From cacf2f3709a570560085e6a95c3a78e8fb8cc0f5 Mon Sep 17 00:00:00 2001
From: Takashi Kokubun <takashikkbn@gmail.com>
Date: Fri, 10 Feb 2023 21:54:35 -0800
Subject: [PATCH] Set 0 to cfp->pc on C func send

---
 lib/ruby_vm/mjit/insn_compiler.rb | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/ruby_vm/mjit/insn_compiler.rb b/lib/ruby_vm/mjit/insn_compiler.rb
index 386a97eb26..33c7db5435 100644
--- a/lib/ruby_vm/mjit/insn_compiler.rb
+++ b/lib/ruby_vm/mjit/insn_compiler.rb
@@ -1294,7 +1294,10 @@ module RubyVM::MJIT
 
       asm.comment('set up new frame')
       cfp_offset = -C.rb_control_frame_t.size # callee CFP
-      # Not setting PC since JIT code will do that as needed
+      # For ISEQ, JIT code will set it as needed. However, C func needs 0 there for svar frame detection.
+      if iseq.nil?
+        asm.mov([CFP, cfp_offset + C.rb_control_frame_t.offsetof(:pc)], 0)
+      end
       asm.mov(:rax, iseq.to_i)
       asm.mov([CFP, cfp_offset + C.rb_control_frame_t.offsetof(:iseq)], :rax)
       self_index = ctx.sp_offset - (1 + argc) # TODO: +1 for VM_CALL_ARGS_BLOCKARG