#define DEBUG_TYPE "loop-simplify"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Constants.h"
-#include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/Function.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Type.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SetOperations.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/DependenceAnalysis.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"
-#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Type.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
-#include "llvm/ADT/SetOperations.h"
-#include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
STATISTIC(NumInserted, "Number of pre-header or exit blocks inserted");
AU.addPreserved<AliasAnalysis>();
AU.addPreserved<ScalarEvolution>();
+ AU.addPreserved<DependenceAnalysis>();
AU.addPreservedID(BreakCriticalEdgesID); // No critical edges added.
}
bool ProcessLoop(Loop *L, LPPassManager &LPM);
BasicBlock *RewriteLoopExitBlock(Loop *L, BasicBlock *Exit);
BasicBlock *InsertPreheaderForLoop(Loop *L);
- Loop *SeparateNestedLoop(Loop *L, LPPassManager &LPM);
+ Loop *SeparateNestedLoop(Loop *L, LPPassManager &LPM,
+ BasicBlock *Preheader);
BasicBlock *InsertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader);
void PlaceSplitBlockCarefully(BasicBlock *NewBB,
SmallVectorImpl<BasicBlock*> &SplitPreds,
BI->setCondition(ConstantInt::get(Cond->getType(),
!L->contains(BI->getSuccessor(0))));
+
+ // This may make the loop analyzable, force SCEV recomputation.
+ if (SE)
+ SE->forgetLoop(L);
+
Changed = true;
}
}
// this for loops with a giant number of backedges, just factor them into a
// common backedge instead.
if (L->getNumBackEdges() < 8) {
- if (SeparateNestedLoop(L, LPM)) {
+ if (SeparateNestedLoop(L, LPM, Preheader)) {
++NumNested;
// This is a big restructuring change, reprocess the whole loop.
Changed = true;
PHINode *PN;
for (BasicBlock::iterator I = L->getHeader()->begin();
(PN = dyn_cast<PHINode>(I++)); )
- if (Value *V = SimplifyInstruction(PN, 0, DT)) {
+ if (Value *V = SimplifyInstruction(PN, 0, 0, DT)) {
if (AA) AA->deleteValue(PN);
if (SE) SE->forgetValue(PN);
PN->replaceAllUsesWith(V);
}
// Split out the loop pre-header.
- BasicBlock *NewBB =
- SplitBlockPredecessors(Header, &OutsideBlocks[0], OutsideBlocks.size(),
- ".preheader", this);
+ BasicBlock *PreheaderBB;
+ if (!Header->isLandingPad()) {
+ PreheaderBB = SplitBlockPredecessors(Header, OutsideBlocks, ".preheader",
+ this);
+ } else {
+ SmallVector<BasicBlock*, 2> NewBBs;
+ SplitLandingPadPredecessors(Header, OutsideBlocks, ".preheader",
+ ".split-lp", this, NewBBs);
+ PreheaderBB = NewBBs[0];
+ }
- NewBB->getTerminator()->setDebugLoc(Header->getFirstNonPHI()->getDebugLoc());
- DEBUG(dbgs() << "LoopSimplify: Creating pre-header " << NewBB->getName()
- << "\n");
+ PreheaderBB->getTerminator()->setDebugLoc(
+ Header->getFirstNonPHI()->getDebugLoc());
+ DEBUG(dbgs() << "LoopSimplify: Creating pre-header "
+ << PreheaderBB->getName() << "\n");
// Make sure that NewBB is put someplace intelligent, which doesn't mess up
// code layout too horribly.
- PlaceSplitBlockCarefully(NewBB, OutsideBlocks, L);
+ PlaceSplitBlockCarefully(PreheaderBB, OutsideBlocks, L);
- return NewBB;
+ return PreheaderBB;
}
/// RewriteLoopExitBlock - Ensure that the loop preheader dominates all exit
/// blocks. This method is used to split exit blocks that have predecessors
/// outside of the loop.
BasicBlock *LoopSimplify::RewriteLoopExitBlock(Loop *L, BasicBlock *Exit) {
- // Don't split a landing pad block.
- if (Exit->isLandingPad()) return 0;
-
SmallVector<BasicBlock*, 8> LoopBlocks;
for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit); I != E; ++I) {
BasicBlock *P = *I;
}
assert(!LoopBlocks.empty() && "No edges coming in from outside the loop?");
- BasicBlock *NewBB = SplitBlockPredecessors(Exit, &LoopBlocks[0],
- LoopBlocks.size(), ".loopexit",
- this);
+ BasicBlock *NewExitBB = 0;
+
+ if (Exit->isLandingPad()) {
+ SmallVector<BasicBlock*, 2> NewBBs;
+ SplitLandingPadPredecessors(Exit, ArrayRef<BasicBlock*>(&LoopBlocks[0],
+ LoopBlocks.size()),
+ ".loopexit", ".nonloopexit",
+ this, NewBBs);
+ NewExitBB = NewBBs[0];
+ } else {
+ NewExitBB = SplitBlockPredecessors(Exit, LoopBlocks, ".loopexit", this);
+ }
DEBUG(dbgs() << "LoopSimplify: Creating dedicated exit block "
- << NewBB->getName() << "\n");
- return NewBB;
+ << NewExitBB->getName() << "\n");
+ return NewExitBB;
}
/// AddBlockAndPredsToSet - Add the specified block, and all of its
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
++I;
- if (Value *V = SimplifyInstruction(PN, 0, DT)) {
+ if (Value *V = SimplifyInstruction(PN, 0, 0, DT)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
if (AA) AA->deleteValue(PN);
/// If we are able to separate out a loop, return the new outer loop that was
/// created.
///
-Loop *LoopSimplify::SeparateNestedLoop(Loop *L, LPPassManager &LPM) {
+Loop *LoopSimplify::SeparateNestedLoop(Loop *L, LPPassManager &LPM,
+ BasicBlock *Preheader) {
+ // Don't try to separate loops without a preheader.
+ if (!Preheader)
+ return 0;
+
+ // The header is not a landing pad; preheader insertion should ensure this.
+ assert(!L->getHeader()->isLandingPad() &&
+ "Can't insert backedge to landing pad");
+
PHINode *PN = FindPHIToPartitionLoops(L, DT, AA, LI);
if (PN == 0) return 0; // No known way to partition.
// handles the case when a PHI node has multiple instances of itself as
// arguments.
SmallVector<BasicBlock*, 8> OuterLoopPreds;
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
if (PN->getIncomingValue(i) != PN ||
!L->contains(PN->getIncomingBlock(i))) {
// We can't split indirectbr edges.
if (isa<IndirectBrInst>(PN->getIncomingBlock(i)->getTerminator()))
return 0;
-
OuterLoopPreds.push_back(PN->getIncomingBlock(i));
}
-
+ }
DEBUG(dbgs() << "LoopSimplify: Splitting out a new outer loop\n");
// If ScalarEvolution is around and knows anything about values in
SE->forgetLoop(L);
BasicBlock *Header = L->getHeader();
- BasicBlock *NewBB = SplitBlockPredecessors(Header, &OuterLoopPreds[0],
- OuterLoopPreds.size(),
- ".outer", this);
+ BasicBlock *NewBB =
+ SplitBlockPredecessors(Header, OuterLoopPreds, ".outer", this);
// Make sure that NewBB is put someplace intelligent, which doesn't mess up
// code layout too horribly.
if (!Preheader)
return 0;
+ // The header is not a landing pad; preheader insertion should ensure this.
+ assert(!Header->isLandingPad() && "Can't insert backedge to landing pad");
+
// Figure out which basic blocks contain back-edges to the loop header.
std::vector<BasicBlock*> BackedgeBlocks;
for (pred_iterator I = pred_begin(Header), E = pred_end(Header); I != E; ++I){
(void)HasIndBrPred;
}
- // Indirectbr and LandingPad can interfere with exit block canonicalization.
+ // Indirectbr can interfere with exit block canonicalization.
if (!L->hasDedicatedExits()) {
bool HasIndBrExiting = false;
- bool HasLPadExiting = false;
SmallVector<BasicBlock*, 8> ExitingBlocks;
L->getExitingBlocks(ExitingBlocks);
for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
HasIndBrExiting = true;
break;
}
- if (const InvokeInst *II =
- dyn_cast<InvokeInst>(ExitingBlocks[i]->getTerminator())) {
- if (L->contains(II->getNormalDest()) &&
- !L->contains(II->getUnwindDest())) {
- HasLPadExiting = true;
- break;
- }
- }
}
- assert((HasIndBrExiting || HasLPadExiting) &&
+ assert(HasIndBrExiting &&
"LoopSimplify has no excuse for missing exit block info!");
- (void)HasIndBrExiting; (void)HasLPadExiting;
+ (void)HasIndBrExiting;
}
}
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