[llvm] [Delinearization] Remove tryDelinearizeFixedSizeImpl (PR #169046)

[Ryotaro Kasuga via llvm-commits]

https://github.com/kasuga-fj created https://github.com/llvm/llvm-project/pull/169046

`tryDelinearizeFixedSizeImpl` is a heuristic function relying on GEP's type information. Using these information to drive an optimization heuristic is not allowed, so this function should be removed. As #161822 and #164798 have eliminated all calls to this, this patch removes the function itself.

>From 6165aebfdc0f078492f8db4d67fae205cee2c7a9 Mon Sep 17 00:00:00 2001
From: Ryotaro Kasuga <kasuga.ryotaro at fujitsu.com>
Date: Fri, 21 Nov 2025 14:26:53 +0000
Subject: [PATCH] [Delinearization] Remove tryDelinearizeFixedSizeImpl

---
 llvm/include/llvm/Analysis/Delinearization.h | 11 ------
 llvm/lib/Analysis/Delinearization.cpp        | 38 --------------------
 2 files changed, 49 deletions(-)

diff --git a/llvm/include/llvm/Analysis/Delinearization.h b/llvm/include/llvm/Analysis/Delinearization.h
index 434cfb61699d6f..cdcc3b67fccf1e 100644
--- a/llvm/include/llvm/Analysis/Delinearization.h
+++ b/llvm/include/llvm/Analysis/Delinearization.h
@@ -155,17 +155,6 @@ bool getIndexExpressionsFromGEP(ScalarEvolution &SE,
                                 SmallVectorImpl<const SCEV *> &Subscripts,
                                 SmallVectorImpl<int> &Sizes);
 
-/// Implementation of fixed size array delinearization. Try to delinearize
-/// access function for a fixed size multi-dimensional array, by deriving
-/// subscripts from GEP instructions. Returns true upon success and false
-/// otherwise. \p Inst is the load/store instruction whose pointer operand is
-/// the one we want to delinearize. \p AccessFn is its corresponding SCEV
-/// expression w.r.t. the surrounding loop.
-bool tryDelinearizeFixedSizeImpl(ScalarEvolution *SE, Instruction *Inst,
-                                 const SCEV *AccessFn,
-                                 SmallVectorImpl<const SCEV *> &Subscripts,
-                                 SmallVectorImpl<int> &Sizes);
-
 struct DelinearizationPrinterPass
     : public PassInfoMixin<DelinearizationPrinterPass> {
   explicit DelinearizationPrinterPass(raw_ostream &OS);
diff --git a/llvm/lib/Analysis/Delinearization.cpp b/llvm/lib/Analysis/Delinearization.cpp
index 4064b25d9d4e73..8a8c2277012ec7 100644
--- a/llvm/lib/Analysis/Delinearization.cpp
+++ b/llvm/lib/Analysis/Delinearization.cpp
@@ -704,44 +704,6 @@ bool llvm::getIndexExpressionsFromGEP(ScalarEvolution &SE,
   return !Subscripts.empty();
 }
 
-bool llvm::tryDelinearizeFixedSizeImpl(
-    ScalarEvolution *SE, Instruction *Inst, const SCEV *AccessFn,
-    SmallVectorImpl<const SCEV *> &Subscripts, SmallVectorImpl<int> &Sizes) {
-  Value *SrcPtr = getLoadStorePointerOperand(Inst);
-
-  // Check the simple case where the array dimensions are fixed size.
-  auto *SrcGEP = dyn_cast<GetElementPtrInst>(SrcPtr);
-  if (!SrcGEP)
-    return false;
-
-  getIndexExpressionsFromGEP(*SE, SrcGEP, Subscripts, Sizes);
-
-  // Check that the two size arrays are non-empty and equal in length and
-  // value.
-  // TODO: it would be better to let the caller to clear Subscripts, similar
-  // to how we handle Sizes.
-  if (Sizes.empty() || Subscripts.size() <= 1) {
-    Subscripts.clear();
-    return false;
-  }
-
-  // Check that for identical base pointers we do not miss index offsets
-  // that have been added before this GEP is applied.
-  Value *SrcBasePtr = SrcGEP->getOperand(0)->stripPointerCasts();
-  const SCEVUnknown *SrcBase =
-      dyn_cast<SCEVUnknown>(SE->getPointerBase(AccessFn));
-  if (!SrcBase || SrcBasePtr != SrcBase->getValue()) {
-    Subscripts.clear();
-    return false;
-  }
-
-  assert(Subscripts.size() == Sizes.size() + 1 &&
-         "Expected equal number of entries in the list of size and "
-         "subscript.");
-
-  return true;
-}
-
 namespace {
 
 void printDelinearization(raw_ostream &O, Function *F, LoopInfo *LI,