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[Arith] Support eq in detect_clip_bound #13746

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Merged
wrongtest-intellif merged 2 commits into from
Jan 28, 2023
Merged

[Arith] Support eq in detect_clip_bound #13746

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bf740d5
Support eq in detect_clip_bound
wrongtest-intellif Jan 10, 2023
db4cd4a
follow review suggestion
wrongtest-intellif Jan 20, 2023
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38 changes: 29 additions & 9 deletions src/arith/detect_linear_equation.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -189,6 +189,7 @@ bool DetectClipBound(const PrimExpr& cond,
PostOrderVisit(cond, fvisit);
if (flag != 1) return false;
// canonical form: exp >= 0
bool is_eq = false;
PrimExpr canonical;
if (const LTNode* op = cond.as<LTNode>()) {
if (!op->a.dtype().is_int()) return false;
Expand All @@ -202,6 +203,10 @@ bool DetectClipBound(const PrimExpr& cond,
} else if (const GENode* op = cond.as<GENode>()) {
if (!op->a.dtype().is_int()) return false;
canonical = op->a - op->b;
} else if (const EQNode* op = cond.as<EQNode>()) {
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@Lunderberg Lunderberg Jan 19, 2023

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For consistency, should this have the same check for if(!op->a.dtype().is_int()) as the other cases?

if (!op->a.dtype().is_int()) return false;
canonical = op->a - op->b;
is_eq = true;
} else {
return false;
}
Expand All @@ -210,25 +215,40 @@ bool DetectClipBound(const PrimExpr& cond,
if (!LinearEqDetector(var).Detect(canonical, &ret)) return false;
ret.coeff = analyzer.Simplify(ret.coeff);
IntervalEntry& p = (*bmap)[var.get()];

Optional<PrimExpr> min_value;
Optional<PrimExpr> max_value;
if (is_const_int(ret.coeff, 1)) {
// var + shift >=0 -> var >= -shift
min_value = -ret.base;
if (is_eq) {
max_value = min_value;
}
} else if (is_const_int(ret.coeff, -1)) {
// -var + shift >=0 -> var <= shift
max_value = ret.base;
if (is_eq) {
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@Lunderberg Lunderberg Jan 19, 2023

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Should this also be conditioned on p.min_value.defined()? Otherwise, if p.max_value has already been set by another condition, this would overwrite that earlier bound. This would be a repetition of the condition inside the if(is_const_int(ret.coeff, -1)).

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@Lunderberg Lunderberg Jan 19, 2023

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Now that I think of it, maybe it would be better to collect an Optional<PrimExpr> min_value and Optional<PrimExpr> max_value. For inequalities, only one of the two is non-empty. For equality expressions, both are non-empty. That way, the logic of how to adjust p.min_value and p.max_value wouldn't need to be duplicated. I'm thinking something like the following:

Optional<PrimExpr> min_value = NullOpt;
Optional<PrimExpr> max_value = NullOpt;

if(is_const_int(ret.coeff, 1)) {
  min_value = -ret.base;
  if(is_eq) {
    max_value = min_value;
  }
} else if(is_const_int(ret.coeff, -1)) {
  max_value = ret.base;
  if(is_eq) {
    min_value = max_value;
  }
}

min_value = max_value;
}
}
if (!min_value.defined() && !max_value.defined()) {
return false;
}
if (min_value.defined()) {
if (p.min_value.defined()) {
p.min_value = max(p.min_value, -ret.base);
p.min_value = max(p.min_value, min_value.value());
} else {
p.min_value = -ret.base;
p.min_value = min_value.value();
}
return true;
}
if (is_const_int(ret.coeff, -1)) {
// -var + shift >=0 -> var <= shift
if (max_value.defined()) {
if (p.max_value.defined()) {
p.max_value = min(p.max_value, ret.base);
p.max_value = min(p.max_value, max_value.value());
} else {
p.max_value = ret.base;
p.max_value = max_value.value();
}
return true;
}
return false;
return true;
}

template <typename OP>
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13 changes: 13 additions & 0 deletions tests/python/unittest/test_arith_detect_clip_bound.py
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Original file line number Diff line number Diff line change
Expand Up @@ -39,5 +39,18 @@ def test_basic():
tvm.testing.assert_prim_expr_equal(m[2], 4)


def test_trivial_eq():
a = te.var("a")
b = te.var("b")
m = tvm.arith.detect_clip_bound(b == 3, [a, b])
tvm.testing.assert_prim_expr_equal(m[2], 3)
tvm.testing.assert_prim_expr_equal(m[3], 3)
m = tvm.arith.detect_clip_bound(tvm.tir.all(a == 4, b == 3), [a, b])
tvm.testing.assert_prim_expr_equal(m[0], 4)
tvm.testing.assert_prim_expr_equal(m[1], 4)
tvm.testing.assert_prim_expr_equal(m[2], 3)
tvm.testing.assert_prim_expr_equal(m[3], 3)


if __name__ == "__main__":
test_basic()