From 63a0f80996eb70217da3d0f7dd18c808d235b2e7 Mon Sep 17 00:00:00 2001
From: Krystine Sherwin <93062060+KrystalDelusion@users.noreply.github.com>
Date: Wed, 17 Jan 2024 08:47:50 +1300
Subject: [PATCH] Docs: opt_share

---
 docs/source/using_yosys/synthesis/opt.rst | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/docs/source/using_yosys/synthesis/opt.rst b/docs/source/using_yosys/synthesis/opt.rst
index 219a139c1..2d543c0b5 100644
--- a/docs/source/using_yosys/synthesis/opt.rst
+++ b/docs/source/using_yosys/synthesis/opt.rst
@@ -132,7 +132,15 @@ is produced.
 Merging mutually exclusive cells with shared inputs - :cmd:ref:`opt_share`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-.. TODO:: ``opt_share``
+This pass identifies mutually exclusive cells of the same type that:
+   a. share an input signal, and
+   b. drive the same ``$mux``, ``$_MUX_``, or ``$pmux`` multiplexing cell,
+
+allowing the cell to be merged and the multiplexer to be moved from
+multiplexing its output to multiplexing the non-shared input signals.
+
+.. todo:: more detailed description of :cmd:ref:`opt_share` (esp. why)
+   so that it's not just a copy-paste of the help output
 
 Performing DFF optimizations - :cmd:ref:`opt_dff`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~