#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLowering.h"
#include "llvm/ADT/STLExtras.h"
+
using namespace llvm;
+/// ReuseOrCreateCast - Arrange for there to be a cast of V to Ty at IP,
+/// reusing an existing cast if a suitable one exists, moving an existing
+/// cast if a suitable one exists but isn't in the right place, or
+/// creating a new one.
+Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
+ Instruction::CastOps Op,
+ BasicBlock::iterator IP) {
+ // This function must be called with the builder having a valid insertion
+ // point. It doesn't need to be the actual IP where the uses of the returned
+ // cast will be added, but it must dominate such IP.
+ // We use this precondition to produce a cast that will dominate all its
+ // uses. In particular, this is crucial for the case where the builder's
+ // insertion point *is* the point where we were asked to put the cast.
+ // Since we don't know the the builder's insertion point is actually
+ // where the uses will be added (only that it dominates it), we are
+ // not allowed to move it.
+ BasicBlock::iterator BIP = Builder.GetInsertPoint();
+
+ Instruction *Ret = NULL;
+
+ // Check to see if there is already a cast!
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
+ UI != E; ++UI) {
+ User *U = *UI;
+ if (U->getType() == Ty)
+ if (CastInst *CI = dyn_cast<CastInst>(U))
+ if (CI->getOpcode() == Op) {
+ // If the cast isn't where we want it, create a new cast at IP.
+ // Likewise, do not reuse a cast at BIP because it must dominate
+ // instructions that might be inserted before BIP.
+ if (BasicBlock::iterator(CI) != IP || BIP == IP) {
+ // Create a new cast, and leave the old cast in place in case
+ // it is being used as an insert point. Clear its operand
+ // so that it doesn't hold anything live.
+ Ret = CastInst::Create(Op, V, Ty, "", IP);
+ Ret->takeName(CI);
+ CI->replaceAllUsesWith(Ret);
+ CI->setOperand(0, UndefValue::get(V->getType()));
+ break;
+ }
+ Ret = CI;
+ break;
+ }
+ }
+
+ // Create a new cast.
+ if (!Ret)
+ Ret = CastInst::Create(Op, V, Ty, V->getName(), IP);
+
+ // We assert at the end of the function since IP might point to an
+ // instruction with different dominance properties than a cast
+ // (an invoke for example) and not dominate BIP (but the cast does).
+ assert(SE.DT->dominates(Ret, BIP));
+
+ rememberInstruction(Ret);
+ return Ret;
+}
+
/// InsertNoopCastOfTo - Insert a cast of V to the specified type,
/// which must be possible with a noop cast, doing what we can to share
/// the casts.
-Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) {
+Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) {
Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false);
assert((Op == Instruction::BitCast ||
Op == Instruction::PtrToInt ||
"InsertNoopCastOfTo cannot change sizes!");
// Short-circuit unnecessary bitcasts.
- if (Op == Instruction::BitCast && V->getType() == Ty)
- return V;
-
+ if (Op == Instruction::BitCast) {
+ if (V->getType() == Ty)
+ return V;
+ if (CastInst *CI = dyn_cast<CastInst>(V)) {
+ if (CI->getOperand(0)->getType() == Ty)
+ return CI->getOperand(0);
+ }
+ }
// Short-circuit unnecessary inttoptr<->ptrtoint casts.
if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) &&
SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {
return CE->getOperand(0);
}
+ // Fold a cast of a constant.
if (Constant *C = dyn_cast<Constant>(V))
return ConstantExpr::getCast(Op, C, Ty);
+ // Cast the argument at the beginning of the entry block, after
+ // any bitcasts of other arguments.
if (Argument *A = dyn_cast<Argument>(V)) {
- // Check to see if there is already a cast!
- for (Value::use_iterator UI = A->use_begin(), E = A->use_end();
- UI != E; ++UI)
- if ((*UI)->getType() == Ty)
- if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI)))
- if (CI->getOpcode() == Op) {
- // If the cast isn't the first instruction of the function, move it.
- if (BasicBlock::iterator(CI) !=
- A->getParent()->getEntryBlock().begin()) {
- // Recreate the cast at the beginning of the entry block.
- // The old cast is left in place in case it is being used
- // as an insert point.
- Instruction *NewCI =
- CastInst::Create(Op, V, Ty, "",
- A->getParent()->getEntryBlock().begin());
- NewCI->takeName(CI);
- CI->replaceAllUsesWith(NewCI);
- return NewCI;
- }
- return CI;
- }
-
- Instruction *I = CastInst::Create(Op, V, Ty, V->getName(),
- A->getParent()->getEntryBlock().begin());
- InsertedValues.insert(I);
- return I;
+ BasicBlock::iterator IP = A->getParent()->getEntryBlock().begin();
+ while ((isa<BitCastInst>(IP) &&
+ isa<Argument>(cast<BitCastInst>(IP)->getOperand(0)) &&
+ cast<BitCastInst>(IP)->getOperand(0) != A) ||
+ isa<DbgInfoIntrinsic>(IP) ||
+ isa<LandingPadInst>(IP))
+ ++IP;
+ return ReuseOrCreateCast(A, Ty, Op, IP);
}
+ // Cast the instruction immediately after the instruction.
Instruction *I = cast<Instruction>(V);
-
- // Check to see if there is already a cast. If there is, use it.
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI) {
- if ((*UI)->getType() == Ty)
- if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI)))
- if (CI->getOpcode() == Op) {
- BasicBlock::iterator It = I; ++It;
- if (isa<InvokeInst>(I))
- It = cast<InvokeInst>(I)->getNormalDest()->begin();
- while (isa<PHINode>(It)) ++It;
- if (It != BasicBlock::iterator(CI)) {
- // Recreate the cast at the beginning of the entry block.
- // The old cast is left in place in case it is being used
- // as an insert point.
- Instruction *NewCI = CastInst::Create(Op, V, Ty, "", It);
- NewCI->takeName(CI);
- CI->replaceAllUsesWith(NewCI);
- return NewCI;
- }
- return CI;
- }
- }
BasicBlock::iterator IP = I; ++IP;
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
IP = II->getNormalDest()->begin();
- while (isa<PHINode>(IP)) ++IP;
- Instruction *CI = CastInst::Create(Op, V, Ty, V->getName(), IP);
- InsertedValues.insert(CI);
- return CI;
+ while (isa<PHINode>(IP) || isa<LandingPadInst>(IP))
+ ++IP;
+ return ReuseOrCreateCast(I, Ty, Op, IP);
}
/// InsertBinop - Insert the specified binary operator, doing a small amount
if (IP != BlockBegin) {
--IP;
for (; ScanLimit; --IP, --ScanLimit) {
+ // Don't count dbg.value against the ScanLimit, to avoid perturbing the
+ // generated code.
+ if (isa<DbgInfoIntrinsic>(IP))
+ ScanLimit++;
if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
IP->getOperand(1) == RHS)
return IP;
}
}
+ // Save the original insertion point so we can restore it when we're done.
+ BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
+ BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+
+ // Move the insertion point out of as many loops as we can.
+ while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
+ if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break;
+ BasicBlock *Preheader = L->getLoopPreheader();
+ if (!Preheader) break;
+
+ // Ok, move up a level.
+ Builder.SetInsertPoint(Preheader, Preheader->getTerminator());
+ }
+
// If we haven't found this binop, insert it.
- Value *BO = Builder.CreateBinOp(Opcode, LHS, RHS, "tmp");
- InsertedValues.insert(BO);
+ Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS));
+ BO->setDebugLoc(SaveInsertPt->getDebugLoc());
+ rememberInstruction(BO);
+
+ // Restore the original insert point.
+ if (SaveInsertBB)
+ restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+
return BO;
}
/// FactorOutConstant - Test if S is divisible by Factor, using signed
/// division. If so, update S with Factor divided out and return true.
-/// S need not be evenly divisble if a reasonable remainder can be
+/// S need not be evenly divisible if a reasonable remainder can be
/// computed.
/// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made
/// unnecessary; in its place, just signed-divide Ops[i] by the scale and
// x/x == 1.
if (S == Factor) {
- S = SE.getIntegerSCEV(1, S->getType());
+ S = SE.getConstant(S->getType(), 1);
return true;
}
const SCEVConstant *FC = cast<SCEVConstant>(Factor);
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
if (!C->getValue()->getValue().srem(FC->getValue()->getValue())) {
- const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
- SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
- MOperands.end());
+ SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
NewMulOps[0] =
SE.getConstant(C->getValue()->getValue().sdiv(
FC->getValue()->getValue()));
// Mul's operands. If so, we can just remove it.
for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
const SCEV *SOp = M->getOperand(i);
- const SCEV *Remainder = SE.getIntegerSCEV(0, SOp->getType());
+ const SCEV *Remainder = SE.getConstant(SOp->getType(), 0);
if (FactorOutConstant(SOp, Remainder, Factor, SE, TD) &&
Remainder->isZero()) {
- const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
- SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
- MOperands.end());
+ SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
NewMulOps[i] = SOp;
S = SE.getMulExpr(NewMulOps);
return true;
// In an AddRec, check if both start and step are divisible.
if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
const SCEV *Step = A->getStepRecurrence(SE);
- const SCEV *StepRem = SE.getIntegerSCEV(0, Step->getType());
+ const SCEV *StepRem = SE.getConstant(Step->getType(), 0);
if (!FactorOutConstant(Step, StepRem, Factor, SE, TD))
return false;
if (!StepRem->isZero())
const SCEV *Start = A->getStart();
if (!FactorOutConstant(Start, Remainder, Factor, SE, TD))
return false;
- S = SE.getAddRecExpr(Start, Step, A->getLoop());
+ // FIXME: can use A->getNoWrapFlags(FlagNW)
+ S = SE.getAddRecExpr(Start, Step, A->getLoop(), SCEV::FlagAnyWrap);
return true;
}
/// the list.
///
static void SimplifyAddOperands(SmallVectorImpl<const SCEV *> &Ops,
- const Type *Ty,
+ Type *Ty,
ScalarEvolution &SE) {
unsigned NumAddRecs = 0;
for (unsigned i = Ops.size(); i > 0 && isa<SCEVAddRecExpr>(Ops[i-1]); --i)
SmallVector<const SCEV *, 8> AddRecs(Ops.end() - NumAddRecs, Ops.end());
// Let ScalarEvolution sort and simplify the non-addrecs list.
const SCEV *Sum = NoAddRecs.empty() ?
- SE.getIntegerSCEV(0, Ty) :
+ SE.getConstant(Ty, 0) :
SE.getAddExpr(NoAddRecs);
// If it returned an add, use the operands. Otherwise it simplified
// the sum into a single value, so just use that.
+ Ops.clear();
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum))
- Ops = Add->getOperands();
- else {
- Ops.clear();
- if (!Sum->isZero())
- Ops.push_back(Sum);
- }
+ Ops.append(Add->op_begin(), Add->op_end());
+ else if (!Sum->isZero())
+ Ops.push_back(Sum);
// Then append the addrecs.
- Ops.insert(Ops.end(), AddRecs.begin(), AddRecs.end());
+ Ops.append(AddRecs.begin(), AddRecs.end());
}
/// SplitAddRecs - Flatten a list of add operands, moving addrec start values
/// into GEP indices.
///
static void SplitAddRecs(SmallVectorImpl<const SCEV *> &Ops,
- const Type *Ty,
+ Type *Ty,
ScalarEvolution &SE) {
// Find the addrecs.
SmallVector<const SCEV *, 8> AddRecs;
while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i])) {
const SCEV *Start = A->getStart();
if (Start->isZero()) break;
- const SCEV *Zero = SE.getIntegerSCEV(0, Ty);
+ const SCEV *Zero = SE.getConstant(Ty, 0);
AddRecs.push_back(SE.getAddRecExpr(Zero,
A->getStepRecurrence(SE),
- A->getLoop()));
+ A->getLoop(),
+ // FIXME: A->getNoWrapFlags(FlagNW)
+ SCEV::FlagAnyWrap));
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
Ops[i] = Zero;
- Ops.insert(Ops.end(), Add->op_begin(), Add->op_end());
+ Ops.append(Add->op_begin(), Add->op_end());
e += Add->getNumOperands();
} else {
Ops[i] = Start;
}
if (!AddRecs.empty()) {
// Add the addrecs onto the end of the list.
- Ops.insert(Ops.end(), AddRecs.begin(), AddRecs.end());
+ Ops.append(AddRecs.begin(), AddRecs.end());
// Resort the operand list, moving any constants to the front.
SimplifyAddOperands(Ops, Ty, SE);
}
/// http://llvm.org/docs/LangRef.html#pointeraliasing
/// for details.
///
-/// Design note: The correctness of using getelmeentptr here depends on
+/// Design note: The correctness of using getelementptr here depends on
/// ScalarEvolution not recognizing inttoptr and ptrtoint operators, as
/// they may introduce pointer arithmetic which may not be safely converted
/// into getelementptr.
///
Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
const SCEV *const *op_end,
- const PointerType *PTy,
- const Type *Ty,
+ PointerType *PTy,
+ Type *Ty,
Value *V) {
- const Type *ElTy = PTy->getElementType();
+ Type *ElTy = PTy->getElementType();
SmallVector<Value *, 4> GepIndices;
SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
bool AnyNonZeroIndices = false;
// the indices index into the element or field type selected by the
// preceding index.
for (;;) {
- const SCEV *ElSize = SE.getAllocSizeExpr(ElTy);
// If the scale size is not 0, attempt to factor out a scale for
// array indexing.
SmallVector<const SCEV *, 8> ScaledOps;
- if (ElTy->isSized() && !ElSize->isZero()) {
- SmallVector<const SCEV *, 8> NewOps;
- for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- const SCEV *Op = Ops[i];
- const SCEV *Remainder = SE.getIntegerSCEV(0, Ty);
- if (FactorOutConstant(Op, Remainder, ElSize, SE, SE.TD)) {
- // Op now has ElSize factored out.
- ScaledOps.push_back(Op);
- if (!Remainder->isZero())
- NewOps.push_back(Remainder);
- AnyNonZeroIndices = true;
- } else {
- // The operand was not divisible, so add it to the list of operands
- // we'll scan next iteration.
- NewOps.push_back(Ops[i]);
+ if (ElTy->isSized()) {
+ const SCEV *ElSize = SE.getSizeOfExpr(ElTy);
+ if (!ElSize->isZero()) {
+ SmallVector<const SCEV *, 8> NewOps;
+ for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
+ const SCEV *Op = Ops[i];
+ const SCEV *Remainder = SE.getConstant(Ty, 0);
+ if (FactorOutConstant(Op, Remainder, ElSize, SE, SE.TD)) {
+ // Op now has ElSize factored out.
+ ScaledOps.push_back(Op);
+ if (!Remainder->isZero())
+ NewOps.push_back(Remainder);
+ AnyNonZeroIndices = true;
+ } else {
+ // The operand was not divisible, so add it to the list of operands
+ // we'll scan next iteration.
+ NewOps.push_back(Ops[i]);
+ }
+ }
+ // If we made any changes, update Ops.
+ if (!ScaledOps.empty()) {
+ Ops = NewOps;
+ SimplifyAddOperands(Ops, Ty, SE);
}
- }
- // If we made any changes, update Ops.
- if (!ScaledOps.empty()) {
- Ops = NewOps;
- SimplifyAddOperands(Ops, Ty, SE);
}
}
GepIndices.push_back(Scaled);
// Collect struct field index operands.
- while (const StructType *STy = dyn_cast<StructType>(ElTy)) {
+ while (StructType *STy = dyn_cast<StructType>(ElTy)) {
bool FoundFieldNo = false;
// An empty struct has no fields.
if (STy->getNumElements() == 0) break;
}
}
} else {
- // Without TargetData, just check for a SCEVFieldOffsetExpr of the
+ // Without TargetData, just check for an offsetof expression of the
// appropriate struct type.
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (const SCEVFieldOffsetExpr *FO =
- dyn_cast<SCEVFieldOffsetExpr>(Ops[i]))
- if (FO->getStructType() == STy) {
- unsigned FieldNo = FO->getFieldNo();
- GepIndices.push_back(
- ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
- FieldNo));
- ElTy = STy->getTypeAtIndex(FieldNo);
+ if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Ops[i])) {
+ Type *CTy;
+ Constant *FieldNo;
+ if (U->isOffsetOf(CTy, FieldNo) && CTy == STy) {
+ GepIndices.push_back(FieldNo);
+ ElTy =
+ STy->getTypeAtIndex(cast<ConstantInt>(FieldNo)->getZExtValue());
Ops[i] = SE.getConstant(Ty, 0);
AnyNonZeroIndices = true;
FoundFieldNo = true;
break;
}
+ }
}
// If no struct field offsets were found, tentatively assume that
// field zero was selected (since the zero offset would obviously
}
}
- if (
const ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
+ if (ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
ElTy = ATy->getElementType();
else
break;
}
- // If none of the operands were convertable to proper GEP indices, cast
+ // If none of the operands were convertible to proper GEP indices, cast
// the base to i8* and do an ugly getelementptr with that. It's still
// better than ptrtoint+arithmetic+inttoptr at least.
if (!AnyNonZeroIndices) {
V = InsertNoopCastOfTo(V,
Type::getInt8PtrTy(Ty->getContext(), PTy->getAddressSpace()));
+ assert(!isa<Instruction>(V) ||
+ SE.DT->dominates(cast<Instruction>(V), Builder.GetInsertPoint()));
+
// Expand the operands for a plain byte offset.
Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
// Fold a GEP with constant operands.
if (Constant *CLHS = dyn_cast<Constant>(V))
if (Constant *CRHS = dyn_cast<Constant>(Idx))
- return ConstantExpr::getGetElementPtr(CLHS, &CRHS, 1);
+ return ConstantExpr::getGetElementPtr(CLHS, CRHS);
// Do a quick scan to see if we have this GEP nearby. If so, reuse it.
unsigned ScanLimit = 6;
if (IP != BlockBegin) {
--IP;
for (; ScanLimit; --IP, --ScanLimit) {
+ // Don't count dbg.value against the ScanLimit, to avoid perturbing the
+ // generated code.
+ if (isa<DbgInfoIntrinsic>(IP))
+ ScanLimit++;
if (IP->getOpcode() == Instruction::GetElementPtr &&
IP->getOperand(0) == V && IP->getOperand(1) == Idx)
return IP;
}
}
+ // Save the original insertion point so we can restore it when we're done.
+ BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
+ BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+
+ // Move the insertion point out of as many loops as we can.
+ while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
+ if (!L->isLoopInvariant(V) || !L->isLoopInvariant(Idx)) break;
+ BasicBlock *Preheader = L->getLoopPreheader();
+ if (!Preheader) break;
+
+ // Ok, move up a level.
+ Builder.SetInsertPoint(Preheader, Preheader->getTerminator());
+ }
+
// Emit a GEP.
Value *GEP = Builder.CreateGEP(V, Idx, "uglygep");
- InsertedValues.insert(GEP);
+ rememberInstruction(GEP);
+
+ // Restore the original insert point.
+ if (SaveInsertBB)
+ restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+
return GEP;
}
+ // Save the original insertion point so we can restore it when we're done.
+ BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
+ BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+
+ // Move the insertion point out of as many loops as we can.
+ while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
+ if (!L->isLoopInvariant(V)) break;
+
+ bool AnyIndexNotLoopInvariant = false;
+ for (SmallVectorImpl<Value *>::const_iterator I = GepIndices.begin(),
+ E = GepIndices.end(); I != E; ++I)
+ if (!L->isLoopInvariant(*I)) {
+ AnyIndexNotLoopInvariant = true;
+ break;
+ }
+ if (AnyIndexNotLoopInvariant)
+ break;
+
+ BasicBlock *Preheader = L->getLoopPreheader();
+ if (!Preheader) break;
+
+ // Ok, move up a level.
+ Builder.SetInsertPoint(Preheader, Preheader->getTerminator());
+ }
+
// Insert a pretty getelementptr. Note that this GEP is not marked inbounds,
// because ScalarEvolution may have changed the address arithmetic to
// compute a value which is beyond the end of the allocated object.
- Value *GEP = Builder.CreateGEP(V,
- GepIndices.begin(),
- GepIndices.end(),
+ Value *Casted = V;
+ if (V->getType() != PTy)
+ Casted = InsertNoopCastOfTo(Casted, PTy);
+ Value *GEP = Builder.CreateGEP(Casted,
+ GepIndices,
"scevgep");
Ops.push_back(SE.getUnknown(GEP));
- InsertedValues.insert(GEP);
+ rememberInstruction(GEP);
+
+ // Restore the original insert point.
+ if (SaveInsertBB)
+ restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+
return expand(SE.getAddExpr(Ops));
}
-Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
- int NumOperands = S->getNumOperands();
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
-
- // Find the index of an operand to start with. Choose the operand with
- // pointer type, if there is one, or the last operand otherwise.
- int PIdx = 0;
- for (; PIdx != NumOperands - 1; ++PIdx)
- if (isa<PointerType>(S->getOperand(PIdx)->getType())) break;
-
- // Expand code for the operand that we chose.
- Value *V = expand(S->getOperand(PIdx));
-
- // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
- // comments on expandAddToGEP for details.
- if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) {
- // Take the operand at PIdx out of the list.
- const SmallVectorImpl<const SCEV *> &Ops = S->getOperands();
- SmallVector<const SCEV *, 8> NewOps;
- NewOps.insert(NewOps.end(), Ops.begin(), Ops.begin() + PIdx);
- NewOps.insert(NewOps.end(), Ops.begin() + PIdx + 1, Ops.end());
- // Make a GEP.
- return expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, V);
- }
-
- // Otherwise, we'll expand the rest of the SCEVAddExpr as plain integer
- // arithmetic.
- V = InsertNoopCastOfTo(V, Ty);
-
- // Emit a bunch of add instructions
- for (int i = NumOperands-1; i >= 0; --i) {
- if (i == PIdx) continue;
- Value *W = expandCodeFor(S->getOperand(i), Ty);
- V = InsertBinop(Instruction::Add, V, W);
+/// PickMostRelevantLoop - Given two loops pick the one that's most relevant for
+/// SCEV expansion. If they are nested, this is the most nested. If they are
+/// neighboring, pick the later.
+static const Loop *PickMostRelevantLoop(const Loop *A, const Loop *B,
+ DominatorTree &DT) {
+ if (!A) return B;
+ if (!B) return A;
+ if (A->contains(B)) return B;
+ if (B->contains(A)) return A;
+ if (DT.dominates(A->getHeader(), B->getHeader())) return B;
+ if (DT.dominates(B->getHeader(), A->getHeader())) return A;
+ return A; // Arbitrarily break the tie.
+}
+
+/// getRelevantLoop - Get the most relevant loop associated with the given
+/// expression, according to PickMostRelevantLoop.
+const Loop *SCEVExpander::getRelevantLoop(const SCEV *S) {
+ // Test whether we've already computed the most relevant loop for this SCEV.
+ std::pair<DenseMap<const SCEV *, const Loop *>::iterator, bool> Pair =
+ RelevantLoops.insert(std::make_pair(S, static_cast<const Loop *>(0)));
+ if (!Pair.second)
+ return Pair.first->second;
+
+ if (isa<SCEVConstant>(S))
+ // A constant has no relevant loops.
+ return 0;
+ if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
+ if (const Instruction *I = dyn_cast<Instruction>(U->getValue()))
+ return Pair.first->second = SE.LI->getLoopFor(I->getParent());
+ // A non-instruction has no relevant loops.
+ return 0;
}
- return V;
+ if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) {
+ const Loop *L = 0;
+ if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
+ L = AR->getLoop();
+ for (SCEVNAryExpr::op_iterator I = N->op_begin(), E = N->op_end();
+ I != E; ++I)
+ L = PickMostRelevantLoop(L, getRelevantLoop(*I), *SE.DT);
+ return RelevantLoops[N] = L;
+ }
+ if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) {
+ const Loop *Result = getRelevantLoop(C->getOperand());
+ return RelevantLoops[C] = Result;
+ }
+ if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
+ const Loop *Result =
+ PickMostRelevantLoop(getRelevantLoop(D->getLHS()),
+ getRelevantLoop(D->getRHS()),
+ *SE.DT);
+ return RelevantLoops[D] = Result;
+ }
+ llvm_unreachable("Unexpected SCEV type!");
}
-Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
- int FirstOp = 0; // Set if we should emit a subtract.
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0)))
- if (SC->getValue()->isAllOnesValue())
- FirstOp = 1;
+namespace {
+
+/// LoopCompare - Compare loops by PickMostRelevantLoop.
+class LoopCompare {
+ DominatorTree &DT;
+public:
+ explicit LoopCompare(DominatorTree &dt) : DT(dt) {}
+
+ bool operator()(std::pair<const Loop *, const SCEV *> LHS,
+ std::pair<const Loop *, const SCEV *> RHS) const {
+ // Keep pointer operands sorted at the end.
+ if (LHS.second->getType()->isPointerTy() !=
+ RHS.second->getType()->isPointerTy())
+ return LHS.second->getType()->isPointerTy();
+
+ // Compare loops with PickMostRelevantLoop.
+ if (LHS.first != RHS.first)
+ return PickMostRelevantLoop(LHS.first, RHS.first, DT) != LHS.first;
+
+ // If one operand is a non-constant negative and the other is not,
+ // put the non-constant negative on the right so that a sub can
+ // be used instead of a negate and add.
+ if (LHS.second->isNonConstantNegative()) {
+ if (!RHS.second->isNonConstantNegative())
+ return false;
+ } else if (RHS.second->isNonConstantNegative())
+ return true;
+
+ // Otherwise they are equivalent according to this comparison.
+ return false;
+ }
+};
- int i = S->getNumOperands()-2;
- Value *V = expandCodeFor(S->getOperand(i+1), Ty);
+}
- // Emit a bunch of multiply instructions
- for (; i >= FirstOp; --i) {
- Value *W = expandCodeFor(S->getOperand(i), Ty);
- V = InsertBinop(Instruction::Mul, V, W);
+Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
+ Type *Ty = SE.getEffectiveSCEVType(S->getType());
+
+ // Collect all the add operands in a loop, along with their associated loops.
+ // Iterate in reverse so that constants are emitted last, all else equal, and
+ // so that pointer operands are inserted first, which the code below relies on
+ // to form more involved GEPs.
+ SmallVector<std::pair<const Loop *, const SCEV *>, 8> OpsAndLoops;
+ for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(S->op_end()),
+ E(S->op_begin()); I != E; ++I)
+ OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
+
+ // Sort by loop. Use a stable sort so that constants follow non-constants and
+ // pointer operands precede non-pointer operands.
+ std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(*SE.DT));
+
+ // Emit instructions to add all the operands. Hoist as much as possible
+ // out of loops, and form meaningful getelementptrs where possible.
+ Value *Sum = 0;
+ for (SmallVectorImpl<std::pair<const Loop *, const SCEV *> >::iterator
+ I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E; ) {
+ const Loop *CurLoop = I->first;
+ const SCEV *Op = I->second;
+ if (!Sum) {
+ // This is the first operand. Just expand it.
+ Sum = expand(Op);
+ ++I;
+ } else if (PointerType *PTy = dyn_cast<PointerType>(Sum->getType())) {
+ // The running sum expression is a pointer. Try to form a getelementptr
+ // at this level with that as the base.
+ SmallVector<const SCEV *, 4> NewOps;
+ for (; I != E && I->first == CurLoop; ++I) {
+ // If the operand is SCEVUnknown and not instructions, peek through
+ // it, to enable more of it to be folded into the GEP.
+ const SCEV *X = I->second;
+ if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(X))
+ if (!isa<Instruction>(U->getValue()))
+ X = SE.getSCEV(U->getValue());
+ NewOps.push_back(X);
+ }
+ Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum);
+ } else if (PointerType *PTy = dyn_cast<PointerType>(Op->getType())) {
+ // The running sum is an integer, and there's a pointer at this level.
+ // Try to form a getelementptr. If the running sum is instructions,
+ // use a SCEVUnknown to avoid re-analyzing them.
+ SmallVector<const SCEV *, 4> NewOps;
+ NewOps.push_back(isa<Instruction>(Sum) ? SE.getUnknown(Sum) :
+ SE.getSCEV(Sum));
+ for (++I; I != E && I->first == CurLoop; ++I)
+ NewOps.push_back(I->second);
+ Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, expand(Op));
+ } else if (Op->isNonConstantNegative()) {
+ // Instead of doing a negate and add, just do a subtract.
+ Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty);
+ Sum = InsertNoopCastOfTo(Sum, Ty);
+ Sum = InsertBinop(Instruction::Sub, Sum, W);
+ ++I;
+ } else {
+ // A simple add.
+ Value *W = expandCodeFor(Op, Ty);
+ Sum = InsertNoopCastOfTo(Sum, Ty);
+ // Canonicalize a constant to the RHS.
+ if (isa<Constant>(Sum)) std::swap(Sum, W);
+ Sum = InsertBinop(Instruction::Add, Sum, W);
+ ++I;
+ }
}
- // -1 * ... ---> 0 - ...
- if (FirstOp == 1)
- V = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), V);
- return V;
+ return Sum;
+}
+
+Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
+ Type *Ty = SE.getEffectiveSCEVType(S->getType());
+
+ // Collect all the mul operands in a loop, along with their associated loops.
+ // Iterate in reverse so that constants are emitted last, all else equal.
+ SmallVector<std::pair<const Loop *, const SCEV *>, 8> OpsAndLoops;
+ for (std::reverse_iterator<SCEVMulExpr::op_iterator> I(S->op_end()),
+ E(S->op_begin()); I != E; ++I)
+ OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
+
+ // Sort by loop. Use a stable sort so that constants follow non-constants.
+ std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(*SE.DT));
+
+ // Emit instructions to mul all the operands. Hoist as much as possible
+ // out of loops.
+ Value *Prod = 0;
+ for (SmallVectorImpl<std::pair<const Loop *, const SCEV *> >::iterator
+ I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E; ) {
+ const SCEV *Op = I->second;
+ if (!Prod) {
+ // This is the first operand. Just expand it.
+ Prod = expand(Op);
+ ++I;
+ } else if (Op->isAllOnesValue()) {
+ // Instead of doing a multiply by negative one, just do a negate.
+ Prod = InsertNoopCastOfTo(Prod, Ty);
+ Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod);
+ ++I;
+ } else {
+ // A simple mul.
+ Value *W = expandCodeFor(Op, Ty);
+ Prod = InsertNoopCastOfTo(Prod, Ty);
+ // Canonicalize a constant to the RHS.
+ if (isa<Constant>(Prod)) std::swap(Prod, W);
+ Prod = InsertBinop(Instruction::Mul, Prod, W);
+ ++I;
+ }
+ }
+
+ return Prod;
}
Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
+ Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *LHS = expandCodeFor(S->getLHS(), Ty);
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) {
Base = A->getStart();
Rest = SE.getAddExpr(Rest,
- SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()),
+ SE.getAddRecExpr(SE.getConstant(A->getType(), 0),
A->getStepRecurrence(SE),
- A->getLoop()));
+ A->getLoop(),
+ // FIXME: A->getNoWrapFlags(FlagNW)
+ SCEV::FlagAnyWrap));
}
if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
Base = A->getOperand(A->getNumOperands()-1);
}
}
+/// Determine if this is a well-behaved chain of instructions leading back to
+/// the PHI. If so, it may be reused by expanded expressions.
+bool SCEVExpander::isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV,
+ const Loop *L) {
+ if (IncV->getNumOperands() == 0 || isa<PHINode>(IncV) ||
+ (isa<CastInst>(IncV) && !isa<BitCastInst>(IncV)))
+ return false;
+ // If any of the operands don't dominate the insert position, bail.
+ // Addrec operands are always loop-invariant, so this can only happen
+ // if there are instructions which haven't been hoisted.
+ if (L == IVIncInsertLoop) {
+ for (User::op_iterator OI = IncV->op_begin()+1,
+ OE = IncV->op_end(); OI != OE; ++OI)
+ if (Instruction *OInst = dyn_cast<Instruction>(OI))
+ if (!SE.DT->dominates(OInst, IVIncInsertPos))
+ return false;
+ }
+ // Advance to the next instruction.
+ IncV = dyn_cast<Instruction>(IncV->getOperand(0));
+ if (!IncV)
+ return false;
+
+ if (IncV->mayHaveSideEffects())
+ return false;
+
+ if (IncV != PN)
+ return true;
+
+ return isNormalAddRecExprPHI(PN, IncV, L);
+}
+
+/// getIVIncOperand returns an induction variable increment's induction
+/// variable operand.
+///
+/// If allowScale is set, any type of GEP is allowed as long as the nonIV
+/// operands dominate InsertPos.
+///
+/// If allowScale is not set, ensure that a GEP increment conforms to one of the
+/// simple patterns generated by getAddRecExprPHILiterally and
+/// expandAddtoGEP. If the pattern isn't recognized, return NULL.
+Instruction *SCEVExpander::getIVIncOperand(Instruction *IncV,
+ Instruction *InsertPos,
+ bool allowScale) {
+ if (IncV == InsertPos)
+ return NULL;
+
+ switch (IncV->getOpcode()) {
+ default:
+ return NULL;
+ // Check for a simple Add/Sub or GEP of a loop invariant step.
+ case Instruction::Add:
+ case Instruction::Sub: {
+ Instruction *OInst = dyn_cast<Instruction>(IncV->getOperand(1));
+ if (!OInst || SE.DT->dominates(OInst, InsertPos))
+ return dyn_cast<Instruction>(IncV->getOperand(0));
+ return NULL;
+ }
+ case Instruction::BitCast:
+ return dyn_cast<Instruction>(IncV->getOperand(0));
+ case Instruction::GetElementPtr:
+ for (Instruction::op_iterator I = IncV->op_begin()+1, E = IncV->op_end();
+ I != E; ++I) {
+ if (isa<Constant>(*I))
+ continue;
+ if (Instruction *OInst = dyn_cast<Instruction>(*I)) {
+ if (!SE.DT->dominates(OInst, InsertPos))
+ return NULL;
+ }
+ if (allowScale) {
+ // allow any kind of GEP as long as it can be hoisted.
+ continue;
+ }
+ // This must be a pointer addition of constants (pretty), which is already
+ // handled, or some number of address-size elements (ugly). Ugly geps
+ // have 2 operands. i1* is used by the expander to represent an
+ // address-size element.
+ if (IncV->getNumOperands() != 2)
+ return NULL;
+ unsigned AS = cast<PointerType>(IncV->getType())->getAddressSpace();
+ if (IncV->getType() != Type::getInt1PtrTy(SE.getContext(), AS)
+ && IncV->getType() != Type::getInt8PtrTy(SE.getContext(), AS))
+ return NULL;
+ break;
+ }
+ return dyn_cast<Instruction>(IncV->getOperand(0));
+ }
+}
+
+/// hoistStep - Attempt to hoist a simple IV increment above InsertPos to make
+/// it available to other uses in this loop. Recursively hoist any operands,
+/// until we reach a value that dominates InsertPos.
+bool SCEVExpander::hoistIVInc(Instruction *IncV, Instruction *InsertPos) {
+ if (SE.DT->dominates(IncV, InsertPos))
+ return true;
+
+ // InsertPos must itself dominate IncV so that IncV's new position satisfies
+ // its existing users.
+ if (!SE.DT->dominates(InsertPos->getParent(), IncV->getParent()))
+ return false;
+
+ // Check that the chain of IV operands leading back to Phi can be hoisted.
+ SmallVector<Instruction*, 4> IVIncs;
+ for(;;) {
+ Instruction *Oper = getIVIncOperand(IncV, InsertPos, /*allowScale*/true);
+ if (!Oper)
+ return false;
+ // IncV is safe to hoist.
+ IVIncs.push_back(IncV);
+ IncV = Oper;
+ if (SE.DT->dominates(IncV, InsertPos))
+ break;
+ }
+ for (SmallVectorImpl<Instruction*>::reverse_iterator I = IVIncs.rbegin(),
+ E = IVIncs.rend(); I != E; ++I) {
+ (*I)->moveBefore(InsertPos);
+ }
+ return true;
+}
+
+/// Determine if this cyclic phi is in a form that would have been generated by
+/// LSR. We don't care if the phi was actually expanded in this pass, as long
+/// as it is in a low-cost form, for example, no implied multiplication. This
+/// should match any patterns generated by getAddRecExprPHILiterally and
+/// expandAddtoGEP.
+bool SCEVExpander::isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV,
+ const Loop *L) {
+ for(Instruction *IVOper = IncV;
+ (IVOper = getIVIncOperand(IVOper, L->getLoopPreheader()->getTerminator(),
+ /*allowScale=*/false));) {
+ if (IVOper == PN)
+ return true;
+ }
+ return false;
+}
+
+/// expandIVInc - Expand an IV increment at Builder's current InsertPos.
+/// Typically this is the LatchBlock terminator or IVIncInsertPos, but we may
+/// need to materialize IV increments elsewhere to handle difficult situations.
+Value *SCEVExpander::expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
+ Type *ExpandTy, Type *IntTy,
+ bool useSubtract) {
+ Value *IncV;
+ // If the PHI is a pointer, use a GEP, otherwise use an add or sub.
+ if (ExpandTy->isPointerTy()) {
+ PointerType *GEPPtrTy = cast<PointerType>(ExpandTy);
+ // If the step isn't constant, don't use an implicitly scaled GEP, because
+ // that would require a multiply inside the loop.
+ if (!isa<ConstantInt>(StepV))
+ GEPPtrTy = PointerType::get(Type::getInt1Ty(SE.getContext()),
+ GEPPtrTy->getAddressSpace());
+ const SCEV *const StepArray[1] = { SE.getSCEV(StepV) };
+ IncV = expandAddToGEP(StepArray, StepArray+1, GEPPtrTy, IntTy, PN);
+ if (IncV->getType() != PN->getType()) {
+ IncV = Builder.CreateBitCast(IncV, PN->getType());
+ rememberInstruction(IncV);
+ }
+ } else {
+ IncV = useSubtract ?
+ Builder.CreateSub(PN, StepV, Twine(IVName) + ".iv.next") :
+ Builder.CreateAdd(PN, StepV, Twine(IVName) + ".iv.next");
+ rememberInstruction(IncV);
+ }
+ return IncV;
+}
+
+/// getAddRecExprPHILiterally - Helper for expandAddRecExprLiterally. Expand
+/// the base addrec, which is the addrec without any non-loop-dominating
+/// values, and return the PHI.
+PHINode *
+SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
+ const Loop *L,
+ Type *ExpandTy,
+ Type *IntTy) {
+ assert((!IVIncInsertLoop||IVIncInsertPos) && "Uninitialized insert position");
+
+ // Reuse a previously-inserted PHI, if present.
+ BasicBlock *LatchBlock = L->getLoopLatch();
+ if (LatchBlock) {
+ for (BasicBlock::iterator I = L->getHeader()->begin();
+ PHINode *PN = dyn_cast<PHINode>(I); ++I) {
+ if (!SE.isSCEVable(PN->getType()) ||
+ (SE.getEffectiveSCEVType(PN->getType()) !=
+ SE.getEffectiveSCEVType(Normalized->getType())) ||
+ SE.getSCEV(PN) != Normalized)
+ continue;
+
+ Instruction *IncV =
+ cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock));
+
+ if (LSRMode) {
+ if (!isExpandedAddRecExprPHI(PN, IncV, L))
+ continue;
+ if (L == IVIncInsertLoop && !hoistIVInc(IncV, IVIncInsertPos))
+ continue;
+ }
+ else {
+ if (!isNormalAddRecExprPHI(PN, IncV, L))
+ continue;
+ if (L == IVIncInsertLoop)
+ do {
+ if (SE.DT->dominates(IncV, IVIncInsertPos))
+ break;
+ // Make sure the increment is where we want it. But don't move it
+ // down past a potential existing post-inc user.
+ IncV->moveBefore(IVIncInsertPos);
+ IVIncInsertPos = IncV;
+ IncV = cast<Instruction>(IncV->getOperand(0));
+ } while (IncV != PN);
+ }
+ // Ok, the add recurrence looks usable.
+ // Remember this PHI, even in post-inc mode.
+ InsertedValues.insert(PN);
+ // Remember the increment.
+ rememberInstruction(IncV);
+ return PN;
+ }
+ }
+
+ // Save the original insertion point so we can restore it when we're done.
+ BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
+ BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+
+ // Another AddRec may need to be recursively expanded below. For example, if
+ // this AddRec is quadratic, the StepV may itself be an AddRec in this
+ // loop. Remove this loop from the PostIncLoops set before expanding such
+ // AddRecs. Otherwise, we cannot find a valid position for the step
+ // (i.e. StepV can never dominate its loop header). Ideally, we could do
+ // SavedIncLoops.swap(PostIncLoops), but we generally have a single element,
+ // so it's not worth implementing SmallPtrSet::swap.
+ PostIncLoopSet SavedPostIncLoops = PostIncLoops;
+ PostIncLoops.clear();
+
+ // Expand code for the start value.
+ Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy,
+ L->getHeader()->begin());
+
+ // StartV must be hoisted into L's preheader to dominate the new phi.
+ assert(!isa<Instruction>(StartV) ||
+ SE.DT->properlyDominates(cast<Instruction>(StartV)->getParent(),
+ L->getHeader()));
+
+ // Expand code for the step value. Do this before creating the PHI so that PHI
+ // reuse code doesn't see an incomplete PHI.
+ const SCEV *Step = Normalized->getStepRecurrence(SE);
+ // If the stride is negative, insert a sub instead of an add for the increment
+ // (unless it's a constant, because subtracts of constants are canonicalized
+ // to adds).
+ bool useSubtract = !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
+ if (useSubtract)
+ Step = SE.getNegativeSCEV(Step);
+ // Expand the step somewhere that dominates the loop header.
+ Value *StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin());
+
+ // Create the PHI.
+ BasicBlock *Header = L->getHeader();
+ Builder.SetInsertPoint(Header, Header->begin());
+ pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
+ PHINode *PN = Builder.CreatePHI(ExpandTy, std::distance(HPB, HPE),
+ Twine(IVName) + ".iv");
+ rememberInstruction(PN);
+
+ // Create the step instructions and populate the PHI.
+ for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
+ BasicBlock *Pred = *HPI;
+
+ // Add a start value.
+ if (!L->contains(Pred)) {
+ PN->addIncoming(StartV, Pred);
+ continue;
+ }
+
+ // Create a step value and add it to the PHI.
+ // If IVIncInsertLoop is non-null and equal to the addrec's loop, insert the
+ // instructions at IVIncInsertPos.
+ Instruction *InsertPos = L == IVIncInsertLoop ?
+ IVIncInsertPos : Pred->getTerminator();
+ Builder.SetInsertPoint(InsertPos);
+ Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
+
+ PN->addIncoming(IncV, Pred);
+ }
+
+ // Restore the original insert point.
+ if (SaveInsertBB)
+ restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+
+ // After expanding subexpressions, restore the PostIncLoops set so the caller
+ // can ensure that IVIncrement dominates the current uses.
+ PostIncLoops = SavedPostIncLoops;
+
+ // Remember this PHI, even in post-inc mode.
+ InsertedValues.insert(PN);
+
+ return PN;
+}
+
+Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
+ Type *STy = S->getType();
+ Type *IntTy = SE.getEffectiveSCEVType(STy);
+ const Loop *L = S->getLoop();
+
+ // Determine a normalized form of this expression, which is the expression
+ // before any post-inc adjustment is made.
+ const SCEVAddRecExpr *Normalized = S;
+ if (PostIncLoops.count(L)) {
+ PostIncLoopSet Loops;
+ Loops.insert(L);
+ Normalized =
+ cast<SCEVAddRecExpr>(TransformForPostIncUse(Normalize, S, 0, 0,
+ Loops, SE, *SE.DT));
+ }
+
+ // Strip off any non-loop-dominating component from the addrec start.
+ const SCEV *Start = Normalized->getStart();
+ const SCEV *PostLoopOffset = 0;
+ if (!SE.properlyDominates(Start, L->getHeader())) {
+ PostLoopOffset = Start;
+ Start = SE.getConstant(Normalized->getType(), 0);
+ Normalized = cast<SCEVAddRecExpr>(
+ SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE),
+ Normalized->getLoop(),
+ // FIXME: Normalized->getNoWrapFlags(FlagNW)
+ SCEV::FlagAnyWrap));
+ }
+
+ // Strip off any non-loop-dominating component from the addrec step.
+ const SCEV *Step = Normalized->getStepRecurrence(SE);
+ const SCEV *PostLoopScale = 0;
+ if (!SE.dominates(Step, L->getHeader())) {
+ PostLoopScale = Step;
+ Step = SE.getConstant(Normalized->getType(), 1);
+ Normalized =
+ cast<SCEVAddRecExpr>(SE.getAddRecExpr(Start, Step,
+ Normalized->getLoop(),
+ // FIXME: Normalized
+ // ->getNoWrapFlags(FlagNW)
+ SCEV::FlagAnyWrap));
+ }
+
+ // Expand the core addrec. If we need post-loop scaling, force it to
+ // expand to an integer type to avoid the need for additional casting.
+ Type *ExpandTy = PostLoopScale ? IntTy : STy;
+ PHINode *PN = getAddRecExprPHILiterally(Normalized, L, ExpandTy, IntTy);
+
+ // Accommodate post-inc mode, if necessary.
+ Value *Result;
+ if (!PostIncLoops.count(L))
+ Result = PN;
+ else {
+ // In PostInc mode, use the post-incremented value.
+ BasicBlock *LatchBlock = L->getLoopLatch();
+ assert(LatchBlock && "PostInc mode requires a unique loop latch!");
+ Result = PN->getIncomingValueForBlock(LatchBlock);
+
+ // For an expansion to use the postinc form, the client must call
+ // expandCodeFor with an InsertPoint that is either outside the PostIncLoop
+ // or dominated by IVIncInsertPos.
+ if (isa<Instruction>(Result)
+ && !SE.DT->dominates(cast<Instruction>(Result),
+ Builder.GetInsertPoint())) {
+ // The induction variable's postinc expansion does not dominate this use.
+ // IVUsers tries to prevent this case, so it is rare. However, it can
+ // happen when an IVUser outside the loop is not dominated by the latch
+ // block. Adjusting IVIncInsertPos before expansion begins cannot handle
+ // all cases. Consider a phi outide whose operand is replaced during
+ // expansion with the value of the postinc user. Without fundamentally
+ // changing the way postinc users are tracked, the only remedy is
+ // inserting an extra IV increment. StepV might fold into PostLoopOffset,
+ // but hopefully expandCodeFor handles that.
+ bool useSubtract =
+ !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
+ if (useSubtract)
+ Step = SE.getNegativeSCEV(Step);
+ // Expand the step somewhere that dominates the loop header.
+ BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
+ BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ Value *StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin());
+ // Restore the insertion point to the place where the caller has
+ // determined dominates all uses.
+ restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+ Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
+ }
+ }
+
+ // Re-apply any non-loop-dominating scale.
+ if (PostLoopScale) {
+ Result = InsertNoopCastOfTo(Result, IntTy);
+ Result = Builder.CreateMul(Result,
+ expandCodeFor(PostLoopScale, IntTy));
+ rememberInstruction(Result);
+ }
+
+ // Re-apply any non-loop-dominating offset.
+ if (PostLoopOffset) {
+ if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
+ const SCEV *const OffsetArray[1] = { PostLoopOffset };
+ Result = expandAddToGEP(OffsetArray, OffsetArray+1, PTy, IntTy, Result);
+ } else {
+ Result = InsertNoopCastOfTo(Result, IntTy);
+ Result = Builder.CreateAdd(Result,
+ expandCodeFor(PostLoopOffset, IntTy));
+ rememberInstruction(Result);
+ }
+ }
+
+ return Result;
+}
+
Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
+ if (!CanonicalMode) return expandAddRecExprLiterally(S);
+
+ Type *Ty = SE.getEffectiveSCEVType(S->getType());
const Loop *L = S->getLoop();
// First check for an existing canonical IV in a suitable type.
PHINode *CanonicalIV = 0;
if (PHINode *PN = L->getCanonicalInductionVariable())
- if (SE.isSCEVable(PN->getType()) &&
- isa<IntegerType>(SE.getEffectiveSCEVType(PN->getType())) &&
- SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
+ if (SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
CanonicalIV = PN;
// Rewrite an AddRec in terms of the canonical induction variable, if
if (CanonicalIV &&
SE.getTypeSizeInBits(CanonicalIV->getType()) >
SE.getTypeSizeInBits(Ty)) {
- const SmallVectorImpl<const SCEV *> &Ops = S->getOperands();
- SmallVector<const SCEV *, 4> NewOps(Ops.size());
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- NewOps[i] = SE.getAnyExtendExpr(Ops[i], CanonicalIV->getType());
- Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop()));
+ SmallVector<const SCEV *, 4> NewOps(S->getNumOperands());
+ for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i)
+ NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
+ Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(),
+ // FIXME: S->getNoWrapFlags(FlagNW)
+ SCEV::FlagAnyWrap));
BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
BasicBlock::iterator NewInsertPt =
llvm::next(BasicBlock::iterator(cast<Instruction>(V)));
- while (isa<PHINode>(NewInsertPt)) ++NewInsertPt;
+ while (isa<PHINode>(NewInsertPt) || isa<DbgInfoIntrinsic>(NewInsertPt) ||
+ isa<LandingPadInst>(NewInsertPt))
+ ++NewInsertPt;
V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0,
NewInsertPt);
- Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
+ restoreInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
// {X,+,F} --> X + {0,+,F}
if (!S->getStart()->isZero()) {
- const SmallVectorImpl<const SCEV *> &SOperands = S->getOperands();
- SmallVector<const SCEV *, 4> NewOps(SOperands.begin(), SOperands.end());
- NewOps[0] = SE.getIntegerSCEV(0, Ty);
- const SCEV *Rest = SE.getAddRecExpr(NewOps, L);
+ SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end());
+ NewOps[0] = SE.getConstant(Ty, 0);
+ // FIXME: can use S->getNoWrapFlags()
+ const SCEV *Rest = SE.getAddRecExpr(NewOps, L, SCEV::FlagAnyWrap);
// Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
// comments on expandAddToGEP for details.
// Dig into the expression to find the pointer base for a GEP.
ExposePointerBase(Base, RestArray[0], SE);
// If we found a pointer, expand the AddRec with a GEP.
- if (
const PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
+ if (PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
// Make sure the Base isn't something exotic, such as a multiplied
// or divided pointer value. In those cases, the result type isn't
// actually a pointer type.
SE.getUnknown(expand(Rest))));
}
- // {0,+,1} --> Insert a canonical induction variable into the loop!
- if (S->isAffine() &&
- S->getOperand(1) == SE.getIntegerSCEV(1, Ty)) {
- // If there's a canonical IV, just use it.
- if (CanonicalIV) {
- assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
- "IVs with types different from the canonical IV should "
- "already have been handled!");
- return CanonicalIV;
- }
-
+ // If we don't yet have a canonical IV, create one.
+ if (!CanonicalIV) {
// Create and insert the PHI node for the induction variable in the
// specified loop.
BasicBlock *Header = L->getHeader();
- PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin());
- InsertedValues.insert(PN);
+ pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
+ CanonicalIV = PHINode::Create(Ty, std::distance(HPB, HPE), "indvar",
+ Header->begin());
+ rememberInstruction(CanonicalIV);
Constant *One = ConstantInt::get(Ty, 1);
- for (pred_iterator HPI = pred_begin(Header), HPE = pred_end(Header);
- HPI != HPE; ++HPI)
- if (L->contains(*HPI)) {
- // Insert a unit add instruction right before the terminator corresponding
- // to the back-edge.
- Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next",
- (*HPI)->getTerminator());
- InsertedValues.insert(Add);
- PN->addIncoming(Add, *HPI);
+ for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
+ BasicBlock *HP = *HPI;
+ if (L->contains(HP)) {
+ // Insert a unit add instruction right before the terminator
+ // corresponding to the back-edge.
+ Instruction *Add = BinaryOperator::CreateAdd(CanonicalIV, One,
+ "indvar.next",
+ HP->getTerminator());
+ Add->setDebugLoc(HP->getTerminator()->getDebugLoc());
+ rememberInstruction(Add);
+ CanonicalIV->addIncoming(Add, HP);
} else {
- PN->addIncoming(Constant::getNullValue(Ty), *HPI);
+ CanonicalIV->addIncoming(Constant::getNullValue(Ty), HP);
}
+ }
+ }
+
+ // {0,+,1} --> Insert a canonical induction variable into the loop!
+ if (S->isAffine() && S->getOperand(1)->isOne()) {
+ assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
+ "IVs with types different from the canonical IV should "
+ "already have been handled!");
+ return CanonicalIV;
}
// {0,+,F} --> {0,+,1} * F
- // Get the canonical induction variable I for this loop.
- Value *I = CanonicalIV ?
- CanonicalIV :
- getOrInsertCanonicalInductionVariable(L, Ty);
// If this is a simple linear addrec, emit it now as a special case.
if (S->isAffine()) // {0,+,F} --> i*F
return
expand(SE.getTruncateOrNoop(
- SE.getMulExpr(SE.getUnknown(I),
+ SE.getMulExpr(SE.getUnknown(CanonicalIV),
SE.getNoopOrAnyExtend(S->getOperand(1),
- I->getType())),
+ CanonicalIV->getType())),
Ty));
// If this is a chain of recurrences, turn it into a closed form, using the
// folders, then expandCodeFor the closed form. This allows the folders to
// simplify the expression without having to build a bunch of special code
// into this folder.
- const SCEV *IH = SE.getUnknown(I); // Get I as a "symbolic" SCEV.
+ const SCEV *IH = SE.getUnknown(CanonicalIV); // Get I as a "symbolic" SCEV.
// Promote S up to the canonical IV type, if the cast is foldable.
const SCEV *NewS = S;
- const SCEV *Ext = SE.getNoopOrAnyExtend(S, I->getType());
+ const SCEV *Ext = SE.getNoopOrAnyExtend(S, CanonicalIV->getType());
if (isa<SCEVAddRecExpr>(Ext))
NewS = Ext;
}
Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
+ Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *V = expandCodeFor(S->getOperand(),
SE.getEffectiveSCEVType(S->getOperand()->getType()));
- Value *I = Builder.CreateTrunc(V, Ty, "tmp");
- InsertedValues.insert(I);
+ Value *I = Builder.CreateTrunc(V, Ty);
+ rememberInstruction(I);
return I;
}
Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
+ Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *V = expandCodeFor(S->getOperand(),
SE.getEffectiveSCEVType(S->getOperand()->getType()));
- Value *I = Builder.CreateZExt(V, Ty, "tmp");
- InsertedValues.insert(I);
+ Value *I = Builder.CreateZExt(V, Ty);
+ rememberInstruction(I);
return I;
}
Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
+ Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *V = expandCodeFor(S->getOperand(),
SE.getEffectiveSCEVType(S->getOperand()->getType()));
- Value *I = Builder.CreateSExt(V, Ty, "tmp");
- InsertedValues.insert(I);
+ Value *I = Builder.CreateSExt(V, Ty);
+ rememberInstruction(I);
return I;
}
Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
- const Type *Ty = LHS->getType();
+ Type *Ty = LHS->getType();
for (int i = S->getNumOperands()-2; i >= 0; --i) {
// In the case of mixed integer and pointer types, do the
// rest of the comparisons as integer.
LHS = InsertNoopCastOfTo(LHS, Ty);
}
Value *RHS = expandCodeFor(S->getOperand(i), Ty);
- Value *ICmp = Builder.CreateICmpSGT(LHS, RHS, "tmp");
- InsertedValues.insert(ICmp);
+ Value *ICmp = Builder.CreateICmpSGT(LHS, RHS);
+ rememberInstruction(ICmp);
Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
- InsertedValues.insert(Sel);
+ rememberInstruction(Sel);
LHS = Sel;
}
// In the case of mixed integer and pointer types, cast the
Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
- const Type *Ty = LHS->getType();
+ Type *Ty = LHS->getType();
for (int i = S->getNumOperands()-2; i >= 0; --i) {
// In the case of mixed integer and pointer types, do the
// rest of the comparisons as integer.
LHS = InsertNoopCastOfTo(LHS, Ty);
}
Value *RHS = expandCodeFor(S->getOperand(i), Ty);
- Value *ICmp = Builder.CreateICmpUGT(LHS, RHS, "tmp");
- InsertedValues.insert(ICmp);
+ Value *ICmp = Builder.CreateICmpUGT(LHS, RHS);
+ rememberInstruction(ICmp);
Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
- InsertedValues.insert(Sel);
+ rememberInstruction(Sel);
LHS = Sel;
}
// In the case of mixed integer and pointer types, cast the
return LHS;
}
-Value *SCEVExpander::visitFieldOffsetExpr(const SCEVFieldOffsetExpr *S) {
- return ConstantExpr::getOffsetOf(S->getStructType(), S->getFieldNo());
+Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty,
+ Instruction *IP) {
+ Builder.SetInsertPoint(IP->getParent(), IP);
+ return expandCodeFor(SH, Ty);
}
-Value *SCEVExpander::visitAllocSizeExpr(const SCEVAllocSizeExpr *S) {
- return ConstantExpr::getSizeOf(S->getAllocType());
-}
-
-Value *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty) {
+Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty) {
// Expand the code for this SCEV.
Value *V = expand(SH);
if (Ty) {
Instruction *InsertPt = Builder.GetInsertPoint();
for (Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock()); ;
L = L->getParentLoop())
- if (S->isLoopInvariant(L)) {
+ if (SE.isLoopInvariant(S, L)) {
if (!L) break;
if (BasicBlock *Preheader = L->getLoopPreheader())
InsertPt = Preheader->getTerminator();
+ else {
+ // LSR sets the insertion point for AddRec start/step values to the
+ // block start to simplify value reuse, even though it's an invalid
+ // position. SCEVExpander must correct for this in all cases.
+ InsertPt = L->getHeader()->getFirstInsertionPt();
+ }
} else {
// If the SCEV is computable at this level, insert it into the header
// after the PHIs (and after any other instructions that we've inserted
// there) so that it is guaranteed to dominate any user inside the loop.
- if (L && S->hasComputableLoopEvolution(L))
- InsertPt = L->getHeader()->getFirstNonPHI();
- while (isInsertedInstruction(InsertPt))
+ if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
+ InsertPt = L->getHeader()->getFirstInsertionPt();
+ while (InsertPt != Builder.GetInsertPoint()
+ && (isInsertedInstruction(InsertPt)
+ || isa<DbgInfoIntrinsic>(InsertPt))) {
InsertPt = llvm::next(BasicBlock::iterator(InsertPt));
+ }
break;
}
Value *V = visit(S);
// Remember the expanded value for this SCEV at this location.
+ //
+ // This is independent of PostIncLoops. The mapped value simply materializes
+ // the expression at this insertion point. If the mapped value happened to be
+ // a postinc expansion, it could be reused by a non postinc user, but only if
+ // its insertion point was already at the head of the loop.
InsertedExpressions[std::make_pair(S, InsertPt)] = V;
- Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
+ restoreInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
+void SCEVExpander::rememberInstruction(Value *I) {
+ if (!PostIncLoops.empty())
+ InsertedPostIncValues.insert(I);
+ else
+ InsertedValues.insert(I);
+}
+
+void SCEVExpander::restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I) {
+ Builder.SetInsertPoint(BB, I);
+}
+
/// getOrInsertCanonicalInductionVariable - This method returns the
/// canonical induction variable of the specified type for the specified
/// loop (inserting one if there is none). A canonical induction variable
/// starts at zero and steps by one on each iteration.
-Value *
+PHINode *
SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
- const Type *Ty) {
- assert(Ty->isInteger() && "Can only insert integer induction variables!");
- const SCEV *H = SE.getAddRecExpr(SE.getIntegerSCEV(0, Ty),
- SE.getIntegerSCEV(1, Ty), L);
+ Type *Ty) {
+ assert(Ty->isIntegerTy() && "Can only insert integer induction variables!");
+
+ // Build a SCEV for {0,+,1}<L>.
+ // Conservatively use FlagAnyWrap for now.
+ const SCEV *H = SE.getAddRecExpr(SE.getConstant(Ty, 0),
+ SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
+
+ // Emit code for it.
BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
- Value *V = expandCodeFor(H, 0, L->getHeader()->begin());
+ PHINode *V = cast<PHINode>(expandCodeFor(H, 0, L->getHeader()->begin()));
if (SaveInsertBB)
- Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
+ restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+
return V;
}
+
+/// Sort values by integer width for replaceCongruentIVs.
+static bool width_descending(Value *lhs, Value *rhs) {
+ // Put pointers at the back and make sure pointer < pointer = false.
+ if (!lhs->getType()->isIntegerTy() || !rhs->getType()->isIntegerTy())
+ return rhs->getType()->isIntegerTy() && !lhs->getType()->isIntegerTy();
+ return rhs->getType()->getPrimitiveSizeInBits()
+ < lhs->getType()->getPrimitiveSizeInBits();
+}
+
+/// replaceCongruentIVs - Check for congruent phis in this loop header and
+/// replace them with their most canonical representative. Return the number of
+/// phis eliminated.
+///
+/// This does not depend on any SCEVExpander state but should be used in
+/// the same context that SCEVExpander is used.
+unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
+ SmallVectorImpl<WeakVH> &DeadInsts,
+ const TargetLowering *TLI) {
+ // Find integer phis in order of increasing width.
+ SmallVector<PHINode*, 8> Phis;
+ for (BasicBlock::iterator I = L->getHeader()->begin();
+ PHINode *Phi = dyn_cast<PHINode>(I); ++I) {
+ Phis.push_back(Phi);
+ }
+ if (TLI)
+ std::sort(Phis.begin(), Phis.end(), width_descending);
+
+ unsigned NumElim = 0;
+ DenseMap<const SCEV *, PHINode *> ExprToIVMap;
+ // Process phis from wide to narrow. Mapping wide phis to the their truncation
+ // so narrow phis can reuse them.
+ for (SmallVectorImpl<PHINode*>::const_iterator PIter = Phis.begin(),
+ PEnd = Phis.end(); PIter != PEnd; ++PIter) {
+ PHINode *Phi = *PIter;
+
+ if (!SE.isSCEVable(Phi->getType()))
+ continue;
+
+ PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
+ if (!OrigPhiRef) {
+ OrigPhiRef = Phi;
+ if (Phi->getType()->isIntegerTy() && TLI
+ && TLI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
+ // This phi can be freely truncated to the narrowest phi type. Map the
+ // truncated expression to it so it will be reused for narrow types.
+ const SCEV *TruncExpr =
+ SE.getTruncateExpr(SE.getSCEV(Phi), Phis.back()->getType());
+ ExprToIVMap[TruncExpr] = Phi;
+ }
+ continue;
+ }
+
+ // Replacing a pointer phi with an integer phi or vice-versa doesn't make
+ // sense.
+ if (OrigPhiRef->getType()->isPointerTy() != Phi->getType()->isPointerTy())
+ continue;
+
+ if (BasicBlock *LatchBlock = L->getLoopLatch()) {
+ Instruction *OrigInc =
+ cast<Instruction>(OrigPhiRef->getIncomingValueForBlock(LatchBlock));
+ Instruction *IsomorphicInc =
+ cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
+
+ // If this phi has the same width but is more canonical, replace the
+ // original with it. As part of the "more canonical" determination,
+ // respect a prior decision to use an IV chain.
+ if (OrigPhiRef->getType() == Phi->getType()
+ && !(ChainedPhis.count(Phi)
+ || isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L))
+ && (ChainedPhis.count(Phi)
+ || isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
+ std::swap(OrigPhiRef, Phi);
+ std::swap(OrigInc, IsomorphicInc);
+ }
+ // Replacing the congruent phi is sufficient because acyclic redundancy
+ // elimination, CSE/GVN, should handle the rest. However, once SCEV proves
+ // that a phi is congruent, it's often the head of an IV user cycle that
+ // is isomorphic with the original phi. It's worth eagerly cleaning up the
+ // common case of a single IV increment so that DeleteDeadPHIs can remove
+ // cycles that had postinc uses.
+ const SCEV *TruncExpr = SE.getTruncateOrNoop(SE.getSCEV(OrigInc),
+ IsomorphicInc->getType());
+ if (OrigInc != IsomorphicInc
+ && TruncExpr == SE.getSCEV(IsomorphicInc)
+ && ((isa<PHINode>(OrigInc) && isa<PHINode>(IsomorphicInc))
+ || hoistIVInc(OrigInc, IsomorphicInc))) {
+ DEBUG_WITH_TYPE(DebugType, dbgs()
+ << "INDVARS: Eliminated congruent iv.inc: "
+ << *IsomorphicInc << '\n');
+ Value *NewInc = OrigInc;
+ if (OrigInc->getType() != IsomorphicInc->getType()) {
+ Instruction *IP = isa<PHINode>(OrigInc)
+ ? (Instruction*)L->getHeader()->getFirstInsertionPt()
+ : OrigInc->getNextNode();
+ IRBuilder<> Builder(IP);
+ Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
+ NewInc = Builder.
+ CreateTruncOrBitCast(OrigInc, IsomorphicInc->getType(), IVName);
+ }
+ IsomorphicInc->replaceAllUsesWith(NewInc);
+ DeadInsts.push_back(IsomorphicInc);
+ }
+ }
+ DEBUG_WITH_TYPE(DebugType, dbgs()
+ << "INDVARS: Eliminated congruent iv: " << *Phi << '\n');
+ ++NumElim;
+ Value *NewIV = OrigPhiRef;
+ if (OrigPhiRef->getType() != Phi->getType()) {
+ IRBuilder<> Builder(L->getHeader()->getFirstInsertionPt());
+ Builder.SetCurrentDebugLocation(Phi->getDebugLoc());
+ NewIV = Builder.CreateTruncOrBitCast(OrigPhiRef, Phi->getType(), IVName);
+ }
+ Phi->replaceAllUsesWith(NewIV);
+ DeadInsts.push_back(Phi);
+ }
+ return NumElim;
+}
projects / oota-llvm.git / blobdiff