Use ALWAYS_INLINE for vm_getinstancevariable

jhawthorn · luke-gru · jhawthorn · commit 8c70def42c45 · 2025-11-28T09:50:38.000-08:00
Recently rb_vm_getinstancevariable was introduced exposing this method
to ZJIT. On clang specifically this ended up causing the compiler not to
inline into vm_exec_core and cause a significant performance regression
in optcarrot for the interpreter.

Co-authored-by: Luke Gruber &lt;luke.gru@gmail.com&gt;
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
@@ -1680,6 +1680,7 @@ rb_vm_setclassvariable(const rb_iseq_t *iseq, const rb_control_frame_t *cfp, ID
     vm_setclassvariable(iseq, cfp, id, val, ic);
 }
 
+ALWAYS_INLINE(static VALUE vm_getinstancevariable(const rb_iseq_t *iseq, VALUE obj, ID id, IVC ic));
 static inline VALUE
 vm_getinstancevariable(const rb_iseq_t *iseq, VALUE obj, ID id, IVC ic)
 {

Original file line number	Diff line number	Diff line change
`@@ -1680,6 +1680,7 @@ rb_vm_setclassvariable(const rb_iseq_t iseq, const rb_control_frame_t cfp, ID`
`1680`	`1680`	`vm_setclassvariable(iseq, cfp, id, val, ic);`
`1681`	`1681`	`}`
`1682`	`1682`
	`1683`	`+ALWAYS_INLINE(static VALUE vm_getinstancevariable(const rb_iseq_t *iseq, VALUE obj, ID id, IVC ic));`
`1683`	`1684`	`static inline VALUE`
`1684`	`1685`	`vm_getinstancevariable(const rb_iseq_t *iseq, VALUE obj, ID id, IVC ic)`
`1685`	`1686`	`{`