================
@@ -3398,6 +3399,101 @@ bool
VectorCombine::foldInterleaveIntrinsics(Instruction &I) {
return true;
}
+// If `I` is a load instruction, used only by shufflevector instructions with
+// poison values, attempt to shrink the load to only the lanes being used.
+bool VectorCombine::shrinkLoadForShuffles(Instruction &I) {
+ auto *OldLoad = dyn_cast<LoadInst>(&I);
+ if (!OldLoad || !OldLoad->isSimple())
+ return false;
+
+ auto *VecTy = dyn_cast<FixedVectorType>(I.getType());
+ if (!VecTy)
+ return false;
+
+ auto IsPoisonOrUndef = [](Value *V) -> bool {
+ if (auto *C = dyn_cast<Constant>(V)) {
+ return isa<PoisonValue>(C) || isa<UndefValue>(C);
+ }
+ return false;
+ };
+
+ using IndexRange = std::pair<int, int>;
+ auto GetIndexRangeInShuffles = [&]() -> std::optional<IndexRange> {
+ auto OutputRange = IndexRange(VecTy->getNumElements(), -1);
+ for (auto &Use : I.uses()) {
+ // All uses must be ShuffleVector instructions.
+ auto *Shuffle = dyn_cast<ShuffleVectorInst>(Use.getUser());
+ if (!Shuffle)
+ return {};
+
+ // Get index range for value.
+ auto *Op0 = Shuffle->getOperand(0u);
+ auto *Op1 = Shuffle->getOperand(1u);
+ if (!IsPoisonOrUndef(Op1))
+ return {};
+
+ // Find the min and max indices used by the ShuffleVector instruction.
+ auto Mask = Shuffle->getShuffleMask();
+ auto *Op0Ty = cast<FixedVectorType>(Op0->getType());
+ auto NumElems = int(Op0Ty->getNumElements());
+
+ for (auto Index : Mask) {
+ if (Index >= 0 && Index < NumElems) {
+ OutputRange.first = std::min(Index, OutputRange.first);
+ OutputRange.second = std::max(Index, OutputRange.second);
+ }
+ }
+
+ if (OutputRange.second < OutputRange.first)
+ return {};
+ }
+ return OutputRange;
+ };
+
+ if (auto Indices = GetIndexRangeInShuffles()) {
+ auto OldSize = VecTy->getNumElements();
+ auto NewSize = Indices->second + 1u;
+
+ if (NewSize < OldSize) {
+ auto Builder = IRBuilder(&I);
+ Builder.SetCurrentDebugLocation(I.getDebugLoc());
+
+ // Create new load of smaller vector.
+ auto *ElemTy = VecTy->getElementType();
+ auto *NewVecTy = FixedVectorType::get(ElemTy, NewSize);
+ auto *NewLoad = cast<LoadInst>(
+ Builder.CreateLoad(NewVecTy, OldLoad->getPointerOperand()));
----------------
PeddleSpam wrote:
Thanks, I've fixed this and updated the load widening tests.
https://github.com/llvm/llvm-project/pull/128938
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
