[llvm] [NFC] add explanation to register flags doc (PR #91803)

[Florian Mayer via llvm-commits]

https://github.com/fmayer created https://github.com/llvm/llvm-project/pull/91803

None

>From d000fdc6cc18421465b012326dbac2efba0e7c3d Mon Sep 17 00:00:00 2001
From: Florian Mayer <fmayer at google.com>
Date: Fri, 10 May 2024 13:27:04 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.4
---
 llvm/docs/MIRLangRef.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/llvm/docs/MIRLangRef.rst b/llvm/docs/MIRLangRef.rst
index 52ff24daa7fba..c617e4661a5fb 100644
--- a/llvm/docs/MIRLangRef.rst
+++ b/llvm/docs/MIRLangRef.rst
@@ -545,36 +545,47 @@ corresponding internal ``llvm::RegState`` representation:
 
    * - Flag
      - Internal Value
+     - Meaning
 
    * - ``implicit``
      - ``RegState::Implicit``
+     - Not emitted register (e.g. carry, or temporary result).
 
    * - ``implicit-def``
      - ``RegState::ImplicitDefine``
+     - `implicit` and `def`
 
    * - ``def``
      - ``RegState::Define``
+     - Register definition.
 
    * - ``dead``
      - ``RegState::Dead``
+     - Unused definition.
 
    * - ``killed``
      - ``RegState::Kill``
+     - The last use of a register.
 
    * - ``undef``
      - ``RegState::Undef``
+     - Value of the register doesn't matter.
 
    * - ``internal``
      - ``RegState::InternalRead``
+     - Register reads a value that is defined inside the same instruction or bundle.
 
    * - ``early-clobber``
      - ``RegState::EarlyClobber``
+     - Register definition happens before uses.
 
    * - ``debug-use``
      - ``RegState::Debug``
+     - Register 'use' is for debugging purpose.
 
    * - ``renamable``
      - ``RegState::Renamable``
+     - Register that may be renamed.
 
 .. _subregister-indices: