+}
+
+/// 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;
+}
+
+/// \brief Hoist the addrec instruction chain rooted in the loop phi above the
+/// position. This routine assumes that this is possible (has been checked).
+static void hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
+ Instruction *Pos, PHINode *LoopPhi) {
+ do {
+ if (DT->dominates(InstToHoist, Pos))
+ break;
+ // Make sure the increment is where we want it. But don't move it
+ // down past a potential existing post-inc user.
+ InstToHoist->moveBefore(Pos);
+ Pos = InstToHoist;
+ InstToHoist = cast<Instruction>(InstToHoist->getOperand(0));
+ } while (InstToHoist != LoopPhi);
+}
+
+/// \brief Check whether we can cheaply express the requested SCEV in terms of
+/// the available PHI SCEV by truncation and/or invertion of the step.
+static bool canBeCheaplyTransformed(ScalarEvolution &SE,
+ const SCEVAddRecExpr *Phi,
+ const SCEVAddRecExpr *Requested,
+ bool &InvertStep) {
+ Type *PhiTy = SE.getEffectiveSCEVType(Phi->getType());
+ Type *RequestedTy = SE.getEffectiveSCEVType(Requested->getType());
+
+ if (RequestedTy->getIntegerBitWidth() > PhiTy->getIntegerBitWidth())