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clang-p2996/libclc/generic/lib/math/exp.cl
Fraser Cormack 82912fd620 [libclc] Update license headers (#132070)
This commit bulk-updates the libclc license headers to the current
Apache-2.0 WITH LLVM-exception license in situations where they were
previously attributed to AMD - and occasionally under an additional
single individual contributor - under an MIT license.

AMD signed the LLVM relicensing agreement and so agreed for their past
contributions under the new LLVM license.

The LLVM project also has had a long-standing, unwritten, policy of not
adding copyright notices to source code. This policy was recently
written up [1]. This commit therefore also removes these copyright
notices at the same time.

Note that there are outstanding copyright notices attributed to others -
and many files missing copyright headers - which will be dealt with in
future work.

[1]
https://llvm.org/docs/DeveloperPolicy.html#embedded-copyright-or-contributed-by-statements
2025-03-20 11:40:09 +00:00

84 lines
2.5 KiB
Common Lisp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include <clc/clc.h>
#include <clc/clcmacro.h>
#include <clc/math/math.h>
_CLC_OVERLOAD _CLC_DEF float exp(float x) {
// Reduce x
const float ln2HI = 0x1.62e300p-1f;
const float ln2LO = 0x1.2fefa2p-17f;
const float invln2 = 0x1.715476p+0f;
float fhalF = x < 0.0f ? -0.5f : 0.5f;
int p = mad(x, invln2, fhalF);
float fp = (float)p;
float hi = mad(fp, -ln2HI, x); // t*ln2HI is exact here
float lo = -fp*ln2LO;
// Evaluate poly
float t = hi + lo;
float tt = t*t;
float v = mad(tt,
-mad(tt,
mad(tt,
mad(tt,
mad(tt, 0x1.637698p-25f, -0x1.bbd41cp-20f),
0x1.1566aap-14f),
-0x1.6c16c2p-9f),
0x1.555556p-3f),
t);
float y = 1.0f - (((-lo) - MATH_DIVIDE(t * v, 2.0f - v)) - hi);
// Scale by 2^p
float r = as_float(as_int(y) + (p << 23));
const float ulim = 0x1.62e430p+6f; // ln(largest_normal) = 88.72283905206835305366
const float llim = -0x1.5d589ep+6f; // ln(smallest_normal) = -87.33654475055310898657
r = x < llim ? 0.0f : r;
r = x < ulim ? r : as_float(0x7f800000);
return isnan(x) ? x : r;
}
_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, float, exp, float)
#ifdef cl_khr_fp64
#include "exp_helper.h"
#pragma OPENCL EXTENSION cl_khr_fp64 : enable
_CLC_OVERLOAD _CLC_DEF double exp(double x) {
const double X_MIN = -0x1.74910d52d3051p+9; // -1075*ln(2)
const double X_MAX = 0x1.62e42fefa39efp+9; // 1024*ln(2)
const double R_64_BY_LOG2 = 0x1.71547652b82fep+6; // 64/ln(2)
const double R_LOG2_BY_64_LD = 0x1.62e42fefa0000p-7; // head ln(2)/64
const double R_LOG2_BY_64_TL = 0x1.cf79abc9e3b39p-46; // tail ln(2)/64
int n = convert_int(x * R_64_BY_LOG2);
double r = fma(-R_LOG2_BY_64_TL, (double)n, fma(-R_LOG2_BY_64_LD, (double)n, x));
return __clc_exp_helper(x, X_MIN, X_MAX, r, n);
}
_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, double, exp, double)
#endif
#ifdef cl_khr_fp16
#pragma OPENCL EXTENSION cl_khr_fp16 : enable
_CLC_DEFINE_UNARY_BUILTIN_FP16(exp)
#endif