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| 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.IsInteger32()) { |
| 45 ASSERT(change->to().IsTagged() || |
| 46 change->to().IsDouble() || |
| 47 change->to().IsSmi()); |
| 48 ASSERT(visited_.IsEmpty()); |
| 49 PropagateMinusZeroChecks(change->value()); |
| 50 visited_.Clear(); |
| 51 } |
| 52 } |
| 53 } |
| 54 } |
| 55 } |
| 56 |
| 57 |
| 58 void HComputeMinusZeroChecksPhase::PropagateMinusZeroChecks(HValue* value) { |
| 59 for (HValue* current = value; |
| 60 current != NULL && !visited_.Contains(current->id()); |
| 61 current = current->EnsureAndPropagateNotMinusZero(&visited_)) { |
| 62 // For phis, we must propagate the check to all of its inputs. |
| 63 if (current->IsPhi()) { |
| 64 visited_.Add(current->id()); |
| 65 HPhi* phi = HPhi::cast(current); |
| 66 for (int i = 0; i < phi->OperandCount(); ++i) { |
| 67 PropagateMinusZeroChecks(phi->OperandAt(i)); |
| 68 } |
| 69 break; |
| 70 } |
| 71 |
| 72 // For multiplication, division, and Math.min/max(), we must propagate |
| 73 // to the left and the right side. |
| 74 if (current->IsMul() || current->IsDiv() || current->IsMathMinMax()) { |
| 75 HBinaryOperation* operation = HBinaryOperation::cast(current); |
| 76 operation->EnsureAndPropagateNotMinusZero(&visited_); |
| 77 PropagateMinusZeroChecks(operation->left()); |
| 78 PropagateMinusZeroChecks(operation->right()); |
| 79 } |
| 80 } |
| 81 } |
| 82 |
| 83 } } // namespace v8::internal |
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