1 /* 2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "opto/loopnode.hpp" 27 #include "opto/opaquenode.hpp" 28 #include "opto/phaseX.hpp" 29 30 //============================================================================= 31 // Do not allow value-numbering 32 uint Opaque1Node::hash() const { return NO_HASH; } 33 uint Opaque1Node::cmp(const Node &n) const { 34 return (&n == this); // Always fail except on self 35 } 36 37 //------------------------------Identity--------------------------------------- 38 // If _major_progress, then more loop optimizations follow. Do NOT remove 39 // the opaque Node until no more loop ops can happen. Note the timing of 40 // _major_progress; it's set in the major loop optimizations THEN comes the 41 // call to IterGVN and any chance of hitting this code. Hence there's no 42 // phase-ordering problem with stripping Opaque1 in IGVN followed by some 43 // more loop optimizations that require it. 44 Node *Opaque1Node::Identity(PhaseTransform *phase) { 45 return phase->C->major_progress() ? this : in(1); 46 } 47 48 Node *Opaque1Node::Ideal(PhaseGVN *phase, bool can_reshape) { 49 if (!phase->C->major_progress() && outcnt() > 0) { 50 assert(can_reshape, "loop opts over but not IGVN?"); 51 if (raw_out(0)->Opcode() == Op_CmpI) { 52 Node* cmp = raw_out(0); 53 if (cmp->in(1)->Opcode() == Op_AddI) { 54 Node *add = cmp->in(1); 55 if (add->in(1)->is_Phi()) { 56 Node* phi = add->in(1); 57 if (phi->in(0)->is_CountedLoop()) { 58 CountedLoopNode* cl = phi->in(0)->as_CountedLoop(); 59 if (cl->phi() == phi) { 60 // If this opaque node feeds into the limit condition of 61 // a CountedLoop, we need to process the Phi node for 62 // the induction variable: the range of values taken by 63 // the Phi is known now and so its type is also known. 64 phase->is_IterGVN()->_worklist.push(phi); 65 } 66 } 67 } 68 } 69 Node* in1 = cmp->in(1); 70 for (uint i = 0; i < in1->outcnt(); i++) { 71 if (in1->raw_out(i)->Opcode() == Op_CastII) { 72 Node* castii = in1->raw_out(i); 73 if (castii->in(0) != NULL && castii->in(0)->in(0) != NULL && castii->in(0)->in(0)->is_If()) { 74 Node* ifnode = castii->in(0)->in(0); 75 if (ifnode->in(1) != NULL && ifnode->in(1)->in(1) == cmp) { 76 // Reprocess a CastII node that may depend on this 77 // opaque node value in case it's inexact and we can do 78 // a better job of setting its type. 79 phase->is_IterGVN()->_worklist.push(castii); 80 } 81 } 82 } 83 } 84 } 85 } 86 return NULL; 87 } 88 89 //============================================================================= 90 // A node to prevent unwanted optimizations. Allows constant folding. Stops 91 // value-numbering, most Ideal calls or Identity functions. This Node is 92 // specifically designed to prevent the pre-increment value of a loop trip 93 // counter from being live out of the bottom of the loop (hence causing the 94 // pre- and post-increment values both being live and thus requiring an extra 95 // temp register and an extra move). If we "accidentally" optimize through 96 // this kind of a Node, we'll get slightly pessimal, but correct, code. Thus 97 // it's OK to be slightly sloppy on optimizations here. 98 99 // Do not allow value-numbering 100 uint Opaque2Node::hash() const { return NO_HASH; } 101 uint Opaque2Node::cmp( const Node &n ) const { 102 return (&n == this); // Always fail except on self 103 } 104 105