[Libclc-dev] [PATCH 1/1] math/fma: Add fp32 software implementation
Tom Stellard via Libclc-dev
libclc-dev at lists.llvm.org
Wed Jun 6 18:26:20 PDT 2018
On 06/06/2018 06:25 PM, Jan Vesely via Libclc-dev wrote:
> On Tue, 2018-05-29 at 16:09 -0400, Jan Vesely wrote:
>> On Sat, 2018-05-19 at 19:46 -0400, Jan Vesely wrote:
>>> Passes CTS on carrizo (when forced to use sw fma) and turks.
>>> Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
>>> ---
>>> generic/include/clc/math/fma.h | 11 +-
>>> generic/include/clc/math/ternary_decl.inc | 1 +
>>> generic/include/math/clc_fma.h | 11 ++
>>> generic/lib/SOURCES | 2 +
>>> generic/lib/math/clc_fma.cl | 158 ++++++++++++++++++++++
>>> generic/lib/math/fma.cl | 7 +
>>> generic/lib/math/fma.inc | 7 +
>>> 7 files changed, 192 insertions(+), 5 deletions(-)
>>> create mode 100644 generic/include/clc/math/ternary_decl.inc
>>> create mode 100644 generic/include/math/clc_fma.h
>>> create mode 100644 generic/lib/math/clc_fma.cl
>>> create mode 100644 generic/lib/math/fma.cl
>>> create mode 100644 generic/lib/math/fma.inc
>>>
>>> diff --git a/generic/include/clc/math/fma.h b/generic/include/clc/math/fma.h
>>> index 02d39f6..c7c23eb 100644
>>> --- a/generic/include/clc/math/fma.h
>>> +++ b/generic/include/clc/math/fma.h
>>> @@ -1,6 +1,7 @@
>>> -#undef fma
>>> -#define fma __clc_fma
>>> +#define __CLC_BODY <clc/math/ternary_decl.inc>
>>> +#define __CLC_FUNCTION fma
>>>
>>> -#define __CLC_FUNCTION __clc_fma
>>> -#define __CLC_INTRINSIC "llvm.fma"
>>> -#include <clc/math/ternary_intrin.inc>
>>> +#include <clc/math/gentype.inc>
>>> +
>>> +#undef __CLC_BODY
>>> +#undef __CLC_FUNCTION
>>> diff --git a/generic/include/clc/math/ternary_decl.inc b/generic/include/clc/math/ternary_decl.inc
>>> new file mode 100644
>>> index 0000000..0598684
>>> --- /dev/null
>>> +++ b/generic/include/clc/math/ternary_decl.inc
>>> @@ -0,0 +1 @@
>>> +_CLC_OVERLOAD _CLC_DECL __CLC_GENTYPE __CLC_FUNCTION(__CLC_GENTYPE a, __CLC_GENTYPE b, __CLC_GENTYPE c);
>>> diff --git a/generic/include/math/clc_fma.h b/generic/include/math/clc_fma.h
>>> new file mode 100644
>>> index 0000000..3ae6a74
>>> --- /dev/null
>>> +++ b/generic/include/math/clc_fma.h
>>> @@ -0,0 +1,11 @@
>>> +#define __CLC_FUNCTION __clc_fma
>>> +#define __CLC_INTRINSIC "llvm.fma"
>>> +#include <clc/math/ternary_intrin.inc>
>>> +
>>> +#define __FLOAT_ONLY
>>> +#define __CLC_FUNCTION __clc_sw_fma
>>> +#define __CLC_BODY <clc/math/ternary_decl.inc>
>>> +#include <clc/math/gentype.inc>
>>> +#undef __CLC_BODY
>>> +#undef __CLC_FUNCTION
>>> +#undef __FLOAT_ONLY
>>> diff --git a/generic/lib/SOURCES b/generic/lib/SOURCES
>>> index 1f1a427..565750e 100644
>>> --- a/generic/lib/SOURCES
>>> +++ b/generic/lib/SOURCES
>>> @@ -101,6 +101,8 @@ math/exp2.cl
>>> math/clc_exp10.cl
>>> math/exp10.cl
>>> math/fdim.cl
>>> +math/clc_fma.cl
>>> +math/fma.cl
>>> math/fmax.cl
>>> math/fmin.cl
>>> math/clc_fmod.cl
>>> diff --git a/generic/lib/math/clc_fma.cl b/generic/lib/math/clc_fma.cl
>>> new file mode 100644
>>> index 0000000..dee90e9
>>> --- /dev/null
>>> +++ b/generic/lib/math/clc_fma.cl
>>> @@ -0,0 +1,158 @@
>>> +/*
>>> + * Copyright (c) 2014 Advanced Micro Devices, Inc.
>>> + *
>>> + * Permission is hereby granted, free of charge, to any person obtaining a copy
>>> + * of this software and associated documentation files (the "Software"), to deal
>>> + * in the Software without restriction, including without limitation the rights
>>> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
>>> + * copies of the Software, and to permit persons to whom the Software is
>>> + * furnished to do so, subject to the following conditions:
>>> + *
>>> + * The above copyright notice and this permission notice shall be included in
>>> + * all copies or substantial portions of the Software.
>>> + *
>>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
>>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
>>> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
>>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
>>> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
>>> + * THE SOFTWARE.
>>> + */
>>> +
>>> +#include <clc/clc.h>
>>> +
>>> +#include "config.h"
>>> +#include "math.h"
>>> +#include "../clcmacro.h"
>>> +
>>> +struct fp {
>>> + ulong mantissa;
>>> + int exponent;
>>> + uint sign;
>>> +};
>>> +
>>> +_CLC_DEF _CLC_OVERLOAD float __clc_sw_fma(float a, float b, float c)
>>> +{
>>> + /* special cases */
>>> + if (isnan(a) || isnan(b) || isnan(c) || isinf(a) || isinf(b))
>>> + return mad(a, b, c);
>>> +
>>> + /* If only c is inf, and both a,b are regular numbers, the result is c*/
>>> + if (isinf(c))
>>> + return c;
>>> +
>>> + a = __clc_flush_denormal_if_not_supported(a);
>>> + b = __clc_flush_denormal_if_not_supported(b);
>>> + c = __clc_flush_denormal_if_not_supported(c);
>>> +
>>> + if (c == 0)
>>> + return a * b;
>>> +
>>> + struct fp st_a, st_b, st_c;
>>> +
>>> + st_a.exponent = a == .0f ? 0 : ((as_uint(a) & 0x7f800000) >> 23) - 127;
>>> + st_b.exponent = b == .0f ? 0 : ((as_uint(b) & 0x7f800000) >> 23) - 127;
>>> + st_c.exponent = c == .0f ? 0 : ((as_uint(c) & 0x7f800000) >> 23) - 127;
>>> +
>>> + st_a.mantissa = a == .0f ? 0 : (as_uint(a) & 0x7fffff) | 0x800000;
>>> + st_b.mantissa = b == .0f ? 0 : (as_uint(b) & 0x7fffff) | 0x800000;
>>> + st_c.mantissa = c == .0f ? 0 : (as_uint(c) & 0x7fffff) | 0x800000;
>>> +
>>> + st_a.sign = as_uint(a) & 0x80000000;
>>> + st_b.sign = as_uint(b) & 0x80000000;
>>> + st_c.sign = as_uint(c) & 0x80000000;
>>> +
>>> + // Multiplication.
>>> + // Move the product to the highest bits to maximize precision
>>> + // mantissa is 24 bits => product is 48 bits, 2bits non-fraction.
>>> + // Add one bit for future addition overflow,
>>> + // add another bit to detect subtraction underflow
>>> + struct fp st_mul;
>>> + st_mul.sign = st_a.sign ^ st_b.sign;
>>> + st_mul.mantissa = (st_a.mantissa * st_b.mantissa) << 14ul;
>>> + st_mul.exponent = st_mul.mantissa ? st_a.exponent + st_b.exponent : 0;
>>> +
>>> + // FIXME: Detecting a == 0 || b == 0 above crashed GCN isel
>>> + if (st_mul.exponent == 0 && st_mul.mantissa == 0)
>>> + return c;
>>> +
>>> +// Mantissa is 23 fractional bits, shift it the same way as product mantissa
>>> +#define C_ADJUST 37ul
>>> +
>>> + // both exponents are bias adjusted
>>> + int exp_diff = st_mul.exponent - st_c.exponent;
>>> +
>>> + st_c.mantissa <<= C_ADJUST;
>>> + ulong cutoff_bits = 0;
>>> + ulong cutoff_mask = (1ul << abs(exp_diff)) - 1ul;
>>> + if (exp_diff > 0) {
>>> + cutoff_bits = exp_diff >= 64 ? st_c.mantissa : (st_c.mantissa & cutoff_mask);
>>> + st_c.mantissa = exp_diff >= 64 ? 0 : (st_c.mantissa >> exp_diff);
>>> + } else {
>>> + cutoff_bits = -exp_diff >= 64 ? st_mul.mantissa : (st_mul.mantissa & cutoff_mask);
>>> + st_mul.mantissa = -exp_diff >= 64 ? 0 : (st_mul.mantissa >> -exp_diff);
>>> + }
>>> +
>>> + struct fp st_fma;
>>> + st_fma.sign = st_mul.sign;
>>> + st_fma.exponent = max(st_mul.exponent, st_c.exponent);
>>> + if (st_c.sign == st_mul.sign) {
>>> + st_fma.mantissa = st_mul.mantissa + st_c.mantissa;
>>> + } else {
>>> + // cutoff bits borrow one
>>> + st_fma.mantissa = st_mul.mantissa - st_c.mantissa - (cutoff_bits && (st_mul.exponent > st_c.exponent) ? 1 : 0);
>>> + }
>>> +
>>> + // underflow: st_c.sign != st_mul.sign, and magnitude switches the sign
>>> + if (st_fma.mantissa > LONG_MAX) {
>>> + st_fma.mantissa = 0 - st_fma.mantissa;
>>> + st_fma.sign = st_mul.sign ^ 0x80000000;
>>> + }
>>> +
>>> + // detect overflow/underflow
>>> + int overflow_bits = 3 - clz(st_fma.mantissa);
>>> +
>>> + // adjust exponent
>>> + st_fma.exponent += overflow_bits;
>>> +
>>> + // handle underflow
>>> + if (overflow_bits < 0) {
>>> + st_fma.mantissa <<= -overflow_bits;
>>> + overflow_bits = 0;
>>> + }
>>> +
>>> + // rounding
>>> + ulong trunc_mask = (1ul << (C_ADJUST + overflow_bits)) - 1;
>>> + ulong trunc_bits = (st_fma.mantissa & trunc_mask) | (cutoff_bits != 0);
>>> + ulong last_bit = st_fma.mantissa & (1ul << (C_ADJUST + overflow_bits));
>>> + ulong grs_bits = (0x4ul << (C_ADJUST - 3 + overflow_bits));
>>> +
>>> + // round to nearest even
>>> + if ((trunc_bits > grs_bits) ||
>>> + (trunc_bits == grs_bits && last_bit != 0))
>>> + st_fma.mantissa += (1ul << (C_ADJUST + overflow_bits));
>>> +
>>> + // Shift mantissa back to bit 23
>>> + st_fma.mantissa = (st_fma.mantissa >> (C_ADJUST + overflow_bits));
>>> +
>>> + // Detect rounding overflow
>>> + if (st_fma.mantissa > 0xffffff) {
>>> + ++st_fma.exponent;
>>> + st_fma.mantissa >>= 1;
>>> + }
>>> +
>>> + if (st_fma.mantissa == 0)
>>> + return .0f;
>>> +
>>> + // Flating point range limit
>>> + if (st_fma.exponent > 127)
>>> + return as_float(as_uint(INFINITY) | st_fma.sign);
>>> +
>>> + // Flush denormals
>>> + if (st_fma.exponent <= -127)
>>> + return as_float(st_fma.sign);
>>> +
>>> + return as_float(st_fma.sign | ((st_fma.exponent + 127) << 23) | ((uint)st_fma.mantissa & 0x7fffff));
>>> +}
>>> +_CLC_TERNARY_VECTORIZE(_CLC_DEF _CLC_OVERLOAD, float, __clc_sw_fma, float, float, float)
>>> diff --git a/generic/lib/math/fma.cl b/generic/lib/math/fma.cl
>>> new file mode 100644
>>> index 0000000..9ad81be
>>> --- /dev/null
>>> +++ b/generic/lib/math/fma.cl
>>> @@ -0,0 +1,7 @@
>>> +#include <clc/clc.h>
>>> +
>>> +#include "math.h"
>>> +#include "math/clc_fma.h"
>>> +
>>> +#define __CLC_BODY <fma.inc>
>>> +#include <clc/math/gentype.inc>
>>> diff --git a/generic/lib/math/fma.inc b/generic/lib/math/fma.inc
>>> new file mode 100644
>>> index 0000000..654208f
>>> --- /dev/null
>>> +++ b/generic/lib/math/fma.inc
>>> @@ -0,0 +1,7 @@
>>> +_CLC_DEF _CLC_OVERLOAD __CLC_GENTYPE fma(__CLC_GENTYPE a, __CLC_GENTYPE b, __CLC_GENTYPE c) {
>>> +#if __CLC_FPSIZE == 32 && HAVE_HW_FMA32() == 0
>>> + return __clc_sw_fma(a, b, c);
>>> +#else
>>> + return __clc_fma(a, b, c);
>>> +#endif
>>> +}
>>
>> ping.
>
> ping2.
>
LGTM.
> Jan
>
>>
>> Jan
>
>
>
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