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GH-130415: Use boolean guards to narrow types to values in the JIT#130659
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markshannon left a comment• edited
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Looks correct, but I'm not keen on the names. Naming is hard, so I don't have much better names.
At least "truthy", rather than just "truth", would suggest Pythonbool(x) semantics.
Maybe "to_bool"?
Also, can you add some C tests to Python/optimizer_symbols.c for the various operations?
Python/optimizer_bytecodes.c Outdated
| @@ -430,6 +431,11 @@ dummy_func(void) { | |||
| } | |||
| } | |||
| op(_UNARY_NOT, (value -- res)) { | |||
| sym_set_type(value, &PyBool_Type); | |||
| res = sym_new_truth(ctx, value, true); | |||
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From casual reading, this looks like an error as thetrue argument implies that this has the valueTrue.
Maybe renamesym_new_truth assym_from_truthiness and havefalse as the argument forNOT andtrue as the argument forTO_BOOL?
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Or symbolic consts, likeTO_BOOL andINVERT?
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I'd like to avoid a double-negative in the arg name (since inverting it from its current meaning would mean something like "not not"). What if I make it an int and use0 and1 instead? I feel like a big part of the friction in reading this is the use oftrue andfalse as arguments.
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0 /1 or false/true doesn't matter. Good symbolic names is what is needed.
Maybe even use two different functions with different names?
I agree the naming is hard. How about |
We can think ahead with the naming too. Soon we’ll have equality and identity as symbols, and we’ll probably want something reasonably consistent (“truth”, “equality”, and “identity” were the planned names). |
Maybe "truthiness" rather than "truthy" then? |
I've heard "truthiness" used to describe the boolean value of a non-boolean in a test. Probably more in a javascript context, but for Python as well. |
Sounds good, thanks for the suggestions. |
7afa476 intopython:mainUh oh!
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bedevere-bot commentedMar 2, 2025
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This adds a symbolic "truth" type to the JIT optimizer, allowing tests like
if not x: ...to narrow the value ofxbased on its type. Currently, it's only implemented for booleans, but I'm working with a few people to open PRs to narrowintandstrvalues as well.(The diff looks much worse than it is, since this requires adding
ctxparameters to a couple of helper functions that are used everywhere. The "real" changes inoptimizer_bytecodes.care limited to_GUARD_IS_FALSE_POP,_GUARD_IS_NONE_POP,_GUARD_IS_TRUE_POP,_TO_BOOL,_TO_BOOL_BOOL, and_UNARY_NOT.