[llvm] [Docs] Remove future extensions section from writing a pass docs (PR #69286)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 updated https://github.com/llvm/llvm-project/pull/69286

>From e8f7a16dfec34fe6e6e9787d9cb9d7e97cf5460a Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Mon, 16 Oct 2023 22:11:12 -0700
Subject: [PATCH] [Docs] Remove future extensions section from writing a pass
 docs

This section is quite outdated at this point and longer relevant given
LLVM (and CPUs) has evolved significantly over the past 20+ years.

This is also aimed at serving as a test of the llvm docs CI that was
recently added in.
---
 llvm/docs/WritingAnLLVMPass.rst | 26 --------------------------
 1 file changed, 26 deletions(-)

diff --git a/llvm/docs/WritingAnLLVMPass.rst b/llvm/docs/WritingAnLLVMPass.rst
index 3e6063e58334359..9b873556209ce46 100644
--- a/llvm/docs/WritingAnLLVMPass.rst
+++ b/llvm/docs/WritingAnLLVMPass.rst
@@ -1350,29 +1350,3 @@ some with solutions, some without.
 Hopefully these tips will help with common case debugging situations.  If you'd
 like to contribute some tips of your own, just contact `Chris
 <mailto:sabre at nondot.org>`_.
-
-Future extensions planned
--------------------------
-
-Although the LLVM Pass Infrastructure is very capable as it stands, and does
-some nifty stuff, there are things we'd like to add in the future.  Here is
-where we are going:
-
-.. _writing-an-llvm-pass-SMP:
-
-Multithreaded LLVM
-^^^^^^^^^^^^^^^^^^
-
-Multiple CPU machines are becoming more common and compilation can never be
-fast enough: obviously we should allow for a multithreaded compiler.  Because
-of the semantics defined for passes above (specifically they cannot maintain
-state across invocations of their ``run*`` methods), a nice clean way to
-implement a multithreaded compiler would be for the ``PassManager`` class to
-create multiple instances of each pass object, and allow the separate instances
-to be hacking on different parts of the program at the same time.
-
-This implementation would prevent each of the passes from having to implement
-multithreaded constructs, requiring only the LLVM core to have locking in a few
-places (for global resources).  Although this is a simple extension, we simply
-haven't had time (or multiprocessor machines, thus a reason) to implement this.
-Despite that, we have kept the LLVM passes SMP ready, and you should too.