Support tracing of attr_reader and attr_writer

In vm_call_method_each_type, check for c_call and c_return events before
dispatching to vm_call_ivar and vm_call_attrset.  With this approach, the
call cache will still dispatch directly to those functions, so this
change will only decrease performance for the first (uncached) call, and
even then, the performance decrease is very minimal.

This approach requires that we clear the call caches when tracing is
enabled or disabled.  The approach currently switches all vm_call_ivar
and vm_call_attrset call caches to vm_call_general any time tracing is
enabled or disabled. So it could theoretically result in a slowdown for
code that constantly enables or disables tracing.

This approach does not handle targeted tracepoints, but from my testing,
c_call and c_return events are not supported for targeted tracepoints,
so that shouldn't matter.

This includes a benchmark showing the performance decrease is minimal
if detectable at all.

Fixes [Bug #16383]
Fixes [Bug #10470]

Co-authored-by: Takashi Kokubun <takashikkbn@gmail.com>

1 files changed, 43 insertions, 4 deletions

diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index e186376b24..e08ba34082 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -3029,6 +3029,12 @@ vm_call_attrset(rb_execution_context_t *ec, rb_control_frame_t *cfp, struct rb_c
     return vm_setivar(calling->recv, vm_cc_cme(cc)->def->body.attr.id, val, NULL, NULL, cc, 1);
 }
 
+bool
+rb_vm_call_ivar_attrset_p(const vm_call_handler ch)
+{
+    return (ch == vm_call_ivar || ch == vm_call_attrset);
+}
+
 static inline VALUE
 vm_call_bmethod_body(rb_execution_context_t *ec, struct rb_calling_info *calling, const VALUE *argv)
 {
@@ -3484,16 +3490,40 @@ vm_call_method_each_type(rb_execution_context_t *ec, rb_control_frame_t *cfp, st
 
 	rb_check_arity(calling->argc, 1, 1);
 	vm_cc_attr_index_set(cc, 0);
-        CC_SET_FASTPATH(cc, vm_call_attrset, !(vm_ci_flag(ci) & (VM_CALL_ARGS_SPLAT | VM_CALL_KW_SPLAT | VM_CALL_KWARG)));
-        return vm_call_attrset(ec, cfp, calling);
+        if (UNLIKELY(ruby_vm_event_flags & (RUBY_EVENT_C_CALL | RUBY_EVENT_C_RETURN))) {
+            const struct rb_callinfo *ci = calling->ci;
+            VALUE v;
+            EXEC_EVENT_HOOK(ec, RUBY_EVENT_C_CALL, calling->recv, vm_cc_cme(cc)->def->original_id,
+                vm_ci_mid(ci), vm_cc_cme(cc)->owner, Qundef);
+            v = vm_call_attrset(ec, cfp, calling);
+            EXEC_EVENT_HOOK(ec, RUBY_EVENT_C_RETURN, calling->recv, vm_cc_cme(cc)->def->original_id,
+                vm_ci_mid(ci), vm_cc_cme(cc)->owner, v);
+            return v;
+        }
+        else {
+            CC_SET_FASTPATH(cc, vm_call_attrset, !(vm_ci_flag(ci) & (VM_CALL_ARGS_SPLAT | VM_CALL_KW_SPLAT | VM_CALL_KWARG)));
+            return vm_call_attrset(ec, cfp, calling);
+        }
 
       case VM_METHOD_TYPE_IVAR:
         CALLER_SETUP_ARG(cfp, calling, ci);
         CALLER_REMOVE_EMPTY_KW_SPLAT(cfp, calling, ci);
 	rb_check_arity(calling->argc, 0, 0);
 	vm_cc_attr_index_set(cc, 0);
-        CC_SET_FASTPATH(cc, vm_call_ivar, !(vm_ci_flag(ci) & (VM_CALL_ARGS_SPLAT | VM_CALL_KW_SPLAT)));
-        return vm_call_ivar(ec, cfp, calling);
+        if (UNLIKELY(ruby_vm_event_flags & (RUBY_EVENT_C_CALL | RUBY_EVENT_C_RETURN))) {
+            const struct rb_callinfo *ci = calling->ci;
+            VALUE v;
+            EXEC_EVENT_HOOK(ec, RUBY_EVENT_C_CALL, calling->recv, vm_cc_cme(cc)->def->original_id,
+                vm_ci_mid(ci), vm_cc_cme(cc)->owner, Qundef);
+            v = vm_call_ivar(ec, cfp, calling);
+            EXEC_EVENT_HOOK(ec, RUBY_EVENT_C_RETURN, calling->recv, vm_cc_cme(cc)->def->original_id,
+                vm_ci_mid(ci), vm_cc_cme(cc)->owner, v);
+            return v;
+        }
+        else {
+            CC_SET_FASTPATH(cc, vm_call_ivar, !(vm_ci_flag(ci) & (VM_CALL_ARGS_SPLAT | VM_CALL_KW_SPLAT)));
+            return vm_call_ivar(ec, cfp, calling);
+        }
 
       case VM_METHOD_TYPE_MISSING:
         vm_cc_method_missing_reason_set(cc, 0);
@@ -3615,6 +3645,15 @@ vm_call_general(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, struct
     return vm_call_method(ec, reg_cfp, calling);
 }
 
+void
+rb_vm_cc_general(const struct rb_callcache *cc)
+{
+    VM_ASSERT(IMEMO_TYPE_P(cc, imemo_callcache));
+    VM_ASSERT(cc != vm_cc_empty());
+
+    *(vm_call_handler *)&cc->call_ = vm_call_general;
+}
+
 static VALUE
 vm_call_super_method(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, struct rb_calling_info *calling)
 {