[llvm] [SandboxIR] IR Tracker (PR #99238)

[via llvm-commits]

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+//===- SandboxIRTracker.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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is the component of SandboxIR that tracks all changes made to its
+// state, such that we can revert the state when needed.
+//
+// Tracking changes
+// ----------------
+// The user needs to call `SandboxIRTracker::save()` to enable tracking changes
+// made to SandboxIR. From that point on, any change made to SandboxIR, will
+// automatically create a change tracking object and register it with the
+// tracker. IR-change objects are subclasses of `IRChangeBase` and get
+// registered with the `SandboxIRTracker::track()` function. The change objects
+// are saved in the order they are registered with the tracker and are stored in
+// the `SandboxIRTracker::Changes` vector. All of this is done transparently to
+// the user.
+//
+// Reverting changes
+// -----------------
+// Calling `SandboxIRTracker::revert()` will restore the state saved when
+// `SandboxIRTracker::save()` was called. Internally this goes through the
+// change objects in `SandboxIRTracker::Changes` in reverse order, calling their
+// `IRChangeBase::revert()` function one by one.
+//
+// Accepting changes
+// -----------------
+// The user needs to either revert or accept changes before the tracker object
+// is destroyed, or else the tracker destructor will cause a crash.
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vporpo wrote:

Done

https://github.com/llvm/llvm-project/pull/99238