From fc3c5d241499e1281e8c3693dcbad0589816a42b Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Mon, 20 Mar 2023 20:18:51 +0100
Subject: [PATCH] Properly use the VersionMarker in CachedFunc (#6062)

---
 cranelift/codegen/src/incremental_cache.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/cranelift/codegen/src/incremental_cache.rs b/cranelift/codegen/src/incremental_cache.rs
index fe41eb57da..8e72d5e76e 100644
--- a/cranelift/codegen/src/incremental_cache.rs
+++ b/cranelift/codegen/src/incremental_cache.rs
@@ -116,8 +116,10 @@ impl std::fmt::Display for CacheKeyHash {
 
 #[derive(serde::Serialize, serde::Deserialize)]
 struct CachedFunc {
-    stencil: CompiledCodeStencil,
+    // Note: The version marker must be first to ensure deserialization stops in case of a version
+    // mismatch before attempting to deserialize the actual compiled code.
     version_marker: VersionMarker,
+    stencil: CompiledCodeStencil,
 }
 
 /// Key for caching a single function's compilation.
@@ -216,8 +218,8 @@ pub fn serialize_compiled(
     result: CompiledCodeStencil,
 ) -> (CompiledCodeStencil, Result<Vec<u8>, bincode::Error>) {
     let cached = CachedFunc {
-        stencil: result,
         version_marker: VersionMarker,
+        stencil: result,
     };
     let result = bincode::serialize(&cached);
     (cached.stencil, result)