//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ScalarEvolutionExpander.h"
-#include "llvm/Analysis/LoopInfo.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Target/TargetData.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Support/Debug.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, const Type *Ty,
+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 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) {
if (U->getType() == Ty)
if (CastInst *CI = dyn_cast<CastInst>(U))
if (CI->getOpcode() == Op) {
- // If the cast isn't where we want it, fix it.
- if (BasicBlock::iterator(CI) != IP) {
+ // 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.
- Instruction *NewCI = CastInst::Create(Op, V, Ty, "", IP);
- NewCI->takeName(CI);
- CI->replaceAllUsesWith(NewCI);
+ Ret = CastInst::Create(Op, V, Ty, "", IP);
+ Ret->takeName(CI);
+ CI->replaceAllUsesWith(Ret);
CI->setOperand(0, UndefValue::get(V->getType()));
- rememberInstruction(NewCI);
- return NewCI;
+ break;
}
- rememberInstruction(CI);
- return CI;
+ Ret = CI;
+ break;
}
}
// Create a new cast.
- Instruction *I = CastInst::Create(Op, V, Ty, V->getName(), IP);
- rememberInstruction(I);
- return I;
+ 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())) {
while ((isa<BitCastInst>(IP) &&
isa<Argument>(cast<BitCastInst>(IP)->getOperand(0)) &&
cast<BitCastInst>(IP)->getOperand(0) != A) ||
- isa<DbgInfoIntrinsic>(IP))
+ isa<DbgInfoIntrinsic>(IP) ||
+ isa<LandingPadInst>(IP))
++IP;
return ReuseOrCreateCast(A, Ty, Op, IP);
}
BasicBlock::iterator IP = I; ++IP;
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
IP = II->getNormalDest()->begin();
- while (isa<PHINode>(IP) || isa<DbgInfoIntrinsic>(IP)) ++IP;
+ while (isa<PHINode>(IP) || isa<LandingPadInst>(IP))
+ ++IP;
return ReuseOrCreateCast(I, Ty, Op, IP);
}
}
// Save the original insertion point so we can restore it when we're done.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
+ BuilderType::InsertPointGuard Guard(Builder);
// Move the insertion point out of as many loops as we can.
while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
}
// If we haven't found this binop, insert it.
- Value *BO = Builder.CreateBinOp(Opcode, LHS, RHS, "tmp");
+ Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS));
+ BO->setDebugLoc(Loc);
rememberInstruction(BO);
- // Restore the original insert point.
- if (SaveInsertBB)
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
-
return BO;
}
const SCEV *&Remainder,
const SCEV *Factor,
ScalarEvolution &SE,
- const TargetData *TD) {
+ const DataLayout *TD) {
// Everything is divisible by one.
if (Factor->isOne())
return true;
// of the given factor.
if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
if (TD) {
- // With TargetData, the size is known. Check if there is a constant
+ // With DataLayout, the size is known. Check if there is a constant
// operand which is a multiple of the given factor. If so, we can
// factor it.
const SCEVConstant *FC = cast<SCEVConstant>(Factor);
return true;
}
} else {
- // Without TargetData, check if Factor can be factored out of any of the
+ // Without DataLayout, check if Factor can be factored out of any of the
// 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 *Start = A->getStart();
if (!FactorOutConstant(Start, Remainder, Factor, SE, TD))
return false;
- // FIXME: can use A->getNoWrapFlags(FlagNW)
- S = SE.getAddRecExpr(Start, Step, A->getLoop(), SCEV::FlagAnyWrap);
+ S = SE.getAddRecExpr(Start, Step, A->getLoop(),
+ A->getNoWrapFlags(SCEV::FlagNW));
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)
/// 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;
AddRecs.push_back(SE.getAddRecExpr(Zero,
A->getStepRecurrence(SE),
A->getLoop(),
- // FIXME: A->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
+ A->getNoWrapFlags(SCEV::FlagNW)));
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
Ops[i] = Zero;
Ops.append(Add->op_begin(), Add->op_end());
///
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;
// without the other.
SplitAddRecs(Ops, Ty, SE);
+ Type *IntPtrTy = SE.TD
+ ? SE.TD->getIntPtrType(PTy)
+ : Type::getInt64Ty(PTy->getContext());
+
// Descend down the pointer's type and attempt to convert the other
// operands into GEP indices, at each level. The first index in a GEP
// indexes into the array implied by the pointer operand; the rest of
// array indexing.
SmallVector<const SCEV *, 8> ScaledOps;
if (ElTy->isSized()) {
- const SCEV *ElSize = SE.getSizeOfExpr(ElTy);
+ const SCEV *ElSize = SE.getSizeOfExpr(IntPtrTy, ElTy);
if (!ElSize->isZero()) {
SmallVector<const SCEV *, 8> NewOps;
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
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;
if (SE.TD) {
- // With TargetData, field offsets are known. See if a constant offset
+ // With DataLayout, field offsets are known. See if a constant offset
// falls within any of the struct fields.
if (Ops.empty()) break;
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
}
}
} else {
- // Without TargetData, just check for an offsetof expression of the
+ // Without DataLayout, just check for an offsetof expression of the
// appropriate struct type.
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Ops[i])) {
- const Type *CTy;
+ Type *CTy;
Constant *FieldNo;
if (U->isOffsetOf(CTy, FieldNo) && CTy == STy) {
GepIndices.push_back(FieldNo);
}
}
- if (
const ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
+ if (ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
ElTy = ATy->getElementType();
else
break;
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;
}
// Save the original insertion point so we can restore it when we're done.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ BuilderType::InsertPointGuard Guard(Builder);
// Move the insertion point out of as many loops as we can.
while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
Value *GEP = Builder.CreateGEP(V, Idx, "uglygep");
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();
+ BuilderType::InsertPoint SaveInsertPt = Builder.saveIP();
// Move the insertion point out of as many loops as we can.
while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
if (V->getType() != PTy)
Casted = InsertNoopCastOfTo(Casted, PTy);
Value *GEP = Builder.CreateGEP(Casted,
- GepIndices.begin(),
- GepIndices.end(),
+ GepIndices,
"scevgep");
Ops.push_back(SE.getUnknown(GEP));
rememberInstruction(GEP);
// Restore the original insert point.
- if (SaveInsertBB)
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+ Builder.restoreIP(SaveInsertPt);
return expand(SE.getAddExpr(Ops));
}
-/// isNonConstantNegative - Return true if the specified scev is negated, but
-/// not a constant.
-static bool isNonConstantNegative(const SCEV *F) {
- const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(F);
- if (!Mul) return false;
-
- // If there is a constant factor, it will be first.
- const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
- if (!SC) return false;
-
- // Return true if the value is negative, this matches things like (-42 * V).
- return SC->getValue()->getValue().isNegative();
-}
-
/// 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.
return RelevantLoops[D] = Result;
}
llvm_unreachable("Unexpected SCEV type!");
- return 0;
}
namespace {
// 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 (isNonConstantNegative(LHS.second)) {
- if (!isNonConstantNegative(RHS.second))
+ if (LHS.second->isNonConstantNegative()) {
+ if (!RHS.second->isNonConstantNegative())
return false;
- } else if (isNonConstantNegative(RHS.second))
+ } else if (RHS.second->isNonConstantNegative())
return true;
// Otherwise they are equivalent according to this comparison.
}
Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
+ 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
// This is the first operand. Just expand it.
Sum = expand(Op);
++I;
- } else if (
const PointerType *PTy = dyn_cast<PointerType>(Sum->getType())) {
+ } 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;
NewOps.push_back(X);
}
Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum);
- } else if (
const PointerType *PTy = dyn_cast<PointerType>(Op->getType())) {
+ } 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.
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 (isNonConstantNegative(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);
}
Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
+ 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.
}
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())) {
SE.getAddRecExpr(SE.getConstant(A->getType(), 0),
A->getStepRecurrence(SE),
A->getLoop(),
- // FIXME: A->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
+ A->getNoWrapFlags(SCEV::FlagNW)));
}
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 (isa<PHINode>(InsertPos)
+ || !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,
- const Type *ExpandTy,
- const Type *IntTy) {
+ Type *ExpandTy,
+ Type *IntTy) {
+ assert((!IVIncInsertLoop||IVIncInsertPos) && "Uninitialized insert position");
+
// Reuse a previously-inserted PHI, if present.
- 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)
- if (BasicBlock *LatchBlock = L->getLoopLatch()) {
- Instruction *IncV =
- cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock));
-
- // Determine if this is a well-behaved chain of instructions leading
- // back to the PHI. It probably will be, if we're scanning an inner
- // loop already visited by LSR for example, but it wouldn't have
- // to be.
- do {
- if (IncV->getNumOperands() == 0 || isa<PHINode>(IncV) ||
- (isa<CastInst>(IncV) && !isa<BitCastInst>(IncV))) {
- IncV = 0;
- break;
- }
- // 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.
- 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)) {
- IncV = 0;
- break;
- }
- if (!IncV)
- break;
- // Advance to the next instruction.
- IncV = dyn_cast<Instruction>(IncV->getOperand(0));
- if (!IncV)
- break;
- if (IncV->mayHaveSideEffects()) {
- IncV = 0;
- break;
- }
- } while (IncV != PN);
-
- if (IncV) {
- // Ok, the add recurrence looks usable.
- // Remember this PHI, even in post-inc mode.
- InsertedValues.insert(PN);
- // Remember the increment.
- IncV = cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock));
- rememberInstruction(IncV);
- 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);
- return PN;
- }
+ 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();
+ BuilderType::InsertPointGuard Guard(Builder);
+
+ // 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());
- // Expand code for the step value. Insert instructions right before the
- // terminator corresponding to the back-edge. Do this before creating the PHI
- // so that PHI reuse code doesn't see an incomplete PHI. 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).
+ // 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);
- bool isPointer = ExpandTy->isPointerTy();
- bool isNegative = !isPointer && isNonConstantNegative(Step);
- if (isNegative)
+ // 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, "lsr.iv");
- PN->reserveOperandSpace(std::distance(HPB, HPE));
+ PHINode *PN = Builder.CreatePHI(ExpandTy, std::distance(HPB, HPE),
+ Twine(IVName) + ".iv");
rememberInstruction(PN);
// Create the step instructions and populate the PHI.
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.
+ // 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->getParent(), InsertPos);
- Value *IncV;
- // If the PHI is a pointer, use a GEP, otherwise use an add or sub.
- if (isPointer) {
- const 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(), "tmp");
- rememberInstruction(IncV);
- }
- } else {
- IncV = isNegative ?
- Builder.CreateSub(PN, StepV, "lsr.iv.next") :
- Builder.CreateAdd(PN, StepV, "lsr.iv.next");
- rememberInstruction(IncV);
+ Builder.SetInsertPoint(InsertPos);
+ Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
+ if (isa<OverflowingBinaryOperator>(IncV)) {
+ if (Normalized->getNoWrapFlags(SCEV::FlagNUW))
+ cast<BinaryOperator>(IncV)->setHasNoUnsignedWrap();
+ if (Normalized->getNoWrapFlags(SCEV::FlagNSW))
+ cast<BinaryOperator>(IncV)->setHasNoSignedWrap();
}
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);
}
Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
- const Type *STy = S->getType();
- const Type *IntTy = SE.getEffectiveSCEVType(STy);
+ 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
Normalized = cast<SCEVAddRecExpr>(
SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE),
Normalized->getLoop(),
- // FIXME: Normalized->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
+ Normalized->getNoWrapFlags(SCEV::FlagNW)));
}
// Strip off any non-loop-dominating component from the addrec step.
PostLoopScale = Step;
Step = SE.getConstant(Normalized->getType(), 1);
Normalized =
- cast<SCEVAddRecExpr>(SE.getAddRecExpr(Start, Step,
- Normalized->getLoop(),
- // FIXME: Normalized
- // ->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
+ cast<SCEVAddRecExpr>(SE.getAddRecExpr(
+ Start, Step, Normalized->getLoop(),
+ Normalized->getNoWrapFlags(SCEV::FlagNW)));
}
// 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.
- const Type *ExpandTy = PostLoopScale ? IntTy : STy;
+ Type *ExpandTy = PostLoopScale ? IntTy : STy;
PHINode *PN = getAddRecExprPHILiterally(Normalized, L, ExpandTy, IntTy);
// Accommodate post-inc mode, if necessary.
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);
+ Value *StepV;
+ {
+ // Expand the step somewhere that dominates the loop header.
+ BuilderType::InsertPointGuard Guard(Builder);
+ StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin());
+ }
+ Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
+ }
}
// Re-apply any non-loop-dominating scale.
if (PostLoopScale) {
+ assert(S->isAffine() && "Can't linearly scale non-affine recurrences.");
Result = InsertNoopCastOfTo(Result, IntTy);
Result = Builder.CreateMul(Result,
expandCodeFor(PostLoopScale, IntTy));
// Re-apply any non-loop-dominating offset.
if (PostLoopOffset) {
- if (
const PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
+ if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
const SCEV *const OffsetArray[1] = { PostLoopOffset };
Result = expandAddToGEP(OffsetArray, OffsetArray+1, PTy, IntTy, Result);
} else {
Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
if (!CanonicalMode) return expandAddRecExprLiterally(S);
- const Type *Ty = SE.getEffectiveSCEVType(S->getType());
+ Type *Ty = SE.getEffectiveSCEVType(S->getType());
const Loop *L = S->getLoop();
// First check for an existing canonical IV in a suitable type.
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();
+ S->getNoWrapFlags(SCEV::FlagNW)));
BasicBlock::iterator NewInsertPt =
llvm::next(BasicBlock::iterator(cast<Instruction>(V)));
- while (isa<PHINode>(NewInsertPt) || isa<DbgInfoIntrinsic>(NewInsertPt))
+ BuilderType::InsertPointGuard Guard(Builder);
+ while (isa<PHINode>(NewInsertPt) || isa<DbgInfoIntrinsic>(NewInsertPt) ||
+ isa<LandingPadInst>(NewInsertPt))
++NewInsertPt;
V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0,
NewInsertPt);
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
if (!S->getStart()->isZero()) {
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);
+ const SCEV *Rest = SE.getAddRecExpr(NewOps, L,
+ S->getNoWrapFlags(SCEV::FlagNW));
// 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.
// specified loop.
BasicBlock *Header = L->getHeader();
pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
- CanonicalIV = PHINode::Create(Ty, "indvar", Header->begin());
- CanonicalIV->reserveOperandSpace(std::distance(HPB, HPE));
+ CanonicalIV = PHINode::Create(Ty, std::distance(HPB, HPE), "indvar",
+ Header->begin());
rememberInstruction(CanonicalIV);
+ SmallSet<BasicBlock *, 4> PredSeen;
Constant *One = ConstantInt::get(Ty, 1);
for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
BasicBlock *HP = *HPI;
+ if (!PredSeen.insert(HP))
+ continue;
+
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 {
}
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");
+ 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");
+ 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");
+ 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");
+ Value *ICmp = Builder.CreateICmpSGT(LHS, RHS);
rememberInstruction(ICmp);
Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
rememberInstruction(Sel);
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");
+ Value *ICmp = Builder.CreateICmpUGT(LHS, RHS);
rememberInstruction(ICmp);
Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
rememberInstruction(Sel);
return LHS;
}
-Value *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty,
- Instruction *I) {
- BasicBlock::iterator IP = I;
- while (isInsertedInstruction(IP) || isa<DbgInfoIntrinsic>(IP))
- ++IP;
+Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty,
+ Instruction *IP) {
Builder.SetInsertPoint(IP->getParent(), IP);
return expandCodeFor(SH, Ty);
}
-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) {
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 && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
- InsertPt = L->getHeader()->getFirstNonPHI();
- while (isInsertedInstruction(InsertPt) || isa<DbgInfoIntrinsic>(InsertPt))
+ InsertPt = L->getHeader()->getFirstInsertionPt();
+ while (InsertPt != Builder.GetInsertPoint()
+ && (isInsertedInstruction(InsertPt)
+ || isa<DbgInfoIntrinsic>(InsertPt))) {
InsertPt = llvm::next(BasicBlock::iterator(InsertPt));
+ }
break;
}
// Check to see if we already expanded this here.
- std::map<std::pair<const SCEV *, Instruction *>,
- AssertingVH<Value> >::iterator I =
- InsertedExpressions.find(std::make_pair(S, InsertPt));
+ std::map<std::pair<const SCEV *, Instruction *>, TrackingVH<Value> >::iterator
+ I = InsertedExpressions.find(std::make_pair(S, InsertPt));
if (I != InsertedExpressions.end())
return I->second;
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ BuilderType::InsertPointGuard Guard(Builder);
Builder.SetInsertPoint(InsertPt->getParent(), InsertPt);
// Expand the expression into instructions.
Value *V = visit(S);
// Remember the expanded value for this SCEV at this location.
- if (PostIncLoops.empty())
- InsertedExpressions[std::make_pair(S, InsertPt)] = V;
-
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+ //
+ // 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;
return V;
}
InsertedPostIncValues.insert(I);
else
InsertedValues.insert(I);
-
- // If we just claimed an existing instruction and that instruction had
- // been the insert point, adjust the insert point forward so that
- // subsequently inserted code will be dominated.
- if (Builder.GetInsertPoint() == I) {
- BasicBlock::iterator It = cast<Instruction>(I);
- do { ++It; } while (isInsertedInstruction(It) ||
- isa<DbgInfoIntrinsic>(It));
- Builder.SetInsertPoint(Builder.GetInsertBlock(), It);
- }
-}
-
-void SCEVExpander::restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I) {
- // If we acquired more instructions since the old insert point was saved,
- // advance past them.
- while (isInsertedInstruction(I) || isa<DbgInfoIntrinsic>(I)) ++I;
-
- Builder.SetInsertPoint(BB, I);
}
/// getOrInsertCanonicalInductionVariable - This method returns the
/// starts at zero and steps by one on each iteration.
PHINode *
SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
- const Type *Ty) {
+ Type *Ty) {
assert(Ty->isIntegerTy() && "Can only insert integer induction variables!");
// Build a SCEV for {0,+,1}<L>.
SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
// Emit code for it.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ BuilderType::InsertPointGuard Guard(Builder);
PHINode *V = cast<PHINode>(expandCodeFor(H, 0, L->getHeader()->begin()));
- if (SaveInsertBB)
- 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 TargetTransformInfo *TTI) {
+ // 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 (TTI)
+ 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;
+
+ // Fold constant phis. They may be congruent to other constant phis and
+ // would confuse the logic below that expects proper IVs.
+ if (Value *V = Phi->hasConstantValue()) {
+ Phi->replaceAllUsesWith(V);
+ DeadInsts.push_back(Phi);
+ ++NumElim;
+ DEBUG_WITH_TYPE(DebugType, dbgs()
+ << "INDVARS: Eliminated constant iv: " << *Phi << '\n');
+ continue;
+ }
+
+ if (!SE.isSCEVable(Phi->getType()))
+ continue;
+
+ PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
+ if (!OrigPhiRef) {
+ OrigPhiRef = Phi;
+ if (Phi->getType()->isIntegerTy() && TTI
+ && TTI->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;
+}
+
+namespace {
+// Search for a SCEV subexpression that is not safe to expand. Any expression
+// that may expand to a !isSafeToSpeculativelyExecute value is unsafe, namely
+// UDiv expressions. We don't know if the UDiv is derived from an IR divide
+// instruction, but the important thing is that we prove the denominator is
+// nonzero before expansion.
+//
+// IVUsers already checks that IV-derived expressions are safe. So this check is
+// only needed when the expression includes some subexpression that is not IV
+// derived.
+//
+// Currently, we only allow division by a nonzero constant here. If this is
+// inadequate, we could easily allow division by SCEVUnknown by using
+// ValueTracking to check isKnownNonZero().
+//
+// We cannot generally expand recurrences unless the step dominates the loop
+// header. The expander handles the special case of affine recurrences by
+// scaling the recurrence outside the loop, but this technique isn't generally
+// applicable. Expanding a nested recurrence outside a loop requires computing
+// binomial coefficients. This could be done, but the recurrence has to be in a
+// perfectly reduced form, which can't be guaranteed.
+struct SCEVFindUnsafe {
+ ScalarEvolution &SE;
+ bool IsUnsafe;
+
+ SCEVFindUnsafe(ScalarEvolution &se): SE(se), IsUnsafe(false) {}
+
+ bool follow(const SCEV *S) {
+ if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
+ const SCEVConstant *SC = dyn_cast<SCEVConstant>(D->getRHS());
+ if (!SC || SC->getValue()->isZero()) {
+ IsUnsafe = true;
+ return false;
+ }
+ }
+ if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
+ const SCEV *Step = AR->getStepRecurrence(SE);
+ if (!AR->isAffine() && !SE.dominates(Step, AR->getLoop()->getHeader())) {
+ IsUnsafe = true;
+ return false;
+ }
+ }
+ return true;
+ }
+ bool isDone() const { return IsUnsafe; }
+};
+}
+
+namespace llvm {
+bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE) {
+ SCEVFindUnsafe Search(SE);
+ visitAll(S, Search);
+ return !Search.IsUnsafe;
+}
+}
projects / oota-llvm.git / blobdiff