effects: add :inaccessiblememonly effect
#46198
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base/expr.jl
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| @@ -570,6 +571,19 @@ moved between tasks without observable results. | |||
| code that is not `:notaskstate`, but is `:effect_free` and `:consistent` | |||
| may still be dead-code-eliminated and thus promoted to `:total`. | |||
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| --- | |||
| ## `:noglobal` | |||
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Is this the same as inaccessiblemem_or_argmemonly in llvm? Asking because at some point it would be useful to start transferring our annotations into LLVM too
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I don't think it's quite the same, since this excludes the case where you're passing in a global as an argument. I think :noglobal probably implies it though?
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Currently :noglobal === true means inaccessiblemem_or_argmemonly and it includes cases we access to (potentially) global memory passed as an argument. And we additionally check that arguments are never be mutable global memory (by a simple type analysis) when trying to refine :consistent or :effect_free information later.
Now I wonder if we should make :noglobal === ALWAYS_TRUE mean inaccessiblemem and :noglobal === INACCESSIBLEMEM_OR_ARGMEMONLY mean that so.
And I guess one more difference is that :noglobal doesn't really reason about immutable global memory, as it doesn't taint :consistent-cy/:effect_free-ness anyway.
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After thinking about this for a bit, now I think it's a bit confusing that currently :noglobal === ALWAYS_TRUE doesn't exclude access to arguments memory, and we may want to make :noglobal === ALWAYS_TRUE mean inaccessiblemem and :noglobal === ARGMEM mean inaccessiblemem_or_argmemonly and also rename :noglobal to :inaccessiblemem.
This property may not necessarily 1-to-1 correspond to LLVM's function attributes since our :inaccessiblemem only reasons about mutable memory.
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llvm also only reasons about mutable memory
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:noglobal effect:inaccessiblememonly effect
This is a preparatory PR for future improvements on the effects analysis. This commit adds the `:inaccessiblememonly` helper effect, that tracks if a method involves any access or modification on any mutable state. This effect property is basically same as LLVM's `inaccessiblememonly` function attribute, except that it only reasons about mutable memory. This effect property can be considered as a very limited and coarse version of escape analysis and allow us prove `:consistent`-cy or `:effect_free`-ness even in a presence of accesses or modifications on local mutable allocations in cases when we can prove they are local and don't escape. Separate PRs that actually improve the effect analysis accuracy will follow.
This is a preparatory PR for future improvements on the effects analysis. This commit adds the `:inaccessiblememonly` helper effect, that tracks if a method involves any access or modification on any mutable state. This effect property is basically same as LLVM's `inaccessiblememonly` function attribute, except that it only reasons about mutable memory. This effect property can be considered as a very limited and coarse version of escape analysis and allow us prove `:consistent`-cy or `:effect_free`-ness even in a presence of accesses or modifications on local mutable allocations in cases when we can prove they are local and don't escape. Separate PRs that actually improve the effect analysis accuracy will follow.
This is a preparatory PR for future improvements on the effects analysis. This commit adds the `:inaccessiblememonly` helper effect, that tracks if a method involves any access or modification on any mutable state. This effect property is basically same as LLVM's `inaccessiblememonly` function attribute, except that it only reasons about mutable memory. This effect property can be considered as a very limited and coarse version of escape analysis and allow us prove `:consistent`-cy or `:effect_free`-ness even in a presence of accesses or modifications on local mutable allocations in cases when we can prove they are local and don't escape. Separate PRs that actually improve the effect analysis accuracy will follow.
This is a preparatory PR for future improvements on the effects analysis.
This commit adds the
:inaccessiblememonlyhelper effect, that tracksif a method involves any access or modification on any mutable state.
This effect property is basically same as LLVM's
inaccessiblememonlyfunction attribute, except that it only reasons about mutable memory.
This effect property can be considered as a very limited and coarse
version of escape analysis and allow us prove
:consistent-cy or:effect_free-ness even in a presence of accesses or modificationson local mutable allocations in cases when we can prove they are local
and don't escape. Separate PRs that actually improve the effect analysis
accuracy will follow.