[llvm] LangRef: rint, nearbyint: mention that default rounding mode is assumed (PR #77191)

[Ralf Jung via llvm-commits]

https://github.com/RalfJung updated https://github.com/llvm/llvm-project/pull/77191

>From 02517287a314c9396a6f04ff2f72f5e508e93413 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post at ralfj.de>
Date: Sat, 6 Jan 2024 13:06:04 +0100
Subject: [PATCH] LangRef: rint, nearbyint: mention that default rounding mode
 is assumed

---
 llvm/docs/LangRef.rst | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index b5918e3063d868..02d4dce557a3d4 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -15751,7 +15751,11 @@ Semantics:
 """"""""""
 
 This function returns the same values as the libm ``rint`` functions
-would, and handles error conditions in the same way.
+would, and handles error conditions in the same way. Since LLVM assumes the
+:ref:`default floating-point environment <floatenv>`, the rounding mode is
+assumed to be set to "nearest", so halfway cases are rounded to the even
+integer. Use :ref:`Constrained Floating-Point Intrinsics <constrainedfp>`
+to avoid that assumption.
 
 .. _int_nearbyint:
 
@@ -15789,7 +15793,11 @@ Semantics:
 """"""""""
 
 This function returns the same values as the libm ``nearbyint``
-functions would, and handles error conditions in the same way.
+functions would, and handles error conditions in the same way. Since LLVM
+assumes the :ref:`default floating-point environment <floatenv>`, the rounding
+mode is assumed to be set to "nearest", so halfway cases are rounded to the even
+integer. Use :ref:`Constrained Floating-Point Intrinsics <constrainedfp>` to
+avoid that assumption.
 
 .. _int_round: