post visit node now
+ (void)bltstack.pop(); // Remove node from stack
+ pre_order = build_loop_tree_impl( n, pre_order );
+ // Check for bailout
+ if (C->failing()) {
+ return;
+ }
+ // Check to grow _preorders[] array for the case when
+ // build_loop_tree_impl() adds new nodes.
+ check_grow_preorders();
+ }
+ }
+ else {
+ (void)bltstack.pop(); // Remove post-visited node from stack
+ }
+ }
+}
+
+//------------------------------build_loop_tree_impl---------------------------
+int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
+ // ---- Post-pass Work ----
+ // Pre-walked but not post-walked nodes need a pre_order number.
+
+ // Tightest enclosing loop for this Node
+ IdealLoopTree *innermost = NULL;
+
+ // For all children, see if any edge is a backedge. If so, make a loop
+ // for it. Then find the tightest enclosing loop for the self Node.
+ for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
+ Node* m = n->fast_out(i); // Child
+ if( n == m ) continue; // Ignore control self-cycles
+ if( !m->is_CFG() ) continue;// Ignore non-CFG edges
+
+ IdealLoopTree *l; // Child's loop
+ if( !is_postvisited(m) ) { // Child visited but not post-visited?
+ // Found a backedge
+ assert( get_preorder(m) < pre_order, "should be backedge" );
+ // Check for the RootNode, which is already a LoopNode and is allowed
+ // to have multiple "backedges".
+ if( m == C->root()) { // Found the root?
+ l = _ltree_root; // Root is the outermost LoopNode
+ } else { // Else found a nested loop
+ // Insert a LoopNode to mark this loop.
+ l = new IdealLoopTree(this, m, n);
+ } // End of Else found a nested loop
+ if( !has_loop(m) ) // If 'm' does not already have a loop set
+ set_loop(m, l); // Set loop header to loop now
+
+ } else { // Else not a nested loop
+ if( !_nodes[m->_idx] ) continue; // Dead code has no loop
+ l = get_loop(m); // Get previously determined loop
+ // If successor is header of a loop (nest), move up-loop till it
+ // is a member of some outer enclosing loop. Since there are no
+ // shared headers (I've split them already) I only need to go up
+ // at most 1 level.
+ while( l && l->_head == m ) // Successor heads loop?
+ l = l->_parent; // Move up 1 for me
+ // If this loop is not properly parented, then this loop
+ // has no exit path out, i.e. its an infinite loop.
+ if( !l ) {
+ // Make loop "reachable" from root so the CFG is reachable. Basically
+ // insert a bogus loop exit that is never taken. 'm', the loop head,
+ // points to 'n', one (of possibly many) fall-in paths. There may be
+ // many backedges as well.
+
+ // Here I set the loop to be the root loop. I could have, after
+ // inserting a bogus loop exit, restarted the recursion and found my
+ // new loop exit. This would make the infinite loop a first-class
+ // loop and it would then get properly optimized. What's the use of
+ // optimizing an infinite loop?
+ l = _ltree_root; // Oops, found infinite loop
+
+ // Insert the NeverBranch between 'm' and it's control user.
+ NeverBranchNode *iff = new (C, 1) NeverBranchNode( m );
+ _igvn.register_new_node_with_optimizer(iff);
+ set_loop(iff, l);
+ Node *if_t = new (C, 1) CProjNode( iff, 0 );
+ _igvn.register_new_node_with_optimizer(if_t);
+ set_loop(if_t, l);
+
+ Node* cfg = NULL; // Find the One True Control User of m
+ for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
+ Node* x = m->fast_out(j);
+ if (x->is_CFG() && x != m && x != iff)
+ { cfg = x; break; }
+ }
+ assert(cfg != NULL, "must find the control user of m");
+ uint k = 0; // Probably cfg->in(0)
+ while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
+ cfg->set_req( k, if_t ); // Now point to NeverBranch
+
+ // Now create the never-taken loop exit
+ Node *if_f = new (C, 1) CProjNode( iff, 1 );
+ _igvn.register_new_node_with_optimizer(if_f);
+ set_loop(if_f, l);
+ // Find frame ptr for Halt. Relies on the optimizer
+ // V-N'ing. Easier and quicker than searching through
+ // the program structure.
+ Node *frame = new (C, 1) ParmNode( C->start(), TypeFunc::FramePtr );
+ _igvn.register_new_node_with_optimizer(frame);
+ // Halt & Catch Fire
+ Node *halt = new (C, TypeFunc::Parms) HaltNode( if_f, frame );
+ _igvn.register_new_node_with_optimizer(halt);
+ set_loop(halt, l);
+ C->root()->add_req(halt);
+ set_loop(C->root(), _ltree_root);
+ }
+ }
+ // Weeny check for irreducible. This child was already visited (this
+ // IS the post-work phase). Is this child's loop header post-visited
+ // as well? If so, then I found another entry into the loop.
+ while( is_postvisited(l->_head) ) {
+ // found irreducible
+ l->_irreducible = true;
+ l = l->_parent;
+ _has_irreducible_loops = true;
+ // Check for bad CFG here to prevent crash, and bailout of compile
+ if (l == NULL) {
+ C->record_method_not_compilable("unhandled CFG detected during loop optimization");
+ return pre_order;
+ }
+ }
+
+ // This Node might be a decision point for loops. It is only if
+ // it's children belong to several different loops. The sort call
+ // does a trivial amount of work if there is only 1 child or all
+ // children belong to the same loop. If however, the children
+ // belong to different loops, the sort call will properly set the
+ // _parent pointers to show how the loops nest.
+ //
+ // In any case, it returns the tightest enclosing loop.
+ innermost = sort( l, innermost );
+ }
+
+ // Def-use info will have some dead stuff; dead stuff will have no
+ // loop decided on.
+
+ // Am I a loop header? If so fix up my parent's child and next ptrs.
+ if( innermost && innermost->_head == n ) {
+ assert( get_loop(n) == innermost, "" );
+ IdealLoopTree *p = innermost->_parent;
+ IdealLoopTree *l = innermost;
+ while( p && l->_head == n ) {
+ l->_next = p->_child; // Put self on parents 'next child'
+ p->_child = l; // Make self as first child of parent
+ l = p; // Now walk up the parent chain
+ p = l->_parent;
+ }
+ } else {
+ // Note that it is possible for a LoopNode to reach here, if the
+ // backedge has been made unreachable (hence the LoopNode no longer
+ // denotes a Loop, and will eventually be removed).
+
+ // Record tightest enclosing loop for self. Mark as post-visited.
+ set_loop(n, innermost);
+ // Also record has_call flag early on
+ if( innermost ) {
+ if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
+ // Do not count uncommon calls
+ if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
+ Node *iff = n->in(0)->in(0);
+ if( !iff->is_If() ||
+ (n->in(0)->Opcode() == Op_IfFalse &&
+ (1.0 - iff->as_If()->_prob) >= 0.01) ||
+ (iff->as_If()->_prob >= 0.01) )
+ innermost->_has_call = 1;
+ }
+ }
+ }
+ }
+
+ // Flag as post-visited now
+ set_postvisited(n);
+ return pre_order;
+}
+
+
+//------------------------------build_loop_early-------------------------------
+// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
+// First pass computes the earliest controlling node possible. This is the
+// controlling input with the deepest dominating depth.
+void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me ) {
+ while (worklist.size() != 0) {
+ // Use local variables nstack_top_n & nstack_top_i to cache values
+ // on nstack's top.
+ Node *nstack_top_n = worklist.pop();
+ uint nstack_top_i = 0;
+//while_nstack_nonempty:
+ while (true) {
+ // Get parent node and next input's index from stack's top.
+ Node *n = nstack_top_n;
+ uint i = nstack_top_i;
+ uint cnt = n->req(); // Count of inputs
+ if (i == 0) { // Pre-process the node.
+ if( has_node(n) && // Have either loop or control already?
+ !has_ctrl(n) ) { // Have loop picked out already?
+ // During "merge_many_backedges" we fold up several nested loops
+ // into a single loop. This makes the members of the original
+ // loop bodies pointing to dead loops; they need to move up
+ // to the new UNION'd larger loop. I set the _head field of these
+ // dead loops to NULL and the _parent field points to the owning
+ // loop. Shades of UNION-FIND algorithm.
+ IdealLoopTree *ilt;
+ while( !(ilt = get_loop(n))->_head ) {
+ // Normally I would use a set_loop here. But in this one special
+ // case, it is legal (and expected) to change what loop a Node
+ // belongs to.
+ _nodes.map(n->_idx, (Node*)(ilt->_parent) );
+ }
+ // Remove safepoints ONLY if I've already seen I don't need one.
+ // (the old code here would yank a 2nd safepoint after seeing a
+ // first one, even though the 1st did not dominate in the loop body
+ // and thus could be avoided indefinitely)
+ if( !verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
+ is_deleteable_safept(n)) {
+ Node *in = n->in(TypeFunc::Control);
+ lazy_replace(n,in); // Pull safepoint now
+ // Carry on with the recursion "as if" we are walking
+ // only the control input
+ if( !visited.test_set( in->_idx ) ) {
+ worklist.push(in); // Visit this guy later, using worklist
+ }
+ // Get next node from nstack:
+ // - skip n's inputs processing by setting i > cnt;
+ // - we also will not call set_early_ctrl(n) since
+ // has_node(n) == true (see the condition above).
+ i = cnt + 1;
+ }
+ }
+ } // if (i == 0)
+
+ // Visit all inputs
+ bool done = true; // Assume all n's inputs will be processed
+ while (i < cnt) {
+ Node *in = n->in(i);
+ ++i;
+ if (in == NULL) continue;
+ if (in->pinned() && !in->is_CFG())
+ set_ctrl(in, in->in(0));
+ int is_visited = visited.test_set( in->_idx );
+ if (!has_node(in)) { // No controlling input yet?
+ assert( !in->is_CFG(), "CFG Node with no controlling input?" );
+ assert( !is_visited, "visit only once" );
+ nstack.push(n, i); // Save parent node and next input's index.
+ nstack_top_n = in; // Process current input now.
+ nstack_top_i = 0;
+ done = false; // Not all n's inputs processed.
+ break; // continue while_nstack_nonempty;
+ } else if (!is_visited) {
+ // This guy has a location picked out for him, but has not yet
+ // been visited. Happens to all CFG nodes, for instance.
+ // Visit him using the worklist instead of recursion, to break
+ // cycles. Since he has a location already we do not need to
+ // find his location before proceeding with the current Node.
+ worklist.push(in); // Visit this guy later, using worklist
+ }
+ }
+ if (done) {
+ // All of n's inputs have been processed, complete post-processing.
+
+ // Compute earilest point this Node can go.
+ // CFG, Phi, pinned nodes already know their controlling input.
+ if (!has_node(n)) {
+ // Record earliest legal location
+ set_early_ctrl( n );
+ }
+ if (nstack.is_empty()) {
+ // Finished all nodes on stack.
+ // Process next node on the worklist.
+ break;
+ }
+ // Get saved parent node and next input's index.
+ nstack_top_n = nstack.node();
+ nstack_top_i = nstack.index();
+ nstack.pop();
+ }
+ } // while (true)
+ }
+}
+
+//------------------------------dom_lca_internal--------------------------------
+// Pair-wise LCA
+Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
+ if( !n1 ) return n2; // Handle NULL original LCA
+ assert( n1->is_CFG(), "" );
+ assert( n2->is_CFG(), "" );
+ // find LCA of all uses
+ uint d1 = dom_depth(n1);
+ uint d2 = dom_depth(n2);
+ while (n1 != n2) {
+ if (d1 > d2) {
+ n1 = idom(n1);
+ d1 = dom_depth(n1);
+ } else if (d1 < d2) {
+ n2 = idom(n2);
+ d2 = dom_depth(n2);
+ } else {
+ // Here d1 == d2. Due to edits of the dominator-tree, sections
+ // of the tree might have the same depth. These sections have
+ // to be searched more carefully.
+
+ // Scan up all the n1's with equal depth, looking for n2.
+ Node *t1 = idom(n1);
+ while (dom_depth(t1) == d1) {
+ if (t1 == n2) return n2;
+ t1 = idom(t1);
+ }
+ // Scan up all the n2's with equal depth, looking for n1.
+ Node *t2 = idom(n2);
+ while (dom_depth(t2) == d2) {
+ if (t2 == n1) return n1;
+ t2 = idom(t2);
+ }
+ // Move up to a new dominator-depth value as well as up the dom-tree.
+ n1 = t1;
+ n2 = t2;
+ d1 = dom_depth(n1);
+ d2 = dom_depth(n2);
+ }
+ }
+ return n1;
+}
+
+//------------------------------compute_idom-----------------------------------
+// Locally compute IDOM using dom_lca call. Correct only if the incoming
+// IDOMs are correct.
+Node *PhaseIdealLoop::compute_idom( Node *region ) const {
+ assert( region->is_Region(), "" );
+ Node *LCA = NULL;
+ for( uint i = 1; i < region->req(); i++ ) {
+ if( region->in(i) != C->top() )
+ LCA = dom_lca( LCA, region->in(i) );
+ }
+ return LCA;
+}
+
+//------------------------------get_late_ctrl----------------------------------
+// Compute latest legal control.
+Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
+ assert(early != NULL, "early control should not be NULL");
+
+ // Compute LCA over list of uses
+ Node *LCA = NULL;
+ for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
+ Node* c = n->fast_out(i);
+ if (_nodes[c->_idx] == NULL)
+ continue; // Skip the occasional dead node
+ if( c->is_Phi() ) { // For Phis, we must land above on the path
+ for( uint j=1; j<c->req(); j++ ) {// For all inputs
+ if( c->in(j) == n ) { // Found matching input?
+ Node *use = c->in(0)->in(j);
+ LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
+ }
+ }
+ } else {
+ // For CFG data-users, use is in the block just prior
+ Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
+ LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
+ }
+ }
+
+ // if this is a load, check for anti-dependent stores
+ // We use a conservative algorithm to identify potential interfering
+ // instructions and for rescheduling the load. The users of the memory
+ // input of this load are examined. Any use which is not a load and is
+ // dominated by early is considered a potentially interfering store.
+ // This can produce false positives.
+ if (n->is_Load() && LCA != early) {
+ Node_List worklist;
+
+ Node *mem = n->in(MemNode::Memory);
+ for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
+ Node* s = mem->fast_out(i);
+ worklist.push(s);
+ }
+ while(worklist.size() != 0 && LCA != early) {
+ Node* s = worklist.pop();
+ if (s->is_Load()) {
+ continue;
+ } else if (s->is_MergeMem()) {
+ for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
+ Node* s1 = s->fast_out(i);
+ worklist.push(s1);
+ }
+ } else {
+ Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
+ assert(sctrl != NULL || s->outcnt() == 0, "must have control");
+ if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
+ LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
+ }
+ }
+ }
+ }
+
+ assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
+ return LCA;
+}
+
+// true if CFG node d dominates CFG node n
+bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
+ if (d == n)
+ return true;
+ assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
+ uint dd = dom_depth(d);
+ while (dom_depth(n) >= dd) {
+ if (n == d)
+ return true;
+ n = idom(n);
+ }
+ return false;
+}
+
+//------------------------------dom_lca_for_get_late_ctrl_internal-------------
+// Pair-wise LCA with tags.
+// Tag each index with the node 'tag' currently being processed
+// before advancing up the dominator chain using idom().
+// Later calls that find a match to 'tag' know that this path has already
+// been considered in the current LCA (which is input 'n1' by convention).
+// Since get_late_ctrl() is only called once for each node, the tag array
+// does not need to be cleared between calls to get_late_ctrl().
+// Algorithm trades a larger constant factor for better asymptotic behavior
+//
+Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
+ uint d1 = dom_depth(n1);
+ uint d2 = dom_depth(n2);
+
+ do {
+ if (d1 > d2) {
+ // current lca is deeper than n2
+ _dom_lca_tags.map(n1->_idx, tag);
+ n1 = idom(n1);
+ d1 = dom_depth(n1);
+ } else if (d1 < d2) {
+ // n2 is deeper than current lca
+ Node *memo = _dom_lca_tags[n2->_idx];
+ if( memo == tag ) {
+ return n1; // Return the current LCA
+ }
+ _dom_lca_tags.map(n2->_idx, tag);
+ n2 = idom(n2);
+ d2 = dom_depth(n2);
+ } else {
+ // Here d1 == d2. Due to edits of the dominator-tree, sections
+ // of the tree might have the same depth. These sections have
+ // to be searched more carefully.
+
+ // Scan up all the n1's with equal depth, looking for n2.
+ _dom_lca_tags.map(n1->_idx, tag);
+ Node *t1 = idom(n1);
+ while (dom_depth(t1) == d1) {
+ if (t1 == n2) return n2;
+ _dom_lca_tags.map(t1->_idx, tag);
+ t1 = idom(t1);
+ }
+ // Scan up all the n2's with equal depth, looking for n1.
+ _dom_lca_tags.map(n2->_idx, tag);
+ Node *t2 = idom(n2);
+ while (dom_depth(t2) == d2) {
+ if (t2 == n1) return n1;
+ _dom_lca_tags.map(t2->_idx, tag);
+ t2 = idom(t2);
+ }
+ // Move up to a new dominator-depth value as well as up the dom-tree.
+ n1 = t1;
+ n2 = t2;
+ d1 = dom_depth(n1);
+ d2 = dom_depth(n2);
+ }
+ } while (n1 != n2);
+ return n1;
+}
+
+//------------------------------init_dom_lca_tags------------------------------
+// Tag could be a node's integer index, 32bits instead of 64bits in some cases
+// Intended use does not involve any growth for the array, so it could
+// be of fixed size.
+void PhaseIdealLoop::init_dom_lca_tags() {
+ uint limit = C->unique() + 1;
+ _dom_lca_tags.map( limit, NULL );
+#ifdef ASSERT
+ for( uint i = 0; i < limit; ++i ) {
+ assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
+ }
+#endif // ASSERT
+}
+
+//------------------------------clear_dom_lca_tags------------------------------
+// Tag could be a node's integer index, 32bits instead of 64bits in some cases
+// Intended use does not involve any growth for the array, so it could
+// be of fixed size.
+void PhaseIdealLoop::clear_dom_lca_tags() {
+ uint limit = C->unique() + 1;
+ _dom_lca_tags.map( limit, NULL );
+ _dom_lca_tags.clear();
+#ifdef ASSERT
+ for( uint i = 0; i < limit; ++i ) {
+ assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
+ }
+#endif // ASSERT
+}
+
+//------------------------------build_loop_late--------------------------------
+// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
+// Second pass finds latest legal placement, and ideal loop placement.
+void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me ) {
+ while (worklist.size() != 0) {
+ Node *n = worklist.pop();
+ // Only visit once
+ if (visited.test_set(n->_idx)) continue;
+ uint cnt = n->outcnt();
+ uint i = 0;
+ while (true) {
+ assert( _nodes[n->_idx], "no dead nodes" );
+ // Visit all children
+ if (i < cnt) {
+ Node* use = n->raw_out(i);
+ ++i;
+ // Check for dead uses. Aggressively prune such junk. It might be
+ // dead in the global sense, but still have local uses so I cannot
+ // easily call 'remove_dead_node'.
+ if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
+ // Due to cycles, we might not hit the same fixed point in the verify
+ // pass as we do in the regular pass. Instead, visit such phis as
+ // simple uses of the loop head.
+ if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
+ if( !visited.test(use->_idx) )
+ worklist.push(use);
+ } else if( !visited.test_set(use->_idx) ) {
+ nstack.push(n, i); // Save parent and next use's index.
+ n = use; // Process all children of current use.
+ cnt = use->outcnt();
+ i = 0;
+ }
+ } else {
+ // Do not visit around the backedge of loops via data edges.
+ // push dead code onto a worklist
+ _deadlist.push(use);
+ }
+ } else {
+ // All of n's children have been processed, complete post-processing.
+ build_loop_late_post(n, verify_me);
+ if (nstack.is_empty()) {
+ // Finished all nodes on stack.
+ // Process next node on the worklist.
+ break;
+ }
+ // Get saved parent node and next use's index. Visit the rest of uses.
+ n = nstack.node();
+ cnt = n->outcnt();
+ i = nstack.index();
+ nstack.pop();
+ }
+ }
+ }
+}
+
+//------------------------------build_loop_late_post---------------------------
+// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
+// Second pass finds latest legal placement, and ideal loop placement.
+void PhaseIdealLoop::build_loop_late_post( Node *n, const PhaseIdealLoop *verify_me ) {
+
+ if (n->req() == 2 && n->Opcode() == Op_ConvI2L && !C->major_progress()) {
+ _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
+ }
+
+ // CFG and pinned nodes already handled
+ if( n->in(0) ) {
+ if( n->in(0)->is_top() ) return; // Dead?
+
+ // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
+ // _must_ be pinned (they have to observe their control edge of course).
+ // Unlike Stores (which modify an unallocable resource, the memory
+ // state), Mods/Loads can float around. So free them up.
+ bool pinned = true;
+ switch( n->Opcode() ) {
+ case Op_DivI:
+ case Op_DivF:
+ case Op_DivD:
+ case Op_ModI:
+ case Op_ModF:
+ case Op_ModD:
+ case Op_LoadB: // Same with Loads; they can sink
+ case Op_LoadC: // during loop optimizations.
+ case Op_LoadD:
+ case Op_LoadF:
+ case Op_LoadI:
+ case Op_LoadKlass:
+ case Op_LoadL:
+ case Op_LoadS:
+ case Op_LoadP:
+ case Op_LoadRange:
+ case Op_LoadD_unaligned:
+ case Op_LoadL_unaligned:
+ case Op_StrComp: // Does a bunch of load-like effects
+ pinned = false;
+ }
+ if( pinned ) {
+ IdealLoopTree *choosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
+ if( !choosen_loop->_child ) // Inner loop?
+ choosen_loop->_body.push(n); // Collect inner loops
+ return;
+ }
+ } else { // No slot zero
+ if( n->is_CFG() ) { // CFG with no slot 0 is dead
+ _nodes.map(n->_idx,0); // No block setting, it's globally dead
+ return;
+ }
+ assert(!n->is_CFG() || n->outcnt() == 0, "");
+ }
+
+ // Do I have a "safe range" I can select over?
+ Node *early = get_ctrl(n);// Early location already computed
+
+ // Compute latest point this Node can go
+ Node *LCA = get_late_ctrl( n, early );
+ // LCA is NULL due to uses being dead
+ if( LCA == NULL ) {
+#ifdef ASSERT
+ for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
+ assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
+ }
+#endif
+ _nodes.map(n->_idx, 0); // This node is useless
+ _deadlist.push(n);
+ return;
+ }
+ assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
+
+ Node *legal = LCA; // Walk 'legal' up the IDOM chain
+ Node *least = legal; // Best legal position so far
+ while( early != legal ) { // While not at earliest legal
+ // Find least loop nesting depth
+ legal = idom(legal); // Bump up the IDOM tree
+ // Check for lower nesting depth
+ if( get_loop(legal)->_nest < get_loop(least)->_nest )
+ least = legal;
+ }
+
+ // Try not to place code on a loop entry projection
+ // which can inhibit range check elimination.
+ if (least != early) {
+ Node* ctrl_out = least->unique_ctrl_out();
+ if (ctrl_out && ctrl_out->is_CountedLoop() &&
+ least == ctrl_out->in(LoopNode::EntryControl)) {
+ Node* least_dom = idom(least);
+ if (get_loop(least_dom)->is_member(get_loop(least))) {
+ least = least_dom;
+ }
+ }
+ }
+
+#ifdef ASSERT
+ // If verifying, verify that 'verify_me' has a legal location
+ // and choose it as our location.
+ if( verify_me ) {
+ Node *v_ctrl = verify_me->get_ctrl_no_update(n);
+ Node *legal = LCA;
+ while( early != legal ) { // While not at earliest legal
+ if( legal == v_ctrl ) break; // Check for prior good location
+ legal = idom(legal) ;// Bump up the IDOM tree
+ }
+ // Check for prior good location
+ if( legal == v_ctrl ) least = legal; // Keep prior if found
+ }
+#endif
+
+ // Assign discovered "here or above" point
+ least = find_non_split_ctrl(least);
+ set_ctrl(n, least);
+
+ // Collect inner loop bodies
+ IdealLoopTree *choosen_loop = get_loop(least);
+ if( !choosen_loop->_child ) // Inner loop?
+ choosen_loop->_body.push(n);// Collect inner loops
+}
+
+#ifndef PRODUCT
+//------------------------------dump-------------------------------------------
+void PhaseIdealLoop::dump( ) const {
+ ResourceMark rm;
+ Arena* arena = Thread::current()->resource_area();
+ Node_Stack stack(arena, C->unique() >> 2);
+ Node_List rpo_list;
+ VectorSet visited(arena);
+ visited.set(C->top()->_idx);
+ 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 );
+}
+
+void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
+
+ // Indent by loop nesting depth
+ for( uint x = 0; x < loop->_nest; x++ )
+ tty->print(" ");
+ tty->print_cr("---- Loop N%d-N%d ----", loop->_head->_idx,loop->_tail->_idx);
+
+ // 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
+ 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
+ continue;
+ }
+
+ // Dump controlling node
+ for( uint x = 0; x < loop->_nest; x++ )
+ tty->print(" ");
+ tty->print("C");
+ if( n == C->root() ) {
+ n->dump();
+ } else {
+ Node* cached_idom = idom_no_update(n);
+ 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);
+ n->dump();
+ 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++ ) {
+ // (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 ) {
+ 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(" ");
+ m->dump();
+ }
+ }
+ }
+ }
+}
+
+// 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 {
+ stk.push(start, 0);
+ visited.set(start->_idx);
+
+ while (stk.is_nonempty()) {
+ Node* m = stk.node();
+ uint idx = stk.index();
+ if (idx < m->outcnt()) {
+ stk.set_index(idx + 1);
+ Node* n = m->raw_out(idx);
+ if (n->is_CFG() && !visited.test_set(n->_idx)) {
+ stk.push(n, 0);
+ }
+ } else {
+ rpo_list.push(m);
+ stk.pop();
+ }
+ }
+}
+#endif
+
+
+//=============================================================================
+//------------------------------LoopTreeIterator-----------------------------------
+
+// Advance to next loop tree using a preorder, left-to-right traversal.
+void LoopTreeIterator::next() {
+ assert(!done(), "must not be done.");
+ if (_curnt->_child != NULL) {
+ _curnt = _curnt->_child;
+ } else if (_curnt->_next != NULL) {
+ _curnt = _curnt->_next;
+ } else {
+ while (_curnt != _root && _curnt->_next == NULL) {
+ _curnt = _curnt->_parent;
+ }
+ if (_curnt == _root) {
+ _curnt = NULL;
+ assert(done(), "must be done.");
+ } else {
+ assert(_curnt->_next != NULL, "must be more to do");
+ _curnt = _curnt->_next;
+ }
+ }
+}