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effects: Do not over-taint :terminates in abstract cycle #49119

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Merged
aviatesk merged 1 commit into from
Mar 28, 2023
Merged

effects: Do not over-taint :terminates in abstract cycle #49119

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4 changes: 0 additions & 4 deletions base/compiler/typeinfer.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -779,13 +779,9 @@ function merge_call_chain!(interp::AbstractInterpreter, parent::InferenceState,
# then add all backedges of parent <- parent.parent
# and merge all of the callers into ancestor.callers_in_cycle
# and ensure that walking the parent list will get the same result (DAG) from everywhere
# Also taint the termination effect, because we can no longer guarantee the absence
# of recursion.
merge_effects!(interp, parent, Effects(EFFECTS_TOTAL; terminates=false))
while true
add_cycle_backedge!(parent, child, parent.currpc)
union_caller_cycle!(ancestor, child)
merge_effects!(interp, child, Effects(EFFECTS_TOTAL; terminates=false))
child = parent
child === ancestor && break
parent = child.parent::InferenceState
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11 changes: 11 additions & 0 deletions test/compiler/effects.jl
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Expand Up @@ -805,5 +805,16 @@ unknown_sparam_nothrow2(x::Ref{Ref{T}}) where T = (T; nothing)
@test Core.Compiler.is_nothrow(Base.infer_effects(unknown_sparam_nothrow1, (Ref,)))
@test Core.Compiler.is_nothrow(Base.infer_effects(unknown_sparam_nothrow2, (Ref{Ref{T}} where T,)))

# purely abstract recursion should not taint :terminates
# https://github.com/JuliaLang/julia/issues/48983
abstractly_recursive1() = abstractly_recursive2()
abstractly_recursive2() = (Core.Compiler._return_type(abstractly_recursive1, Tuple{}); 1)
abstractly_recursive3() = abstractly_recursive2()
@test Core.Compiler.is_terminates(Base.infer_effects(abstractly_recursive3, ()))
actually_recursive1(x) = actually_recursive2(x)
actually_recursive2(x) = (x <= 0) ? 1 : actually_recursive1(x - 1)
actually_recursive3(x) = actually_recursive2(x)
@test !Core.Compiler.is_terminates(Base.infer_effects(actually_recursive3, (Int,)))

# https://github.com/JuliaLang/julia/issues/48856
@test Base.ismutationfree(Vector{Any}) == false