| /* |
| * Copyright 2016 WebAssembly Community Group participants |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "Relooper.h" |
| |
| #include <string.h> |
| #include <stdlib.h> |
| |
| #include <list> |
| #include <stack> |
| #include <string> |
| |
| #include "ast_utils.h" |
| #include "parsing.h" |
| |
| namespace CFG { |
| |
| template <class T, class U> static bool contains(const T& container, const U& contained) { |
| return !!container.count(contained); |
| } |
| |
| #ifdef RELOOPER_DEBUG |
| static void PrintDebug(const char *Format, ...); |
| #define DebugDump(x, ...) Debugging::Dump(x, __VA_ARGS__) |
| #else |
| #define PrintDebug(x, ...) |
| #define DebugDump(x, ...) |
| #endif |
| |
| // Rendering utilities |
| |
| static wasm::Expression* HandleFollowupMultiples(wasm::Expression* Ret, Shape* Parent, RelooperBuilder& Builder, bool InLoop) { |
| if (!Parent->Next) return Ret; |
| |
| auto* Curr = Ret->dynCast<wasm::Block>(); |
| if (!Curr || Curr->name.is()) { |
| Curr = Builder.makeBlock(Ret); |
| } |
| // for each multiple after us, we create a block target for breaks to reach |
| while (Parent->Next) { |
| auto* Multiple = Shape::IsMultiple(Parent->Next); |
| if (!Multiple) break; |
| for (auto& iter : Multiple->InnerMap) { |
| int Id = iter.first; |
| Shape* Body = iter.second; |
| Curr->name = Builder.getBlockBreakName(Id); |
| auto* Outer = Builder.makeBlock(Curr); |
| Outer->list.push_back(Body->Render(Builder, InLoop)); |
| Outer->finalize(); // TODO: not really necessary |
| Curr = Outer; |
| } |
| Parent->Next = Parent->Next->Next; |
| } |
| // after the multiples is a simple or a loop, in both cases we must hit an entry |
| // block, and so this is the last one we need to take into account now (this |
| // is why we require that loops hit an entry). |
| if (Parent->Next) { |
| auto* Simple = Shape::IsSimple(Parent->Next); |
| if (Simple) { |
| // breaking on the next block's id takes us out, where we |
| // will reach its rendering |
| Curr->name = Builder.getBlockBreakName(Simple->Inner->Id); |
| } else { |
| // add one break target per entry for the loop |
| auto* Loop = Shape::IsLoop(Parent->Next); |
| assert(Loop); |
| assert(Loop->Entries.size() > 0); |
| if (Loop->Entries.size() == 1) { |
| Curr->name = Builder.getBlockBreakName((*Loop->Entries.begin())->Id); |
| } else { |
| for (auto* Entry : Loop->Entries) { |
| Curr->name = Builder.getBlockBreakName(Entry->Id); |
| auto* Outer = Builder.makeBlock(Curr); |
| Outer->finalize(); // TODO: not really necessary |
| Curr = Outer; |
| } |
| } |
| } |
| } |
| Curr->finalize(); |
| return Curr; |
| } |
| |
| // Branch |
| |
| Branch::Branch(wasm::Expression* ConditionInit, wasm::Expression* CodeInit) : Ancestor(nullptr), Condition(ConditionInit), Code(CodeInit) {} |
| |
| Branch::Branch(std::vector<wasm::Index>&& ValuesInit, wasm::Expression* CodeInit) : Ancestor(nullptr), Code(CodeInit) { |
| if (ValuesInit.size() > 0) { |
| SwitchValues = wasm::make_unique<std::vector<wasm::Index>>(ValuesInit); |
| } |
| // otherwise, it is the default |
| } |
| |
| wasm::Expression* Branch::Render(RelooperBuilder& Builder, Block *Target, bool SetLabel) { |
| auto* Ret = Builder.makeBlock(); |
| if (Code) Ret->list.push_back(Code); |
| if (SetLabel) Ret->list.push_back(Builder.makeSetLabel(Target->Id)); |
| if (Type == Break) { |
| Ret->list.push_back(Builder.makeBlockBreak(Target->Id)); |
| } else if (Type == Continue) { |
| assert(Ancestor); |
| Ret->list.push_back(Builder.makeShapeContinue(Ancestor->Id)); |
| } |
| Ret->finalize(); |
| return Ret; |
| } |
| |
| // Block |
| |
| Block::Block(wasm::Expression* CodeInit, wasm::Expression* SwitchConditionInit) : Parent(nullptr), Id(-1), Code(CodeInit), SwitchCondition(SwitchConditionInit), IsCheckedMultipleEntry(false) {} |
| |
| Block::~Block() { |
| for (BlockBranchMap::iterator iter = ProcessedBranchesOut.begin(); iter != ProcessedBranchesOut.end(); iter++) { |
| delete iter->second; |
| } |
| for (BlockBranchMap::iterator iter = BranchesOut.begin(); iter != BranchesOut.end(); iter++) { |
| delete iter->second; |
| } |
| } |
| |
| void Block::AddBranchTo(Block *Target, wasm::Expression* Condition, wasm::Expression* Code) { |
| assert(!contains(BranchesOut, Target)); // cannot add more than one branch to the same target |
| BranchesOut[Target] = new Branch(Condition, Code); |
| } |
| |
| void Block::AddSwitchBranchTo(Block *Target, std::vector<wasm::Index>&& Values, wasm::Expression* Code) { |
| assert(!contains(BranchesOut, Target)); // cannot add more than one branch to the same target |
| BranchesOut[Target] = new Branch(std::move(Values), Code); |
| } |
| |
| wasm::Expression* Block::Render(RelooperBuilder& Builder, bool InLoop) { |
| auto* Ret = Builder.makeBlock(); |
| if (IsCheckedMultipleEntry && InLoop) { |
| Ret->list.push_back(Builder.makeSetLabel(0)); |
| } |
| if (Code) Ret->list.push_back(Code); |
| |
| if (!ProcessedBranchesOut.size()) { |
| Ret->finalize(); |
| return Ret; |
| } |
| |
| bool SetLabel = true; // in some cases it is clear we can avoid setting label, see later |
| |
| // A setting of the label variable (label = x) is necessary if it can |
| // cause an impact. The main case is where we set label to x, then elsewhere |
| // we check if label is equal to that value, i.e., that label is an entry |
| // in a multiple block. We also need to reset the label when we enter |
| // that block, so that each setting is a one-time action: consider |
| // |
| // while (1) { |
| // if (check) label = 1; |
| // if (label == 1) { label = 0 } |
| // } |
| // |
| // (Note that this case is impossible due to fusing, but that is not |
| // material here.) So setting to 0 is important just to clear the 1 for |
| // future iterations. |
| // TODO: When inside a loop, if necessary clear the label variable |
| // once on the top, and never do settings that are in effect clears |
| |
| // Fusing: If the next is a Multiple, we can fuse it with this block. Note |
| // that we must be the Inner of a Simple, so fusing means joining a Simple |
| // to a Multiple. What happens there is that all options in the Multiple |
| // *must* appear in the Simple (the Simple is the only one reaching the |
| // Multiple), so we can remove the Multiple and add its independent groups |
| // into the Simple's branches. |
| MultipleShape *Fused = Shape::IsMultiple(Parent->Next); |
| if (Fused) { |
| PrintDebug("Fusing Multiple to Simple\n", 0); |
| Parent->Next = Parent->Next->Next; |
| // When the Multiple has the same number of groups as we have branches, |
| // they will all be fused, so it is safe to not set the label at all. |
| // If a switch, then we can have multiple branches to the same target |
| // (in different table indexes), and so this check is not sufficient TODO: optimize |
| if (SetLabel && Fused->InnerMap.size() == ProcessedBranchesOut.size() && !SwitchCondition) { |
| SetLabel = false; |
| } |
| } |
| |
| Block *DefaultTarget = nullptr; // The block we branch to without checking the condition, if none of the other conditions held. |
| |
| // Find the default target, the one without a condition |
| for (BlockBranchMap::iterator iter = ProcessedBranchesOut.begin(); iter != ProcessedBranchesOut.end(); iter++) { |
| if ((!SwitchCondition && !iter->second->Condition) || (SwitchCondition && !iter->second->SwitchValues)) { |
| assert(!DefaultTarget && "block has branches without a default (nullptr for the condition)"); // Must be exactly one default // nullptr |
| DefaultTarget = iter->first; |
| } |
| } |
| assert(DefaultTarget); // Since each block *must* branch somewhere, this must be set |
| |
| wasm::Expression* Root = nullptr; // root of the main part, that we are about to emit |
| |
| if (!SwitchCondition) { |
| // We'll emit a chain of if-elses |
| wasm::If* CurrIf = nullptr; |
| |
| wasm::Expression* RemainingConditions = nullptr; |
| |
| for (BlockBranchMap::iterator iter = ProcessedBranchesOut.begin();; iter++) { |
| Block *Target; |
| Branch *Details; |
| if (iter != ProcessedBranchesOut.end()) { |
| Target = iter->first; |
| if (Target == DefaultTarget) continue; // done at the end |
| Details = iter->second; |
| assert(Details->Condition); // must have a condition if this is not the default target |
| } else { |
| Target = DefaultTarget; |
| Details = ProcessedBranchesOut[DefaultTarget]; |
| } |
| bool SetCurrLabel = SetLabel && Target->IsCheckedMultipleEntry; |
| bool HasFusedContent = Fused && contains(Fused->InnerMap, Target->Id); |
| if (HasFusedContent) { |
| assert(Details->Type == Branch::Break); |
| Details->Type = Branch::Direct; |
| } |
| wasm::Expression* CurrContent = nullptr; |
| bool IsDefault = iter == ProcessedBranchesOut.end(); |
| if (SetCurrLabel || Details->Type != Branch::Direct || HasFusedContent || Details->Code) { |
| CurrContent = Details->Render(Builder, Target, SetCurrLabel); |
| if (HasFusedContent) { |
| CurrContent = Builder.blockify(CurrContent, Fused->InnerMap.find(Target->Id)->second->Render(Builder, InLoop)); |
| } |
| } |
| // If there is nothing to show in this branch, omit the condition |
| if (CurrContent) { |
| if (IsDefault) { |
| wasm::Expression* Now; |
| if (RemainingConditions) { |
| Now = Builder.makeIf(RemainingConditions, CurrContent); |
| } else { |
| Now = CurrContent; |
| } |
| if (!CurrIf) { |
| assert(!Root); |
| Root = Now; |
| } else { |
| CurrIf->ifFalse = Now; |
| } |
| } else { |
| auto* Now = Builder.makeIf(Details->Condition, CurrContent); |
| if (!CurrIf) { |
| assert(!Root); |
| Root = CurrIf = Now; |
| } else { |
| CurrIf->ifFalse = Now; |
| CurrIf = Now; |
| } |
| } |
| } else { |
| auto* Now = Builder.makeUnary(wasm::EqZInt32, Details->Condition); |
| if (RemainingConditions) { |
| RemainingConditions = Builder.makeBinary(wasm::AndInt32, RemainingConditions, Now); |
| } else { |
| RemainingConditions = Now; |
| } |
| } |
| if (IsDefault) break; |
| } |
| } else { |
| // Emit a switch |
| auto Base = std::string("switch$") + std::to_string(Id); |
| auto SwitchDefault = wasm::Name(Base + "$default"); |
| auto SwitchLeave = wasm::Name(Base + "$leave"); |
| std::map<Block*, wasm::Name> BlockNameMap; |
| auto* Outer = Builder.makeBlock(); |
| auto* Inner = Outer; |
| std::vector<wasm::Name> Table; |
| for (auto& iter : ProcessedBranchesOut) { |
| Block *Target = iter.first; |
| Branch *Details = iter.second; |
| wasm::Name CurrName; |
| if (Details->SwitchValues) { |
| CurrName = wasm::Name(Base + "$case$" + std::to_string(Target->Id)); |
| } else { |
| CurrName = SwitchDefault; |
| } |
| // generate the content for this block |
| bool SetCurrLabel = SetLabel && Target->IsCheckedMultipleEntry; |
| bool HasFusedContent = Fused && contains(Fused->InnerMap, Target->Id); |
| if (HasFusedContent) { |
| assert(Details->Type == Branch::Break); |
| Details->Type = Branch::Direct; |
| } |
| wasm::Expression* CurrContent = nullptr; |
| if (SetCurrLabel || Details->Type != Branch::Direct || HasFusedContent || Details->Code) { |
| CurrContent = Details->Render(Builder, Target, SetCurrLabel); |
| if (HasFusedContent) { |
| CurrContent = Builder.blockify(CurrContent, Fused->InnerMap.find(Target->Id)->second->Render(Builder, InLoop)); |
| } |
| } |
| // generate a block to branch to, if we have content |
| if (CurrContent) { |
| auto* NextOuter = Builder.makeBlock(); |
| NextOuter->list.push_back(Outer); |
| Outer->name = CurrName; // breaking on Outer leads to the content in NextOuter |
| NextOuter->list.push_back(CurrContent); |
| NextOuter->list.push_back(Builder.makeBreak(SwitchLeave)); |
| // prepare for more nesting |
| Outer = NextOuter; |
| } else { |
| CurrName = SwitchLeave; // just go out straight from the table |
| if (!Details->SwitchValues) { |
| // this is the default, and it has no content. So make the default be the leave |
| for (auto& Value : Table) { |
| if (Value == SwitchDefault) Value = SwitchLeave; |
| } |
| SwitchDefault = SwitchLeave; |
| } |
| } |
| if (Details->SwitchValues) { |
| for (auto Value : *Details->SwitchValues) { |
| while (Table.size() <= Value) Table.push_back(SwitchDefault); |
| Table[Value] = CurrName; |
| } |
| } |
| } |
| // finish up the whole pattern |
| Outer->name = SwitchLeave; |
| Inner->list.push_back(Builder.makeSwitch(Table, SwitchDefault, SwitchCondition)); |
| Root = Outer; |
| } |
| |
| if (Root) { |
| Ret->list.push_back(Root); |
| } |
| Ret->finalize(); |
| |
| return Ret; |
| } |
| |
| // SimpleShape |
| |
| wasm::Expression* SimpleShape::Render(RelooperBuilder& Builder, bool InLoop) { |
| auto* Ret = Inner->Render(Builder, InLoop); |
| Ret = HandleFollowupMultiples(Ret, this, Builder, InLoop); |
| if (Next) { |
| Ret = Builder.makeSequence(Ret, Next->Render(Builder, InLoop)); |
| } |
| return Ret; |
| } |
| |
| |
| // MultipleShape |
| |
| wasm::Expression* MultipleShape::Render(RelooperBuilder& Builder, bool InLoop) { |
| // TODO: consider switch |
| // emit an if-else chain |
| wasm::If *FirstIf = nullptr, *CurrIf = nullptr; |
| for (IdShapeMap::iterator iter = InnerMap.begin(); iter != InnerMap.end(); iter++) { |
| auto* Now = Builder.makeIf( |
| Builder.makeCheckLabel(iter->first), |
| iter->second->Render(Builder, InLoop) |
| ); |
| if (!CurrIf) { |
| FirstIf = CurrIf = Now; |
| } else { |
| CurrIf->ifFalse = Now; |
| CurrIf = Now; |
| } |
| } |
| wasm::Expression* Ret = Builder.makeBlock(FirstIf); |
| Ret = HandleFollowupMultiples(Ret, this, Builder, InLoop); |
| if (Next) { |
| Ret = Builder.makeSequence(Ret, Next->Render(Builder, InLoop)); |
| } |
| return Ret; |
| } |
| |
| // LoopShape |
| |
| wasm::Expression* LoopShape::Render(RelooperBuilder& Builder, bool InLoop) { |
| wasm::Expression* Ret = Builder.makeLoop(Builder.getShapeContinueName(Id), Inner->Render(Builder, true)); |
| Ret = HandleFollowupMultiples(Ret, this, Builder, InLoop); |
| if (Next) { |
| Ret = Builder.makeSequence(Ret, Next->Render(Builder, InLoop)); |
| } |
| return Ret; |
| } |
| |
| // Relooper |
| |
| Relooper::Relooper() : Root(nullptr), MinSize(false), BlockIdCounter(1), ShapeIdCounter(0) { // block ID 0 is reserved for clearings |
| } |
| |
| Relooper::~Relooper() { |
| for (unsigned i = 0; i < Blocks.size(); i++) delete Blocks[i]; |
| for (unsigned i = 0; i < Shapes.size(); i++) delete Shapes[i]; |
| } |
| |
| void Relooper::AddBlock(Block *New, int Id) { |
| New->Id = Id == -1 ? BlockIdCounter++ : Id; |
| Blocks.push_back(New); |
| } |
| |
| struct RelooperRecursor { |
| Relooper *Parent; |
| RelooperRecursor(Relooper *ParentInit) : Parent(ParentInit) {} |
| }; |
| |
| typedef std::list<Block*> BlockList; |
| |
| void Relooper::Calculate(Block *Entry) { |
| // Scan and optimize the input |
| struct PreOptimizer : public RelooperRecursor { |
| PreOptimizer(Relooper *Parent) : RelooperRecursor(Parent) {} |
| BlockSet Live; |
| |
| void FindLive(Block *Root) { |
| BlockList ToInvestigate; |
| ToInvestigate.push_back(Root); |
| while (ToInvestigate.size() > 0) { |
| Block *Curr = ToInvestigate.front(); |
| ToInvestigate.pop_front(); |
| if (contains(Live, Curr)) continue; |
| Live.insert(Curr); |
| for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) { |
| ToInvestigate.push_back(iter->first); |
| } |
| } |
| } |
| }; |
| PreOptimizer Pre(this); |
| Pre.FindLive(Entry); |
| |
| // Add incoming branches from live blocks, ignoring dead code |
| for (unsigned i = 0; i < Blocks.size(); i++) { |
| Block *Curr = Blocks[i]; |
| if (!contains(Pre.Live, Curr)) continue; |
| for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) { |
| iter->first->BranchesIn.insert(Curr); |
| } |
| } |
| |
| // Recursively process the graph |
| |
| struct Analyzer : public RelooperRecursor { |
| Analyzer(Relooper *Parent) : RelooperRecursor(Parent) {} |
| |
| // Add a shape to the list of shapes in this Relooper calculation |
| void Notice(Shape *New) { |
| New->Id = Parent->ShapeIdCounter++; |
| Parent->Shapes.push_back(New); |
| } |
| |
| // Create a list of entries from a block. If LimitTo is provided, only results in that set |
| // will appear |
| void GetBlocksOut(Block *Source, BlockSet& Entries, BlockSet *LimitTo = nullptr) { |
| for (BlockBranchMap::iterator iter = Source->BranchesOut.begin(); iter != Source->BranchesOut.end(); iter++) { |
| if (!LimitTo || contains(*LimitTo, iter->first)) { |
| Entries.insert(iter->first); |
| } |
| } |
| } |
| |
| // Converts/processes all branchings to a specific target |
| void Solipsize(Block *Target, Branch::FlowType Type, Shape *Ancestor, BlockSet &From) { |
| PrintDebug("Solipsizing branches into %d\n", Target->Id); |
| DebugDump(From, " relevant to solipsize: "); |
| for (BlockSet::iterator iter = Target->BranchesIn.begin(); iter != Target->BranchesIn.end();) { |
| Block *Prior = *iter; |
| if (!contains(From, Prior)) { |
| iter++; |
| continue; |
| } |
| Branch *PriorOut = Prior->BranchesOut[Target]; |
| PriorOut->Ancestor = Ancestor; |
| PriorOut->Type = Type; |
| iter++; // carefully increment iter before erasing |
| Target->BranchesIn.erase(Prior); |
| Target->ProcessedBranchesIn.insert(Prior); |
| Prior->BranchesOut.erase(Target); |
| Prior->ProcessedBranchesOut[Target] = PriorOut; |
| PrintDebug(" eliminated branch from %d\n", Prior->Id); |
| } |
| } |
| |
| Shape *MakeSimple(BlockSet &Blocks, Block *Inner, BlockSet &NextEntries) { |
| PrintDebug("creating simple block with block #%d\n", Inner->Id); |
| SimpleShape *Simple = new SimpleShape; |
| Notice(Simple); |
| Simple->Inner = Inner; |
| Inner->Parent = Simple; |
| if (Blocks.size() > 1) { |
| Blocks.erase(Inner); |
| GetBlocksOut(Inner, NextEntries, &Blocks); |
| BlockSet JustInner; |
| JustInner.insert(Inner); |
| for (BlockSet::iterator iter = NextEntries.begin(); iter != NextEntries.end(); iter++) { |
| Solipsize(*iter, Branch::Break, Simple, JustInner); |
| } |
| } |
| return Simple; |
| } |
| |
| Shape *MakeLoop(BlockSet &Blocks, BlockSet& Entries, BlockSet &NextEntries) { |
| // Find the inner blocks in this loop. Proceed backwards from the entries until |
| // you reach a seen block, collecting as you go. |
| BlockSet InnerBlocks; |
| BlockSet Queue = Entries; |
| while (Queue.size() > 0) { |
| Block *Curr = *(Queue.begin()); |
| Queue.erase(Queue.begin()); |
| if (!contains(InnerBlocks, Curr)) { |
| // This element is new, mark it as inner and remove from outer |
| InnerBlocks.insert(Curr); |
| Blocks.erase(Curr); |
| // Add the elements prior to it |
| for (BlockSet::iterator iter = Curr->BranchesIn.begin(); iter != Curr->BranchesIn.end(); iter++) { |
| Queue.insert(*iter); |
| } |
| #if 0 |
| // Add elements it leads to, if they are dead ends. There is no reason not to hoist dead ends |
| // into loops, as it can avoid multiple entries after the loop |
| for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) { |
| Block *Target = iter->first; |
| if (Target->BranchesIn.size() <= 1 && Target->BranchesOut.size() == 0) { |
| Queue.insert(Target); |
| } |
| } |
| #endif |
| } |
| } |
| assert(InnerBlocks.size() > 0); |
| |
| for (BlockSet::iterator iter = InnerBlocks.begin(); iter != InnerBlocks.end(); iter++) { |
| Block *Curr = *iter; |
| for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) { |
| Block *Possible = iter->first; |
| if (!contains(InnerBlocks, Possible)) { |
| NextEntries.insert(Possible); |
| } |
| } |
| } |
| |
| #if 0 |
| // We can avoid multiple next entries by hoisting them into the loop. |
| if (NextEntries.size() > 1) { |
| BlockBlockSetMap IndependentGroups; |
| FindIndependentGroups(NextEntries, IndependentGroups, &InnerBlocks); |
| |
| while (IndependentGroups.size() > 0 && NextEntries.size() > 1) { |
| Block *Min = nullptr; |
| int MinSize = 0; |
| for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end(); iter++) { |
| Block *Entry = iter->first; |
| BlockSet &Blocks = iter->second; |
| if (!Min || Blocks.size() < MinSize) { // TODO: code size, not # of blocks |
| Min = Entry; |
| MinSize = Blocks.size(); |
| } |
| } |
| // check how many new entries this would cause |
| BlockSet &Hoisted = IndependentGroups[Min]; |
| bool abort = false; |
| for (BlockSet::iterator iter = Hoisted.begin(); iter != Hoisted.end() && !abort; iter++) { |
| Block *Curr = *iter; |
| for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) { |
| Block *Target = iter->first; |
| if (!contains(Hoisted, Target) && !contains(NextEntries, Target)) { |
| // abort this hoisting |
| abort = true; |
| break; |
| } |
| } |
| } |
| if (abort) { |
| IndependentGroups.erase(Min); |
| continue; |
| } |
| // hoist this entry |
| PrintDebug("hoisting %d into loop\n", Min->Id); |
| NextEntries.erase(Min); |
| for (BlockSet::iterator iter = Hoisted.begin(); iter != Hoisted.end(); iter++) { |
| Block *Curr = *iter; |
| InnerBlocks.insert(Curr); |
| Blocks.erase(Curr); |
| } |
| IndependentGroups.erase(Min); |
| } |
| } |
| #endif |
| |
| PrintDebug("creating loop block:\n", 0); |
| DebugDump(InnerBlocks, " inner blocks:"); |
| DebugDump(Entries, " inner entries:"); |
| DebugDump(Blocks, " outer blocks:"); |
| DebugDump(NextEntries, " outer entries:"); |
| |
| LoopShape *Loop = new LoopShape(); |
| Notice(Loop); |
| |
| // Solipsize the loop, replacing with break/continue and marking branches as Processed (will not affect later calculations) |
| // A. Branches to the loop entries become a continue to this shape |
| for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) { |
| Solipsize(*iter, Branch::Continue, Loop, InnerBlocks); |
| } |
| // B. Branches to outside the loop (a next entry) become breaks on this shape |
| for (BlockSet::iterator iter = NextEntries.begin(); iter != NextEntries.end(); iter++) { |
| Solipsize(*iter, Branch::Break, Loop, InnerBlocks); |
| } |
| // Finish up |
| Shape *Inner = Process(InnerBlocks, Entries); |
| Loop->Inner = Inner; |
| Loop->Entries = Entries; |
| return Loop; |
| } |
| |
| // For each entry, find the independent group reachable by it. The independent group is |
| // the entry itself, plus all the blocks it can reach that cannot be directly reached by another entry. Note that we |
| // ignore directly reaching the entry itself by another entry. |
| // @param Ignore - previous blocks that are irrelevant |
| void FindIndependentGroups(BlockSet &Entries, BlockBlockSetMap& IndependentGroups, BlockSet *Ignore = nullptr) { |
| typedef std::map<Block*, Block*> BlockBlockMap; |
| |
| struct HelperClass { |
| BlockBlockSetMap& IndependentGroups; |
| BlockBlockMap Ownership; // For each block, which entry it belongs to. We have reached it from there. |
| |
| HelperClass(BlockBlockSetMap& IndependentGroupsInit) : IndependentGroups(IndependentGroupsInit) {} |
| void InvalidateWithChildren(Block *New) { // TODO: rename New |
| BlockList ToInvalidate; // Being in the list means you need to be invalidated |
| ToInvalidate.push_back(New); |
| while (ToInvalidate.size() > 0) { |
| Block *Invalidatee = ToInvalidate.front(); |
| ToInvalidate.pop_front(); |
| Block *Owner = Ownership[Invalidatee]; |
| if (contains(IndependentGroups, Owner)) { // Owner may have been invalidated, do not add to IndependentGroups! |
| IndependentGroups[Owner].erase(Invalidatee); |
| } |
| if (Ownership[Invalidatee]) { // may have been seen before and invalidated already |
| Ownership[Invalidatee] = nullptr; |
| for (BlockBranchMap::iterator iter = Invalidatee->BranchesOut.begin(); iter != Invalidatee->BranchesOut.end(); iter++) { |
| Block *Target = iter->first; |
| BlockBlockMap::iterator Known = Ownership.find(Target); |
| if (Known != Ownership.end()) { |
| Block *TargetOwner = Known->second; |
| if (TargetOwner) { |
| ToInvalidate.push_back(Target); |
| } |
| } |
| } |
| } |
| } |
| } |
| }; |
| HelperClass Helper(IndependentGroups); |
| |
| // We flow out from each of the entries, simultaneously. |
| // When we reach a new block, we add it as belonging to the one we got to it from. |
| // If we reach a new block that is already marked as belonging to someone, it is reachable by |
| // two entries and is not valid for any of them. Remove it and all it can reach that have been |
| // visited. |
| |
| BlockList Queue; // Being in the queue means we just added this item, and we need to add its children |
| for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) { |
| Block *Entry = *iter; |
| Helper.Ownership[Entry] = Entry; |
| IndependentGroups[Entry].insert(Entry); |
| Queue.push_back(Entry); |
| } |
| while (Queue.size() > 0) { |
| Block *Curr = Queue.front(); |
| Queue.pop_front(); |
| Block *Owner = Helper.Ownership[Curr]; // Curr must be in the ownership map if we are in the queue |
| if (!Owner) continue; // we have been invalidated meanwhile after being reached from two entries |
| // Add all children |
| for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) { |
| Block *New = iter->first; |
| BlockBlockMap::iterator Known = Helper.Ownership.find(New); |
| if (Known == Helper.Ownership.end()) { |
| // New node. Add it, and put it in the queue |
| Helper.Ownership[New] = Owner; |
| IndependentGroups[Owner].insert(New); |
| Queue.push_back(New); |
| continue; |
| } |
| Block *NewOwner = Known->second; |
| if (!NewOwner) continue; // We reached an invalidated node |
| if (NewOwner != Owner) { |
| // Invalidate this and all reachable that we have seen - we reached this from two locations |
| Helper.InvalidateWithChildren(New); |
| } |
| // otherwise, we have the same owner, so do nothing |
| } |
| } |
| |
| // Having processed all the interesting blocks, we remain with just one potential issue: |
| // If a->b, and a was invalidated, but then b was later reached by someone else, we must |
| // invalidate b. To check for this, we go over all elements in the independent groups, |
| // if an element has a parent which does *not* have the same owner, we must remove it |
| // and all its children. |
| |
| for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) { |
| BlockSet &CurrGroup = IndependentGroups[*iter]; |
| BlockList ToInvalidate; |
| for (BlockSet::iterator iter = CurrGroup.begin(); iter != CurrGroup.end(); iter++) { |
| Block *Child = *iter; |
| for (BlockSet::iterator iter = Child->BranchesIn.begin(); iter != Child->BranchesIn.end(); iter++) { |
| Block *Parent = *iter; |
| if (Ignore && contains(*Ignore, Parent)) continue; |
| if (Helper.Ownership[Parent] != Helper.Ownership[Child]) { |
| ToInvalidate.push_back(Child); |
| } |
| } |
| } |
| while (ToInvalidate.size() > 0) { |
| Block *Invalidatee = ToInvalidate.front(); |
| ToInvalidate.pop_front(); |
| Helper.InvalidateWithChildren(Invalidatee); |
| } |
| } |
| |
| // Remove empty groups |
| for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) { |
| if (IndependentGroups[*iter].size() == 0) { |
| IndependentGroups.erase(*iter); |
| } |
| } |
| |
| #ifdef RELOOPER_DEBUG |
| PrintDebug("Investigated independent groups:\n"); |
| for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end(); iter++) { |
| DebugDump(iter->second, " group: "); |
| } |
| #endif |
| } |
| |
| Shape *MakeMultiple(BlockSet &Blocks, BlockSet& Entries, BlockBlockSetMap& IndependentGroups, BlockSet &NextEntries, bool IsCheckedMultiple) { |
| PrintDebug("creating multiple block with %d inner groups\n", IndependentGroups.size()); |
| MultipleShape *Multiple = new MultipleShape(); |
| Notice(Multiple); |
| BlockSet CurrEntries; |
| for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end(); iter++) { |
| Block *CurrEntry = iter->first; |
| BlockSet &CurrBlocks = iter->second; |
| PrintDebug(" multiple group with entry %d:\n", CurrEntry->Id); |
| DebugDump(CurrBlocks, " "); |
| // Create inner block |
| CurrEntries.clear(); |
| CurrEntries.insert(CurrEntry); |
| for (BlockSet::iterator iter = CurrBlocks.begin(); iter != CurrBlocks.end(); iter++) { |
| Block *CurrInner = *iter; |
| // Remove the block from the remaining blocks |
| Blocks.erase(CurrInner); |
| // Find new next entries and fix branches to them |
| for (BlockBranchMap::iterator iter = CurrInner->BranchesOut.begin(); iter != CurrInner->BranchesOut.end();) { |
| Block *CurrTarget = iter->first; |
| BlockBranchMap::iterator Next = iter; |
| Next++; |
| if (!contains(CurrBlocks, CurrTarget)) { |
| NextEntries.insert(CurrTarget); |
| Solipsize(CurrTarget, Branch::Break, Multiple, CurrBlocks); |
| } |
| iter = Next; // increment carefully because Solipsize can remove us |
| } |
| } |
| Multiple->InnerMap[CurrEntry->Id] = Process(CurrBlocks, CurrEntries); |
| if (IsCheckedMultiple) { |
| CurrEntry->IsCheckedMultipleEntry = true; |
| } |
| } |
| DebugDump(Blocks, " remaining blocks after multiple:"); |
| // Add entries not handled as next entries, they are deferred |
| for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) { |
| Block *Entry = *iter; |
| if (!contains(IndependentGroups, Entry)) { |
| NextEntries.insert(Entry); |
| } |
| } |
| return Multiple; |
| } |
| |
| // Main function. |
| // Process a set of blocks with specified entries, returns a shape |
| // The Make* functions receive a NextEntries. If they fill it with data, those are the entries for the |
| // ->Next block on them, and the blocks are what remains in Blocks (which Make* modify). In this way |
| // we avoid recursing on Next (imagine a long chain of Simples, if we recursed we could blow the stack). |
| Shape *Process(BlockSet &Blocks, BlockSet& InitialEntries) { |
| PrintDebug("Process() called\n", 0); |
| BlockSet *Entries = &InitialEntries; |
| BlockSet TempEntries[2]; |
| int CurrTempIndex = 0; |
| BlockSet *NextEntries; |
| Shape *Ret = nullptr; |
| Shape *Prev = nullptr; |
| #define Make(call) \ |
| Shape *Temp = call; \ |
| if (Prev) Prev->Next = Temp; \ |
| if (!Ret) Ret = Temp; \ |
| if (!NextEntries->size()) { PrintDebug("Process() returning\n", 0); return Ret; } \ |
| Prev = Temp; \ |
| Entries = NextEntries; \ |
| continue; |
| while (1) { |
| PrintDebug("Process() running\n", 0); |
| DebugDump(Blocks, " blocks : "); |
| DebugDump(*Entries, " entries: "); |
| |
| CurrTempIndex = 1-CurrTempIndex; |
| NextEntries = &TempEntries[CurrTempIndex]; |
| NextEntries->clear(); |
| |
| if (Entries->size() == 0) return Ret; |
| if (Entries->size() == 1) { |
| Block *Curr = *(Entries->begin()); |
| if (Curr->BranchesIn.size() == 0) { |
| // One entry, no looping ==> Simple |
| Make(MakeSimple(Blocks, Curr, *NextEntries)); |
| } |
| // One entry, looping ==> Loop |
| Make(MakeLoop(Blocks, *Entries, *NextEntries)); |
| } |
| |
| // More than one entry, try to eliminate through a Multiple groups of |
| // independent blocks from an entry/ies. It is important to remove through |
| // multiples as opposed to looping since the former is more performant. |
| BlockBlockSetMap IndependentGroups; |
| FindIndependentGroups(*Entries, IndependentGroups); |
| |
| PrintDebug("Independent groups: %d\n", IndependentGroups.size()); |
| |
| if (IndependentGroups.size() > 0) { |
| // We can handle a group in a multiple if its entry cannot be reached by another group. |
| // Note that it might be reachable by itself - a loop. But that is fine, we will create |
| // a loop inside the multiple block, which is both the performant order to do it, and |
| // preserves the property that a loop will always reach an entry. |
| for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end();) { |
| Block *Entry = iter->first; |
| BlockSet &Group = iter->second; |
| BlockBlockSetMap::iterator curr = iter++; // iterate carefully, we may delete |
| for (BlockSet::iterator iterBranch = Entry->BranchesIn.begin(); iterBranch != Entry->BranchesIn.end(); iterBranch++) { |
| Block *Origin = *iterBranch; |
| if (!contains(Group, Origin)) { |
| // Reached from outside the group, so we cannot handle this |
| PrintDebug("Cannot handle group with entry %d because of incoming branch from %d\n", Entry->Id, Origin->Id); |
| IndependentGroups.erase(curr); |
| break; |
| } |
| } |
| } |
| |
| // As an optimization, if we have 2 independent groups, and one is a small dead end, we can handle only that dead end. |
| // The other then becomes a Next - without nesting in the code and recursion in the analysis. |
| // TODO: if the larger is the only dead end, handle that too |
| // TODO: handle >2 groups |
| // TODO: handle not just dead ends, but also that do not branch to the NextEntries. However, must be careful |
| // there since we create a Next, and that Next can prevent eliminating a break (since we no longer |
| // naturally reach the same place), which may necessitate a one-time loop, which makes the unnesting |
| // pointless. |
| if (IndependentGroups.size() == 2) { |
| // Find the smaller one |
| BlockBlockSetMap::iterator iter = IndependentGroups.begin(); |
| Block *SmallEntry = iter->first; |
| int SmallSize = iter->second.size(); |
| iter++; |
| Block *LargeEntry = iter->first; |
| int LargeSize = iter->second.size(); |
| if (SmallSize != LargeSize) { // ignore the case where they are identical - keep things symmetrical there |
| if (SmallSize > LargeSize) { |
| Block *Temp = SmallEntry; |
| SmallEntry = LargeEntry; |
| LargeEntry = Temp; // Note: we did not flip the Sizes too, they are now invalid. TODO: use the smaller size as a limit? |
| } |
| // Check if dead end |
| bool DeadEnd = true; |
| BlockSet &SmallGroup = IndependentGroups[SmallEntry]; |
| for (BlockSet::iterator iter = SmallGroup.begin(); iter != SmallGroup.end(); iter++) { |
| Block *Curr = *iter; |
| for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) { |
| Block *Target = iter->first; |
| if (!contains(SmallGroup, Target)) { |
| DeadEnd = false; |
| break; |
| } |
| } |
| if (!DeadEnd) break; |
| } |
| if (DeadEnd) { |
| PrintDebug("Removing nesting by not handling large group because small group is dead end\n", 0); |
| IndependentGroups.erase(LargeEntry); |
| } |
| } |
| } |
| |
| PrintDebug("Handleable independent groups: %d\n", IndependentGroups.size()); |
| |
| if (IndependentGroups.size() > 0) { |
| // Some groups removable ==> Multiple |
| // This is a checked multiple if it has an entry that is an entry to this Process call, that is, |
| // if we can reach it from outside this set of blocks, then we must check the label variable |
| // to do so. Otherwise, if it is just internal blocks, those can always be jumped to forward, |
| // without using the label variable |
| bool Checked = false; |
| for (auto* Entry : *Entries) { |
| if (InitialEntries.count(Entry)) { |
| Checked = true; |
| break; |
| } |
| } |
| Make(MakeMultiple(Blocks, *Entries, IndependentGroups, *NextEntries, Checked)); |
| } |
| } |
| // No independent groups, must be loopable ==> Loop |
| Make(MakeLoop(Blocks, *Entries, *NextEntries)); |
| } |
| } |
| }; |
| |
| // Main |
| |
| BlockSet AllBlocks; |
| for (BlockSet::iterator iter = Pre.Live.begin(); iter != Pre.Live.end(); iter++) { |
| Block *Curr = *iter; |
| AllBlocks.insert(Curr); |
| #ifdef RELOOPER_DEBUG |
| PrintDebug("Adding block %d (%s)\n", Curr->Id, Curr->Code); |
| #endif |
| } |
| |
| BlockSet Entries; |
| Entries.insert(Entry); |
| Root = Analyzer(this).Process(AllBlocks, Entries); |
| assert(Root); |
| } |
| |
| wasm::Expression* Relooper::Render(RelooperBuilder& Builder) { |
| assert(Root); |
| auto* ret = Root->Render(Builder, false); |
| // we may use the same name for more than one block in HandleFollowupMultiples |
| wasm::UniqueNameMapper::uniquify(ret); |
| return ret; |
| } |
| |
| #ifdef RELOOPER_DEBUG |
| // Debugging |
| |
| void Debugging::Dump(BlockSet &Blocks, const char *prefix) { |
| if (prefix) printf("%s ", prefix); |
| for (BlockSet::iterator iter = Blocks.begin(); iter != Blocks.end(); iter++) { |
| Block *Curr = *iter; |
| printf("%d:\n", Curr->Id); |
| for (BlockBranchMap::iterator iter2 = Curr->BranchesOut.begin(); iter2 != Curr->BranchesOut.end(); iter2++) { |
| Block *Other = iter2->first; |
| printf(" -> %d\n", Other->Id); |
| assert(contains(Other->BranchesIn, Curr)); |
| } |
| } |
| } |
| |
| void Debugging::Dump(Shape *S, const char *prefix) { |
| if (prefix) printf("%s ", prefix); |
| if (!S) { |
| printf(" (null)\n"); |
| return; |
| } |
| printf(" %d ", S->Id); |
| if (SimpleShape *Simple = Shape::IsSimple(S)) { |
| printf("<< Simple with block %d\n", Simple->Inner->Id); |
| } else if (MultipleShape *Multiple = Shape::IsMultiple(S)) { |
| printf("<< Multiple\n"); |
| for (IdShapeMap::iterator iter = Multiple->InnerMap.begin(); iter != Multiple->InnerMap.end(); iter++) { |
| printf(" with entry %d\n", iter->first); |
| } |
| } else if (Shape::IsLoop(S)) { |
| printf("<< Loop\n"); |
| } else { |
| abort(); |
| } |
| } |
| |
| static void PrintDebug(const char *Format, ...) { |
| printf("// "); |
| va_list Args; |
| va_start(Args, Format); |
| vprintf(Format, Args); |
| va_end(Args); |
| } |
| #endif |
| |
| } // namespace CFG |
