bool Changed;
public:
- SimplifyIndvar(Loop *Loop, LPPassManager *LPM,
+ SimplifyIndvar(Loop *Loop, ScalarEvolution *SE, LPPassManager *LPM,
SmallVectorImpl<WeakVH> &Dead, IVUsers *IVU = NULL) :
L(Loop),
LI(LPM->getAnalysisIfAvailable<LoopInfo>()),
- SE(LPM->getAnalysisIfAvailable<ScalarEvolution>()),
+ SE(SE),
IU(IVU),
TD(LPM->getAnalysisIfAvailable<TargetData>()),
DeadInsts(Dead),
Changed(false) {
- assert(LI && SE && "IV simplification requires ScalarEvolution");
+ assert(LI && "IV simplification requires LoopInfo");
}
bool hasChanged() const { return Changed; }
/// all simplicitions to users of an IV.
void simplifyUsers(PHINode *CurrIV, IVVisitor *V = NULL);
- bool foldIVUser(Instruction *UseInst, Instruction *IVOperand);
+ Value *foldIVUser(Instruction *UseInst, Instruction *IVOperand);
bool eliminateIVUser(Instruction *UseInst, Instruction *IVOperand);
void eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand);
/// foldIVUser - Fold an IV operand into its use. This removes increments of an
/// aligned IV when used by a instruction that ignores the low bits.
-bool SimplifyIndvar::foldIVUser(Instruction *UseInst, Instruction *IVOperand) {
+///
+/// IVOperand is guaranteed SCEVable, but UseInst may not be.
+///
+/// Return the operand of IVOperand for this induction variable if IVOperand can
+/// be folded (in case more folding opportunities have been exposed).
+/// Otherwise return null.
+Value *SimplifyIndvar::foldIVUser(Instruction *UseInst, Instruction *IVOperand) {
Value *IVSrc = 0;
unsigned OperIdx = 0;
const SCEV *FoldedExpr = 0;
switch (UseInst->getOpcode()) {
default:
- return false;
+ return 0;
case Instruction::UDiv:
case Instruction::LShr:
// We're only interested in the case where we know something about
// the numerator and have a constant denominator.
if (IVOperand != UseInst->getOperand(OperIdx) ||
!isa<ConstantInt>(UseInst->getOperand(1)))
- return false;
+ return 0;
// Attempt to fold a binary operator with constant operand.
// e.g. ((I + 1) >> 2) => I >> 2
- if (IVOperand->getNumOperands() != 2 ||
- !isa<ConstantInt>(IVOperand->getOperand(1)))
- return false;
+ if (!isa<BinaryOperator>(IVOperand)
+ || !isa<ConstantInt>(IVOperand->getOperand(1)))
+ return 0;
IVSrc = IVOperand->getOperand(0);
// IVSrc must be the (SCEVable) IV, since the other operand is const.
// Get a constant for the divisor. See createSCEV.
uint32_t BitWidth = cast<IntegerType>(UseInst->getType())->getBitWidth();
if (D->getValue().uge(BitWidth))
- return false;
+ return 0;
D = ConstantInt::get(UseInst->getContext(),
APInt(BitWidth, 1).shl(D->getZExtValue()));
}
// We have something that might fold it's operand. Compare SCEVs.
if (!SE->isSCEVable(UseInst->getType()))
- return false;
+ return 0;
// Bypass the operand if SCEV can prove it has no effect.
if (SE->getSCEV(UseInst) != FoldedExpr)
- return false;
+ return 0;
DEBUG(dbgs() << "INDVARS: Eliminated IV operand: " << *IVOperand
<< " -> " << *UseInst << '\n');
Changed = true;
if (IVOperand->use_empty())
DeadInsts.push_back(IVOperand);
- return true;
+ return IVSrc;
}
/// eliminateIVComparison - SimplifyIVUsers helper for eliminating useless
return;
ICmpInst *ICmp = new ICmpInst(Rem, ICmpInst::ICMP_EQ,
- Rem->getOperand(0), Rem->getOperand(1),
- "tmp");
+ Rem->getOperand(0), Rem->getOperand(1));
SelectInst *Sel =
SelectInst::Create(ICmp,
ConstantInt::get(Rem->getType(), 0),
/// eliminateIVUser - Eliminate an operation that consumes a simple IV and has
/// no observable side-effect given the range of IV values.
+/// IVOperand is guaranteed SCEVable, but UseInst may not be.
bool SimplifyIndvar::eliminateIVUser(Instruction *UseInst,
Instruction *IVOperand) {
if (ICmpInst *ICmp = dyn_cast<ICmpInst>(UseInst)) {
/// isSimpleIVUser - Return true if this instruction generates a simple SCEV
/// expression in terms of that IV.
///
-/// This is similar to IVUsers' isInsteresting() but processes each instruction
+/// This is similar to IVUsers' isInteresting() but processes each instruction
/// non-recursively when the operand is already known to be a simpleIVUser.
///
static bool isSimpleIVUser(Instruction *I, const Loop *L, ScalarEvolution *SE) {
/// Once DisableIVRewrite is default, LSR will be the only client of IVUsers.
///
void SimplifyIndvar::simplifyUsers(PHINode *CurrIV, IVVisitor *V) {
+ if (!SE->isSCEVable(CurrIV->getType()))
+ return;
+
// Instructions processed by SimplifyIndvar for CurrIV.
SmallPtrSet<Instruction*,16> Simplified;
// Bypass back edges to avoid extra work.
if (UseOper.first == CurrIV) continue;
- foldIVUser(UseOper.first, UseOper.second);
+ Instruction *IVOperand = UseOper.second;
+ for (unsigned N = 0; IVOperand; ++N) {
+ assert(N <= Simplified.size() && "runaway iteration");
+
+ Value *NewOper = foldIVUser(UseOper.first, IVOperand);
+ if (!NewOper)
+ break; // done folding
+ IVOperand = dyn_cast<Instruction>(NewOper);
+ }
+ if (!IVOperand)
+ continue;
- if (eliminateIVUser(UseOper.first, UseOper.second)) {
- pushIVUsers(UseOper.second, Simplified, SimpleIVUsers);
+ if (eliminateIVUser(UseOper.first, IVOperand)) {
+ pushIVUsers(IVOperand, Simplified, SimpleIVUsers);
continue;
}
CastInst *Cast = dyn_cast<CastInst>(UseOper.first);
/// simplifyUsersOfIV - Simplify instructions that use this induction variable
/// by using ScalarEvolution to analyze the IV's recurrence.
-bool simplifyUsersOfIV(PHINode *CurrIV, LPPassManager *LPM,
+bool simplifyUsersOfIV(PHINode *CurrIV, ScalarEvolution *SE, LPPassManager *LPM,
SmallVectorImpl<WeakVH> &Dead, IVVisitor *V)
{
LoopInfo *LI = &LPM->getAnalysis<LoopInfo>();
- SimplifyIndvar SIV(LI->getLoopFor(CurrIV->getParent()), LPM, Dead);
+ SimplifyIndvar SIV(LI->getLoopFor(CurrIV->getParent()), SE, LPM, Dead);
SIV.simplifyUsers(CurrIV, V);
return SIV.hasChanged();
}
/// simplifyLoopIVs - Simplify users of induction variables within this
/// loop. This does not actually change or add IVs.
-bool simplifyLoopIVs(Loop *L, LPPassManager *LPM,
+bool simplifyLoopIVs(Loop *L, ScalarEvolution *SE, LPPassManager *LPM,
SmallVectorImpl<WeakVH> &Dead) {
bool Changed = false;
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) {
- Changed |= simplifyUsersOfIV(cast<PHINode>(I), LPM, Dead);
+ Changed |= simplifyUsersOfIV(cast<PHINode>(I), SE, LPM, Dead);
}
return Changed;
}
///
/// This is the old approach to IV simplification to be replaced by
/// SimplifyLoopIVs.
-bool simplifyIVUsers(IVUsers *IU, LPPassManager *LPM,
+bool simplifyIVUsers(IVUsers *IU, ScalarEvolution *SE, LPPassManager *LPM,
SmallVectorImpl<WeakVH> &Dead) {
- SimplifyIndvar SIV(IU->getLoop(), LPM, Dead);
+ SimplifyIndvar SIV(IU->getLoop(), SE, LPM, Dead);
// Each round of simplification involves a round of eliminating operations
// followed by a round of widening IVs. A single IVUsers worklist is used
projects / oota-llvm.git / blobdiff