[llvm] [SandboxVec][Interval] Convert InstrInterval class to a class template (PR #110021)

[Sriraman Tallam via llvm-commits]

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@@ -0,0 +1,125 @@
+//===- Interval.h -----------------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// The Interval class is a generic interval of ordered objects that implement:
+// - T * T::getPrevNode()
+// - T * T::getNextNode()
+// - bool T::comesBefore(const T *) const
+//
+// This is currently used for Instruction intervals.
+// It provides an API for some basic operations on the interval, including some
+// simple set operations, like union, interseciton and others.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_VECTORIZE_SANDBOXVECTORIZER_INSTRINTERVAL_H
+#define LLVM_TRANSFORMS_VECTORIZE_SANDBOXVECTORIZER_INSTRINTERVAL_H
+
+#include "llvm/SandboxIR/SandboxIR.h"
+#include <iterator>
+
+namespace llvm::sandboxir {
+
+/// A simple iterator for iterating the interval.
+template <typename T, typename IntervalType> class IntervalIterator {
+  T *I;
+  IntervalType &R;
+
+public:
+  using difference_type = std::ptrdiff_t;
+  using value_type = T;
+  using pointer = value_type *;
+  using reference = T &;
+  using iterator_category = std::bidirectional_iterator_tag;
+
+  IntervalIterator(T *I, IntervalType &R) : I(I), R(R) {}
+  bool operator==(const IntervalIterator &Other) const {
+    assert(&R == &Other.R && "Iterators belong to different regions!");
+    return Other.I == I;
+  }
+  bool operator!=(const IntervalIterator &Other) const {
+    return !(*this == Other);
+  }
+  IntervalIterator &operator++() {
+    assert(I != nullptr && "already at end()!");
+    I = I->getNextNode();
+    return *this;
+  }
+  IntervalIterator operator++(int) {
+    auto ItCopy = *this;
+    ++*this;
+    return ItCopy;
+  }
+  IntervalIterator &operator--() {
+    // `I` is nullptr for end() when ToI is the BB terminator.
+    I = I != nullptr ? I->getPrevNode() : R.ToI;
+    return *this;
+  }
+  IntervalIterator operator--(int) {
+    auto ItCopy = *this;
+    --*this;
+    return ItCopy;
+  }
+  template <typename HT = std::enable_if<std::is_same<T, T *&>::value>>
+  T &operator*() {
+    return *I;
+  }
+  T &operator*() const { return *I; }
+};
+
+template <typename T> class Interval {
+  T *From;
+  T *To;
+
+public:
+  Interval() : From(nullptr), To(nullptr) {}
+  Interval(T *From, T *To) : From(From), To(To) {
+    assert((From == To || From->comesBefore(To)) &&
+           "From should come before TopI!");
+  }
+  Interval(ArrayRef<T *> Instrs) {
+    assert(!Instrs.empty() && "Expected non-empty Instrs!");
----------------
tmsri wrote:

Shouldn't Instrs be re-named here?  Like Say Items?

https://github.com/llvm/llvm-project/pull/110021