From 33edcc112081f96856d52e73253d73c97a5c4a3c Mon Sep 17 00:00:00 2001
From: Takashi Kokubun <takashikkbn@gmail.com>
Date: Tue, 7 Mar 2023 13:10:07 -0800
Subject: [PATCH] YJIT: Protect strings from GC on String#<< (#7466)

Fix https://github.com/Shopify/yjit/issues/310

[Bug #19483]

Co-authored-by: Maxime Chevalier-Boisvert <maxime.chevalierboisvert@shopify.com>
Co-authored-by: Jimmy Miller <jimmy.miller@shopify.com>
---
 yjit/src/codegen.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/yjit/src/codegen.rs b/yjit/src/codegen.rs
index 869c93fdbb..64f2d6e654 100644
--- a/yjit/src/codegen.rs
+++ b/yjit/src/codegen.rs
@@ -4288,6 +4288,9 @@ fn jit_rb_str_concat(
     // Guard that the argument is of class String at runtime.
     let arg_type = ctx.get_opnd_type(StackOpnd(0));
 
+    // Guard buffers from GC since rb_str_buf_append may allocate.
+    gen_save_sp(asm, ctx);
+
     let concat_arg = ctx.stack_pop(1);
     let recv = ctx.stack_pop(1);