| // Copyright 2013 the V8 project authors. All rights reserved. |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #include "hydrogen-sce.h" |
| #include "v8.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| void HStackCheckEliminationPhase::Run() { |
| // For each loop block walk the dominator tree from the backwards branch to |
| // the loop header. If a call instruction is encountered the backwards branch |
| // is dominated by a call and the stack check in the backwards branch can be |
| // removed. |
| for (int i = 0; i < graph()->blocks()->length(); i++) { |
| HBasicBlock* block = graph()->blocks()->at(i); |
| if (block->IsLoopHeader()) { |
| HBasicBlock* back_edge = block->loop_information()->GetLastBackEdge(); |
| HBasicBlock* dominator = back_edge; |
| while (true) { |
| for (HInstructionIterator it(dominator); !it.Done(); it.Advance()) { |
| if (it.Current()->IsCall()) { |
| block->loop_information()->stack_check()->Eliminate(); |
| break; |
| } |
| } |
| |
| // Done when the loop header is processed. |
| if (dominator == block) break; |
| |
| // Move up the dominator tree. |
| dominator = dominator->dominator(); |
| } |
| } |
| } |
| } |
| |
| } } // namespace v8::internal |