From 2ef98c076b4c6ebab135db85ecd833884c5954d0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ralph=20K=C3=BCpper?= <ralph@skelpo.com>
Date: Wed, 2 Sep 2026 05:56:49 +0200
Subject: [PATCH] =?UTF-8?q?fix(build-cache):=20key=20PERRY=5FU8=5FINLINE?=
 =?UTF-8?q?=5FREAD=20=E2=80=94=20it=20changes=20emitted=20code=20(#9342)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 crates/perry/src/commands/compile/build_cache.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/crates/perry/src/commands/compile/build_cache.rs b/crates/perry/src/commands/compile/build_cache.rs
index f2270fed8a..e5d7b9b4fb 100644
--- a/crates/perry/src/commands/compile/build_cache.rs
+++ b/crates/perry/src/commands/compile/build_cache.rs
@@ -37,6 +37,10 @@ const BUILD_CACHE_ENV_VARS: &[&str] = &[
     // a different backend means different object bytes.
     "PERRY_LLVM_INPROCESS",
     "PERRY_WRITE_BARRIERS",
+    // #9342 kill switch: `PERRY_U8_INLINE_READ=0` removes the inline u8-read
+    // lane from the emitted code, so an object built with the lane must not be
+    // served from cache to a build that turned it off (and vice versa).
+    "PERRY_U8_INLINE_READ",
     "PERRY_SHADOW_STACK",
     "PERRY_RS4GC",
     // `-Os` vs `-O3` for every native module.