//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "indvars"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFG.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.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/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/SimplifyIndVar.h"
using namespace llvm;
+#define DEBUG_TYPE "indvars"
+
STATISTIC(NumWidened , "Number of indvars widened");
STATISTIC(NumReplaced , "Number of exit values replaced");
STATISTIC(NumLFTR , "Number of loop exit tests replaced");
LoopInfo *LI;
ScalarEvolution *SE;
DominatorTree *DT;
- DataLayout *TD;
+ const DataLayout *DL;
TargetLibraryInfo *TLI;
SmallVector<WeakVH, 16> DeadInsts;
public:
static char ID; // Pass identification, replacement for typeid
- IndVarSimplify() : LoopPass(ID), LI(0), SE(0), DT(0), TD(0),
+ IndVarSimplify() : LoopPass(ID), LI(0), SE(0), DT(0), DL(0),
Changed(false) {
initializeIndVarSimplifyPass(*PassRegistry::getPassRegistry());
}
- virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
+ bool runOnLoop(Loop *L, LPPassManager &LPM) override;
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<DominatorTree>();
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<LoopInfo>();
AU.addRequired<ScalarEvolution>();
AU.addRequiredID(LoopSimplifyID);
}
private:
- virtual void releaseMemory() {
+ void releaseMemory() override {
DeadInsts.clear();
}
char IndVarSimplify::ID = 0;
INITIALIZE_PASS_BEGIN(IndVarSimplify, "indvars",
"Induction Variable Simplification", false, false)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LoopInfo)
INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
// Check Incr uses. One user is PN and the other user is an exit condition
// used by the conditional terminator.
- Value::use_iterator IncrUse = Incr->use_begin();
+ Value::user_iterator IncrUse = Incr->user_begin();
Instruction *U1 = cast<Instruction>(*IncrUse++);
- if (IncrUse == Incr->use_end()) return;
+ if (IncrUse == Incr->user_end()) return;
Instruction *U2 = cast<Instruction>(*IncrUse++);
- if (IncrUse != Incr->use_end()) return;
+ if (IncrUse != Incr->user_end()) return;
// Find exit condition, which is an fcmp. If it doesn't exist, or if it isn't
// only used by a branch, we can't transform it.
if (!Compare)
Compare = dyn_cast<FCmpInst>(U2);
if (Compare == 0 || !Compare->hasOneUse() ||
- !isa<BranchInst>(Compare->use_back()))
+ !isa<BranchInst>(Compare->user_back()))
return;
- BranchInst *TheBr = cast<BranchInst>(Compare->use_back());
+ BranchInst *TheBr = cast<BranchInst>(Compare->user_back());
// We need to verify that the branch actually controls the iteration count
// of the loop. If not, the new IV can overflow and no one will notice.
unsigned NumPreds = PN->getNumIncomingValues();
+ // We would like to be able to RAUW single-incoming value PHI nodes. We
+ // have to be certain this is safe even when this is an LCSSA PHI node.
+ // While the computed exit value is no longer varying in *this* loop, the
+ // exit block may be an exit block for an outer containing loop as well,
+ // the exit value may be varying in the outer loop, and thus it may still
+ // require an LCSSA PHI node. The safe case is when this is
+ // single-predecessor PHI node (LCSSA) and the exit block containing it is
+ // part of the enclosing loop, or this is the outer most loop of the nest.
+ // In either case the exit value could (at most) be varying in the same
+ // loop body as the phi node itself. Thus if it is in turn used outside of
+ // an enclosing loop it will only be via a separate LCSSA node.
+ bool LCSSASafePhiForRAUW =
+ NumPreds == 1 &&
+ (!L->getParentLoop() || L->getParentLoop() == LI->getLoopFor(ExitBB));
+
// Iterate over all of the PHI nodes.
BasicBlock::iterator BBI = ExitBB->begin();
while ((PN = dyn_cast<PHINode>(BBI++))) {
unsigned NumHardInternalUses = 0;
unsigned NumSoftExternalUses = 0;
unsigned NumUses = 0;
- for (Value::use_iterator IB=Inst->use_begin(), IE=Inst->use_end();
- IB!=IE && NumUses<=6 ; ++IB) {
+ for (auto IB = Inst->user_begin(), IE = Inst->user_end();
+ IB != IE && NumUses <= 6; ++IB) {
Instruction *UseInstr = cast<Instruction>(*IB);
unsigned Opc = UseInstr->getOpcode();
NumUses++;
// Do not count the Phi as a use. LCSSA may have inserted
// plenty of trivial ones.
NumUses--;
- for (Value::use_iterator PB=UseInstr->use_begin(),
- PE=UseInstr->use_end();
- PB!=PE && NumUses<=6 ; ++PB, ++NumUses) {
+ for (auto PB = UseInstr->user_begin(),
+ PE = UseInstr->user_end();
+ PB != PE && NumUses <= 6; ++PB, ++NumUses) {
unsigned PhiOpc = cast<Instruction>(*PB)->getOpcode();
if (PhiOpc != Instruction::Call && PhiOpc != Instruction::Ret)
NumSoftExternalUses++;
if (isInstructionTriviallyDead(Inst, TLI))
DeadInsts.push_back(Inst);
- if (NumPreds == 1) {
- // Completely replace a single-pred PHI. This is safe, because the
- // NewVal won't be variant in the loop, so we don't need an LCSSA phi
- // node anymore.
+ // If we determined that this PHI is safe to replace even if an LCSSA
+ // PHI, do so.
+ if (LCSSASafePhiForRAUW) {
PN->replaceAllUsesWith(ExitVal);
PN->eraseFromParent();
}
}
- if (NumPreds != 1) {
- // Clone the PHI and delete the original one. This lets IVUsers and
- // any other maps purge the original user from their records.
+
+ // If we were unable to completely replace the PHI node, clone the PHI
+ // and delete the original one. This lets IVUsers and any other maps
+ // purge the original user from their records.
+ if (!LCSSASafePhiForRAUW) {
PHINode *NewPN = cast<PHINode>(PN->clone());
NewPN->takeName(PN);
NewPN->insertBefore(PN);
WideIVInfo() : NarrowIV(0), WidestNativeType(0), IsSigned(false) {}
};
-
- class WideIVVisitor : public IVVisitor {
- ScalarEvolution *SE;
- const DataLayout *TD;
-
- public:
- WideIVInfo WI;
-
- WideIVVisitor(PHINode *NarrowIV, ScalarEvolution *SCEV,
- const DataLayout *TData, const DominatorTree *DTree):
- SE(SCEV), TD(TData) {
- DT = DTree;
- WI.NarrowIV = NarrowIV;
- }
-
- // Implement the interface used by simplifyUsersOfIV.
- virtual void visitCast(CastInst *Cast);
- };
}
/// visitCast - Update information about the induction variable that is
/// extended by this sign or zero extend operation. This is used to determine
/// the final width of the IV before actually widening it.
-void WideIVVisitor::visitCast(CastInst *Cast) {
+static void visitIVCast(CastInst *Cast, WideIVInfo &WI, ScalarEvolution *SE,
+ const DataLayout *DL) {
bool IsSigned = Cast->getOpcode() == Instruction::SExt;
if (!IsSigned && Cast->getOpcode() != Instruction::ZExt)
return;
Type *Ty = Cast->getType();
uint64_t Width = SE->getTypeSizeInBits(Ty);
- if (TD && !TD->isLegalInteger(Width))
+ if (DL && !DL->isLegalInteger(Width))
return;
if (!WI.WidestNativeType) {
return AddRec;
}
+/// This IV user cannot be widen. Replace this use of the original narrow IV
+/// with a truncation of the new wide IV to isolate and eliminate the narrow IV.
+static void truncateIVUse(NarrowIVDefUse DU, DominatorTree *DT) {
+ DEBUG(dbgs() << "INDVARS: Truncate IV " << *DU.WideDef
+ << " for user " << *DU.NarrowUse << "\n");
+ IRBuilder<> Builder(getInsertPointForUses(DU.NarrowUse, DU.NarrowDef, DT));
+ Value *Trunc = Builder.CreateTrunc(DU.WideDef, DU.NarrowDef->getType());
+ DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, Trunc);
+}
+
/// WidenIVUse - Determine whether an individual user of the narrow IV can be
/// widened. If so, return the wide clone of the user.
Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter) {
// Stop traversing the def-use chain at inner-loop phis or post-loop phis.
- if (isa<PHINode>(DU.NarrowUse) &&
- LI->getLoopFor(DU.NarrowUse->getParent()) != L)
- return 0;
-
+ if (PHINode *UsePhi = dyn_cast<PHINode>(DU.NarrowUse)) {
+ if (LI->getLoopFor(UsePhi->getParent()) != L) {
+ // For LCSSA phis, sink the truncate outside the loop.
+ // After SimplifyCFG most loop exit targets have a single predecessor.
+ // Otherwise fall back to a truncate within the loop.
+ if (UsePhi->getNumOperands() != 1)
+ truncateIVUse(DU, DT);
+ else {
+ PHINode *WidePhi =
+ PHINode::Create(DU.WideDef->getType(), 1, UsePhi->getName() + ".wide",
+ UsePhi);
+ WidePhi->addIncoming(DU.WideDef, UsePhi->getIncomingBlock(0));
+ IRBuilder<> Builder(WidePhi->getParent()->getFirstInsertionPt());
+ Value *Trunc = Builder.CreateTrunc(WidePhi, DU.NarrowDef->getType());
+ UsePhi->replaceAllUsesWith(Trunc);
+ DeadInsts.push_back(UsePhi);
+ DEBUG(dbgs() << "INDVARS: Widen lcssa phi " << *UsePhi
+ << " to " << *WidePhi << "\n");
+ }
+ return 0;
+ }
+ }
// Our raison d'etre! Eliminate sign and zero extension.
if (IsSigned ? isa<SExtInst>(DU.NarrowUse) : isa<ZExtInst>(DU.NarrowUse)) {
Value *NewDef = DU.WideDef;
// This user does not evaluate to a recurence after widening, so don't
// follow it. Instead insert a Trunc to kill off the original use,
// eventually isolating the original narrow IV so it can be removed.
- IRBuilder<> Builder(getInsertPointForUses(DU.NarrowUse, DU.NarrowDef, DT));
- Value *Trunc = Builder.CreateTrunc(DU.WideDef, DU.NarrowDef->getType());
- DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, Trunc);
+ truncateIVUse(DU, DT);
return 0;
}
// Assume block terminators cannot evaluate to a recurrence. We can't to
/// pushNarrowIVUsers - Add eligible users of NarrowDef to NarrowIVUsers.
///
void WidenIV::pushNarrowIVUsers(Instruction *NarrowDef, Instruction *WideDef) {
- for (Value::use_iterator UI = NarrowDef->use_begin(),
- UE = NarrowDef->use_end(); UI != UE; ++UI) {
- Instruction *NarrowUse = cast<Instruction>(*UI);
+ for (User *U : NarrowDef->users()) {
+ Instruction *NarrowUser = cast<Instruction>(U);
// Handle data flow merges and bizarre phi cycles.
- if (!Widened.insert(NarrowUse))
+ if (!Widened.insert(NarrowUser))
continue;
- NarrowIVUsers.push_back(NarrowIVDefUse(NarrowDef, NarrowUse, WideDef));
+ NarrowIVUsers.push_back(NarrowIVDefUse(NarrowDef, NarrowUser, WideDef));
}
}
return WidePhi;
}
+//===----------------------------------------------------------------------===//
+// Live IV Reduction - Minimize IVs live across the loop.
+//===----------------------------------------------------------------------===//
+
+
//===----------------------------------------------------------------------===//
// Simplification of IV users based on SCEV evaluation.
//===----------------------------------------------------------------------===//
+namespace {
+ class IndVarSimplifyVisitor : public IVVisitor {
+ ScalarEvolution *SE;
+ const DataLayout *DL;
+ PHINode *IVPhi;
+
+ public:
+ WideIVInfo WI;
+
+ IndVarSimplifyVisitor(PHINode *IV, ScalarEvolution *SCEV,
+ const DataLayout *DL, const DominatorTree *DTree):
+ SE(SCEV), DL(DL), IVPhi(IV) {
+ DT = DTree;
+ WI.NarrowIV = IVPhi;
+ if (ReduceLiveIVs)
+ setSplitOverflowIntrinsics();
+ }
+
+ // Implement the interface used by simplifyUsersOfIV.
+ void visitCast(CastInst *Cast) override { visitIVCast(Cast, WI, SE, DL); }
+ };
+}
/// SimplifyAndExtend - Iteratively perform simplification on a worklist of IV
/// users. Each successive simplification may push more users which may
PHINode *CurrIV = LoopPhis.pop_back_val();
// Information about sign/zero extensions of CurrIV.
- WideIVVisitor WIV(CurrIV, SE, TD, DT);
- if (ReduceLiveIVs)
- WIV.setSplitOverflowIntrinsics();
+ IndVarSimplifyVisitor Visitor(CurrIV, SE, DL, DT);
- Changed |= simplifyUsersOfIV(CurrIV, SE, &LPM, DeadInsts, &WIV);
+ Changed |= simplifyUsersOfIV(CurrIV, SE, &LPM, DeadInsts, &Visitor);
- if (WIV.WI.WidestNativeType) {
- WideIVs.push_back(WIV.WI);
+ if (Visitor.WI.WidestNativeType) {
+ WideIVs.push_back(Visitor.WI);
}
} while(!LoopPhis.empty());
int LatchIdx = Phi->getBasicBlockIndex(LatchBlock);
Value *IncV = Phi->getIncomingValue(LatchIdx);
- for (Value::use_iterator UI = Phi->use_begin(), UE = Phi->use_end();
- UI != UE; ++UI) {
- if (*UI != Cond && *UI != IncV) return false;
- }
+ for (User *U : Phi->users())
+ if (U != Cond && U != IncV) return false;
- for (Value::use_iterator UI = IncV->use_begin(), UE = IncV->use_end();
- UI != UE; ++UI) {
- if (*UI != Cond && *UI != Phi) return false;
- }
+ for (User *U : IncV->users())
+ if (U != Cond && U != Phi) return false;
return true;
}
/// could at least handle constant BECounts.
static PHINode *
FindLoopCounter(Loop *L, const SCEV *BECount,
- ScalarEvolution *SE, DominatorTree *DT, const DataLayout *TD) {
+ ScalarEvolution *SE, DominatorTree *DT, const DataLayout *DL) {
uint64_t BCWidth = SE->getTypeSizeInBits(BECount->getType());
Value *Cond =
// AR may be wider than BECount. With eq/ne tests overflow is immaterial.
// AR may not be a narrower type, or we may never exit.
uint64_t PhiWidth = SE->getTypeSizeInBits(AR->getType());
- if (PhiWidth < BCWidth || (TD && !TD->isLegalInteger(PhiWidth)))
+ if (PhiWidth < BCWidth || (DL && !DL->isLegalInteger(PhiWidth)))
continue;
const SCEV *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*SE));
// Determine if there is a use in or before the loop (direct or
// otherwise).
bool UsedInLoop = false;
- for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
- UI != UE; ++UI) {
- User *U = *UI;
- BasicBlock *UseBB = cast<Instruction>(U)->getParent();
- if (PHINode *P = dyn_cast<PHINode>(U)) {
+ for (Use &U : I->uses()) {
+ Instruction *User = cast<Instruction>(U.getUser());
+ BasicBlock *UseBB = User->getParent();
+ if (PHINode *P = dyn_cast<PHINode>(User)) {
unsigned i =
- PHINode::getIncomingValueNumForOperand(UI.getOperandNo());
+ PHINode::getIncomingValueNumForOperand(U.getOperandNo());
UseBB = P->getIncomingBlock(i);
}
if (UseBB == Preheader || L->contains(UseBB)) {
//===----------------------------------------------------------------------===//
bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
+ if (skipOptnoneFunction(L))
+ return false;
+
// If LoopSimplify form is not available, stay out of trouble. Some notes:
// - LSR currently only supports LoopSimplify-form loops. Indvars'
// canonicalization can be a pessimization without LSR to "clean up"
LI = &getAnalysis<LoopInfo>();
SE = &getAnalysis<ScalarEvolution>();
- DT = &getAnalysis<DominatorTree>();
- TD = getAnalysisIfAvailable<DataLayout>();
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+ DL = DLP ? &DLP->getDataLayout() : 0;
TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
DeadInsts.clear();
// If we have a trip count expression, rewrite the loop's exit condition
// using it. We can currently only handle loops with a single exit.
if (canExpandBackedgeTakenCount(L, SE) && needsLFTR(L, DT)) {
- PHINode *IndVar = FindLoopCounter(L, BackedgeTakenCount, SE, DT, TD);
+ PHINode *IndVar = FindLoopCounter(L, BackedgeTakenCount, SE, DT, DL);
if (IndVar) {
// Check preconditions for proper SCEVExpander operation. SCEV does not
// express SCEVExpander's dependencies, such as LoopSimplify. Instead any
// pass that uses the SCEVExpander must do it. This does not work well for
- // loop passes because SCEVExpander makes assumptions about all loops, while
- // LoopPassManager only forces the current loop to be simplified.
+ // loop passes because SCEVExpander makes assumptions about all loops,
+ // while LoopPassManager only forces the current loop to be simplified.
//
// FIXME: SCEV expansion has no way to bail out, so the caller must
// explicitly check any assumptions made by SCEV. Brittle.
projects / oota-llvm.git / blobdiff