From ec65d89176827a8ff0e87ce553739bcae0a0265b Mon Sep 17 00:00:00 2001
From: quaternic <57393910+quaternic@users.noreply.github.com>
Date: Fri, 5 Dec 2025 14:29:37 +0200
Subject: [PATCH] Document the purpose of a helper module

---
 library/compiler-builtins/libm/src/math/support/modular.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/library/compiler-builtins/libm/src/math/support/modular.rs b/library/compiler-builtins/libm/src/math/support/modular.rs
index dbf1f0513a0d..e599ede0776e 100644
--- a/library/compiler-builtins/libm/src/math/support/modular.rs
+++ b/library/compiler-builtins/libm/src/math/support/modular.rs
@@ -1,5 +1,9 @@
 /* SPDX-License-Identifier: MIT OR Apache-2.0 */
 
+//! This module provides accelerated modular multiplication by large powers
+//! of two, which is needed for computing floating point remainders in `fmod`
+//! and similar functions.
+//!
 //! To keep the equations somewhat concise, the following conventions are used:
 //!  - all integer operations are in the mathematical sense, without overflow
 //!  - concatenation means multiplication: `2xq = 2 * x * q`