[llvm] 6e3e21d - [InstCombine] Remove unnecessary removeBitcastsFromLoadStoreOnMinMax() fold (NFCI)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-10-24T17:31:35+02:00
New Revision: 6e3e21d2032216b5d01b47a0442638225e66dc1b

URL: https://github.com/llvm/llvm-project/commit/6e3e21d2032216b5d01b47a0442638225e66dc1b
DIFF: https://github.com/llvm/llvm-project/commit/6e3e21d2032216b5d01b47a0442638225e66dc1b.diff

LOG: [InstCombine] Remove unnecessary removeBitcastsFromLoadStoreOnMinMax() fold (NFCI)

This optimizes a very specific pointer bitcast pattern, and as
such is no longer relevant with opaque pointers.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 5b5760665fa68cb..b72b68c68d985bd 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -648,29 +648,6 @@ static StoreInst *combineStoreToNewValue(InstCombinerImpl &IC, StoreInst &SI,
   return NewStore;
 }
 
-/// Returns true if instruction represent minmax pattern like:
-///   select ((cmp load V1, load V2), V1, V2).
-static bool isMinMaxWithLoads(Value *V, Type *&LoadTy) {
-  assert(V->getType()->isPointerTy() && "Expected pointer type.");
-  // Ignore possible ty* to ixx* bitcast.
-  V = InstCombiner::peekThroughBitcast(V);
-  // Check that select is select ((cmp load V1, load V2), V1, V2) - minmax
-  // pattern.
-  CmpInst::Predicate Pred;
-  Instruction *L1;
-  Instruction *L2;
-  Value *LHS;
-  Value *RHS;
-  if (!match(V, m_Select(m_Cmp(Pred, m_Instruction(L1), m_Instruction(L2)),
-                         m_Value(LHS), m_Value(RHS))))
-    return false;
-  LoadTy = L1->getType();
-  return (match(L1, m_Load(m_Specific(LHS))) &&
-          match(L2, m_Load(m_Specific(RHS)))) ||
-         (match(L1, m_Load(m_Specific(RHS))) &&
-          match(L2, m_Load(m_Specific(LHS))));
-}
-
 /// Combine loads to match the type of their uses' value after looking
 /// through intervening bitcasts.
 ///
@@ -1394,58 +1371,6 @@ static bool equivalentAddressValues(Value *A, Value *B) {
   return false;
 }
 
-/// Converts store (bitcast (load (bitcast (select ...)))) to
-/// store (load (select ...)), where select is minmax:
-/// select ((cmp load V1, load V2), V1, V2).
-static bool removeBitcastsFromLoadStoreOnMinMax(InstCombinerImpl &IC,
-                                                StoreInst &SI) {
-  // bitcast?
-  if (!match(SI.getPointerOperand(), m_BitCast(m_Value())))
-    return false;
-  // load? integer?
-  Value *LoadAddr;
-  if (!match(SI.getValueOperand(), m_Load(m_BitCast(m_Value(LoadAddr)))))
-    return false;
-  auto *LI = cast<LoadInst>(SI.getValueOperand());
-  if (!LI->getType()->isIntegerTy())
-    return false;
-  Type *CmpLoadTy;
-  if (!isMinMaxWithLoads(LoadAddr, CmpLoadTy))
-    return false;
-
-  // Make sure the type would actually change.
-  // This condition can be hit with chains of bitcasts.
-  if (LI->getType() == CmpLoadTy)
-    return false;
-
-  // Make sure we're not changing the size of the load/store.
-  const auto &DL = IC.getDataLayout();
-  if (DL.getTypeStoreSizeInBits(LI->getType()) !=
-      DL.getTypeStoreSizeInBits(CmpLoadTy))
-    return false;
-
-  if (!all_of(LI->users(), [LI, LoadAddr](User *U) {
-        auto *SI = dyn_cast<StoreInst>(U);
-        return SI && SI->getPointerOperand() != LI &&
-               InstCombiner::peekThroughBitcast(SI->getPointerOperand()) !=
-                   LoadAddr &&
-               !SI->getPointerOperand()->isSwiftError();
-      }))
-    return false;
-
-  IC.Builder.SetInsertPoint(LI);
-  LoadInst *NewLI = IC.combineLoadToNewType(*LI, CmpLoadTy);
-  // Replace all the stores with stores of the newly loaded value.
-  for (auto *UI : LI->users()) {
-    auto *USI = cast<StoreInst>(UI);
-    IC.Builder.SetInsertPoint(USI);
-    combineStoreToNewValue(IC, *USI, NewLI);
-  }
-  IC.replaceInstUsesWith(*LI, PoisonValue::get(LI->getType()));
-  IC.eraseInstFromFunction(*LI);
-  return true;
-}
-
 Instruction *InstCombinerImpl::visitStoreInst(StoreInst &SI) {
   Value *Val = SI.getOperand(0);
   Value *Ptr = SI.getOperand(1);
@@ -1466,9 +1391,6 @@ Instruction *InstCombinerImpl::visitStoreInst(StoreInst &SI) {
   if (unpackStoreToAggregate(*this, SI))
     return eraseInstFromFunction(SI);
 
-  if (removeBitcastsFromLoadStoreOnMinMax(*this, SI))
-    return eraseInstFromFunction(SI);
-
   // Replace GEP indices if possible.
   if (Instruction *NewGEPI = replaceGEPIdxWithZero(*this, Ptr, SI))
     return replaceOperand(SI, 1, NewGEPI);