1 // Copyright 2013 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #include "hydrogen-minus-zero.h" 29 30 namespace v8 { 31 namespace internal { 32 33 void HComputeMinusZeroChecksPhase::Run() { 34 const ZoneList<HBasicBlock*>* blocks(graph()->blocks()); 35 for (int i = 0; i < blocks->length(); ++i) { 36 for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) { 37 HInstruction* current = it.Current(); 38 if (current->IsChange()) { 39 HChange* change = HChange::cast(current); 40 // Propagate flags for negative zero checks upwards from conversions 41 // int32-to-tagged and int32-to-double. 42 Representation from = change->value()->representation(); 43 ASSERT(from.Equals(change->from())); 44 if (from.IsSmiOrInteger32()) { 45 ASSERT(change->to().IsTagged() || 46 change->to().IsDouble() || 47 change->to().IsSmiOrInteger32()); 48 ASSERT(visited_.IsEmpty()); 49 PropagateMinusZeroChecks(change->value()); 50 visited_.Clear(); 51 } 52 } else if (current->IsCompareMinusZeroAndBranch()) { 53 HCompareMinusZeroAndBranch* check = 54 HCompareMinusZeroAndBranch::cast(current); 55 if (check->value()->representation().IsSmiOrInteger32()) { 56 ASSERT(visited_.IsEmpty()); 57 PropagateMinusZeroChecks(check->value()); 58 visited_.Clear(); 59 } 60 } 61 } 62 } 63 } 64 65 66 void HComputeMinusZeroChecksPhase::PropagateMinusZeroChecks(HValue* value) { 67 for (HValue* current = value; 68 current != NULL && !visited_.Contains(current->id()); 69 current = current->EnsureAndPropagateNotMinusZero(&visited_)) { 70 // For phis, we must propagate the check to all of its inputs. 71 if (current->IsPhi()) { 72 visited_.Add(current->id()); 73 HPhi* phi = HPhi::cast(current); 74 for (int i = 0; i < phi->OperandCount(); ++i) { 75 PropagateMinusZeroChecks(phi->OperandAt(i)); 76 } 77 break; 78 } 79 80 // For multiplication, division, and Math.min/max(), we must propagate 81 // to the left and the right side. 82 if (current->IsMul() || current->IsDiv() || current->IsMathMinMax()) { 83 HBinaryOperation* operation = HBinaryOperation::cast(current); 84 operation->EnsureAndPropagateNotMinusZero(&visited_); 85 PropagateMinusZeroChecks(operation->left()); 86 PropagateMinusZeroChecks(operation->right()); 87 } 88 } 89 } 90 91 } } // namespace v8::internal 92
