[llvm] [GlobalISel] Document minimum legality requirements for G_IMPLICIT_DEF. (PR #117609)

[Amara Emerson via llvm-commits]

https://github.com/aemerson created https://github.com/llvm/llvm-project/pull/117609

So that @tschuett can fix up #117439

>From f6d47a8d9fd93b96b02e89560e1528a07bc1ec4c Mon Sep 17 00:00:00 2001
From: Amara Emerson <amara at apple.com>
Date: Mon, 25 Nov 2024 10:51:31 -0800
Subject: [PATCH] [GlobalISel] Document minimum legality requirements for
 G_IMPLICIT_DEF.

---
 llvm/docs/GlobalISel/Legalizer.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/llvm/docs/GlobalISel/Legalizer.rst b/llvm/docs/GlobalISel/Legalizer.rst
index 1ff7b304b3a013..cd27a0249c4b3e 100644
--- a/llvm/docs/GlobalISel/Legalizer.rst
+++ b/llvm/docs/GlobalISel/Legalizer.rst
@@ -338,8 +338,8 @@ G_BUILD_VECTOR_TRUNC, G_CONCAT_VECTORS, G_UNMERGE_VALUES, G_PTRTOINT, and
 G_INTTOPTR have already been noted above. In addition to those, the following
 operations have requirements:
 
-* At least one G_IMPLICIT_DEF must be legal. This is usually trivial as it
-  requires no code to be selected.
+* For every type that can be produced by any instruction, G_IMPLICIT_DEF must be
+  legal. This is usually trivial as it requires no code to be selected.
 * G_PHI must be legal for all types in the producer and consumer typesets. This
   is usually trivial as it requires no code to be selected.
 * At least one G_FRAME_INDEX must be legal