gh-131798: JIT: Split CALL_TYPE_1 into several uops

[tomasr8]

This mostly works now, though the there are now two unused stackref variables in executor_cases.c.h (null and callable) and I'm not sure how to convince the cases generator to remove them. I tried:

• using DEAD(x) in the guard uops - does not work because the stack variable also appears in the output of the uop. I also can't easily pop them off the stack since neither null or callable is TOS.
• removing DEAD(x) from _CALL_TYPE_1: not possible, apparently this is needed before I can set res.

I'm out of ideas so if anyone knows how to fix it, I'd love to know :)

• Issue: Better uop coverage in the JIT optimizer #131798

[tomasr8]

I am not entirely sure why I cannot do this here:

Suggested change

	op(_GUARD_CALLABLE_TYPE_1, (callable, unused, unused2 -- callable, unused, unused2)) {
	op(_GUARD_CALLABLE_TYPE_1, (callable, unused, unused -- callable, unused, unused)) {

I get SyntaxError: Duplicate name unused, though bytecodes.c allows it 🤔

[brandtbucher]

Weird. Maybe unused isn't a meaningful value here like it is in bytecodes.c (maybe @markshannon knows)?

[brandtbucher]

We can leave it like this. I'll create an issue for Mark to update the cases generator and mention this line.

[tomasr8]

ok!

[tomasr8]

Appears to be fixed now thanks to #132615, I updated the PR

[brandtbucher]

Weird. Maybe unused isn't a meaningful value here like it is in bytecodes.c (maybe @markshannon knows)?

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[tomasr8]

Just to update the status:

I have made the requested changes; please review again

[bedevere-app]

Thanks for making the requested changes!

@brandtbucher: please review the changes made to this pull request.

[brandtbucher]

Up to you if you want to add the additional test. I'll leave this open for a bit longer just in case.

[tomasr8]

I added the test you suggested since it was quite easy to do :)

Also, should we care about the compiler warnings I mentioned in the PR description? There are now two unused variable warnings:

In file included from Python/ceval.c:1121:
Python/executor_cases.c.h: In function ‘_PyEval_EvalFrameDefault’:
Python/executor_cases.c.h:5142:25: warning: variable ‘callable’ set but not used [-Wunused-but-set-variable]
 5142 |             _PyStackRef callable;
      |                         ^~~~~~~~
Python/executor_cases.c.h:5141:25: warning: variable ‘null’ set but not used [-Wunused-but-set-variable]
 5141 |             _PyStackRef null;
      |                         ^~~~

[brandtbucher]

Yeah, we should fix those. Can you rename them to unused, and remove the two DEAD calls, and add an INPUTS_DEAD() call at the very end, after the arg is closed?

[tomasr8]

Yeah, we should fix those. Can you rename them to unused, and remove the two DEAD calls, and add an INPUTS_DEAD() call at the very end, after the arg is closed?

it's getting a bit late here so maybe I missed something, but I'm getting SyntaxError: Input 'null' is still live when output 'res' is defined. FTR, this is what I did:

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index 22bb4097611..129e606bde2 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -3969,15 +3969,14 @@ dummy_func(
             DEOPT_IF(callable_o != (PyObject *)&PyType_Type);
         }
 
-        op(_CALL_TYPE_1, (callable, null, arg -- res)) {
+        op(_CALL_TYPE_1, (unused, unused, arg -- res)) {
             PyObject *arg_o = PyStackRef_AsPyObjectBorrow(arg);
 
             assert(oparg == 1);
-            DEAD(null);
-            DEAD(callable);
             STAT_INC(CALL, hit);
             res = PyStackRef_FromPyObjectNew(Py_TYPE(arg_o));
             PyStackRef_CLOSE(arg);
+            INPUTS_DEAD();
         }
 
         macro(CALL_TYPE_1) =

[tomasr8]

How about we add

(void)null;
(void)callable;

I've seen it used in some other instructions. Not sure whether it's the best fix but it does get rid of the warnings.

[brandtbucher]

Looks great! Just one more suggestion (then you should merge in main and make regen-cases to fix the conflicts).

[brandtbucher]

This should work!

Suggested change

	op(_CALL_TYPE_1, (callable, null, arg -- res)) {
	(void)callable;
	(void)null;
	op(_CALL_TYPE_1, (unused, unused, arg -- res)) {

[tomasr8]

Hmm that doesn't help silence the warnings in executor_cases.c.h :/ only thing that I found that works is (void)foo like in 0925179. Is there a better way?

[brandtbucher]

Nope, that's fine!