GH-130415: Improve the JIT's unneeded uop removal pass #132333
+44
−18
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
brandtbucher
added
performance
17 tasks
Fidget-Spinner
approved these changes
Apr 11, 2025
markshannon
reviewed
Apr 14, 2025
| @@ -1283,7 +1283,7 @@ class Bar: | |||
| load_attr_top = opnames.index("_LOAD_ATTR_NONDESCRIPTOR_WITH_VALUES", 0, call) | |||
| load_attr_bottom = opnames.index("_LOAD_ATTR_NONDESCRIPTOR_WITH_VALUES", call) | |||
| self.assertEqual(opnames[:load_attr_top].count("_GUARD_TYPE_VERSION"), 1) | |||
| self.assertEqual(opnames[call:load_attr_bottom].count("_CHECK_VALIDITY"), 1) | |||
| self.assertEqual(opnames[call:load_attr_bottom].count("_CHECK_VALIDITY"), 2) | |||
There was a problem hiding this comment.
Why do we have two _CHECK_VALIDITYs now?
| switch (last->opcode) { | ||
| case _POP_TWO_LOAD_CONST_INLINE_BORROW: | ||
| last->opcode = _POP_TOP; | ||
| goto optimize_pop_top_again; |
There was a problem hiding this comment.
Do we want to optimize again here?
If the previous instruction is _POP_TOP I see no further optimization to apply here.
| last->opcode = _NOP; | ||
| buffer[pc].opcode = _NOP; | ||
| } | ||
| if (last->opcode == _REPLACE_WITH_TRUE) { |
There was a problem hiding this comment.
Are we not optimizing this any more? I would have thought it would go in the same case as _POP_TOP_LOAD_CONST_INLINE_BORROW.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This improves our ability to remove unused constant and local variable loads during the
remove_unneeded_uopspass in the JIT's optimizer.It now handles all combinations of:
_COPY_LOAD_CONST_INLINE_LOAD_CONST_INLINE_BORROW_LOAD_FAST_LOAD_FAST_BORROW_LOAD_SMALL_INT...followed by...
_POP_TOP_POP_TOP_LOAD_CONST_INLINE_POP_TOP_LOAD_CONST_INLINE_BORROW_POP_TWO_LOAD_CONST_INLINE_BORROW(It also fixes an issue where
CHECK_VALIDITYwasn't being added after these latter four instructions, due to how the oldswitch-casewas structured.)According to the stats, this results in:
_LOAD_FAST_POP_TOP_LOAD_CONST_INLINE_BORROW_POP_TOP_LOAD_CONST_INLINE@savannahostrowski: We should see even more impact once you start using
_POP_TWO_LOAD_CONST_INLINE_BORROWin more places. I'm currently working on turning basically all cached class attribute/method loads into constants too, which should help here as well.