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ensure binding type is set consistently for consts #44232

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ensure binding type is set consistently for consts #44232

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14 changes: 7 additions & 7 deletions src/module.c
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Original file line number Diff line number Diff line change
Expand Up @@ -680,14 +680,13 @@ JL_DLLEXPORT void jl_set_const(jl_module_t *m JL_ROOTING_ARGUMENT, jl_sym_t *var
uint8_t constp = 0;
// if (jl_atomic_cmpswap(&bp->constp, &constp, 1)) {
if (constp = bp->constp, bp->constp = 1, constp == 0) {
jl_value_t *old = NULL;
jl_value_t *old_ty = NULL, *old = NULL;
jl_atomic_cmpswap_relaxed(&bp->ty, &old_ty, jl_typeof(val));
if (jl_atomic_cmpswap(&bp->value, &old, val)) {
jl_gc_wb_binding(bp, val);
return;
}
}
jl_value_t *old_ty = NULL;
jl_atomic_cmpswap_relaxed(&bp->ty, &old_ty, (jl_value_t*)jl_any_type);
}
jl_errorf("invalid redefinition of constant %s",
jl_symbol_name(bp->name));
Expand Down Expand Up @@ -807,11 +806,8 @@ void jl_binding_deprecation_warning(jl_module_t *m, jl_binding_t *b)
JL_DLLEXPORT void jl_checked_assignment(jl_binding_t *b, jl_value_t *rhs)
{
jl_value_t *old_ty = NULL;
if (!jl_atomic_cmpswap_relaxed(&b->ty, &old_ty, (jl_value_t*)jl_any_type) && !jl_isa(rhs, old_ty)) {
jl_errorf("cannot assign an incompatible value to the global %s.",
jl_symbol_name(b->name));
}
if (b->constp) {
jl_atomic_cmpswap_relaxed(&b->ty, &old_ty, jl_typeof(rhs));
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A bit fussy perhaps, but I think it would make sense to move this inside the if (jl_atomic_cmpswap for the value.

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Same above.

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I'm pretty sure right now we always assume that a non-null value implies that the binding type is also set, while setting a type for an uninitialized binding is perfectly fine. In case of a race we might have set the wrong type, but this should then be caught and error appropriately before we set the value to something inconsistent. Or is there another reason for doing it the other way around?

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I forgot to add another check of the binding type here though, I can add that. (Although declaring constants isn't really thread-safe right now anyways.)

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I was just thinking of making setting the value and type more atomic, but I guess the behavior ends up being the same either way.

jl_value_t *old = NULL;
if (jl_atomic_cmpswap(&b->value, &old, rhs)) {
jl_gc_wb_binding(b, rhs);
Expand All @@ -828,6 +824,10 @@ JL_DLLEXPORT void jl_checked_assignment(jl_binding_t *b, jl_value_t *rhs)
jl_safe_printf("WARNING: redefinition of constant %s. This may fail, cause incorrect answers, or produce other errors.\n",
jl_symbol_name(b->name));
}
if (!jl_atomic_cmpswap_relaxed(&b->ty, &old_ty, (jl_value_t*)jl_any_type) && !jl_isa(rhs, old_ty)) {
jl_errorf("cannot assign an incompatible value to the global %s.",
jl_symbol_name(b->name));
}
jl_atomic_store_relaxed(&b->value, rhs);
jl_gc_wb_binding(b, rhs);
}
Expand Down
3 changes: 3 additions & 0 deletions test/misc.jl
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Expand Up @@ -1109,3 +1109,6 @@ end
@testset "Base/timing.jl" begin
@test Base.jit_total_bytes() >= 0
end

const I_AM_A_CONSTANT_INT = 1
@test Core.get_binding_type(@__MODULE__, :I_AM_A_CONSTANT_INT) == Int