//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "loopsimplify"
+#define DEBUG_TYPE "loop-simplify"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
namespace {
struct LoopSimplify : public LoopPass {
static char ID; // Pass identification, replacement for typeid
- LoopSimplify() : LoopPass(&ID) {}
+ LoopSimplify() : LoopPass(ID) {
+ initializeLoopSimplifyPass(*PassRegistry::getPassRegistry());
+ }
// AA - If we have an alias analysis object to update, this is it, otherwise
// this is null.
AliasAnalysis *AA;
LoopInfo *LI;
DominatorTree *DT;
+ ScalarEvolution *SE;
Loop *L;
virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
AU.addPreserved<AliasAnalysis>();
AU.addPreserved<ScalarEvolution>();
AU.addPreservedID(BreakCriticalEdgesID); // No critical edges added.
- AU.addPreserved<DominanceFrontier>();
- AU.addPreservedID(LCSSAID);
}
/// verifyAnalysis() - Verify LoopSimplifyForm's guarantees.
}
char LoopSimplify::ID = 0;
-static RegisterPass<LoopSimplify>
-X("loopsimplify", "Canonicalize natural loops", true);
-
-// Publically exposed interface to pass...
-const PassInfo *const llvm::LoopSimplifyID = &X;
+INITIALIZE_PASS_BEGIN(LoopSimplify, "loop-simplify",
+ "Canonicalize natural loops", true, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_END(LoopSimplify, "loop-simplify",
+ "Canonicalize natural loops", true, 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
LI = &getAnalysis<LoopInfo>();
AA = getAnalysisIfAvailable<AliasAnalysis>();
DT = &getAnalysis<DominatorTree>();
+ SE = getAnalysisIfAvailable<ScalarEvolution>();
Changed |= ProcessLoop(L, LPM);
for (SmallPtrSet<BasicBlock*, 4>::iterator I = BadPreds.begin(),
E = BadPreds.end(); I != E; ++I) {
- DEBUG(dbgs() << "LoopSimplify: Deleting edge from dead predecessor ";
- WriteAsOperand(dbgs(), *I, false);
- dbgs() << "\n");
+ DEBUG(dbgs() << "LoopSimplify: Deleting edge from dead predecessor "
+ << (*I)->getName() << "\n");
// Inform each successor of each dead pred.
for (succ_iterator SI = succ_begin(*I), SE = succ_end(*I); SI != SE; ++SI)
if (BI->isConditional()) {
if (UndefValue *Cond = dyn_cast<UndefValue>(BI->getCondition())) {
- DEBUG(dbgs() << "LoopSimplify: Resolving \"br i1 undef\" to exit in ";
- WriteAsOperand(dbgs(), *I, false);
- dbgs() << "\n");
+ DEBUG(dbgs() << "LoopSimplify: Resolving \"br i1 undef\" to exit in "
+ << (*I)->getName() << "\n");
BI->setCondition(ConstantInt::get(Cond->getType(),
!L->contains(BI->getSuccessor(0))));
// predecessors from outside of the loop, split the edge now.
SmallVector<BasicBlock*, 8> ExitBlocks;
L->getExitBlocks(ExitBlocks);
-
+
SmallSetVector<BasicBlock *, 8> ExitBlockSet(ExitBlocks.begin(),
ExitBlocks.end());
for (SmallSetVector<BasicBlock *, 8>::iterator I = ExitBlockSet.begin(),
PHINode *PN;
for (BasicBlock::iterator I = L->getHeader()->begin();
(PN = dyn_cast<PHINode>(I++)); )
- if (Value *V = PN->hasConstantValue(DT)) {
+ if (Value *V = SimplifyInstruction(PN, 0, DT)) {
if (AA) AA->deleteValue(PN);
+ if (SE) SE->forgetValue(PN);
PN->replaceAllUsesWith(V);
PN->eraseFromParent();
}
if (!FoldBranchToCommonDest(BI)) continue;
// Success. The block is now dead, so remove it from the loop,
- // update the dominator tree and dominance frontier, and delete it.
-
- DEBUG(dbgs() << "LoopSimplify: Eliminating exiting block ";
- WriteAsOperand(dbgs(), ExitingBlock, false);
- dbgs() << "\n");
+ // update the dominator tree and delete it.
+ DEBUG(dbgs() << "LoopSimplify: Eliminating exiting block "
+ << ExitingBlock->getName() << "\n");
+
+ // If any reachable control flow within this loop has changed, notify
+ // ScalarEvolution. Currently assume the parent loop doesn't change
+ // (spliting edges doesn't count). If blocks, CFG edges, or other values
+ // in the parent loop change, then we need call to forgetLoop() for the
+ // parent instead.
+ if (SE)
+ SE->forgetLoop(L);
assert(pred_begin(ExitingBlock) == pred_end(ExitingBlock));
Changed = true;
LI->removeBlock(ExitingBlock);
- DominanceFrontier *DF = getAnalysisIfAvailable<DominanceFrontier>();
DomTreeNode *Node = DT->getNode(ExitingBlock);
const std::vector<DomTreeNodeBase<BasicBlock> *> &Children =
Node->getChildren();
while (!Children.empty()) {
DomTreeNode *Child = Children.front();
DT->changeImmediateDominator(Child, Node->getIDom());
- if (DF) DF->changeImmediateDominator(Child->getBlock(),
- Node->getIDom()->getBlock(),
- DT);
}
DT->eraseNode(ExitingBlock);
- if (DF) DF->removeBlock(ExitingBlock);
BI->getSuccessor(0)->removePredecessor(ExitingBlock);
BI->getSuccessor(1)->removePredecessor(ExitingBlock);
SplitBlockPredecessors(Header, &OutsideBlocks[0], OutsideBlocks.size(),
".preheader", this);
- DEBUG(dbgs() << "LoopSimplify: Creating pre-header ";
- WriteAsOperand(dbgs(), NewBB, false);
- dbgs() << "\n");
+ NewBB->getTerminator()->setDebugLoc(Header->getFirstNonPHI()->getDebugLoc());
+ DEBUG(dbgs() << "LoopSimplify: Creating pre-header " << NewBB->getName()
+ << "\n");
// Make sure that NewBB is put someplace intelligent, which doesn't mess up
// code layout too horribly.
}
assert(!LoopBlocks.empty() && "No edges coming in from outside the loop?");
- BasicBlock *NewBB = SplitBlockPredecessors(Exit, &LoopBlocks[0],
+ BasicBlock *NewBB = SplitBlockPredecessors(Exit, &LoopBlocks[0],
LoopBlocks.size(), ".loopexit",
this);
- DEBUG(dbgs() << "LoopSimplify: Creating dedicated exit block ";
- WriteAsOperand(dbgs(), NewBB, false);
- dbgs() << "\n");
-
+ DEBUG(dbgs() << "LoopSimplify: Creating dedicated exit block "
+ << NewBB->getName() << "\n");
return NewBB;
}
/// FindPHIToPartitionLoops - 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, DominatorTree *DT,
- AliasAnalysis *AA) {
+ AliasAnalysis *AA, LoopInfo *LI) {
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
++I;
- if (Value *V = PN->hasConstantValue(DT)) {
+ if (Value *V = SimplifyInstruction(PN, 0, DT)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
if (AA) AA->deleteValue(PN);
if (&*BBI == SplitPreds[i])
return;
}
-
+
// If it isn't already after an outside block, move it after one. This is
// always good as it makes the uncond branch from the outside block into a
// fall-through.
-
+
// Figure out *which* outside block to put this after. Prefer an outside
// block that neighbors a BB actually in the loop.
BasicBlock *FoundBB = 0;
for (unsigned i = 0, e = SplitPreds.size(); i != e; ++i) {
Function::iterator BBI = SplitPreds[i];
- if (++BBI != NewBB->getParent()->end() &&
+ if (++BBI != NewBB->getParent()->end() &&
L->contains(BBI)) {
FoundBB = SplitPreds[i];
break;
}
}
-
+
// If our heuristic for a *good* bb to place this after doesn't find
// anything, just pick something. It's likely better than leaving it within
// the loop.
/// created.
///
Loop *LoopSimplify::SeparateNestedLoop(Loop *L, LPPassManager &LPM) {
- PHINode *PN = FindPHIToPartitionLoops(L, DT, AA);
+ PHINode *PN = FindPHIToPartitionLoops(L, DT, AA, LI);
if (PN == 0) return 0; // No known way to partition.
// Pull out all predecessors that have varying values in the loop. This
DEBUG(dbgs() << "LoopSimplify: Splitting out a new outer loop\n");
+ // If ScalarEvolution is around and knows anything about values in
+ // this loop, tell it to forget them, because we're about to
+ // substantially change it.
+ if (SE)
+ SE->forgetLoop(L);
+
BasicBlock *Header = L->getHeader();
BasicBlock *NewBB = SplitBlockPredecessors(Header, &OuterLoopPreds[0],
OuterLoopPreds.size(),
// Make sure that NewBB is put someplace intelligent, which doesn't mess up
// code layout too horribly.
PlaceSplitBlockCarefully(NewBB, OuterLoopPreds, L);
-
+
// Create the new outer loop.
Loop *NewOuter = new Loop();
std::vector<BasicBlock*> BackedgeBlocks;
for (pred_iterator I = pred_begin(Header), E = pred_end(Header); I != E; ++I){
BasicBlock *P = *I;
+
+ // Indirectbr edges cannot be split, so we must fail if we find one.
+ if (isa<IndirectBrInst>(P->getTerminator()))
+ return 0;
+
if (P != Preheader) BackedgeBlocks.push_back(P);
}
Header->getName()+".backedge", F);
BranchInst *BETerminator = BranchInst::Create(Header, BEBlock);
- DEBUG(dbgs() << "LoopSimplify: Inserting unique backedge block ";
- WriteAsOperand(dbgs(), BEBlock, false);
- dbgs() << "\n");
+ DEBUG(dbgs() << "LoopSimplify: Inserting unique backedge block "
+ << BEBlock->getName() << "\n");
// Move the new backedge block to right after the last backedge block.
Function::iterator InsertPos = BackedgeBlocks.back(); ++InsertPos;
// the backedge block which correspond to any PHI nodes in the header block.
for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
PHINode *PN = cast<PHINode>(I);
- PHINode *NewPN = PHINode::Create(PN->getType(), PN->getName()+".be",
- BETerminator);
- NewPN->reserveOperandSpace(BackedgeBlocks.size());
+ 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
// Update dominator information
DT->splitBlock(BEBlock);
- if (DominanceFrontier *DF = getAnalysisIfAvailable<DominanceFrontier>())
- DF->splitBlock(BEBlock);
return BEBlock;
}
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