--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/opto/ifnode.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,922 @@
+/*
+ * 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
+}