//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "structurizecfg"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SCCIterator.h"
+#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/RegionInfo.h"
#include "llvm/Analysis/RegionIterator.h"
#include "llvm/Analysis/RegionPass.h"
#include "llvm/IR/Module.h"
-#include "llvm/Support/PatternMatch.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
using namespace llvm;
using namespace llvm::PatternMatch;
+#define DEBUG_TYPE "structurizecfg"
+
namespace {
// Definition of the complex types used in this pass.
// The name for newly created blocks.
-static const char *FlowBlockName = "Flow";
+static const char *const FlowBlockName = "Flow";
/// @brief Find the nearest common dominator for multiple BasicBlocks
///
/// \brief Start a new query
NearestCommonDominator(DominatorTree *DomTree) {
DT = DomTree;
- Result = 0;
+ Result = nullptr;
}
/// \brief Add BB to the resulting dominator
void addBlock(BasicBlock *BB, bool Remember = true) {
DomTreeNode *Node = DT->getNode(BB);
- if (Result == 0) {
+ if (!Result) {
unsigned Numbering = 0;
for (;Node;Node = Node->getIDom())
IndexMap[Node] = ++Numbering;
Region *ParentRegion;
DominatorTree *DT;
+ LoopInfo *LI;
RNVector Order;
BBSet Visited;
StructurizeCFG() :
RegionPass(ID) {
- initializeRegionInfoPass(*PassRegistry::getPassRegistry());
+ initializeStructurizeCFGPass(*PassRegistry::getPassRegistry());
}
using Pass::doInitialization;
- virtual bool doInitialization(Region *R, RGPassManager &RGM);
+ bool doInitialization(Region *R, RGPassManager &RGM) override;
- virtual bool runOnRegion(Region *R, RGPassManager &RGM);
+ bool runOnRegion(Region *R, RGPassManager &RGM) override;
- virtual const char *getPassName() const {
+ const char *getPassName() const override {
return "Structurize control flow";
}
- void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<DominatorTree>();
- AU.addPreserved<DominatorTree>();
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequiredID(LowerSwitchID);
+ AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addRequired<LoopInfoWrapperPass>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
RegionPass::getAnalysisUsage(AU);
}
};
INITIALIZE_PASS_BEGIN(StructurizeCFG, "structurizecfg", "Structurize the CFG",
false, false)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
-INITIALIZE_PASS_DEPENDENCY(RegionInfo)
+INITIALIZE_PASS_DEPENDENCY(LowerSwitch)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(RegionInfoPass)
INITIALIZE_PASS_END(StructurizeCFG, "structurizecfg", "Structurize the CFG",
false, false)
/// \brief Build up the general order of nodes
void StructurizeCFG::orderNodes() {
- scc_iterator<Region *> I = scc_begin(ParentRegion),
- E = scc_end(ParentRegion);
- for (Order.clear(); I != E; ++I) {
- std::vector<RegionNode *> &Nodes = *I;
- Order.append(Nodes.begin(), Nodes.end());
+ RNVector TempOrder;
+ ReversePostOrderTraversal<Region*> RPOT(ParentRegion);
+ TempOrder.append(RPOT.begin(), RPOT.end());
+
+ std::map<Loop*, unsigned> LoopBlocks;
+
+
+ // The reverse post-order traversal of the list gives us an ordering close
+ // to what we want. The only problem with it is that sometimes backedges
+ // for outer loops will be visited before backedges for inner loops.
+ for (RegionNode *RN : TempOrder) {
+ BasicBlock *BB = RN->getEntry();
+ Loop *Loop = LI->getLoopFor(BB);
+ if (!LoopBlocks.count(Loop)) {
+ LoopBlocks[Loop] = 1;
+ continue;
+ }
+ LoopBlocks[Loop]++;
}
+
+ unsigned CurrentLoopDepth = 0;
+ Loop *CurrentLoop = nullptr;
+ BBSet TempVisited;
+ for (RNVector::iterator I = TempOrder.begin(), E = TempOrder.end(); I != E; ++I) {
+ BasicBlock *BB = (*I)->getEntry();
+ unsigned LoopDepth = LI->getLoopDepth(BB);
+
+ if (std::find(Order.begin(), Order.end(), *I) != Order.end())
+ continue;
+
+ if (LoopDepth < CurrentLoopDepth) {
+ // Make sure we have visited all blocks in this loop before moving back to
+ // the outer loop.
+
+ RNVector::iterator LoopI = I;
+ while(LoopBlocks[CurrentLoop]) {
+ LoopI++;
+ BasicBlock *LoopBB = (*LoopI)->getEntry();
+ if (LI->getLoopFor(LoopBB) == CurrentLoop) {
+ LoopBlocks[CurrentLoop]--;
+ Order.push_back(*LoopI);
+ }
+ }
+ }
+
+ CurrentLoop = LI->getLoopFor(BB);
+ if (CurrentLoop) {
+ LoopBlocks[CurrentLoop]--;
+ }
+
+ CurrentLoopDepth = LoopDepth;
+ Order.push_back(*I);
+ }
+
+ // This pass originally used a post-order traversal and then operated on
+ // the list in reverse. Now that we are using a reverse post-order traversal
+ // rather than re-working the whole pass to operate on the list in order,
+ // we just reverse the list and continue to operate on it in reverse.
+ std::reverse(Order.begin(), Order.end());
}
/// \brief Determine the end of the loops
BasicBlock *BB = N->getNodeAs<BasicBlock>();
BranchInst *Term = cast<BranchInst>(BB->getTerminator());
- for (unsigned i = 0, e = Term->getNumSuccessors(); i != e; ++i) {
- BasicBlock *Succ = Term->getSuccessor(i);
-
+ for (BasicBlock *Succ : Term->successors())
if (Visited.count(Succ))
Loops[Succ] = BB;
- }
}
}
if (match(Condition, m_Not(m_Value(Condition))))
return Condition;
- // Third: Check all the users for an invert
- BasicBlock *Parent = cast<Instruction>(Condition)->getParent();
- for (Value::use_iterator I = Condition->use_begin(),
- E = Condition->use_end(); I != E; ++I) {
+ if (Instruction *Inst = dyn_cast<Instruction>(Condition)) {
+ // Third: Check all the users for an invert
+ BasicBlock *Parent = Inst->getParent();
+ for (User *U : Condition->users())
+ if (Instruction *I = dyn_cast<Instruction>(U))
+ if (I->getParent() == Parent && match(I, m_Not(m_Specific(Condition))))
+ return I;
- Instruction *User = dyn_cast<Instruction>(*I);
- if (!User || User->getParent() != Parent)
- continue;
+ // Last option: Create a new instruction
+ return BinaryOperator::CreateNot(Condition, "", Parent->getTerminator());
+ }
- if (match(*I, m_Not(m_Specific(Condition))))
- return *I;
+ if (Argument *Arg = dyn_cast<Argument>(Condition)) {
+ BasicBlock &EntryBlock = Arg->getParent()->getEntryBlock();
+ return BinaryOperator::CreateNot(Condition,
+ Arg->getName() + ".inv",
+ EntryBlock.getTerminator());
}
- // Last option: Create a new instruction
- return BinaryOperator::CreateNot(Condition, "", Parent->getTerminator());
+ llvm_unreachable("Unhandled condition to invert");
}
/// \brief Build the condition for one edge
} else {
// It's an exit from a sub region
- while(R->getParent() != ParentRegion)
+ while (R->getParent() != ParentRegion)
R = R->getParent();
// Edge from inside a subregion to its entry, ignore it
- if (R == N)
+ if (*R == *N)
continue;
BasicBlock *Entry = R->getEntry();
for (RNVector::reverse_iterator OI = Order.rbegin(), OE = Order.rend();
OI != OE; ++OI) {
+ DEBUG(dbgs() << "Visiting: " <<
+ ((*OI)->isSubRegion() ? "SubRegion with entry: " : "") <<
+ (*OI)->getEntry()->getName() << " Loop Depth: " << LI->getLoopDepth((*OI)->getEntry()) << "\n");
+
// Analyze all the conditions leading to a node
gatherPredicates(*OI);
Value *Default = Loops ? BoolTrue : BoolFalse;
SSAUpdater PhiInserter;
- for (BranchVector::iterator I = Conds.begin(),
- E = Conds.end(); I != E; ++I) {
-
- BranchInst *Term = *I;
+ for (BranchInst *Term : Conds) {
assert(Term->isConditional());
BasicBlock *Parent = Term->getParent();
NearestCommonDominator Dominator(DT);
Dominator.addBlock(Parent, false);
- Value *ParentValue = 0;
+ Value *ParentValue = nullptr;
for (BBPredicates::iterator PI = Preds.begin(), PE = Preds.end();
PI != PE; ++PI) {
if (Node->isSubRegion()) {
Region *SubRegion = Node->getNodeAs<Region>();
BasicBlock *OldExit = SubRegion->getExit();
- BasicBlock *Dominator = 0;
+ BasicBlock *Dominator = nullptr;
// Find all the edges from the sub region to the exit
for (pred_iterator I = pred_begin(OldExit), E = pred_end(OldExit);
/// \brief Set the previous node
void StructurizeCFG::setPrevNode(BasicBlock *BB) {
- PrevNode = ParentRegion->contains(BB) ? ParentRegion->getBBNode(BB) : 0;
+ PrevNode = ParentRegion->contains(BB) ? ParentRegion->getBBNode(BB)
+ : nullptr;
}
/// \brief Does BB dominate all the predicates of Node ?
bool Dominated = false;
// Regionentry is always true
- if (PrevNode == 0)
+ if (!PrevNode)
return true;
for (BBPredicates::iterator I = Preds.begin(), E = Preds.end();
handleLoops(false, LoopEnd);
}
+ // If the start of the loop is the entry block, we can't branch to it so
+ // insert a new dummy entry block.
+ Function *LoopFunc = LoopStart->getParent();
+ if (LoopStart == &LoopFunc->getEntryBlock()) {
+ LoopStart->setName("entry.orig");
+
+ BasicBlock *NewEntry =
+ BasicBlock::Create(LoopStart->getContext(),
+ "entry",
+ LoopFunc,
+ LoopStart);
+ BranchInst::Create(LoopStart, NewEntry);
+ }
+
// Create an extra loop end node
LoopEnd = needPrefix(false);
BasicBlock *Next = needPostfix(LoopEnd, ExitUseAllowed);
Conditions.clear();
LoopConds.clear();
- PrevNode = 0;
+ PrevNode = nullptr;
Visited.clear();
while (!Order.empty()) {
- handleLoops(EntryDominatesExit, 0);
+ handleLoops(EntryDominatesExit, nullptr);
}
if (PrevNode)
/// no longer dominate all their uses. Not sure if this is really nessasary
void StructurizeCFG::rebuildSSA() {
SSAUpdater Updater;
- for (Region::block_iterator I = ParentRegion->block_begin(),
- E = ParentRegion->block_end();
- I != E; ++I) {
-
- BasicBlock *BB = *I;
+ for (auto *BB : ParentRegion->blocks())
for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
II != IE; ++II) {
bool Initialized = false;
- for (Use *I = &II->use_begin().getUse(), *Next; I; I = Next) {
-
- Next = I->getNext();
-
- Instruction *User = cast<Instruction>(I->getUser());
+ for (auto I = II->use_begin(), E = II->use_end(); I != E;) {
+ Use &U = *I++;
+ Instruction *User = cast<Instruction>(U.getUser());
if (User->getParent() == BB) {
continue;
} else if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
- if (UserPN->getIncomingBlock(*I) == BB)
+ if (UserPN->getIncomingBlock(U) == BB)
continue;
}
- if (DT->dominates(II, User))
+ if (DT->dominates(&*II, User))
continue;
if (!Initialized) {
Value *Undef = UndefValue::get(II->getType());
Updater.Initialize(II->getType(), "");
Updater.AddAvailableValue(&Func->getEntryBlock(), Undef);
- Updater.AddAvailableValue(BB, II);
+ Updater.AddAvailableValue(BB, &*II);
Initialized = true;
}
- Updater.RewriteUseAfterInsertions(*I);
+ Updater.RewriteUseAfterInsertions(U);
}
}
- }
}
/// \brief Run the transformation for each region found
Func = R->getEntry()->getParent();
ParentRegion = R;
- DT = &getAnalysis<DominatorTree>();
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
orderNodes();
collectInfos();
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