From 720da20588e0e984b1c1ff5eb63b84206b026d65 Mon Sep 17 00:00:00 2001
From: bjorn3 <bjorn3@users.noreply.github.com>
Date: Thu, 11 Feb 2021 11:08:54 +0100
Subject: [PATCH] Describe serialization format

---
 cranelift/codegen/src/ir/layout.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/cranelift/codegen/src/ir/layout.rs b/cranelift/codegen/src/ir/layout.rs
index 9359c309df..f6272199bb 100644
--- a/cranelift/codegen/src/ir/layout.rs
+++ b/cranelift/codegen/src/ir/layout.rs
@@ -781,6 +781,17 @@ impl<'f> DoubleEndedIterator for Insts<'f> {
     }
 }
 
+/// A custom serialize and deserialize implementation for [`Layout`].
+///
+/// This doesn't use a derived implementation as [`Layout`] is a manual implementation of a linked
+/// list. Storing it directly as a regular list saves a lot of space.
+///
+/// The following format is used. (notated in EBNF form)
+///
+/// ```plain
+/// data = block_data * ;
+/// block_data = "block_id" , "inst_count" , ( "inst_id" * ) ;
+/// ```
 #[cfg(feature = "enable-serde")]
 mod serde {
     use ::serde::de::{Deserializer, Error, SeqAccess, Visitor};