[clang] [llvm] [VectorCombine] Shrink loads used in shufflevector rebroadcasts (PR #128938)
Simon Pilgrim via cfe-commits
cfe-commits at lists.llvm.org
Thu May 29 01:39:45 PDT 2025
================
@@ -3483,6 +3487,127 @@ bool VectorCombine::foldInterleaveIntrinsics(Instruction &I) {
return true;
}
+// Attempt to shrink loads that are only used by shufflevector instructions.
+bool VectorCombine::shrinkLoadForShuffles(Instruction &I) {
+ auto *OldLoad = dyn_cast<LoadInst>(&I);
+ if (!OldLoad || !OldLoad->isSimple())
+ return false;
+
+ auto *VecTy = dyn_cast<FixedVectorType>(OldLoad->getType());
+ if (!VecTy)
+ return false;
+
+ // Search all uses of load. If all uses are shufflevector instructions, and
+ // the second operands are all poison values, find the minimum and maximum
+ // indices of the vector elements referenced by all shuffle masks.
+ // Otherwise return `std::nullopt`.
+ using IndexRange = std::pair<int, int>;
+ auto GetIndexRangeInShuffles = [&]() -> std::optional<IndexRange> {
+ IndexRange OutputRange = IndexRange(VecTy->getNumElements(), -1);
+ for (auto &Use : I.uses()) {
+ // Ensure all uses match the required pattern.
+ User *Shuffle = Use.getUser();
+ Value *Op0 = nullptr;
+ ArrayRef<int> Mask;
+
+ if (!match(Shuffle, m_Shuffle(m_Value(Op0), m_Undef(), m_Mask(Mask))))
----------------
RKSimon wrote:
Should m_Value(Op0) be m_Specific(OldLoad) ?
https://github.com/llvm/llvm-project/pull/128938
More information about the cfe-commits
mailing list