+ if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
+ // An addrec. This is the interesting part.
+ SmallVector<const SCEV *, 8> Operands;
+ const Loop *L = AR->getLoop();
+ // The addrec conceptually uses its operands at loop entry.
+ Instruction *LUser = L->getHeader()->begin();
+ // Transform each operand.
+ for (SCEVNAryExpr::op_iterator I = AR->op_begin(), E = AR->op_end();
+ I != E; ++I) {
+ Operands.push_back(TransformSubExpr(*I, LUser, 0));
+ }
+ // Conservatively use AnyWrap until/unless we need FlagNW.
+ const SCEV *Result = SE.getAddRecExpr(Operands, L, SCEV::FlagAnyWrap);
+ switch (Kind) {
+ default: llvm_unreachable("Unexpected transform name!");
+ case NormalizeAutodetect:
+ if (IVUseShouldUsePostIncValue(User, OperandValToReplace, L, &DT)) {
+ const SCEV *TransformedStep =
+ TransformSubExpr(AR->getStepRecurrence(SE),
+ User, OperandValToReplace);
+ Result = SE.getMinusSCEV(Result, TransformedStep);
+ Loops.insert(L);
+ }
+#if 0
+ // This assert is conceptually correct, but ScalarEvolution currently
+ // sometimes fails to canonicalize two equal SCEVs to exactly the same
+ // form. It's possibly a pessimization when this happens, but it isn't a
+ // correctness problem, so disable this assert for now.
+ assert(S == TransformSubExpr(Result, User, OperandValToReplace) &&
+ "SCEV normalization is not invertible!");
+#endif
+ break;
+ case Normalize:
+ if (Loops.count(L)) {
+ const SCEV *TransformedStep =
+ TransformSubExpr(AR->getStepRecurrence(SE),
+ User, OperandValToReplace);
+ Result = SE.getMinusSCEV(Result, TransformedStep);
+ }
+#if 0
+ // See the comment on the assert above.
+ assert(S == TransformSubExpr(Result, User, OperandValToReplace) &&
+ "SCEV normalization is not invertible!");
+#endif
+ break;
+ case Denormalize:
+ if (Loops.count(L))
+ Result = cast<SCEVAddRecExpr>(Result)->getPostIncExpr(SE);
+ break;
+ }
+ return Result;
+ }
+