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specificity: ensure fast-path in sub/eq_msp handle missing UnionAll wrapper correctly. #54736

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Jul 29, 2024
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specificity: ensure fast-path in sub/eq_msp handle missing UnionAll wrapper correctly. #54736

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60 changes: 57 additions & 3 deletions src/subtype.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4730,6 +4730,56 @@ JL_DLLEXPORT jl_value_t *jl_widen_diagonal(jl_value_t *t, jl_unionall_t *ua)
}

// specificity comparison
static int count_missing_wrap(jl_value_t *x, jl_typeenv_t *env)
{
if (!jl_has_free_typevars(x))
return 0;
jl_typeenv_t *wrapped = NULL;
int count = 0;
for (jl_typeenv_t *env2 = env; env2 != NULL; env2 = env2->prev) {
int need_wrap = 0;
for (jl_typeenv_t *env3 = wrapped; env3 != NULL && need_wrap == 0; env3 = env3->prev) {
if (env3->var == env2->var)
need_wrap = -1;
else if (jl_has_typevar(env3->var->lb, env2->var) || jl_has_typevar(env3->var->ub, env2->var))
need_wrap = 1;
}
need_wrap = need_wrap == 0 ? jl_has_typevar(x, env2->var) :
need_wrap == -1 ? 0 : 1;
if (need_wrap) {
count++;
jl_typeenv_t *newenv = (jl_typeenv_t*)alloca(sizeof(jl_typeenv_t));
newenv->var = env2->var;
newenv->val = NULL;
newenv->prev = wrapped;
wrapped = newenv;
}
}
return count;
}

static int obvious_subtype_msp(jl_value_t *x, jl_value_t *y, jl_value_t *y0, int *subtype, int wrapx, int wrapy)
{
if (wrapx != 0 || wrapy != 0) {
int wrap_count = wrapx - wrapy;
while (wrap_count > 0 && jl_is_unionall(y))
{
y = ((jl_unionall_t*)y)->body;
wrap_count--;
}
while (wrap_count < 0 && jl_is_unionall(x))
{
x = ((jl_unionall_t*)x)->body;
wrap_count++;
}
if (wrap_count > 0) {
if (obvious_subtype(jl_unwrap_unionall(x), y, y0, subtype) && !*subtype)
return 1;
return 0;
}
}
return obvious_subtype(x, y, y0, subtype);
}

static int eq_msp(jl_value_t *a, jl_value_t *b, jl_value_t *a0, jl_value_t *b0, jl_typeenv_t *env)
{
Expand All @@ -4752,12 +4802,14 @@ static int eq_msp(jl_value_t *a, jl_value_t *b, jl_value_t *a0, jl_value_t *b0,
a = b;
b = temp;
}
int wrapa = count_missing_wrap(a, env);
int wrapb = count_missing_wrap(b, env);
// first check if a <: b has an obvious answer
int subtype_ab = 2;
if (b == (jl_value_t*)jl_any_type || a == jl_bottom_type) {
subtype_ab = 1;
}
else if (obvious_subtype(a, b, b0, &subtype_ab)) {
else if (obvious_subtype_msp(a, b, b0, &subtype_ab, wrapa, wrapb)) {
#ifdef NDEBUG
if (subtype_ab == 0)
return 0;
Expand All @@ -4771,7 +4823,7 @@ static int eq_msp(jl_value_t *a, jl_value_t *b, jl_value_t *a0, jl_value_t *b0,
if (a == (jl_value_t*)jl_any_type || b == jl_bottom_type) {
subtype_ba = 1;
}
else if (obvious_subtype(b, a, a0, &subtype_ba)) {
else if (obvious_subtype_msp(b, a, a0, &subtype_ba, wrapb, wrapa)) {
#ifdef NDEBUG
if (subtype_ba == 0)
return 0;
Expand Down Expand Up @@ -4836,7 +4888,9 @@ static int sub_msp(jl_value_t *x, jl_value_t *y, jl_value_t *y0, jl_typeenv_t *e
return 1;
}
int obvious_sub = 2;
if (obvious_subtype(x, y, y0, &obvious_sub)) {
int wrapx = count_missing_wrap(x, env);
int wrapy = count_missing_wrap(y, env);
if (obvious_subtype_msp(x, y, y0, &obvious_sub, wrapx, wrapy)) {
#ifdef NDEBUG
return obvious_sub;
#endif
Expand Down
11 changes: 11 additions & 0 deletions test/specificity.jl
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Expand Up @@ -316,3 +316,14 @@ end
@test args_morespecific(Tuple{typeof(Union{}), Any}, Tuple{Any, Type{Union{}}})
@test args_morespecific(Tuple{Type{Union{}}, Type{Union{}}, Any}, Tuple{Type{Union{}}, Any, Type{Union{}}})
@test args_morespecific(Tuple{Type{Union{}}, Type{Union{}}, Any, Type{Union{}}}, Tuple{Type{Union{}}, Any, Type{Union{}}, Type{Union{}}})

# requires assertions enabled
let root = NTuple
N = root.var
T = root.body.var
x1 = root.body.body
x2 = Dict{T,Tuple{N}}
A = UnionAll(N, UnionAll(T, Tuple{Union{x1, x2}}))
B = Tuple{Union{UnionAll(N, UnionAll(T, x1)), UnionAll(N, UnionAll(T, x2))}}
@ccall jl_type_morespecific_no_subtype(A::Any, B::Any)::Cint
end