| /* |
| * Copyright (C) 2017 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. 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. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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 "config.h" |
| #include "B3HoistLoopInvariantValues.h" |
| |
| #if ENABLE(B3_JIT) |
| |
| #include "B3BackwardsDominators.h" |
| #include "B3BasicBlockInlines.h" |
| #include "B3Dominators.h" |
| #include "B3EnsureLoopPreHeaders.h" |
| #include "B3NaturalLoops.h" |
| #include "B3PhaseScope.h" |
| #include "B3ProcedureInlines.h" |
| #include "B3ValueInlines.h" |
| #include <wtf/RangeSet.h> |
| |
| namespace JSC { namespace B3 { |
| |
| bool hoistLoopInvariantValues(Procedure& proc) |
| { |
| PhaseScope phaseScope(proc, "hoistLoopInvariantValues"); |
| |
| ensureLoopPreHeaders(proc); |
| |
| NaturalLoops& loops = proc.naturalLoops(); |
| if (!loops.numLoops()) |
| return false; |
| |
| proc.resetValueOwners(); |
| Dominators& dominators = proc.dominators(); |
| BackwardsDominators& backwardsDominators = proc.backwardsDominators(); |
| |
| // FIXME: We should have a reusable B3::EffectsSet data structure. |
| // https://bugs.webkit.org/show_bug.cgi?id=174762 |
| struct LoopData { |
| RangeSet<HeapRange> writes; |
| bool writesLocalState { false }; |
| bool writesPinned { false }; |
| bool sideExits { false }; |
| BasicBlock* preHeader { nullptr }; |
| }; |
| |
| IndexMap<NaturalLoop, LoopData> data(loops.numLoops()); |
| |
| for (unsigned loopIndex = loops.numLoops(); loopIndex--;) { |
| const NaturalLoop& loop = loops.loop(loopIndex); |
| for (BasicBlock* predecessor : loop.header()->predecessors()) { |
| if (loops.belongsTo(predecessor, loop)) |
| continue; |
| RELEASE_ASSERT(!data[loop].preHeader); |
| data[loop].preHeader = predecessor; |
| } |
| } |
| |
| for (BasicBlock* block : proc) { |
| const NaturalLoop* loop = loops.innerMostLoopOf(block); |
| if (!loop) |
| continue; |
| for (Value* value : *block) { |
| Effects effects = value->effects(); |
| data[*loop].writes.add(effects.writes); |
| data[*loop].writesLocalState |= effects.writesLocalState; |
| data[*loop].writesPinned |= effects.writesPinned; |
| data[*loop].sideExits |= effects.exitsSideways; |
| } |
| } |
| |
| for (unsigned loopIndex = loops.numLoops(); loopIndex--;) { |
| const NaturalLoop& loop = loops.loop(loopIndex); |
| for (const NaturalLoop* current = loops.innerMostOuterLoop(loop); current; current = loops.innerMostOuterLoop(*current)) { |
| data[*current].writes.addAll(data[loop].writes); |
| data[*current].writesLocalState |= data[loop].writesLocalState; |
| data[*current].writesPinned |= data[loop].writesPinned; |
| data[*current].sideExits |= data[loop].sideExits; |
| } |
| } |
| |
| bool changed = false; |
| |
| // Pre-order ensures that we visit our dominators before we visit ourselves. Otherwise we'd miss some |
| // hoisting opportunities in complex CFGs. |
| for (BasicBlock* block : proc.blocksInPreOrder()) { |
| Vector<const NaturalLoop*> blockLoops = loops.loopsOf(block); |
| if (blockLoops.isEmpty()) |
| continue; |
| |
| for (Value*& value : *block) { |
| Effects effects = value->effects(); |
| |
| // We never hoist write effects or control constructs. |
| if (effects.mustExecute()) |
| continue; |
| |
| // Try outermost loop first. |
| for (unsigned i = blockLoops.size(); i--;) { |
| const NaturalLoop& loop = *blockLoops[i]; |
| |
| bool ok = true; |
| for (Value* child : value->children()) { |
| if (!dominators.dominates(child->owner, data[loop].preHeader)) { |
| ok = false; |
| break; |
| } |
| } |
| if (!ok) |
| continue; |
| |
| if (effects.controlDependent) { |
| if (!backwardsDominators.dominates(block, data[loop].preHeader)) |
| continue; |
| |
| // FIXME: This is super conservative. In reality, we just need to make sure that there |
| // aren't any side exits between here and the pre-header according to backwards search. |
| // https://bugs.webkit.org/show_bug.cgi?id=174763 |
| if (data[loop].sideExits) |
| continue; |
| } |
| |
| if (effects.readsPinned && data[loop].writesPinned) |
| continue; |
| |
| if (effects.readsLocalState && data[loop].writesLocalState) |
| continue; |
| |
| if (data[loop].writes.overlaps(effects.reads)) |
| continue; |
| |
| data[loop].preHeader->appendNonTerminal(value); |
| value = proc.add<Value>(Nop, Void, value->origin()); |
| changed = true; |
| } |
| } |
| } |
| |
| return changed; |
| } |
| |
| } } // namespace JSC::B3 |
| |
| #endif // ENABLE(B3_JIT) |
| |