[llvm] [PatternMatching] Add generic API for matching constants using custom conditions (PR #85676)

[Nikita Popov via llvm-commits]

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@@ -460,6 +460,39 @@ template <typename Predicate> struct apf_pred_ty : public Predicate {
 //
 ///////////////////////////////////////////////////////////////////////////////
 
+template <typename APTy> struct custom_checkfn {
+  function_ref<bool(const APTy &)> CheckFn;
+  bool isValue(const APTy &C) { return CheckFn(C); }
+};
+
+/// Match an integer or vector where CheckFn(ele) for each element is true.
+/// For vectors, poison elements are assumed to match.
+inline cst_pred_ty<custom_checkfn<APInt>>
+m_CheckedInt(function_ref<bool(const APInt &)> CheckFn) {
+  return cst_pred_ty<custom_checkfn<APInt>>{CheckFn};
+}
+
+inline api_pred_ty<custom_checkfn<APInt>>
+m_CheckedInt(const APInt *&V, function_ref<bool(const APInt &)> CheckFn) {
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nikic wrote:

Assuming there are not a lot of uses of them, replacing them should be fine. Something to be careful about is that the direct replacement here would be m_APIntAllowPoison, not m_APInt.

If there are many uses, it may make sense to retain them as a convenience (I don't think m_CheckedInt with APInt makes sense as a convenience though, it's strictly more complicated than just writing out the check).

https://github.com/llvm/llvm-project/pull/85676