diff options
Diffstat (limited to 'llvm/lib/Analysis/ScalarEvolutionExpander.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolutionExpander.cpp | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp index 921403ddc0f..5b490194159 100644 --- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp @@ -1600,6 +1600,12 @@ Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty) { return V; } +// The expansion of SCEV will either reuse a previous Value in ExprValueMap, +// or expand the SCEV literally. Specifically, if the expansion is in LSRMode, +// and the SCEV contains any sub scAddRecExpr type SCEV, it will be expanded +// literally, to prevent LSR's transformed SCEV from being reverted. Otherwise, +// the expansion will try to reuse Value from ExprValueMap, and only when it +// fails, expand the SCEV literally. Value *SCEVExpander::expand(const SCEV *S) { // Compute an insertion point for this SCEV object. Hoist the instructions // as far out in the loop nest as possible. @@ -1639,7 +1645,25 @@ Value *SCEVExpander::expand(const SCEV *S) { Builder.SetInsertPoint(InsertPt); // Expand the expression into instructions. - Value *V = visit(S); + SetVector<Value *> *Set = SE.getSCEVValues(S); + Value *V = nullptr; + // If the expansion is in LSRMode, and the SCEV contains any sub scAddRecExpr + // type SCEV, it will be expanded literally, to prevent LSR's transformed SCEV + // from being reverted. + if (!(LSRMode && SE.containsAddRecurrence(S))) { + if (Set) { + // Choose a Value from the set which dominates the insertPt. + for (auto const &Ent : *Set) { + if (Ent && isa<Instruction>(Ent) && S->getType() == Ent->getType() && + SE.DT.dominates(cast<Instruction>(Ent), InsertPt)) { + V = Ent; + break; + } + } + } + } + if (!V) + V = visit(S); // Remember the expanded value for this SCEV at this location. // |
