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6894779: Loop Predication for Loop Optimizer in C2
Loop predication implementation Reviewed-by: never, kvn
This commit is contained in:
Changpeng Fang
parent
96612c6e23
commit
815db4fcba
13 changed files with 838 additions and 30 deletions
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@ -549,6 +549,10 @@ bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
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// Comparing trip+off vs limit
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Node *bol = iff->in(1);
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if( bol->req() != 2 ) continue; // dead constant test
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if (!bol->is_Bool()) {
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assert(UseLoopPredicate && bol->Opcode() == Op_Conv2B, "predicate check only");
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continue;
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}
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Node *cmp = bol->in(1);
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Node *rc_exp = cmp->in(1);
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@ -875,7 +879,7 @@ void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_
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//------------------------------is_invariant-----------------------------
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// Return true if n is invariant
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bool IdealLoopTree::is_invariant(Node* n) const {
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Node *n_c = _phase->get_ctrl(n);
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Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n;
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if (n_c->is_top()) return false;
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return !is_member(_phase->get_loop(n_c));
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}
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@ -1594,7 +1598,7 @@ bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
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bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) {
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// Check and remove empty loops (spam micro-benchmarks)
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if( policy_do_remove_empty_loop(phase) )
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return true; // Here we removed an empty loop
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return true; // Here we removed an empty loop
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bool should_peel = policy_peeling(phase); // Should we peel?
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@ -1688,8 +1692,8 @@ bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_
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// an even number of trips). If we are peeling, we might enable some RCE
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// and we'd rather unroll the post-RCE'd loop SO... do not unroll if
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// peeling.
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if( should_unroll && !should_peel )
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phase->do_unroll(this,old_new, true);
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if( should_unroll && !should_peel )
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phase->do_unroll(this,old_new, true);
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// Adjust the pre-loop limits to align the main body
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// iterations.
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@ -1731,9 +1735,9 @@ bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new )
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_allow_optimizations &&
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!tail()->is_top() ) { // Also ignore the occasional dead backedge
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if (!_has_call) {
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if (!iteration_split_impl( phase, old_new )) {
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return false;
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}
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if (!iteration_split_impl( phase, old_new )) {
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return false;
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}
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} else if (policy_unswitching(phase)) {
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phase->do_unswitching(this, old_new);
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}
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@ -1746,3 +1750,576 @@ bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new )
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return false;
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return true;
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}
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//-------------------------------is_uncommon_trap_proj----------------------------
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// Return true if proj is the form of "proj->[region->..]call_uct"
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bool PhaseIdealLoop::is_uncommon_trap_proj(ProjNode* proj, bool must_reason_predicate) {
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int path_limit = 10;
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assert(proj, "invalid argument");
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Node* out = proj;
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for (int ct = 0; ct < path_limit; ct++) {
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out = out->unique_ctrl_out();
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if (out == NULL || out->is_Root() || out->is_Start())
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return false;
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if (out->is_CallStaticJava()) {
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int req = out->as_CallStaticJava()->uncommon_trap_request();
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if (req != 0) {
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Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(req);
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if (!must_reason_predicate || reason == Deoptimization::Reason_predicate){
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return true;
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}
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}
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return false; // don't do further after call
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}
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}
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return false;
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}
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//-------------------------------is_uncommon_trap_if_pattern-------------------------
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// Return true for "if(test)-> proj -> ...
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// |
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// V
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// other_proj->[region->..]call_uct"
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//
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// "must_reason_predicate" means the uct reason must be Reason_predicate
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bool PhaseIdealLoop::is_uncommon_trap_if_pattern(ProjNode *proj, bool must_reason_predicate) {
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Node *in0 = proj->in(0);
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if (!in0->is_If()) return false;
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IfNode* iff = in0->as_If();
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// we need "If(Conv2B(Opaque1(...)))" pattern for must_reason_predicate
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if (must_reason_predicate) {
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if (iff->in(1)->Opcode() != Op_Conv2B ||
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iff->in(1)->in(1)->Opcode() != Op_Opaque1) {
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return false;
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}
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}
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ProjNode* other_proj = iff->proj_out(1-proj->_con)->as_Proj();
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return is_uncommon_trap_proj(other_proj, must_reason_predicate);
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}
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//------------------------------create_new_if_for_predicate------------------------
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// create a new if above the uct_if_pattern for the predicate to be promoted.
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//
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// before after
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// ---------- ----------
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// ctrl ctrl
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// | |
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// | |
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// v v
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// iff new_iff
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// / \ / \
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// / \ / \
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// v v v v
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// uncommon_proj cont_proj if_uct if_cont
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// \ | | | |
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// \ | | | |
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// v v v | v
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// rgn loop | iff
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// | | / \
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// | | / \
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// v | v v
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// uncommon_trap | uncommon_proj cont_proj
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// \ \ | |
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// \ \ | |
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// v v v v
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// rgn loop
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// |
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// |
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// v
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// uncommon_trap
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//
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//
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// We will create a region to guard the uct call if there is no one there.
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// The true projecttion (if_cont) of the new_iff is returned.
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ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj) {
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assert(is_uncommon_trap_if_pattern(cont_proj, true), "must be a uct if pattern!");
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IfNode* iff = cont_proj->in(0)->as_If();
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ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
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Node *rgn = uncommon_proj->unique_ctrl_out();
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assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
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if (!rgn->is_Region()) { // create a region to guard the call
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assert(rgn->is_Call(), "must be call uct");
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CallNode* call = rgn->as_Call();
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rgn = new (C, 1) RegionNode(1);
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_igvn.set_type(rgn, rgn->bottom_type());
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rgn->add_req(uncommon_proj);
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set_idom(rgn, idom(uncommon_proj), dom_depth(uncommon_proj)+1);
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_igvn.hash_delete(call);
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call->set_req(0, rgn);
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}
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// Create new_iff
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uint iffdd = dom_depth(iff);
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IdealLoopTree* lp = get_loop(iff);
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IfNode *new_iff = new (C, 2) IfNode(iff->in(0), NULL, iff->_prob, iff->_fcnt);
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register_node(new_iff, lp, idom(iff), iffdd);
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Node *if_cont = new (C, 1) IfTrueNode(new_iff);
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Node *if_uct = new (C, 1) IfFalseNode(new_iff);
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if (cont_proj->is_IfFalse()) {
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// Swap
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Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
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}
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register_node(if_cont, lp, new_iff, iffdd);
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register_node(if_uct, get_loop(rgn), new_iff, iffdd);
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// if_cont to iff
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_igvn.hash_delete(iff);
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iff->set_req(0, if_cont);
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set_idom(iff, if_cont, dom_depth(iff));
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// if_uct to rgn
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_igvn.hash_delete(rgn);
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rgn->add_req(if_uct);
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Node* ridom = idom(rgn);
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Node* nrdom = dom_lca(ridom, new_iff);
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set_idom(rgn, nrdom, dom_depth(rgn));
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// rgn must have no phis
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assert(!rgn->as_Region()->has_phi(), "region must have no phis");
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return if_cont->as_Proj();
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}
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//------------------------------find_predicate_insertion_point--------------------------
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// Find a good location to insert a predicate
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ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c) {
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if (start_c == C->root() || !start_c->is_Proj())
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return NULL;
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if (is_uncommon_trap_if_pattern(start_c->as_Proj(), true/*Reason_Predicate*/)) {
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return start_c->as_Proj();
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}
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return NULL;
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}
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//------------------------------Invariance-----------------------------------
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// Helper class for loop_predication_impl to compute invariance on the fly and
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// clone invariants.
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class Invariance : public StackObj {
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VectorSet _visited, _invariant;
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Node_Stack _stack;
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VectorSet _clone_visited;
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Node_List _old_new; // map of old to new (clone)
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IdealLoopTree* _lpt;
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PhaseIdealLoop* _phase;
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// Helper function to set up the invariance for invariance computation
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// If n is a known invariant, set up directly. Otherwise, look up the
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// the possibility to push n onto the stack for further processing.
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void visit(Node* use, Node* n) {
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if (_lpt->is_invariant(n)) { // known invariant
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_invariant.set(n->_idx);
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} else if (!n->is_CFG()) {
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Node *n_ctrl = _phase->ctrl_or_self(n);
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Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG
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if (_phase->is_dominator(n_ctrl, u_ctrl)) {
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_stack.push(n, n->in(0) == NULL ? 1 : 0);
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}
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}
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}
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// Compute invariance for "the_node" and (possibly) all its inputs recursively
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// on the fly
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void compute_invariance(Node* n) {
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assert(_visited.test(n->_idx), "must be");
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visit(n, n);
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while (_stack.is_nonempty()) {
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Node* n = _stack.node();
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uint idx = _stack.index();
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if (idx == n->req()) { // all inputs are processed
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_stack.pop();
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// n is invariant if it's inputs are all invariant
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bool all_inputs_invariant = true;
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for (uint i = 0; i < n->req(); i++) {
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Node* in = n->in(i);
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if (in == NULL) continue;
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assert(_visited.test(in->_idx), "must have visited input");
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if (!_invariant.test(in->_idx)) { // bad guy
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all_inputs_invariant = false;
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break;
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}
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}
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if (all_inputs_invariant) {
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_invariant.set(n->_idx); // I am a invariant too
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}
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} else { // process next input
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_stack.set_index(idx + 1);
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Node* m = n->in(idx);
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if (m != NULL && !_visited.test_set(m->_idx)) {
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visit(n, m);
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}
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}
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}
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}
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// Helper function to set up _old_new map for clone_nodes.
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// If n is a known invariant, set up directly ("clone" of n == n).
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// Otherwise, push n onto the stack for real cloning.
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void clone_visit(Node* n) {
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assert(_invariant.test(n->_idx), "must be invariant");
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if (_lpt->is_invariant(n)) { // known invariant
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_old_new.map(n->_idx, n);
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} else{ // to be cloned
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assert (!n->is_CFG(), "should not see CFG here");
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_stack.push(n, n->in(0) == NULL ? 1 : 0);
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}
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}
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// Clone "n" and (possibly) all its inputs recursively
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void clone_nodes(Node* n, Node* ctrl) {
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clone_visit(n);
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while (_stack.is_nonempty()) {
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Node* n = _stack.node();
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uint idx = _stack.index();
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if (idx == n->req()) { // all inputs processed, clone n!
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_stack.pop();
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// clone invariant node
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Node* n_cl = n->clone();
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_old_new.map(n->_idx, n_cl);
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_phase->register_new_node(n_cl, ctrl);
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for (uint i = 0; i < n->req(); i++) {
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Node* in = n_cl->in(i);
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if (in == NULL) continue;
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n_cl->set_req(i, _old_new[in->_idx]);
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}
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} else { // process next input
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_stack.set_index(idx + 1);
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Node* m = n->in(idx);
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if (m != NULL && !_clone_visited.test_set(m->_idx)) {
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clone_visit(m); // visit the input
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}
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}
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}
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}
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public:
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Invariance(Arena* area, IdealLoopTree* lpt) :
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_lpt(lpt), _phase(lpt->_phase),
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_visited(area), _invariant(area), _stack(area, 10 /* guess */),
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_clone_visited(area), _old_new(area)
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{}
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// Map old to n for invariance computation and clone
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void map_ctrl(Node* old, Node* n) {
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assert(old->is_CFG() && n->is_CFG(), "must be");
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_old_new.map(old->_idx, n); // "clone" of old is n
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_invariant.set(old->_idx); // old is invariant
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_clone_visited.set(old->_idx);
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}
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// Driver function to compute invariance
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bool is_invariant(Node* n) {
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if (!_visited.test_set(n->_idx))
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compute_invariance(n);
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return (_invariant.test(n->_idx) != 0);
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}
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// Driver function to clone invariant
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Node* clone(Node* n, Node* ctrl) {
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assert(ctrl->is_CFG(), "must be");
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assert(_invariant.test(n->_idx), "must be an invariant");
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if (!_clone_visited.test(n->_idx))
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clone_nodes(n, ctrl);
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return _old_new[n->_idx];
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}
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};
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//------------------------------is_range_check_if -----------------------------------
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// Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format
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// Note: this function is particularly designed for loop predication. We require load_range
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// and offset to be loop invariant computed on the fly by "invar"
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bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const {
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if (!is_loop_exit(iff)) {
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return false;
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}
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if (!iff->in(1)->is_Bool()) {
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return false;
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}
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const BoolNode *bol = iff->in(1)->as_Bool();
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if (bol->_test._test != BoolTest::lt) {
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return false;
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}
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if (!bol->in(1)->is_Cmp()) {
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return false;
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}
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const CmpNode *cmp = bol->in(1)->as_Cmp();
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if (cmp->Opcode() != Op_CmpU ) {
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return false;
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}
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if (cmp->in(2)->Opcode() != Op_LoadRange) {
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return false;
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}
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LoadRangeNode* lr = (LoadRangeNode*)cmp->in(2);
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if (!invar.is_invariant(lr)) { // loadRange must be invariant
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return false;
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}
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Node *iv = _head->as_CountedLoop()->phi();
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int scale = 0;
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Node *offset = NULL;
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if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) {
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return false;
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}
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if(offset && !invar.is_invariant(offset)) { // offset must be invariant
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return false;
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}
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return true;
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}
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//------------------------------rc_predicate-----------------------------------
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// Create a range check predicate
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//
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// for (i = init; i < limit; i += stride) {
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// a[scale*i+offset]
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// }
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//
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// Compute max(scale*i + offset) for init <= i < limit and build the predicate
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// as "max(scale*i + offset) u< a.length".
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//
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// There are two cases for max(scale*i + offset):
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// (1) stride*scale > 0
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// max(scale*i + offset) = scale*(limit-stride) + offset
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// (2) stride*scale < 0
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// max(scale*i + offset) = scale*init + offset
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BoolNode* PhaseIdealLoop::rc_predicate(Node* ctrl,
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int scale, Node* offset,
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Node* init, Node* limit, Node* stride,
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Node* range) {
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Node* max_idx_expr = init;
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int stride_con = stride->get_int();
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if ((stride_con > 0) == (scale > 0)) {
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max_idx_expr = new (C, 3) SubINode(limit, stride);
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register_new_node(max_idx_expr, ctrl);
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}
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if (scale != 1) {
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ConNode* con_scale = _igvn.intcon(scale);
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max_idx_expr = new (C, 3) MulINode(max_idx_expr, con_scale);
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register_new_node(max_idx_expr, ctrl);
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}
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if (offset && (!offset->is_Con() || offset->get_int() != 0)){
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max_idx_expr = new (C, 3) AddINode(max_idx_expr, offset);
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register_new_node(max_idx_expr, ctrl);
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}
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CmpUNode* cmp = new (C, 3) CmpUNode(max_idx_expr, range);
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register_new_node(cmp, ctrl);
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BoolNode* bol = new (C, 2) BoolNode(cmp, BoolTest::lt);
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register_new_node(bol, ctrl);
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return bol;
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}
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//------------------------------ loop_predication_impl--------------------------
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// Insert loop predicates for null checks and range checks
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bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
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if (!UseLoopPredicate) return false;
|
||||
|
||||
// Too many traps seen?
|
||||
bool tmt = C->too_many_traps(C->method(), 0, Deoptimization::Reason_predicate);
|
||||
int tc = C->trap_count(Deoptimization::Reason_predicate);
|
||||
if (tmt || tc > 0) {
|
||||
if (TraceLoopPredicate) {
|
||||
tty->print_cr("too many predicate traps: %d", tc);
|
||||
C->method()->print(); // which method has too many predicate traps
|
||||
tty->print_cr("");
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
CountedLoopNode *cl = NULL;
|
||||
if (loop->_head->is_CountedLoop()) {
|
||||
cl = loop->_head->as_CountedLoop();
|
||||
// do nothing for iteration-splitted loops
|
||||
if(!cl->is_normal_loop()) return false;
|
||||
}
|
||||
|
||||
LoopNode *lpn = loop->_head->as_Loop();
|
||||
Node* entry = lpn->in(LoopNode::EntryControl);
|
||||
|
||||
ProjNode *predicate_proj = find_predicate_insertion_point(entry);
|
||||
if (!predicate_proj){
|
||||
#ifndef PRODUCT
|
||||
if (TraceLoopPredicate) {
|
||||
tty->print("missing predicate:");
|
||||
loop->dump_head();
|
||||
}
|
||||
#endif
|
||||
return false;
|
||||
}
|
||||
|
||||
ConNode* zero = _igvn.intcon(0);
|
||||
set_ctrl(zero, C->root());
|
||||
Node *cond_false = new (C, 2) Conv2BNode(zero);
|
||||
register_new_node(cond_false, C->root());
|
||||
ConNode* one = _igvn.intcon(1);
|
||||
set_ctrl(one, C->root());
|
||||
Node *cond_true = new (C, 2) Conv2BNode(one);
|
||||
register_new_node(cond_true, C->root());
|
||||
|
||||
ResourceArea *area = Thread::current()->resource_area();
|
||||
Invariance invar(area, loop);
|
||||
|
||||
// Create list of if-projs such that a newer proj dominates all older
|
||||
// projs in the list, and they all dominate loop->tail()
|
||||
Node_List if_proj_list(area);
|
||||
LoopNode *head = loop->_head->as_Loop();
|
||||
Node *current_proj = loop->tail(); //start from tail
|
||||
while ( current_proj != head ) {
|
||||
if (loop == get_loop(current_proj) && // still in the loop ?
|
||||
current_proj->is_Proj() && // is a projection ?
|
||||
current_proj->in(0)->Opcode() == Op_If) { // is a if projection ?
|
||||
if_proj_list.push(current_proj);
|
||||
}
|
||||
current_proj = idom(current_proj);
|
||||
}
|
||||
|
||||
bool hoisted = false; // true if at least one proj is promoted
|
||||
while (if_proj_list.size() > 0) {
|
||||
// Following are changed to nonnull when a predicate can be hoisted
|
||||
ProjNode* new_predicate_proj = NULL;
|
||||
BoolNode* new_predicate_bol = NULL;
|
||||
|
||||
ProjNode* proj = if_proj_list.pop()->as_Proj();
|
||||
IfNode* iff = proj->in(0)->as_If();
|
||||
|
||||
if (!is_uncommon_trap_if_pattern(proj)) {
|
||||
if (loop->is_loop_exit(iff)) {
|
||||
// stop processing the remaining projs in the list because the execution of them
|
||||
// depends on the condition of "iff" (iff->in(1)).
|
||||
break;
|
||||
} else {
|
||||
// Both arms are inside the loop. There are two cases:
|
||||
// (1) there is one backward branch. In this case, any remaining proj
|
||||
// in the if_proj list post-dominates "iff". So, the condition of "iff"
|
||||
// does not determine the execution the remining projs directly, and we
|
||||
// can safely continue.
|
||||
// (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
|
||||
// does not dominate loop->tail(), so it can not be in the if_proj list.
|
||||
continue;
|
||||
}
|
||||
}
|
||||
|
||||
Node* test = iff->in(1);
|
||||
if (!test->is_Bool()){ //Conv2B, ...
|
||||
continue;
|
||||
}
|
||||
BoolNode* bol = test->as_Bool();
|
||||
if (invar.is_invariant(bol)) {
|
||||
// Invariant test
|
||||
new_predicate_proj = create_new_if_for_predicate(predicate_proj);
|
||||
Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
|
||||
new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
|
||||
if (TraceLoopPredicate) tty->print("invariant");
|
||||
} else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) {
|
||||
// Range check (only for counted loops)
|
||||
new_predicate_proj = create_new_if_for_predicate(predicate_proj);
|
||||
Node *ctrl = new_predicate_proj->in(0)->as_If()->in(0);
|
||||
const Node* cmp = bol->in(1)->as_Cmp();
|
||||
Node* idx = cmp->in(1);
|
||||
assert(!invar.is_invariant(idx), "index is variant");
|
||||
assert(cmp->in(2)->Opcode() == Op_LoadRange, "must be");
|
||||
LoadRangeNode* ld_rng = (LoadRangeNode*)cmp->in(2); // LoadRangeNode
|
||||
assert(invar.is_invariant(ld_rng), "load range must be invariant");
|
||||
ld_rng = (LoadRangeNode*)invar.clone(ld_rng, ctrl);
|
||||
int scale = 1;
|
||||
Node* offset = zero;
|
||||
bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset);
|
||||
assert(ok, "must be index expression");
|
||||
if (offset && offset != zero) {
|
||||
assert(invar.is_invariant(offset), "offset must be loop invariant");
|
||||
offset = invar.clone(offset, ctrl);
|
||||
}
|
||||
Node* init = cl->init_trip();
|
||||
Node* limit = cl->limit();
|
||||
Node* stride = cl->stride();
|
||||
new_predicate_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, ld_rng);
|
||||
if (TraceLoopPredicate) tty->print("range check");
|
||||
}
|
||||
|
||||
if (new_predicate_proj == NULL) {
|
||||
// The other proj of the "iff" is a uncommon trap projection, and we can assume
|
||||
// the other proj will not be executed ("executed" means uct raised).
|
||||
continue;
|
||||
} else {
|
||||
// Success - attach condition (new_predicate_bol) to predicate if
|
||||
invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate
|
||||
IfNode* new_iff = new_predicate_proj->in(0)->as_If();
|
||||
|
||||
// Negate test if necessary
|
||||
if (proj->_con != predicate_proj->_con) {
|
||||
new_predicate_bol = new (C, 2) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
|
||||
register_new_node(new_predicate_bol, new_iff->in(0));
|
||||
if (TraceLoopPredicate) tty->print_cr(" if negated: %d", iff->_idx);
|
||||
} else {
|
||||
if (TraceLoopPredicate) tty->print_cr(" if: %d", iff->_idx);
|
||||
}
|
||||
|
||||
_igvn.hash_delete(new_iff);
|
||||
new_iff->set_req(1, new_predicate_bol);
|
||||
|
||||
_igvn.hash_delete(iff);
|
||||
iff->set_req(1, proj->is_IfFalse() ? cond_false : cond_true);
|
||||
|
||||
Node* ctrl = new_predicate_proj; // new control
|
||||
ProjNode* dp = proj; // old control
|
||||
assert(get_loop(dp) == loop, "guarenteed at the time of collecting proj");
|
||||
// Find nodes (depends only on the test) off the surviving projection;
|
||||
// move them outside the loop with the control of proj_clone
|
||||
for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
|
||||
Node* cd = dp->fast_out(i); // Control-dependent node
|
||||
if (cd->depends_only_on_test()) {
|
||||
assert(cd->in(0) == dp, "");
|
||||
_igvn.hash_delete(cd);
|
||||
cd->set_req(0, ctrl); // ctrl, not NULL
|
||||
set_early_ctrl(cd);
|
||||
_igvn._worklist.push(cd);
|
||||
IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
|
||||
if (new_loop != loop) {
|
||||
if (!loop->_child) loop->_body.yank(cd);
|
||||
if (!new_loop->_child ) new_loop->_body.push(cd);
|
||||
}
|
||||
--i;
|
||||
--imax;
|
||||
}
|
||||
}
|
||||
|
||||
hoisted = true;
|
||||
C->set_major_progress();
|
||||
}
|
||||
} // end while
|
||||
|
||||
#ifndef PRODUCT
|
||||
// report that the loop predication has been actually performed
|
||||
// for this loop
|
||||
if (TraceLoopPredicate && hoisted) {
|
||||
tty->print("Loop Predication Performed:");
|
||||
loop->dump_head();
|
||||
}
|
||||
#endif
|
||||
|
||||
return hoisted;
|
||||
}
|
||||
|
||||
//------------------------------loop_predication--------------------------------
|
||||
// driver routine for loop predication optimization
|
||||
bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
|
||||
bool hoisted = false;
|
||||
// Recursively promote predicates
|
||||
if ( _child ) {
|
||||
hoisted = _child->loop_predication( phase);
|
||||
}
|
||||
|
||||
// self
|
||||
if (!_irreducible && !tail()->is_top()) {
|
||||
hoisted |= phase->loop_predication_impl(this);
|
||||
}
|
||||
|
||||
if ( _next ) { //sibling
|
||||
hoisted |= _next->loop_predication( phase);
|
||||
}
|
||||
|
||||
return hoisted;
|
||||
}
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue