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Add LLVM Legalization for tir.erf #18104

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Merged
merged 1 commit into from
Jul 3, 2025
Merged

Add LLVM Legalization for tir.erf #18104

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18 changes: 18 additions & 0 deletions src/target/llvm/intrin_rule_llvm.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -242,6 +242,24 @@ TVM_REGISTER_OP("tir.atanh")
return (log(one + x) - log(one - x)) * make_const(x.dtype(), 0.5);
});

TVM_REGISTER_OP("tir.erf").set_attr<FLegalize>("llvm.FLegalize", [](const PrimExpr& e) -> PrimExpr {
using tir::make_const;
const tir::CallNode* call = e.as<tir::CallNode>();
ICHECK(call != nullptr) << "Invalid call node in erf legalization";
const PrimExpr& x = call->args[0];
PrimExpr abs_x = tvm::abs(x);
PrimExpr t = make_const(x.dtype(), 1.0) /
(make_const(x.dtype(), 1.0) + make_const(x.dtype(), 0.3275911) * abs_x);
PrimExpr a1 = make_const(x.dtype(), 0.254829592);
PrimExpr a2 = make_const(x.dtype(), -0.284496736);
PrimExpr a3 = make_const(x.dtype(), 1.421413741);
PrimExpr a4 = make_const(x.dtype(), -1.453152027);
PrimExpr a5 = make_const(x.dtype(), 1.061405429);
PrimExpr poly = (((((a5 * t + a4) * t + a3) * t + a2) * t + a1) * t);
PrimExpr approx = make_const(x.dtype(), 1.0) - poly * exp(-abs_x * abs_x);
return tvm::tir::Select(x < 0, -approx, approx);
});

TVM_REGISTER_OP("tir.clz").set_attr<FLegalize>("llvm.FLegalize", [](const PrimExpr& e) -> PrimExpr {
const tir::CallNode* call = e.as<tir::CallNode>();
ICHECK(call != nullptr);
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2 changes: 2 additions & 0 deletions tests/python/tir-base/test_tir_intrin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
import numpy as np
import ctypes
import math
import scipy


def test_nearbyint():
Expand Down Expand Up @@ -77,6 +78,7 @@ def test_unary_intrin():
(tvm.tir.asinh, lambda x: np.arcsinh(x)),
(tvm.tir.acosh, lambda x: np.arccosh(x)),
(tvm.tir.atanh, lambda x: np.arctanh(x)),
(tvm.tir.erf, lambda x: scipy.special.erf(x)),
]

def run_test(tvm_intrin, np_func, atol=1e-5, rtol=1e-5):
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