[llvm] [InstCombine] Create a class to lazily track computed known bits (PR #66611)

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,97 @@
+//===- llvm/Analysis/WithCache.h - KnownBits cache for pointers -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Store a pointer to any type along with the KnownBits information for it
+// that is computed lazily (if required).
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_WITHCACHE_H
+#define LLVM_ANALYSIS_WITHCACHE_H
+
+#include "llvm/IR/Value.h"
+#include "llvm/Support/KnownBits.h"
+#include <type_traits>
+
+namespace llvm {
+struct SimplifyQuery;
+}
+
+llvm::KnownBits computeKnownBits(const llvm::Value *V, unsigned Depth,
+                                 const llvm::SimplifyQuery &Q);
+
+namespace llvm {
+template <typename Arg> class WithCache {
+  static_assert(std::is_pointer_v<Arg>, "WithCache requires a pointer type!");
+
+  using UnderlyingType = std::remove_pointer_t<Arg>;
+  constexpr static bool IsConst = std::is_const_v<Arg>;
+
+  template <typename T, bool Const>
+  using conditionally_const_t = std::conditional_t<Const, const T, T>;
+
+  using PointerType = conditionally_const_t<UnderlyingType *, IsConst>;
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nikic wrote:

I think `PointerType` is just `Arg`?

https://github.com/llvm/llvm-project/pull/66611