#include "Relooper.h" #include #include #include #include #if EMSCRIPTEN #include "ministring.h" #else #include typedef std::string ministring; #endif template bool contains(const T& container, const U& contained) { return container.find(contained) != container.end(); } #if DEBUG static void PrintDebug(const char *Format, ...); #define DebugDump(x, ...) Debugging::Dump(x, __VA_ARGS__) #else #define PrintDebug(x, ...) #define DebugDump(x, ...) #endif #define INDENTATION 1 struct Indenter { static int CurrIndent; static void Indent() { CurrIndent++; } static void Unindent() { CurrIndent--; } }; static void PrintIndented(const char *Format, ...); static void PutIndented(const char *String); static char *OutputBufferRoot = NULL; static char *OutputBuffer = NULL; static int OutputBufferSize = 0; void PrintIndented(const char *Format, ...) { assert(OutputBuffer); assert(OutputBuffer + Indenter::CurrIndent*INDENTATION - OutputBufferRoot < OutputBufferSize); for (int i = 0; i < Indenter::CurrIndent*INDENTATION; i++, OutputBuffer++) *OutputBuffer = ' '; va_list Args; va_start(Args, Format); int left = OutputBufferSize - (OutputBuffer - OutputBufferRoot); int written = vsnprintf(OutputBuffer, left, Format, Args); assert(written < left); OutputBuffer += written; va_end(Args); } void PutIndented(const char *String) { assert(OutputBuffer); assert(OutputBuffer + Indenter::CurrIndent*INDENTATION - OutputBufferRoot < OutputBufferSize); for (int i = 0; i < Indenter::CurrIndent*INDENTATION; i++, OutputBuffer++) *OutputBuffer = ' '; int left = OutputBufferSize - (OutputBuffer - OutputBufferRoot); int needed = strlen(String)+1; assert(needed < left); strcpy(OutputBuffer, String); OutputBuffer += strlen(String); *OutputBuffer++ = '\n'; *OutputBuffer = 0; } static int AsmJS = 0; // Indenter int Indenter::CurrIndent = 1; // Branch Branch::Branch(const char *ConditionInit, const char *CodeInit) : Ancestor(NULL), Labeled(true) { Condition = ConditionInit ? strdup(ConditionInit) : NULL; Code = CodeInit ? strdup(CodeInit) : NULL; } Branch::~Branch() { if (Condition) free((void*)Condition); if (Code) free((void*)Code); } void Branch::Render(Block *Target, bool SetLabel) { if (Code) PrintIndented("%s\n", Code); if (SetLabel) PrintIndented("label = %d;\n", Target->Id); if (Ancestor) { if (Type != Direct) { if (Labeled) { PrintIndented("%s L%d;\n", Type == Break ? "break" : "continue", Ancestor->Id); } else { PrintIndented("%s;\n", Type == Break ? "break" : "continue"); } } } } // Block Block::Block(const char *CodeInit, const char *BranchVarInit) : Parent(NULL), Id(-1), IsCheckedMultipleEntry(false) { Code = strdup(CodeInit); BranchVar = BranchVarInit ? strdup(BranchVarInit) : NULL; } Block::~Block() { if (Code) free((void*)Code); if (BranchVar) free((void*)BranchVar); for (BlockBranchMap::iterator iter = ProcessedBranchesOut.begin(); iter != ProcessedBranchesOut.end(); iter++) { delete iter->second; } // XXX If not reachable, expected to have branches here. But need to clean them up to prevent leaks! } void Block::AddBranchTo(Block *Target, const char *Condition, const char *Code) { assert(!contains(BranchesOut, Target)); // cannot add more than one branch to the same target BranchesOut[Target] = new Branch(Condition, Code); } void Block::Render(bool InLoop) { if (IsCheckedMultipleEntry && InLoop) { PrintIndented("label = 0;\n"); } if (Code) { // Print code in an indented manner, even over multiple lines char *Start = const_cast(Code); while (*Start) { char *End = strchr(Start, '\n'); if (End) *End = 0; PutIndented(Start); if (End) *End = '\n'; else break; Start = End+1; } } if (!ProcessedBranchesOut.size()) return; bool SetLabel = true; // in some cases it is clear we can avoid setting label, see later bool ForceSetLabel = Shape::IsEmulated(Parent); // 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"); Parent->Next = Parent->Next->Next; Fused->RenderLoopPrefix(); // 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 (SetLabel && Fused->InnerMap.size() == ProcessedBranchesOut.size()) { SetLabel = false; } } Block *DefaultTarget(NULL); // 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 (!iter->second->Condition) { assert(!DefaultTarget); // Must be exactly one default DefaultTarget = iter->first; } } assert(DefaultTarget); // Since each block *must* branch somewhere, this must be set bool useSwitch = BranchVar != NULL; if (useSwitch) { PrintIndented("switch (%s) {\n", BranchVar); } ministring RemainingConditions; bool First = !useSwitch; // when using a switch, there is no special first 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) || ForceSetLabel; bool HasFusedContent = Fused && contains(Fused->InnerMap, Target); bool HasContent = SetCurrLabel || Details->Type != Branch::Direct || HasFusedContent || Details->Code; if (iter != ProcessedBranchesOut.end()) { // If there is nothing to show in this branch, omit the condition if (useSwitch) { PrintIndented("%s {\n", Details->Condition); } else { if (HasContent) { PrintIndented("%sif (%s) {\n", First ? "" : "} else ", Details->Condition); First = false; } else { if (RemainingConditions.size() > 0) RemainingConditions += " && "; RemainingConditions += "!("; if (BranchVar) { RemainingConditions += BranchVar; RemainingConditions += " == "; } RemainingConditions += Details->Condition; RemainingConditions += ")"; } } } else { // this is the default if (useSwitch) { PrintIndented("default: {\n"); } else { if (HasContent) { if (RemainingConditions.size() > 0) { if (First) { PrintIndented("if (%s) {\n", RemainingConditions.c_str()); First = false; } else { PrintIndented("} else if (%s) {\n", RemainingConditions.c_str()); } } else if (!First) { PrintIndented("} else {\n"); } } } } if (!First) Indenter::Indent(); Details->Render(Target, SetCurrLabel); if (HasFusedContent) { Fused->InnerMap.find(Target)->second->Render(InLoop); } if (useSwitch && iter != ProcessedBranchesOut.end()) { PrintIndented("break;\n"); } if (!First) Indenter::Unindent(); if (useSwitch) { PrintIndented("}\n"); } if (iter == ProcessedBranchesOut.end()) break; } if (!First) PrintIndented("}\n"); if (Fused) { Fused->RenderLoopPostfix(); } } // MultipleShape void MultipleShape::RenderLoopPrefix() { if (NeedLoop) { if (Labeled) { PrintIndented("L%d: do {\n", Id); } else { PrintIndented("do {\n"); } Indenter::Indent(); } } void MultipleShape::RenderLoopPostfix() { if (NeedLoop) { Indenter::Unindent(); PrintIndented("} while(0);\n"); } } void MultipleShape::Render(bool InLoop) { RenderLoopPrefix(); bool First = true; for (BlockShapeMap::iterator iter = InnerMap.begin(); iter != InnerMap.end(); iter++) { if (AsmJS) { PrintIndented("%sif ((label|0) == %d) {\n", First ? "" : "else ", iter->first->Id); } else { PrintIndented("%sif (label == %d) {\n", First ? "" : "else ", iter->first->Id); } First = false; Indenter::Indent(); iter->second->Render(InLoop); Indenter::Unindent(); PrintIndented("}\n"); } RenderLoopPostfix(); if (Next) Next->Render(InLoop); } // LoopShape void LoopShape::Render(bool InLoop) { if (Labeled) { PrintIndented("L%d: while(1) {\n", Id); } else { PrintIndented("while(1) {\n"); } Indenter::Indent(); Inner->Render(true); Indenter::Unindent(); PrintIndented("}\n"); if (Next) Next->Render(InLoop); } // EmulatedShape void EmulatedShape::Render(bool InLoop) { PrintIndented("label = %d;\n", Entry->Id); if (Labeled) { PrintIndented("L%d: ", Id); } PrintIndented("while(1) {\n"); Indenter::Indent(); PrintIndented("switch(label|0) {\n"); Indenter::Indent(); for (BlockSet::iterator iter = Blocks.begin(); iter != Blocks.end(); iter++) { Block *Curr = *iter; PrintIndented("case %d: {\n", Curr->Id); Indenter::Indent(); Curr->Render(InLoop); PrintIndented("break;\n"); Indenter::Unindent(); PrintIndented("}\n"); } Indenter::Unindent(); PrintIndented("}\n"); Indenter::Unindent(); PrintIndented("}\n"); if (Next) Next->Render(InLoop); } // Relooper Relooper::Relooper() : Root(NULL), Emulate(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) { New->Id = BlockIdCounter++; Blocks.push_back(New); } struct RelooperRecursor { Relooper *Parent; RelooperRecursor(Relooper *ParentInit) : Parent(ParentInit) {} }; typedef std::list 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); } } } // If a block has multiple entries but no exits, and it is small enough, it is useful to split it. // A common example is a C++ function where everything ends up at a final exit block and does some // RAII cleanup. Without splitting, we will be forced to introduce labelled loops to allow // reaching the final block void SplitDeadEnds() { unsigned TotalCodeSize = 0; for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) { Block *Curr = *iter; TotalCodeSize += strlen(Curr->Code); } BlockSet Splits; BlockSet Removed; //DebugDump(Live, "before"); for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) { Block *Original = *iter; if (Original->BranchesIn.size() <= 1 || Original->BranchesOut.size() > 0) continue; // only dead ends, for now if (contains(Original->BranchesOut, Original)) continue; // cannot split a looping node if (strlen(Original->Code)*(Original->BranchesIn.size()-1) > TotalCodeSize/5) continue; // if splitting increases raw code size by a significant amount, abort // Split the node (for simplicity, we replace all the blocks, even though we could have reused the original) PrintDebug("Splitting block %d\n", Original->Id); for (BlockSet::iterator iter = Original->BranchesIn.begin(); iter != Original->BranchesIn.end(); iter++) { Block *Prior = *iter; Block *Split = new Block(Original->Code, Original->BranchVar); Parent->AddBlock(Split); PrintDebug(" to %d\n", Split->Id); Split->BranchesIn.insert(Prior); Branch *Details = Prior->BranchesOut[Original]; Prior->BranchesOut[Split] = new Branch(Details->Condition, Details->Code); Prior->BranchesOut.erase(Original); for (BlockBranchMap::iterator iter = Original->BranchesOut.begin(); iter != Original->BranchesOut.end(); iter++) { Block *Post = iter->first; Branch *Details = iter->second; Split->BranchesOut[Post] = new Branch(Details->Condition, Details->Code); Post->BranchesIn.insert(Split); } Splits.insert(Split); Removed.insert(Original); } for (BlockBranchMap::iterator iter = Original->BranchesOut.begin(); iter != Original->BranchesOut.end(); iter++) { Block *Post = iter->first; Post->BranchesIn.erase(Original); } //DebugDump(Live, "mid"); } for (BlockSet::iterator iter = Splits.begin(); iter != Splits.end(); iter++) { Live.insert(*iter); } for (BlockSet::iterator iter = Removed.begin(); iter != Removed.end(); iter++) { Live.erase(*iter); } //DebugDump(Live, "after"); } }; 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); } } if (!Emulate) Pre.SplitDeadEnds(); // 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=NULL) { 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; if (MultipleShape *Multiple = Shape::IsMultiple(Ancestor)) { Multiple->NeedLoop++; // We are breaking out of this Multiple, so need a loop } 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::Direct, Simple, JustInner); } } return Simple; } Shape *MakeEmulated(BlockSet &Blocks, Block *Entry, BlockSet &NextEntries) { PrintDebug("creating emulated block with entry #%d and everything it can reach, %d blocks\n", Entry->Id, Blocks.size()); EmulatedShape *Emulated = new EmulatedShape; Notice(Emulated); Emulated->Entry = Entry; for (BlockSet::iterator iter = Blocks.begin(); iter != Blocks.end(); iter++) { Block *Curr = *iter; Emulated->Blocks.insert(Curr); Curr->Parent = Emulated; Solipsize(Curr, Branch::Continue, Emulated, Blocks); } Blocks.clear(); return Emulated; } 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 = NULL; 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 (Hoisted.find(Target) == Hoisted.end() && NextEntries.find(Target) == NextEntries.end()) { // 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"); 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, NULL); Loop->Inner = Inner; 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=NULL) { typedef std::map 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] = NULL; 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); } } #if 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, Shape *Prev, BlockSet &NextEntries) { PrintDebug("creating multiple block with %d inner groups\n", IndependentGroups.size()); bool Fused = !!(Shape::IsSimple(Prev)); 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] = Process(CurrBlocks, CurrEntries, NULL); // If we are not fused, then our entries will actually be checked if (!Fused) { 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, Shape *Prev) { PrintDebug("Process() called\n"); BlockSet *Entries = &InitialEntries; BlockSet TempEntries[2]; int CurrTempIndex = 0; BlockSet *NextEntries; Shape *Ret = NULL; #define Make(call) \ Shape *Temp = call; \ if (Prev) Prev->Next = Temp; \ if (!Ret) Ret = Temp; \ if (!NextEntries->size()) { PrintDebug("Process() returning\n"); return Ret; } \ Prev = Temp; \ Entries = NextEntries; \ continue; while (1) { PrintDebug("Process() running\n"); 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 (Parent->Emulate) { Make(MakeEmulated(Blocks, Curr, *NextEntries)); } 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 the performant order to do it). 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"); IndependentGroups.erase(LargeEntry); } } } PrintDebug("Handleable independent groups: %d\n", IndependentGroups.size()); if (IndependentGroups.size() > 0) { // Some groups removable ==> Multiple Make(MakeMultiple(Blocks, *Entries, IndependentGroups, Prev, *NextEntries)); } } // 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); #if DEBUG PrintDebug("Adding block %d (%s)\n", Curr->Id, Curr->Code); #endif } BlockSet Entries; Entries.insert(Entry); Root = Analyzer(this).Process(AllBlocks, Entries, NULL); assert(Root); // Post optimizations struct PostOptimizer { Relooper *Parent; void *Closure; PostOptimizer(Relooper *ParentInit) : Parent(ParentInit), Closure(NULL) {} #define RECURSE_Multiple(shape, func) \ for (BlockShapeMap::iterator iter = shape->InnerMap.begin(); iter != shape->InnerMap.end(); iter++) { \ func(iter->second); \ } #define RECURSE_Loop(shape, func) \ func(shape->Inner); #define RECURSE(shape, func) RECURSE_##shape(shape, func); #define SHAPE_SWITCH(var, simple, multiple, loop) \ if (SimpleShape *Simple = Shape::IsSimple(var)) { \ simple; \ } else if (MultipleShape *Multiple = Shape::IsMultiple(var)) { \ multiple; \ } else if (LoopShape *Loop = Shape::IsLoop(var)) { \ loop; \ } // Find the blocks that natural control flow can get us directly to, or through a multiple that we ignore void FollowNaturalFlow(Shape *S, BlockSet &Out) { SHAPE_SWITCH(S, { Out.insert(Simple->Inner); }, { for (BlockShapeMap::iterator iter = Multiple->InnerMap.begin(); iter != Multiple->InnerMap.end(); iter++) { FollowNaturalFlow(iter->second, Out); } FollowNaturalFlow(Multiple->Next, Out); }, { FollowNaturalFlow(Loop->Inner, Out); }); } void FindNaturals(Shape *Root, Shape *Otherwise=NULL) { if (Root->Next) { Root->Natural = Root->Next; FindNaturals(Root->Next, Otherwise); } else { Root->Natural = Otherwise; } SHAPE_SWITCH(Root, { }, { for (BlockShapeMap::iterator iter = Multiple->InnerMap.begin(); iter != Multiple->InnerMap.end(); iter++) { FindNaturals(iter->second, Root->Natural); } }, { FindNaturals(Loop->Inner, Loop->Inner); }); } // Remove unneeded breaks and continues. // A flow operation is trivially unneeded if the shape we naturally get to by normal code // execution is the same as the flow forces us to. void RemoveUnneededFlows(Shape *Root, Shape *Natural=NULL, LoopShape *LastLoop=NULL) { BlockSet NaturalBlocks; FollowNaturalFlow(Natural, NaturalBlocks); Shape *Next = Root; while (Next) { Root = Next; Next = NULL; SHAPE_SWITCH(Root, { if (Simple->Inner->BranchVar) LastLoop = NULL; // a switch clears out the loop (TODO: only for breaks, not continue) // If there is a next block, we already know at Simple creation time to make direct branches, // and we can do nothing more. If there is no next however, then Natural is where we will // go to by doing nothing, so we can potentially optimize some branches to direct. if (Simple->Next) { Next = Simple->Next; } else { for (BlockBranchMap::iterator iter = Simple->Inner->ProcessedBranchesOut.begin(); iter != Simple->Inner->ProcessedBranchesOut.end(); iter++) { Block *Target = iter->first; Branch *Details = iter->second; if (Details->Type != Branch::Direct && contains(NaturalBlocks, Target)) { // note: cannot handle split blocks Details->Type = Branch::Direct; if (MultipleShape *Multiple = Shape::IsMultiple(Details->Ancestor)) { Multiple->NeedLoop--; } } else if (Details->Type == Branch::Break && LastLoop && LastLoop->Natural == Details->Ancestor->Natural) { // it is important to simplify breaks, as simpler breaks enable other optimizations Details->Labeled = false; if (MultipleShape *Multiple = Shape::IsMultiple(Details->Ancestor)) { Multiple->NeedLoop--; } } } } }, { for (BlockShapeMap::iterator iter = Multiple->InnerMap.begin(); iter != Multiple->InnerMap.end(); iter++) { RemoveUnneededFlows(iter->second, Multiple->Next, Multiple->NeedLoop ? NULL : LastLoop); } Next = Multiple->Next; }, { RemoveUnneededFlows(Loop->Inner, Loop->Inner, Loop); Next = Loop->Next; }); } } // After we know which loops exist, we can calculate which need to be labeled void FindLabeledLoops(Shape *Root) { bool First = Closure == NULL; if (First) { Closure = (void*)(new std::stack); } std::stack &LoopStack = *((std::stack*)Closure); Shape *Next = Root; while (Next) { Root = Next; Next = NULL; SHAPE_SWITCH(Root, { MultipleShape *Fused = Shape::IsMultiple(Root->Next); // If we are fusing a Multiple with a loop into this Simple, then visit it now if (Fused && Fused->NeedLoop) { LoopStack.push(Fused); } if (Simple->Inner->BranchVar) { LoopStack.push(NULL); // a switch means breaks are now useless, push a dummy } if (Fused) { RECURSE_Multiple(Fused, FindLabeledLoops); } for (BlockBranchMap::iterator iter = Simple->Inner->ProcessedBranchesOut.begin(); iter != Simple->Inner->ProcessedBranchesOut.end(); iter++) { Block *Target = iter->first; Branch *Details = iter->second; if (Details->Type != Branch::Direct) { assert(LoopStack.size() > 0); if (Details->Ancestor != LoopStack.top() && Details->Labeled) { LabeledShape *Labeled = Shape::IsLabeled(Details->Ancestor); Labeled->Labeled = true; } else { Details->Labeled = false; } } } if (Simple->Inner->BranchVar) { LoopStack.pop(); } if (Fused && Fused->NeedLoop) { LoopStack.pop(); } if (Fused) { Next = Fused->Next; } else { Next = Root->Next; } }, { if (Multiple->NeedLoop) { LoopStack.push(Multiple); } RECURSE(Multiple, FindLabeledLoops); if (Multiple->NeedLoop) { LoopStack.pop(); } Next = Root->Next; }, { LoopStack.push(Loop); RECURSE(Loop, FindLabeledLoops); LoopStack.pop(); Next = Root->Next; }); } if (First) { delete (std::stack*)Closure; } } void Process(Shape *Root) { FindNaturals(Root); RemoveUnneededFlows(Root); FindLabeledLoops(Root); } }; PrintDebug("=== Optimizing shapes ===\n"); PostOptimizer(this).Process(Root); } void Relooper::Render() { OutputBuffer = OutputBufferRoot; assert(Root); Root->Render(false); } void Relooper::SetOutputBuffer(char *Buffer, int Size) { OutputBufferRoot = OutputBuffer = Buffer; OutputBufferSize = Size; } void Relooper::MakeOutputBuffer(int Size) { OutputBufferRoot = OutputBuffer = (char*)malloc(Size); OutputBufferSize = Size; } void Relooper::SetAsmJSMode(int On) { AsmJS = On; } #if 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); SHAPE_SWITCH(S, { printf("<< Simple with block %d\n", Simple->Inner->Id); }, { printf("<< Multiple\n"); for (BlockShapeMap::iterator iter = Multiple->InnerMap.begin(); iter != Multiple->InnerMap.end(); iter++) { printf(" with entry %d\n", iter->first->Id); } }, { printf("<< Loop\n"); }); } static void PrintDebug(const char *Format, ...) { printf("// "); va_list Args; va_start(Args, Format); vprintf(Format, Args); va_end(Args); } #endif // C API - useful for binding to other languages typedef std::map VoidIntMap; VoidIntMap __blockDebugMap__; // maps block pointers in currently running code to block ids, for generated debug output extern "C" { void rl_set_output_buffer(char *buffer, int size) { #if DEBUG printf("#include \"Relooper.h\"\n"); printf("int main() {\n"); printf(" char buffer[100000];\n"); printf(" rl_set_output_buffer(buffer);\n"); #endif Relooper::SetOutputBuffer(buffer, size); } void rl_make_output_buffer(int size) { Relooper::SetOutputBuffer((char*)malloc(size), size); } void rl_set_asm_js_mode(int on) { Relooper::SetAsmJSMode(on); } void *rl_new_block(const char *text, const char *branch_var) { Block *ret = new Block(text, branch_var); #if DEBUG printf(" void *b%d = rl_new_block(\"// code %d\");\n", ret->Id, ret->Id); __blockDebugMap__[ret] = ret->Id; printf(" block_map[%d] = b%d;\n", ret->Id, ret->Id); #endif return ret; } void rl_delete_block(void *block) { #if DEBUG printf(" rl_delete_block(block_map[%d]);\n", ((Block*)block)->Id); #endif delete (Block*)block; } void rl_block_add_branch_to(void *from, void *to, const char *condition, const char *code) { #if DEBUG printf(" rl_block_add_branch_to(block_map[%d], block_map[%d], %s%s%s, %s%s%s);\n", ((Block*)from)->Id, ((Block*)to)->Id, condition ? "\"" : "", condition ? condition : "NULL", condition ? "\"" : "", code ? "\"" : "", code ? code : "NULL", code ? "\"" : ""); #endif ((Block*)from)->AddBranchTo((Block*)to, condition, code); } void *rl_new_relooper() { #if DEBUG printf(" void *block_map[10000];\n"); printf(" void *rl = rl_new_relooper();\n"); #endif return new Relooper; } void rl_delete_relooper(void *relooper) { delete (Relooper*)relooper; } void rl_relooper_add_block(void *relooper, void *block) { #if DEBUG printf(" rl_relooper_add_block(rl, block_map[%d]);\n", ((Block*)block)->Id); #endif ((Relooper*)relooper)->AddBlock((Block*)block); } void rl_relooper_calculate(void *relooper, void *entry) { #if DEBUG printf(" rl_relooper_calculate(rl, block_map[%d]);\n", ((Block*)entry)->Id); printf(" rl_relooper_render(rl);\n"); printf(" rl_delete_relooper(rl);\n"); printf(" puts(buffer);\n"); printf(" return 0;\n"); printf("}\n"); #endif ((Relooper*)relooper)->Calculate((Block*)entry); } void rl_relooper_render(void *relooper) { ((Relooper*)relooper)->Render(); } }