| /* |
| * Copyright 2000-2006 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. |
| * |
| */ |
| |
| // Portions of code courtesy of Clifford Click |
| |
| // Optimization - Graph Style |
| |
| #include "incls/_precompiled.incl" |
| #include "incls/_ifnode.cpp.incl" |
| |
| |
| extern int explicit_null_checks_elided; |
| |
| //============================================================================= |
| //------------------------------Value------------------------------------------ |
| // Return a tuple for whichever arm of the IF is reachable |
| const Type *IfNode::Value( PhaseTransform *phase ) const { |
| if( !in(0) ) return Type::TOP; |
| if( phase->type(in(0)) == Type::TOP ) |
| return Type::TOP; |
| const Type *t = phase->type(in(1)); |
| if( t == Type::TOP ) // data is undefined |
| return TypeTuple::IFNEITHER; // unreachable altogether |
| if( t == TypeInt::ZERO ) // zero, or false |
| return TypeTuple::IFFALSE; // only false branch is reachable |
| if( t == TypeInt::ONE ) // 1, or true |
| return TypeTuple::IFTRUE; // only true branch is reachable |
| assert( t == TypeInt::BOOL, "expected boolean type" ); |
| |
| return TypeTuple::IFBOTH; // No progress |
| } |
| |
| const RegMask &IfNode::out_RegMask() const { |
| return RegMask::Empty; |
| } |
| |
| //------------------------------split_if--------------------------------------- |
| // Look for places where we merge constants, then test on the merged value. |
| // If the IF test will be constant folded on the path with the constant, we |
| // win by splitting the IF to before the merge point. |
| static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) { |
| // I could be a lot more general here, but I'm trying to squeeze this |
| // in before the Christmas '98 break so I'm gonna be kinda restrictive |
| // on the patterns I accept. CNC |
| |
| // Look for a compare of a constant and a merged value |
| Node *i1 = iff->in(1); |
| if( !i1->is_Bool() ) return NULL; |
| BoolNode *b = i1->as_Bool(); |
| Node *cmp = b->in(1); |
| if( !cmp->is_Cmp() ) return NULL; |
| i1 = cmp->in(1); |
| if( i1 == NULL || !i1->is_Phi() ) return NULL; |
| PhiNode *phi = i1->as_Phi(); |
| if( phi->is_copy() ) return NULL; |
| Node *con2 = cmp->in(2); |
| if( !con2->is_Con() ) return NULL; |
| // See that the merge point contains some constants |
| Node *con1=NULL; |
| uint i4; |
| for( i4 = 1; i4 < phi->req(); i4++ ) { |
| con1 = phi->in(i4); |
| if( !con1 ) return NULL; // Do not optimize partially collaped merges |
| if( con1->is_Con() ) break; // Found a constant |
| // Also allow null-vs-not-null checks |
| const TypePtr *tp = igvn->type(con1)->isa_ptr(); |
| if( tp && tp->_ptr == TypePtr::NotNull ) |
| break; |
| } |
| if( i4 >= phi->req() ) return NULL; // Found no constants |
| |
| igvn->C->set_has_split_ifs(true); // Has chance for split-if |
| |
| // Make sure that the compare can be constant folded away |
| Node *cmp2 = cmp->clone(); |
| cmp2->set_req(1,con1); |
| cmp2->set_req(2,con2); |
| const Type *t = cmp2->Value(igvn); |
| // This compare is dead, so whack it! |
| igvn->remove_dead_node(cmp2); |
| if( !t->singleton() ) return NULL; |
| |
| // No intervening control, like a simple Call |
| Node *r = iff->in(0); |
| if( !r->is_Region() ) return NULL; |
| if( phi->region() != r ) return NULL; |
| // No other users of the cmp/bool |
| if (b->outcnt() != 1 || cmp->outcnt() != 1) { |
| //tty->print_cr("many users of cmp/bool"); |
| return NULL; |
| } |
| |
| // Make sure we can determine where all the uses of merged values go |
| for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) { |
| Node* u = r->fast_out(j); |
| if( u == r ) continue; |
| if( u == iff ) continue; |
| if( u->outcnt() == 0 ) continue; // use is dead & ignorable |
| if( !u->is_Phi() ) { |
| /* |
| if( u->is_Start() ) { |
| tty->print_cr("Region has inlined start use"); |
| } else { |
| tty->print_cr("Region has odd use"); |
| u->dump(2); |
| }*/ |
| return NULL; |
| } |
| if( u != phi ) { |
| // CNC - do not allow any other merged value |
| //tty->print_cr("Merging another value"); |
| //u->dump(2); |
| return NULL; |
| } |
| // Make sure we can account for all Phi uses |
| for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) { |
| Node* v = u->fast_out(k); // User of the phi |
| // CNC - Allow only really simple patterns. |
| // In particular I disallow AddP of the Phi, a fairly common pattern |
| if( v == cmp ) continue; // The compare is OK |
| if( (v->is_ConstraintCast()) && |
| v->in(0)->in(0) == iff ) |
| continue; // CastPP/II of the IfNode is OK |
| // Disabled following code because I cannot tell if exactly one |
| // path dominates without a real dominator check. CNC 9/9/1999 |
| //uint vop = v->Opcode(); |
| //if( vop == Op_Phi ) { // Phi from another merge point might be OK |
| // Node *r = v->in(0); // Get controlling point |
| // if( !r ) return NULL; // Degraded to a copy |
| // // Find exactly one path in (either True or False doms, but not IFF) |
| // int cnt = 0; |
| // for( uint i = 1; i < r->req(); i++ ) |
| // if( r->in(i) && r->in(i)->in(0) == iff ) |
| // cnt++; |
| // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi |
| //} |
| if( !v->is_Call() ) { |
| /* |
| if( v->Opcode() == Op_AddP ) { |
| tty->print_cr("Phi has AddP use"); |
| } else if( v->Opcode() == Op_CastPP ) { |
| tty->print_cr("Phi has CastPP use"); |
| } else if( v->Opcode() == Op_CastII ) { |
| tty->print_cr("Phi has CastII use"); |
| } else { |
| tty->print_cr("Phi has use I cant be bothered with"); |
| } |
| */ |
| } |
| return NULL; |
| |
| /* CNC - Cut out all the fancy acceptance tests |
| // Can we clone this use when doing the transformation? |
| // If all uses are from Phis at this merge or constants, then YES. |
| if( !v->in(0) && v != cmp ) { |
| tty->print_cr("Phi has free-floating use"); |
| v->dump(2); |
| return NULL; |
| } |
| for( uint l = 1; l < v->req(); l++ ) { |
| if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) && |
| !v->in(l)->is_Con() ) { |
| tty->print_cr("Phi has use"); |
| v->dump(2); |
| return NULL; |
| } // End of if Phi-use input is neither Phi nor Constant |
| } // End of for all inputs to Phi-use |
| */ |
| } // End of for all uses of Phi |
| } // End of for all uses of Region |
| |
| // Only do this if the IF node is in a sane state |
| if (iff->outcnt() != 2) |
| return NULL; |
| |
| // Got a hit! Do the Mondo Hack! |
| // |
| //ABC a1c def ghi B 1 e h A C a c d f g i |
| // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi |
| // cmp - 2 cmp - 2 cmp - 2 |
| // bool bool_c bool_x |
| // if if_c if_x |
| // T F T F T F |
| // ..s.. ..t .. ..s.. ..t.. ..s.. ..t.. |
| // |
| // Split the paths coming into the merge point into 2 seperate groups of |
| // merges. On the left will be all the paths feeding constants into the |
| // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi |
| // will fold up into a constant; this will let the Cmp fold up as well as |
| // all the control flow. Below the original IF we have 2 control |
| // dependent regions, 's' and 't'. Now we will merge the two paths |
| // just prior to 's' and 't' from the two IFs. At least 1 path (and quite |
| // likely 2 or more) will promptly constant fold away. |
| PhaseGVN *phase = igvn; |
| |
| // Make a region merging constants and a region merging the rest |
| uint req_c = 0; |
| for (uint ii = 1; ii < r->req(); ii++) { |
| if( phi->in(ii) == con1 ) { |
| req_c++; |
| } |
| } |
| Node *region_c = new (igvn->C, req_c + 1) RegionNode(req_c + 1); |
| Node *phi_c = con1; |
| uint len = r->req(); |
| Node *region_x = new (igvn->C, len - req_c + 1) RegionNode(len - req_c + 1); |
| Node *phi_x = PhiNode::make_blank(region_x, phi); |
| for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) { |
| if( phi->in(i) == con1 ) { |
| region_c->init_req( i_c++, r ->in(i) ); |
| } else { |
| region_x->init_req( i_x, r ->in(i) ); |
| phi_x ->init_req( i_x++, phi->in(i) ); |
| } |
| } |
| |
| // Register the new RegionNodes but do not transform them. Cannot |
| // transform until the entire Region/Phi conglerate has been hacked |
| // as a single huge transform. |
| igvn->register_new_node_with_optimizer( region_c ); |
| igvn->register_new_node_with_optimizer( region_x ); |
| phi_x = phase->transform( phi_x ); |
| // Prevent the untimely death of phi_x. Currently he has no uses. He is |
| // about to get one. If this only use goes away, then phi_x will look dead. |
| // However, he will be picking up some more uses down below. |
| Node *hook = new (igvn->C, 4) Node(4); |
| hook->init_req(0, phi_x); |
| hook->init_req(1, phi_c); |
| |
| // Make the compare |
| Node *cmp_c = phase->makecon(t); |
| Node *cmp_x = cmp->clone(); |
| cmp_x->set_req(1,phi_x); |
| cmp_x->set_req(2,con2); |
| cmp_x = phase->transform(cmp_x); |
| // Make the bool |
| Node *b_c = phase->transform(new (igvn->C, 2) BoolNode(cmp_c,b->_test._test)); |
| Node *b_x = phase->transform(new (igvn->C, 2) BoolNode(cmp_x,b->_test._test)); |
| // Make the IfNode |
| IfNode *iff_c = new (igvn->C, 2) IfNode(region_c,b_c,iff->_prob,iff->_fcnt); |
| igvn->set_type_bottom(iff_c); |
| igvn->_worklist.push(iff_c); |
| hook->init_req(2, iff_c); |
| |
| IfNode *iff_x = new (igvn->C, 2) IfNode(region_x,b_x,iff->_prob, iff->_fcnt); |
| igvn->set_type_bottom(iff_x); |
| igvn->_worklist.push(iff_x); |
| hook->init_req(3, iff_x); |
| |
| // Make the true/false arms |
| Node *iff_c_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_c)); |
| Node *iff_c_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_c)); |
| Node *iff_x_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_x)); |
| Node *iff_x_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_x)); |
| |
| // Merge the TRUE paths |
| Node *region_s = new (igvn->C, 3) RegionNode(3); |
| igvn->_worklist.push(region_s); |
| region_s->init_req(1, iff_c_t); |
| region_s->init_req(2, iff_x_t); |
| igvn->register_new_node_with_optimizer( region_s ); |
| |
| // Merge the FALSE paths |
| Node *region_f = new (igvn->C, 3) RegionNode(3); |
| igvn->_worklist.push(region_f); |
| region_f->init_req(1, iff_c_f); |
| region_f->init_req(2, iff_x_f); |
| igvn->register_new_node_with_optimizer( region_f ); |
| |
| igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table. |
| cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead |
| cmp->set_req(2,NULL); |
| // Check for all uses of the Phi and give them a new home. |
| // The 'cmp' got cloned, but CastPP/IIs need to be moved. |
| Node *phi_s = NULL; // do not construct unless needed |
| Node *phi_f = NULL; // do not construct unless needed |
| for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) { |
| Node* v = phi->last_out(i2);// User of the phi |
| igvn->hash_delete(v); // Have to fixup other Phi users |
| igvn->_worklist.push(v); |
| uint vop = v->Opcode(); |
| Node *proj = NULL; |
| if( vop == Op_Phi ) { // Remote merge point |
| Node *r = v->in(0); |
| for (uint i3 = 1; i3 < r->req(); i3++) |
| if (r->in(i3) && r->in(i3)->in(0) == iff) { |
| proj = r->in(i3); |
| break; |
| } |
| } else if( v->is_ConstraintCast() ) { |
| proj = v->in(0); // Controlling projection |
| } else { |
| assert( 0, "do not know how to handle this guy" ); |
| } |
| |
| Node *proj_path_data, *proj_path_ctrl; |
| if( proj->Opcode() == Op_IfTrue ) { |
| if( phi_s == NULL ) { |
| // Only construct phi_s if needed, otherwise provides |
| // interfering use. |
| phi_s = PhiNode::make_blank(region_s,phi); |
| phi_s->init_req( 1, phi_c ); |
| phi_s->init_req( 2, phi_x ); |
| phi_s = phase->transform(phi_s); |
| } |
| proj_path_data = phi_s; |
| proj_path_ctrl = region_s; |
| } else { |
| if( phi_f == NULL ) { |
| // Only construct phi_f if needed, otherwise provides |
| // interfering use. |
| phi_f = PhiNode::make_blank(region_f,phi); |
| phi_f->init_req( 1, phi_c ); |
| phi_f->init_req( 2, phi_x ); |
| phi_f = phase->transform(phi_f); |
| } |
| proj_path_data = phi_f; |
| proj_path_ctrl = region_f; |
| } |
| |
| // Fixup 'v' for for the split |
| if( vop == Op_Phi ) { // Remote merge point |
| uint i; |
| for( i = 1; i < v->req(); i++ ) |
| if( v->in(i) == phi ) |
| break; |
| v->set_req(i, proj_path_data ); |
| } else if( v->is_ConstraintCast() ) { |
| v->set_req(0, proj_path_ctrl ); |
| v->set_req(1, proj_path_data ); |
| } else |
| ShouldNotReachHere(); |
| } |
| |
| // Now replace the original iff's True/False with region_s/region_t. |
| // This makes the original iff go dead. |
| for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) { |
| Node* p = iff->last_out(i3); |
| assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" ); |
| Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f; |
| // Replace p with u |
| igvn->add_users_to_worklist(p); |
| for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) { |
| Node* x = p->last_out(l); |
| igvn->hash_delete(x); |
| uint uses_found = 0; |
| for( uint j = 0; j < x->req(); j++ ) { |
| if( x->in(j) == p ) { |
| x->set_req(j, u); |
| uses_found++; |
| } |
| } |
| l -= uses_found; // we deleted 1 or more copies of this edge |
| } |
| igvn->remove_dead_node(p); |
| } |
| |
| // Force the original merge dead |
| igvn->hash_delete(r); |
| r->set_req_X(0,NULL,igvn); |
| |
| // Now remove the bogus extra edges used to keep things alive |
| igvn->remove_dead_node( hook ); |
| |
| // Must return either the original node (now dead) or a new node |
| // (Do not return a top here, since that would break the uniqueness of top.) |
| return new (igvn->C, 1) ConINode(TypeInt::ZERO); |
| } |
| |
| //------------------------------is_range_check--------------------------------- |
| // Return 0 if not a range check. Return 1 if a range check and set index and |
| // offset. Return 2 if we had to negate the test. Index is NULL if the check |
| // is versus a constant. |
| int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) { |
| Node* b = in(1); |
| if (b == NULL || !b->is_Bool()) return 0; |
| BoolNode* bn = b->as_Bool(); |
| Node* cmp = bn->in(1); |
| if (cmp == NULL) return 0; |
| if (cmp->Opcode() != Op_CmpU) return 0; |
| |
| Node* l = cmp->in(1); |
| Node* r = cmp->in(2); |
| int flip_test = 1; |
| if (bn->_test._test == BoolTest::le) { |
| l = cmp->in(2); |
| r = cmp->in(1); |
| flip_test = 2; |
| } else if (bn->_test._test != BoolTest::lt) { |
| return 0; |
| } |
| if (l->is_top()) return 0; // Top input means dead test |
| if (r->Opcode() != Op_LoadRange) return 0; |
| |
| // We have recognized one of these forms: |
| // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ... |
| // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ... |
| |
| // Make sure it's a real range check by requiring an uncommon trap |
| // along the OOB path. Otherwise, it's possible that the user wrote |
| // something which optimized to look like a range check but behaves |
| // in some other way. |
| Node* iftrap = proj_out(flip_test == 2 ? true : false); |
| bool found_trap = false; |
| if (iftrap != NULL) { |
| Node* u = iftrap->unique_ctrl_out(); |
| if (u != NULL) { |
| // It could be a merge point (Region) for uncommon trap. |
| if (u->is_Region()) { |
| Node* c = u->unique_ctrl_out(); |
| if (c != NULL) { |
| iftrap = u; |
| u = c; |
| } |
| } |
| if (u->in(0) == iftrap && u->is_CallStaticJava()) { |
| int req = u->as_CallStaticJava()->uncommon_trap_request(); |
| if (Deoptimization::trap_request_reason(req) == |
| Deoptimization::Reason_range_check) { |
| found_trap = true; |
| } |
| } |
| } |
| } |
| if (!found_trap) return 0; // sorry, no cigar |
| |
| // Look for index+offset form |
| Node* ind = l; |
| jint off = 0; |
| if (l->is_top()) { |
| return 0; |
| } else if (l->is_Add()) { |
| if ((off = l->in(1)->find_int_con(0)) != 0) { |
| ind = l->in(2); |
| } else if ((off = l->in(2)->find_int_con(0)) != 0) { |
| ind = l->in(1); |
| } |
| } else if ((off = l->find_int_con(-1)) >= 0) { |
| // constant offset with no variable index |
| ind = NULL; |
| } else { |
| // variable index with no constant offset (or dead negative index) |
| off = 0; |
| } |
| |
| // Return all the values: |
| index = ind; |
| offset = off; |
| range = r; |
| return flip_test; |
| } |
| |
| //------------------------------adjust_check----------------------------------- |
| // Adjust (widen) a prior range check |
| static void adjust_check(Node* proj, Node* range, Node* index, |
| int flip, jint off_lo, PhaseIterGVN* igvn) { |
| PhaseGVN *gvn = igvn; |
| // Break apart the old check |
| Node *iff = proj->in(0); |
| Node *bol = iff->in(1); |
| if( bol->is_top() ) return; // In case a partially dead range check appears |
| // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode |
| DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } ) |
| if( !bol->is_Bool() ) return; |
| |
| Node *cmp = bol->in(1); |
| // Compute a new check |
| Node *new_add = gvn->intcon(off_lo); |
| if( index ) { |
| new_add = off_lo ? gvn->transform(new (gvn->C, 3) AddINode( index, new_add )) : index; |
| } |
| Node *new_cmp = (flip == 1) |
| ? new (gvn->C, 3) CmpUNode( new_add, range ) |
| : new (gvn->C, 3) CmpUNode( range, new_add ); |
| new_cmp = gvn->transform(new_cmp); |
| // See if no need to adjust the existing check |
| if( new_cmp == cmp ) return; |
| // Else, adjust existing check |
| Node *new_bol = gvn->transform( new (gvn->C, 2) BoolNode( new_cmp, bol->as_Bool()->_test._test ) ); |
| igvn->hash_delete( iff ); |
| iff->set_req_X( 1, new_bol, igvn ); |
| } |
| |
| //------------------------------up_one_dom------------------------------------- |
| // Walk up the dominator tree one step. Return NULL at root or true |
| // complex merges. Skips through small diamonds. |
| Node* IfNode::up_one_dom(Node *curr, bool linear_only) { |
| Node *dom = curr->in(0); |
| if( !dom ) // Found a Region degraded to a copy? |
| return curr->nonnull_req(); // Skip thru it |
| |
| if( curr != dom ) // Normal walk up one step? |
| return dom; |
| |
| // Use linear_only if we are still parsing, since we cannot |
| // trust the regions to be fully filled in. |
| if (linear_only) |
| return NULL; |
| |
| // Else hit a Region. Check for a loop header |
| if( dom->is_Loop() ) |
| return dom->in(1); // Skip up thru loops |
| |
| // Check for small diamonds |
| Node *din1, *din2, *din3, *din4; |
| if( dom->req() == 3 && // 2-path merge point |
| (din1 = dom ->in(1)) && // Left path exists |
| (din2 = dom ->in(2)) && // Right path exists |
| (din3 = din1->in(0)) && // Left path up one |
| (din4 = din2->in(0)) ) { // Right path up one |
| if( din3->is_Call() && // Handle a slow-path call on either arm |
| (din3 = din3->in(0)) ) |
| din3 = din3->in(0); |
| if( din4->is_Call() && // Handle a slow-path call on either arm |
| (din4 = din4->in(0)) ) |
| din4 = din4->in(0); |
| if( din3 == din4 && din3->is_If() ) |
| return din3; // Skip around diamonds |
| } |
| |
| // Give up the search at true merges |
| return NULL; // Dead loop? Or hit root? |
| } |
| |
| //------------------------------remove_useless_bool---------------------------- |
| // Check for people making a useless boolean: things like |
| // if( (x < y ? true : false) ) { ... } |
| // Replace with if( x < y ) { ... } |
| static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) { |
| Node *i1 = iff->in(1); |
| if( !i1->is_Bool() ) return NULL; |
| BoolNode *bol = i1->as_Bool(); |
| |
| Node *cmp = bol->in(1); |
| if( cmp->Opcode() != Op_CmpI ) return NULL; |
| |
| // Must be comparing against a bool |
| const Type *cmp2_t = phase->type( cmp->in(2) ); |
| if( cmp2_t != TypeInt::ZERO && |
| cmp2_t != TypeInt::ONE ) |
| return NULL; |
| |
| // Find a prior merge point merging the boolean |
| i1 = cmp->in(1); |
| if( !i1->is_Phi() ) return NULL; |
| PhiNode *phi = i1->as_Phi(); |
| if( phase->type( phi ) != TypeInt::BOOL ) |
| return NULL; |
| |
| // Check for diamond pattern |
| int true_path = phi->is_diamond_phi(); |
| if( true_path == 0 ) return NULL; |
| |
| // phi->region->if_proj->ifnode->bool->cmp |
| BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool(); |
| |
| // Now get the 'sense' of the test correct so we can plug in |
| // either iff2->in(1) or its complement. |
| int flip = 0; |
| if( bol->_test._test == BoolTest::ne ) flip = 1-flip; |
| else if( bol->_test._test != BoolTest::eq ) return NULL; |
| if( cmp2_t == TypeInt::ZERO ) flip = 1-flip; |
| |
| const Type *phi1_t = phase->type( phi->in(1) ); |
| const Type *phi2_t = phase->type( phi->in(2) ); |
| // Check for Phi(0,1) and flip |
| if( phi1_t == TypeInt::ZERO ) { |
| if( phi2_t != TypeInt::ONE ) return NULL; |
| flip = 1-flip; |
| } else { |
| // Check for Phi(1,0) |
| if( phi1_t != TypeInt::ONE ) return NULL; |
| if( phi2_t != TypeInt::ZERO ) return NULL; |
| } |
| if( true_path == 2 ) { |
| flip = 1-flip; |
| } |
| |
| Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2); |
| iff->set_req(1, new_bol); |
| // Intervening diamond probably goes dead |
| phase->C->set_major_progress(); |
| return iff; |
| } |
| |
| static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff); |
| |
| //------------------------------Ideal------------------------------------------ |
| // Return a node which is more "ideal" than the current node. Strip out |
| // control copies |
| Node *IfNode::Ideal(PhaseGVN *phase, bool can_reshape) { |
| if (remove_dead_region(phase, can_reshape)) return this; |
| // No Def-Use info? |
| if (!can_reshape) return NULL; |
| PhaseIterGVN *igvn = phase->is_IterGVN(); |
| |
| // Don't bother trying to transform a dead if |
| if (in(0)->is_top()) return NULL; |
| // Don't bother trying to transform an if with a dead test |
| if (in(1)->is_top()) return NULL; |
| // Another variation of a dead test |
| if (in(1)->is_Con()) return NULL; |
| // Another variation of a dead if |
| if (outcnt() < 2) return NULL; |
| |
| // Canonicalize the test. |
| Node* idt_if = idealize_test(phase, this); |
| if (idt_if != NULL) return idt_if; |
| |
| // Try to split the IF |
| Node *s = split_if(this, igvn); |
| if (s != NULL) return s; |
| |
| // Check for people making a useless boolean: things like |
| // if( (x < y ? true : false) ) { ... } |
| // Replace with if( x < y ) { ... } |
| Node *bol2 = remove_useless_bool(this, phase); |
| if( bol2 ) return bol2; |
| |
| // Setup to scan up the CFG looking for a dominating test |
| Node *dom = in(0); |
| Node *prev_dom = this; |
| |
| // Check for range-check vs other kinds of tests |
| Node *index1, *range1; |
| jint offset1; |
| int flip1 = is_range_check(range1, index1, offset1); |
| if( flip1 ) { |
| Node *first_prev_dom = NULL; |
| |
| // Try to remove extra range checks. All 'up_one_dom' gives up at merges |
| // so all checks we inspect post-dominate the top-most check we find. |
| // If we are going to fail the current check and we reach the top check |
| // then we are guarenteed to fail, so just start interpreting there. |
| // We 'expand' the top 2 range checks to include all post-dominating |
| // checks. |
| |
| // The top 2 range checks seen |
| Node *prev_chk1 = NULL; |
| Node *prev_chk2 = NULL; |
| // Low and high offsets seen so far |
| jint off_lo = offset1; |
| jint off_hi = offset1; |
| |
| // Scan for the top 2 checks and collect range of offsets |
| for( int dist = 0; dist < 999; dist++ ) { // Range-Check scan limit |
| if( dom->Opcode() == Op_If && // Not same opcode? |
| prev_dom->in(0) == dom ) { // One path of test does dominate? |
| if( dom == this ) return NULL; // dead loop |
| // See if this is a range check |
| Node *index2, *range2; |
| jint offset2; |
| int flip2 = dom->as_If()->is_range_check(range2, index2, offset2); |
| // See if this is a _matching_ range check, checking against |
| // the same array bounds. |
| if( flip2 == flip1 && range2 == range1 && index2 == index1 && |
| dom->outcnt() == 2 ) { |
| // Gather expanded bounds |
| off_lo = MIN2(off_lo,offset2); |
| off_hi = MAX2(off_hi,offset2); |
| // Record top 2 range checks |
| prev_chk2 = prev_chk1; |
| prev_chk1 = prev_dom; |
| // If we match the test exactly, then the top test covers |
| // both our lower and upper bounds. |
| if( dom->in(1) == in(1) ) |
| prev_chk2 = prev_chk1; |
| } |
| } |
| prev_dom = dom; |
| dom = up_one_dom( dom ); |
| if( !dom ) break; |
| } |
| |
| |
| // Attempt to widen the dominating range check to cover some later |
| // ones. Since range checks "fail" by uncommon-trapping to the |
| // interpreter, widening a check can make us speculative enter the |
| // interpreter. If we see range-check deopt's, do not widen! |
| if (!phase->C->allow_range_check_smearing()) return NULL; |
| |
| // Constant indices only need to check the upper bound. |
| // Non-constance indices must check both low and high. |
| if( index1 ) { |
| // Didn't find 2 prior covering checks, so cannot remove anything. |
| if( !prev_chk2 ) return NULL; |
| // 'Widen' the offsets of the 1st and 2nd covering check |
| adjust_check( prev_chk1, range1, index1, flip1, off_lo, igvn ); |
| // Do not call adjust_check twice on the same projection |
| // as the first call may have transformed the BoolNode to a ConI |
| if( prev_chk1 != prev_chk2 ) { |
| adjust_check( prev_chk2, range1, index1, flip1, off_hi, igvn ); |
| } |
| // Test is now covered by prior checks, dominate it out |
| prev_dom = prev_chk2; |
| } else { |
| // Didn't find prior covering check, so cannot remove anything. |
| if( !prev_chk1 ) return NULL; |
| // 'Widen' the offset of the 1st and only covering check |
| adjust_check( prev_chk1, range1, index1, flip1, off_hi, igvn ); |
| // Test is now covered by prior checks, dominate it out |
| prev_dom = prev_chk1; |
| } |
| |
| |
| } else { // Scan for an equivalent test |
| |
| Node *cmp; |
| int dist = 0; // Cutoff limit for search |
| int op = Opcode(); |
| if( op == Op_If && |
| (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) { |
| if( cmp->in(2) != NULL && // make sure cmp is not already dead |
| cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) { |
| dist = 64; // Limit for null-pointer scans |
| } else { |
| dist = 4; // Do not bother for random pointer tests |
| } |
| } else { |
| dist = 4; // Limit for random junky scans |
| } |
| |
| // Normal equivalent-test check. |
| if( !dom ) return NULL; // Dead loop? |
| |
| // Search up the dominator tree for an If with an identical test |
| while( dom->Opcode() != op || // Not same opcode? |
| dom->in(1) != in(1) || // Not same input 1? |
| (req() == 3 && dom->in(2) != in(2)) || // Not same input 2? |
| prev_dom->in(0) != dom ) { // One path of test does not dominate? |
| if( dist < 0 ) return NULL; |
| |
| dist--; |
| prev_dom = dom; |
| dom = up_one_dom( dom ); |
| if( !dom ) return NULL; |
| } |
| |
| // Check that we did not follow a loop back to ourselves |
| if( this == dom ) |
| return NULL; |
| |
| if( dist > 2 ) // Add to count of NULL checks elided |
| explicit_null_checks_elided++; |
| |
| } // End of Else scan for an equivalent test |
| |
| // Hit! Remove this IF |
| #ifndef PRODUCT |
| if( TraceIterativeGVN ) { |
| tty->print(" Removing IfNode: "); this->dump(); |
| } |
| if( VerifyOpto && !phase->allow_progress() ) { |
| // Found an equivalent dominating test, |
| // we can not guarantee reaching a fix-point for these during iterativeGVN |
| // since intervening nodes may not change. |
| return NULL; |
| } |
| #endif |
| |
| // Replace dominated IfNode |
| dominated_by( prev_dom, igvn ); |
| |
| // Must return either the original node (now dead) or a new node |
| // (Do not return a top here, since that would break the uniqueness of top.) |
| return new (phase->C, 1) ConINode(TypeInt::ZERO); |
| } |
| |
| //------------------------------dominated_by----------------------------------- |
| void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) { |
| igvn->hash_delete(this); // Remove self to prevent spurious V-N |
| Node *idom = in(0); |
| // Need opcode to decide which way 'this' test goes |
| int prev_op = prev_dom->Opcode(); |
| Node *top = igvn->C->top(); // Shortcut to top |
| |
| // Now walk the current IfNode's projections. |
| // Loop ends when 'this' has no more uses. |
| for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { |
| Node *ifp = last_out(i); // Get IfTrue/IfFalse |
| igvn->add_users_to_worklist(ifp); |
| // Check which projection it is and set target. |
| // Data-target is either the dominating projection of the same type |
| // or TOP if the dominating projection is of opposite type. |
| // Data-target will be used as the new control edge for the non-CFG |
| // nodes like Casts and Loads. |
| Node *data_target = (ifp->Opcode() == prev_op ) ? prev_dom : top; |
| // Control-target is just the If's immediate dominator or TOP. |
| Node *ctrl_target = (ifp->Opcode() == prev_op ) ? idom : top; |
| |
| // For each child of an IfTrue/IfFalse projection, reroute. |
| // Loop ends when projection has no more uses. |
| for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) { |
| Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse |
| igvn->hash_delete(s); // Yank from hash table before edge hacking |
| if( !s->depends_only_on_test() ) { |
| // Find the control input matching this def-use edge. |
| // For Regions it may not be in slot 0. |
| uint l; |
| for( l = 0; s->in(l) != ifp; l++ ) { } |
| s->set_req(l, ctrl_target); |
| } else { // Else, for control producers, |
| s->set_req(0, data_target); // Move child to data-target |
| } |
| igvn->_worklist.push(s); // Revisit collapsed Phis |
| } // End for each child of a projection |
| |
| igvn->remove_dead_node(ifp); |
| } // End for each IfTrue/IfFalse child of If |
| |
| // Kill the IfNode |
| igvn->remove_dead_node(this); |
| } |
| |
| //------------------------------Identity--------------------------------------- |
| // If the test is constant & we match, then we are the input Control |
| Node *IfTrueNode::Identity( PhaseTransform *phase ) { |
| // Can only optimize if cannot go the other way |
| const TypeTuple *t = phase->type(in(0))->is_tuple(); |
| return ( t == TypeTuple::IFNEITHER || t == TypeTuple::IFTRUE ) |
| ? in(0)->in(0) // IfNode control |
| : this; // no progress |
| } |
| |
| //------------------------------dump_spec-------------------------------------- |
| #ifndef PRODUCT |
| void IfNode::dump_spec(outputStream *st) const { |
| st->print("P=%f, C=%f",_prob,_fcnt); |
| } |
| #endif |
| |
| //------------------------------idealize_test---------------------------------- |
| // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and |
| // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms |
| // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as |
| // needed. |
| static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) { |
| assert(iff->in(0) != NULL, "If must be live"); |
| |
| if (iff->outcnt() != 2) return NULL; // Malformed projections. |
| Node* old_if_f = iff->proj_out(false); |
| Node* old_if_t = iff->proj_out(true); |
| |
| // CountedLoopEnds want the back-control test to be TRUE, irregardless of |
| // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition |
| // happens in count-down loops |
| if (iff->is_CountedLoopEnd()) return NULL; |
| if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests |
| BoolNode *b = iff->in(1)->as_Bool(); |
| BoolTest bt = b->_test; |
| // Test already in good order? |
| if( bt.is_canonical() ) |
| return NULL; |
| |
| // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and |
| // cloning the IfNode. |
| Node* new_b = phase->transform( new (phase->C, 2) BoolNode(b->in(1), bt.negate()) ); |
| if( !new_b->is_Bool() ) return NULL; |
| b = new_b->as_Bool(); |
| |
| PhaseIterGVN *igvn = phase->is_IterGVN(); |
| assert( igvn, "Test is not canonical in parser?" ); |
| |
| // The IF node never really changes, but it needs to be cloned |
| iff = new (phase->C, 2) IfNode( iff->in(0), b, 1.0-iff->_prob, iff->_fcnt); |
| |
| Node *prior = igvn->hash_find_insert(iff); |
| if( prior ) { |
| igvn->remove_dead_node(iff); |
| iff = (IfNode*)prior; |
| } else { |
| // Cannot call transform on it just yet |
| igvn->set_type_bottom(iff); |
| } |
| igvn->_worklist.push(iff); |
| |
| // Now handle projections. Cloning not required. |
| Node* new_if_f = (Node*)(new (phase->C, 1) IfFalseNode( iff )); |
| Node* new_if_t = (Node*)(new (phase->C, 1) IfTrueNode ( iff )); |
| |
| igvn->register_new_node_with_optimizer(new_if_f); |
| igvn->register_new_node_with_optimizer(new_if_t); |
| igvn->hash_delete(old_if_f); |
| igvn->hash_delete(old_if_t); |
| // Flip test, so flip trailing control |
| igvn->subsume_node(old_if_f, new_if_t); |
| igvn->subsume_node(old_if_t, new_if_f); |
| |
| // Progress |
| return iff; |
| } |
| |
| //------------------------------Identity--------------------------------------- |
| // If the test is constant & we match, then we are the input Control |
| Node *IfFalseNode::Identity( PhaseTransform *phase ) { |
| // Can only optimize if cannot go the other way |
| const TypeTuple *t = phase->type(in(0))->is_tuple(); |
| return ( t == TypeTuple::IFNEITHER || t == TypeTuple::IFFALSE ) |
| ? in(0)->in(0) // IfNode control |
| : this; // no progress |
| } |
