[llvm] [doc] `_or_null` -> `_if_present` (PR #98586)

[via llvm-commits]

https://github.com/zwuis created https://github.com/llvm/llvm-project/pull/98586

`cast_or_null` is deprecated.

https://github.com/llvm/llvm-project/blob/062844615db5e141da118c1ad780bf102537f40a/llvm/include/llvm/Support/Casting.h#L717-L722

>From 502946f1cf8564eb97cb06618804a9521862f1da Mon Sep 17 00:00:00 2001
From: YanzuoLiu <zwuis at outlook.com>
Date: Fri, 12 Jul 2024 12:03:05 +0800
Subject: [PATCH] `_or_null` -> `_if_present`

---
 llvm/docs/ProgrammersManual.rst | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/llvm/docs/ProgrammersManual.rst b/llvm/docs/ProgrammersManual.rst
index e00165caae0c9..fc132963e63ce 100644
--- a/llvm/docs/ProgrammersManual.rst
+++ b/llvm/docs/ProgrammersManual.rst
@@ -164,20 +164,20 @@ rarely have to include this file directly).
   efficient to use the ``InstVisitor`` class to dispatch over the instruction
   type directly.
 
-``isa_and_nonnull<>``:
-  The ``isa_and_nonnull<>`` operator works just like the ``isa<>`` operator,
+``isa_and_present<>``:
+  The ``isa_and_present<>`` operator works just like the ``isa<>`` operator,
   except that it allows for a null pointer as an argument (which it then
   returns false).  This can sometimes be useful, allowing you to combine several
   null checks into one.
 
-``cast_or_null<>``:
-  The ``cast_or_null<>`` operator works just like the ``cast<>`` operator,
+``cast_if_present<>``:
+  The ``cast_if_present<>`` operator works just like the ``cast<>`` operator,
   except that it allows for a null pointer as an argument (which it then
   propagates).  This can sometimes be useful, allowing you to combine several
   null checks into one.
 
-``dyn_cast_or_null<>``:
-  The ``dyn_cast_or_null<>`` operator works just like the ``dyn_cast<>``
+``dyn_cast_if_present<>``:
+  The ``dyn_cast_if_present<>`` operator works just like the ``dyn_cast<>``
   operator, except that it allows for a null pointer as an argument (which it
   then propagates).  This can sometimes be useful, allowing you to combine
   several null checks into one.