//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "loop-simplify"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/DependenceAnalysis.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/IR/CFG.h"
#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
-#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
using namespace llvm;
+#define DEBUG_TYPE "loop-simplify"
+
STATISTIC(NumInserted, "Number of pre-header or exit blocks inserted");
STATISTIC(NumNested , "Number of nested loops split out");
// Figure out *which* outside block to put this after. Prefer an outside
// block that neighbors a BB actually in the loop.
- BasicBlock *FoundBB = 0;
+ BasicBlock *FoundBB = nullptr;
for (unsigned i = 0, e = SplitPreds.size(); i != e; ++i) {
Function::iterator BBI = SplitPreds[i];
if (++BBI != NewBB->getParent()->end() &&
BasicBlock *llvm::InsertPreheaderForLoop(Loop *L, Pass *PP) {
BasicBlock *Header = L->getHeader();
+ // Get analyses that we try to update.
+ auto *DTWP = PP->getAnalysisIfAvailable<DominatorTreeWrapperPass>();
+ auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
+ auto *LIWP = PP->getAnalysisIfAvailable<LoopInfoWrapperPass>();
+ auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
+ bool PreserveLCSSA = PP->mustPreserveAnalysisID(LCSSAID);
+
// Compute the set of predecessors of the loop that are not in the loop.
SmallVector<BasicBlock*, 8> OutsideBlocks;
for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
// If the loop is branched to from an indirect branch, we won't
// be able to fully transform the loop, because it prohibits
// edge splitting.
- if (isa<IndirectBrInst>(P->getTerminator())) return 0;
+ if (isa<IndirectBrInst>(P->getTerminator())) return nullptr;
// Keep track of it.
OutsideBlocks.push_back(P);
// Split out the loop pre-header.
BasicBlock *PreheaderBB;
- if (!Header->isLandingPad()) {
- PreheaderBB = SplitBlockPredecessors(Header, OutsideBlocks, ".preheader",
- PP);
- } else {
- SmallVector<BasicBlock*, 2> NewBBs;
- SplitLandingPadPredecessors(Header, OutsideBlocks, ".preheader",
- ".split-lp", PP, NewBBs);
- PreheaderBB = NewBBs[0];
- }
+ PreheaderBB = SplitBlockPredecessors(Header, OutsideBlocks, ".preheader", DT,
+ LI, PreserveLCSSA);
+ if (!PreheaderBB)
+ return nullptr;
- PreheaderBB->getTerminator()->setDebugLoc(
- Header->getFirstNonPHI()->getDebugLoc());
DEBUG(dbgs() << "LoopSimplify: Creating pre-header "
<< PreheaderBB->getName() << "\n");
///
/// This method is used to split exit blocks that have predecessors outside of
/// the loop.
-static BasicBlock *rewriteLoopExitBlock(Loop *L, BasicBlock *Exit, Pass *PP) {
+static BasicBlock *rewriteLoopExitBlock(Loop *L, BasicBlock *Exit,
+ DominatorTree *DT, LoopInfo *LI,
+ Pass *PP) {
SmallVector<BasicBlock*, 8> LoopBlocks;
for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit); I != E; ++I) {
BasicBlock *P = *I;
if (L->contains(P)) {
// Don't do this if the loop is exited via an indirect branch.
- if (isa<IndirectBrInst>(P->getTerminator())) return 0;
+ if (isa<IndirectBrInst>(P->getTerminator())) return nullptr;
LoopBlocks.push_back(P);
}
}
assert(!LoopBlocks.empty() && "No edges coming in from outside the loop?");
- BasicBlock *NewExitBB = 0;
-
- if (Exit->isLandingPad()) {
- SmallVector<BasicBlock*, 2> NewBBs;
- SplitLandingPadPredecessors(Exit, ArrayRef<BasicBlock*>(&LoopBlocks[0],
- LoopBlocks.size()),
- ".loopexit", ".nonloopexit",
- PP, NewBBs);
- NewExitBB = NewBBs[0];
- } else {
- NewExitBB = SplitBlockPredecessors(Exit, LoopBlocks, ".loopexit", PP);
- }
+ BasicBlock *NewExitBB = nullptr;
+
+ bool PreserveLCSSA = PP->mustPreserveAnalysisID(LCSSAID);
+
+ NewExitBB = SplitBlockPredecessors(Exit, LoopBlocks, ".loopexit", DT, LI,
+ PreserveLCSSA);
+ if (!NewExitBB)
+ return nullptr;
DEBUG(dbgs() << "LoopSimplify: Creating dedicated exit block "
<< NewExitBB->getName() << "\n");
/// \brief The first part of loop-nestification is to find a PHI node that tells
/// us how to partition the loops.
-static PHINode *findPHIToPartitionLoops(Loop *L, AliasAnalysis *AA,
- DominatorTree *DT) {
+static PHINode *findPHIToPartitionLoops(Loop *L, DominatorTree *DT,
+ AssumptionCache *AC) {
+ const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
++I;
- if (Value *V = SimplifyInstruction(PN, 0, 0, DT)) {
+ if (Value *V = SimplifyInstruction(PN, DL, nullptr, DT, AC)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
- if (AA) AA->deleteValue(PN);
PN->eraseFromParent();
continue;
}
// We found something tasty to remove.
return PN;
}
- return 0;
+ return nullptr;
}
/// \brief If this loop has multiple backedges, try to pull one of them out into
/// created.
///
static Loop *separateNestedLoop(Loop *L, BasicBlock *Preheader,
- AliasAnalysis *AA, DominatorTree *DT,
- LoopInfo *LI, ScalarEvolution *SE, Pass *PP) {
+ DominatorTree *DT, LoopInfo *LI,
+ ScalarEvolution *SE, Pass *PP,
+ AssumptionCache *AC) {
// Don't try to separate loops without a preheader.
if (!Preheader)
- return 0;
+ return nullptr;
// The header is not a landing pad; preheader insertion should ensure this.
- assert(!L->getHeader()->isLandingPad() &&
- "Can't insert backedge to landing pad");
+ BasicBlock *Header = L->getHeader();
+ assert(!Header->isEHPad() && "Can't insert backedge to EH pad");
- PHINode *PN = findPHIToPartitionLoops(L, AA, DT);
- if (PN == 0) return 0; // No known way to partition.
+ PHINode *PN = findPHIToPartitionLoops(L, DT, AC);
+ if (!PN) return nullptr; // No known way to partition.
// Pull out all predecessors that have varying values in the loop. This
// handles the case when a PHI node has multiple instances of itself as
!L->contains(PN->getIncomingBlock(i))) {
// We can't split indirectbr edges.
if (isa<IndirectBrInst>(PN->getIncomingBlock(i)->getTerminator()))
- return 0;
+ return nullptr;
OuterLoopPreds.push_back(PN->getIncomingBlock(i));
}
}
if (SE)
SE->forgetLoop(L);
- BasicBlock *Header = L->getHeader();
- BasicBlock *NewBB =
- SplitBlockPredecessors(Header, OuterLoopPreds, ".outer", PP);
+ bool PreserveLCSSA = PP->mustPreserveAnalysisID(LCSSAID);
+
+ BasicBlock *NewBB = SplitBlockPredecessors(Header, OuterLoopPreds, ".outer",
+ DT, LI, PreserveLCSSA);
// Make sure that NewBB is put someplace intelligent, which doesn't mess up
// code layout too horribly.
/// and have that block branch to the loop header. This ensures that loops
/// have exactly one backedge.
static BasicBlock *insertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader,
- AliasAnalysis *AA,
DominatorTree *DT, LoopInfo *LI) {
assert(L->getNumBackEdges() > 1 && "Must have > 1 backedge!");
// Unique backedge insertion currently depends on having a preheader.
if (!Preheader)
- return 0;
+ return nullptr;
- // The header is not a landing pad; preheader insertion should ensure this.
- assert(!Header->isLandingPad() && "Can't insert backedge to landing pad");
+ // The header is not an EH pad; preheader insertion should ensure this.
+ assert(!Header->isEHPad() && "Can't insert backedge to EH pad");
// Figure out which basic blocks contain back-edges to the loop header.
std::vector<BasicBlock*> BackedgeBlocks;
// Indirectbr edges cannot be split, so we must fail if we find one.
if (isa<IndirectBrInst>(P->getTerminator()))
- return 0;
+ return nullptr;
if (P != Preheader) BackedgeBlocks.push_back(P);
}
// Create and insert the new backedge block...
BasicBlock *BEBlock = BasicBlock::Create(Header->getContext(),
- Header->getName()+".backedge", F);
+ Header->getName() + ".backedge", F);
BranchInst *BETerminator = BranchInst::Create(Header, BEBlock);
+ BETerminator->setDebugLoc(Header->getFirstNonPHI()->getDebugLoc());
DEBUG(dbgs() << "LoopSimplify: Inserting unique backedge block "
<< BEBlock->getName() << "\n");
PHINode *PN = cast<PHINode>(I);
PHINode *NewPN = PHINode::Create(PN->getType(), BackedgeBlocks.size(),
PN->getName()+".be", BETerminator);
- if (AA) AA->copyValue(PN, NewPN);
// Loop over the PHI node, moving all entries except the one for the
// preheader over to the new PHI node.
unsigned PreheaderIdx = ~0U;
bool HasUniqueIncomingValue = true;
- Value *UniqueValue = 0;
+ Value *UniqueValue = nullptr;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
BasicBlock *IBB = PN->getIncomingBlock(i);
Value *IV = PN->getIncomingValue(i);
} else {
NewPN->addIncoming(IV, IBB);
if (HasUniqueIncomingValue) {
- if (UniqueValue == 0)
+ if (!UniqueValue)
UniqueValue = IV;
else if (UniqueValue != IV)
HasUniqueIncomingValue = false;
// eliminate the PHI Node.
if (HasUniqueIncomingValue) {
NewPN->replaceAllUsesWith(UniqueValue);
- if (AA) AA->deleteValue(NewPN);
BEBlock->getInstList().erase(NewPN);
}
}
// Update Loop Information - we know that this block is now in the current
// loop and all parent loops.
- L->addBasicBlockToLoop(BEBlock, LI->getBase());
+ L->addBasicBlockToLoop(BEBlock, *LI);
// Update dominator information
DT->splitBlock(BEBlock);
/// specific analyses. Rather than a pass it would be much cleaner and more
/// explicit if they accepted the analysis directly and then updated it.
static bool simplifyOneLoop(Loop *L, SmallVectorImpl<Loop *> &Worklist,
- AliasAnalysis *AA, DominatorTree *DT, LoopInfo *LI,
- ScalarEvolution *SE, Pass *PP) {
+ DominatorTree *DT, LoopInfo *LI,
+ ScalarEvolution *SE, Pass *PP,
+ AssumptionCache *AC) {
bool Changed = false;
ReprocessLoop:
}
// Delete each unique out-of-loop (and thus dead) predecessor.
- for (SmallPtrSet<BasicBlock*, 4>::iterator I = BadPreds.begin(),
- E = BadPreds.end(); I != E; ++I) {
+ for (BasicBlock *P : BadPreds) {
DEBUG(dbgs() << "LoopSimplify: Deleting edge from dead predecessor "
- << (*I)->getName() << "\n");
+ << P->getName() << "\n");
// Inform each successor of each dead pred.
- for (succ_iterator SI = succ_begin(*I), SE = succ_end(*I); SI != SE; ++SI)
- (*SI)->removePredecessor(*I);
+ for (succ_iterator SI = succ_begin(P), SE = succ_end(P); SI != SE; ++SI)
+ (*SI)->removePredecessor(P);
// Zap the dead pred's terminator and replace it with unreachable.
- TerminatorInst *TI = (*I)->getTerminator();
+ TerminatorInst *TI = P->getTerminator();
TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
- (*I)->getTerminator()->eraseFromParent();
- new UnreachableInst((*I)->getContext(), *I);
+ P->getTerminator()->eraseFromParent();
+ new UnreachableInst(P->getContext(), P);
Changed = true;
}
}
// Must be exactly this loop: no subloops, parent loops, or non-loop preds
// allowed.
if (!L->contains(*PI)) {
- if (rewriteLoopExitBlock(L, ExitBlock, PP)) {
+ if (rewriteLoopExitBlock(L, ExitBlock, DT, LI, PP)) {
++NumInserted;
Changed = true;
}
// this for loops with a giant number of backedges, just factor them into a
// common backedge instead.
if (L->getNumBackEdges() < 8) {
- if (Loop *OuterL = separateNestedLoop(L, Preheader, AA, DT, LI, SE, PP)) {
+ if (Loop *OuterL = separateNestedLoop(L, Preheader, DT, LI, SE, PP, AC)) {
++NumNested;
// Enqueue the outer loop as it should be processed next in our
// depth-first nest walk.
// If we either couldn't, or didn't want to, identify nesting of the loops,
// insert a new block that all backedges target, then make it jump to the
// loop header.
- LoopLatch = insertUniqueBackedgeBlock(L, Preheader, AA, DT, LI);
+ LoopLatch = insertUniqueBackedgeBlock(L, Preheader, DT, LI);
if (LoopLatch) {
++NumInserted;
Changed = true;
}
}
+ const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
+
// Scan over the PHI nodes in the loop header. Since they now have only two
// incoming values (the loop is canonicalized), we may have simplified the PHI
// down to 'X = phi [X, Y]', which should be replaced with 'Y'.
PHINode *PN;
for (BasicBlock::iterator I = L->getHeader()->begin();
(PN = dyn_cast<PHINode>(I++)); )
- if (Value *V = SimplifyInstruction(PN, 0, 0, DT)) {
- if (AA) AA->deleteValue(PN);
+ if (Value *V = SimplifyInstruction(PN, DL, nullptr, DT, AC)) {
if (SE) SE->forgetValue(PN);
PN->replaceAllUsesWith(V);
PN->eraseFromParent();
if (Inst == CI)
continue;
if (!L->makeLoopInvariant(Inst, AnyInvariant,
- Preheader ? Preheader->getTerminator() : 0)) {
+ Preheader ? Preheader->getTerminator()
+ : nullptr)) {
AllInvariant = false;
break;
}
// The block has now been cleared of all instructions except for
// a comparison and a conditional branch. SimplifyCFG may be able
// to fold it now.
- if (!FoldBranchToCommonDest(BI)) continue;
+ if (!FoldBranchToCommonDest(BI))
+ continue;
// Success. The block is now dead, so remove it from the loop,
// update the dominator tree and delete it.
}
bool llvm::simplifyLoop(Loop *L, DominatorTree *DT, LoopInfo *LI, Pass *PP,
- AliasAnalysis *AA, ScalarEvolution *SE) {
+ ScalarEvolution *SE, AssumptionCache *AC) {
bool Changed = false;
// Worklist maintains our depth-first queue of loops in this nest to process.
// order. We can use this simple process because loops form a tree.
for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
Loop *L2 = Worklist[Idx];
- for (Loop::iterator I = L2->begin(), E = L2->end(); I != E; ++I)
- Worklist.push_back(*I);
+ Worklist.append(L2->begin(), L2->end());
}
while (!Worklist.empty())
- Changed |= simplifyOneLoop(Worklist.pop_back_val(), Worklist, AA, DT, LI, SE, PP);
+ Changed |=
+ simplifyOneLoop(Worklist.pop_back_val(), Worklist, DT, LI, SE, PP, AC);
return Changed;
}
initializeLoopSimplifyPass(*PassRegistry::getPassRegistry());
}
- // AA - If we have an alias analysis object to update, this is it, otherwise
- // this is null.
- AliasAnalysis *AA;
DominatorTree *DT;
LoopInfo *LI;
ScalarEvolution *SE;
+ AssumptionCache *AC;
+
+ bool runOnFunction(Function &F) override;
- virtual bool runOnFunction(Function &F);
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<AssumptionCacheTracker>();
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
// We need loop information to identify the loops...
AU.addRequired<DominatorTreeWrapperPass>();
AU.addPreserved<DominatorTreeWrapperPass>();
- AU.addRequired<LoopInfo>();
- AU.addPreserved<LoopInfo>();
+ AU.addRequired<LoopInfoWrapperPass>();
+ AU.addPreserved<LoopInfoWrapperPass>();
AU.addPreserved<AliasAnalysis>();
AU.addPreserved<ScalarEvolution>();
}
/// verifyAnalysis() - Verify LoopSimplifyForm's guarantees.
- void verifyAnalysis() const;
-
- private:
- bool ProcessLoop(Loop *L);
- BasicBlock *RewriteLoopExitBlock(Loop *L, BasicBlock *Exit);
- Loop *SeparateNestedLoop(Loop *L, BasicBlock *Preheader);
- BasicBlock *InsertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader);
+ void verifyAnalysis() const override;
};
}
char LoopSimplify::ID = 0;
INITIALIZE_PASS_BEGIN(LoopSimplify, "loop-simplify",
- "Canonicalize natural loops", true, false)
+ "Canonicalize natural loops", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_END(LoopSimplify, "loop-simplify",
- "Canonicalize natural loops", true, false)
+ "Canonicalize natural loops", false, false)
// Publicly exposed interface to pass...
char &llvm::LoopSimplifyID = LoopSimplify::ID;
Pass *llvm::createLoopSimplifyPass() { return new LoopSimplify(); }
-/// runOnLoop - Run down all loops in the CFG (recursively, but we could do
+/// runOnFunction - Run down all loops in the CFG (recursively, but we could do
/// it in any convenient order) inserting preheaders...
///
bool LoopSimplify::runOnFunction(Function &F) {
bool Changed = false;
- AA = getAnalysisIfAvailable<AliasAnalysis>();
- LI = &getAnalysis<LoopInfo>();
+ LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
SE = getAnalysisIfAvailable<ScalarEvolution>();
+ AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
// Simplify each loop nest in the function.
for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
- Changed |= simplifyLoop(*I, DT, LI, this, AA, SE);
+ Changed |= simplifyLoop(*I, DT, LI, this, SE, AC);
return Changed;
}
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