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[ARITH] Simplify casts of constants 0 and 1 #3758

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merged 4 commits into from
Aug 13, 2019
Merged

[ARITH] Simplify casts of constants 0 and 1 #3758

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7e1b346
[EXPR] is_const_value to check whether non-ints are consts
sgrechanik-h Aug 12, 2019
7bf0961
[ARITH] Simplify casts of constants 0 and 1
sgrechanik-h May 29, 2019
273a4bf
Revert "[EXPR] is_const_value to check whether non-ints are consts"
sgrechanik-h Aug 13, 2019
4424c62
Use tvm::cast
sgrechanik-h Aug 13, 2019
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7 changes: 7 additions & 0 deletions src/arithmetic/rewrite_simplify.cc
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Expand Up @@ -1757,6 +1757,13 @@ Mutate_(const Variable* op, const Expr& self) {
return self;
}

Expr RewriteSimplifier::Impl::
Mutate_(const Cast* op, const Expr& self) {
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Let us just add cast between (uint/float/int here), ignore vector types for now as they are not as common.

Expr ret = IRMutator::Mutate_(op, self);
op = ret.as<Cast>();
return cast(op->type, op->value);
}

Expr RewriteSimplifier::operator()(const Expr& expr) {
// Run simplification in post order
Expr res = expr;
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1 change: 1 addition & 0 deletions src/arithmetic/rewrite_simplify.h
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Expand Up @@ -70,6 +70,7 @@ class RewriteSimplifier::Impl : public IRMutator {
Expr Mutate_(const Call* op, const Expr& self) override;
Expr Mutate_(const Let* op, const Expr& self) override;
Expr Mutate_(const Variable* op, const Expr& self) override;
Expr Mutate_(const Cast* op, const Expr& self) override;

protected:
/*! \brief internal structure for comparison. */
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5 changes: 5 additions & 0 deletions src/lang/expr_operator.cc
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Expand Up @@ -105,12 +105,15 @@ bool is_const_power_of_two_integer(const Expr& x, int* shift) {

Expr cast(const Type& t, Expr value) {
using ir::IntImm;
using ir::UIntImm;
using ir::FloatImm;
if (value.type() == t) return value;
// const fold IntImm as they are used in index computations
if (t.lanes() == 1) {
if (const IntImm* op = value.as<IntImm>()) {
return make_const(t, op->value);
} else if (const UIntImm* op = value.as<UIntImm>()) {
return make_const(t, op->value);
} else if (const FloatImm* op = value.as<FloatImm>()) {
return make_const(t, op->value);
}
Expand All @@ -122,6 +125,8 @@ Expr cast(const Type& t, Expr value) {
if (value.type() != vtype) {
if (const IntImm* op = value.as<IntImm>()) {
value = make_const(vtype, op->value);
} else if (const UIntImm* op = value.as<UIntImm>()) {
return make_const(t, op->value);
} else if (const FloatImm* op = value.as<FloatImm>()) {
value = make_const(vtype, op->value);
} else {
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13 changes: 13 additions & 0 deletions tests/python/unittest/test_arith_rewrite_simplify.py
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Expand Up @@ -804,6 +804,18 @@ def test_let_simplify():
z = tvm.expr.Let(x, 1, x + 1)
ck.verify(z + z, 4)

def test_cast_simplify():
ck = RewriteChecker()
x = tvm.var("x")

dtypes = ["float32", "float16", "int32", "int8", "bool"]
for dtype1 in dtypes:
ck.verify(tvm.expr.Cast(dtype1, x - x), tvm.const(0, dtype1))
ck.verify(tvm.expr.Cast(dtype1, x == x), tvm.const(1, dtype1))
for dtype2 in dtypes:
for i in [0, 1, 2, 3]:
ck.verify(tvm.expr.Cast(dtype1, tvm.const(i, dtype2)), tvm.const(i, dtype1))

if __name__ == "__main__":
test_floordiv_index_simplify()
test_floormod_index_simplify()
Expand All @@ -819,3 +831,4 @@ def test_let_simplify():
test_select_simplify()
test_logical_simplify()
test_let_simplify()
test_cast_simplify()