YJIT: Save PC and SP before calling leaf builtins (#7090)

Previously, we did not update `cfp->sp` before calling the C function of
ISEQs marked with `Primitive.attr! "inline"` (leaf builtins). This
caused the GC to miss temporary values on the stack in case the function
allocates and triggers a GC run. Right now, there is only a few leaf
builtins in numeric.rb on Integer methods such as `Integer#~`. Since
these methods only allocate when operating on big numbers, we missed
this issue.

Fix by saving PC and SP before calling the functions -- our usual
protocol for calling C functions that may allocate on the GC heap.

[Bug #19316]

1 files changed, 4 insertions, 0 deletions

diff --git a/yjit/src/codegen.rs b/yjit/src/codegen.rs
index f99c592e18..a7c2b37eeb 100644
--- a/yjit/src/codegen.rs
+++ b/yjit/src/codegen.rs
@@ -5181,6 +5181,10 @@ fn gen_send_iseq(
         if builtin_argc + 1 < (C_ARG_OPNDS.len() as i32) {
             asm.comment("inlined leaf builtin");
 
+            // Save the PC and SP because the callee may allocate
+            // e.g. Integer#abs on a bignum
+            jit_prepare_routine_call(jit, ctx, asm);
+
             // Call the builtin func (ec, recv, arg1, arg2, ...)
             let mut args = vec![EC];