[llvm] [AArch64][SVE] Use loop.dependence.war.mask in vector.memcheck (PR #175943)

[Benjamin Maxwell via llvm-commits]

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@@ -2173,38 +2173,85 @@ Value *llvm::addRuntimeChecks(
   return MemoryRuntimeCheck;
 }
 
-Value *llvm::addDiffRuntimeChecks(
-    Instruction *Loc, ArrayRef<PointerDiffInfo> Checks, SCEVExpander &Expander,
-    function_ref<Value *(IRBuilderBase &, unsigned)> GetVF, unsigned IC) {
+Value *llvm::addDiffRuntimeChecks(Instruction *Loc,
+                                  ArrayRef<PointerDiffInfo> Checks,
+                                  SCEVExpander &Expander, ElementCount VF,
+                                  unsigned IC, const TargetTransformInfo &TTI,
+                                  TTI::TargetCostKind CostKind) {
 
   LLVMContext &Ctx = Loc->getContext();
   IRBuilder ChkBuilder(Ctx, InstSimplifyFolder(Loc->getDataLayout()));
   ChkBuilder.SetInsertPoint(Loc);
+  Value *RuntimeVF = nullptr;
   // Our instructions might fold to a constant.
   Value *MemoryRuntimeCheck = nullptr;
-
   auto &SE = *Expander.getSE();
+
+  constexpr Intrinsic::ID LoopDeskMaskIID = Intrinsic::loop_dependence_war_mask;
+  auto LoopDepMaskIsCheap = [&](Type *MaskTy, Value *AccessSize) {
+    Value *NullPtr = ConstantPointerNull::get(PointerType::getUnqual(Ctx));
+    // The pointer values should not change the cost. The access size (constant)
+    // is needed to by targets to cost the mask.
+    IntrinsicCostAttributes ICA(LoopDeskMaskIID, MaskTy,
+                                {NullPtr, NullPtr, AccessSize});
+    InstructionCost Cost = TTI.getIntrinsicInstrCost(ICA, CostKind);
+    return Cost.isValid() && Cost <= 1;
+  };
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MacDue wrote:

Done :+1: 

https://github.com/llvm/llvm-project/pull/175943