FMA(a,b,c) keeps extra precision (usually 1 more bit of mantissa,
afaik) for the result a*b and add this to c, to finally produce a
IEEE754 32bit float result.
MAD(a,b,c) product a IEEE754 32bit float product a*b and add it to C.
So, fma can be slightly more accurate. An accuracy that is something
very appreciate.
2014/1/5 Marek Olšák <mar...@gmail.com>:
> How is FMA different from MAD?
>
> Please document the new opcodes in src/gallium/docs/source/tgsi.rst.
>
> Marek
>
> On Sun, Jan 5, 2014 at 12:42 AM, Maxence Le Doré
> <maxence.led...@gmail.com> wrote:
>> From: Maxence Le Doré <Maxence Le Doré>
>>
>> ---
>> src/gallium/auxiliary/tgsi/tgsi_info.c | 16 ++++++++++++++++
>> src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h | 6 ++++++
>> src/gallium/include/pipe/p_shader_tokens.h | 9 ++++++++-
>> 3 files changed, 30 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/gallium/auxiliary/tgsi/tgsi_info.c
>> b/src/gallium/auxiliary/tgsi/tgsi_info.c
>> index 0beef44..ed55940 100644
>> --- a/src/gallium/auxiliary/tgsi/tgsi_info.c
>> +++ b/src/gallium/auxiliary/tgsi/tgsi_info.c
>> @@ -221,6 +221,12 @@ static const struct tgsi_opcode_info
>> opcode_info[TGSI_OPCODE_LAST] =
>> { 1, 3, 1, 0, 0, 0, OTHR, "TXL2", TGSI_OPCODE_TXL2 },
>> { 1, 2, 0, 0, 0, 0, COMP, "IMUL_HI", TGSI_OPCODE_IMUL_HI },
>> { 1, 2, 0, 0, 0, 0, COMP, "UMUL_HI", TGSI_OPCODE_UMUL_HI },
>> + { 1, 3, 0, 0, 0, 0, COMP, "FMA", TGSI_OPCODE_FMA },
>> + { 1, 1, 0, 0, 0, 0, COMP, "POPCNT", TGSI_OPCODE_POPCNT },
>> + { 1, 1, 0, 0, 0, 0, COMP, "IMSB", TGSI_OPCODE_IMSB },
>> + { 1, 1, 0, 0, 0, 0, COMP, "ILSB", TGSI_OPCODE_ILSB },
>> + { 1, 1, 0, 0, 0, 0, COMP, "UMSB", TGSI_OPCODE_UMSB },
>> + { 1, 1, 0, 0, 0, 0, COMP, "ULSB", TGSI_OPCODE_ULSB },
>> };
>>
>> const struct tgsi_opcode_info *
>> @@ -321,6 +327,11 @@ tgsi_opcode_infer_type( uint opcode )
>> case TGSI_OPCODE_IABS:
>> case TGSI_OPCODE_ISSG:
>> case TGSI_OPCODE_IMUL_HI:
>> + case TGSI_OPCODE_POPCNT:
>> + case TGSI_OPCODE_ILSB:
>> + case TGSI_OPCODE_IMSB:
>> + case TGSI_OPCODE_ULSB:
>> + case TGSI_OPCODE_UMSB:
>> return TGSI_TYPE_SIGNED;
>> default:
>> return TGSI_TYPE_FLOAT;
>> @@ -344,9 +355,14 @@ tgsi_opcode_infer_src_type( uint opcode )
>> case TGSI_OPCODE_SAMPLE_I:
>> case TGSI_OPCODE_SAMPLE_I_MS:
>> case TGSI_OPCODE_UMUL_HI:
>> + case TGSI_OPCODE_POPCNT:
>> + case TGSI_OPCODE_ULSB:
>> + case TGSI_OPCODE_UMSB:
>> return TGSI_TYPE_UNSIGNED;
>> case TGSI_OPCODE_IMUL_HI:
>> case TGSI_OPCODE_I2F:
>> + case TGSI_OPCODE_ILSB:
>> + case TGSI_OPCODE_IMSB:
>> return TGSI_TYPE_SIGNED;
>> case TGSI_OPCODE_ARL:
>> case TGSI_OPCODE_ARR:
>> diff --git a/src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h
>> b/src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h
>> index 1ef78dd..cba0975 100644
>> --- a/src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h
>> +++ b/src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h
>> @@ -206,6 +206,12 @@ OP13(UCMP)
>>
>> OP12(IMUL_HI)
>> OP12(UMUL_HI)
>> +OP13(FMA)
>> +OP11(POPCNT)
>> +OP11(IMSB)
>> +OP11(ILSB)
>> +OP11(UMSB)
>> +OP11(ULSB)
>>
>> #undef OP00
>> #undef OP01
>> diff --git a/src/gallium/include/pipe/p_shader_tokens.h
>> b/src/gallium/include/pipe/p_shader_tokens.h
>> index 8010902..5ed0c34 100644
>> --- a/src/gallium/include/pipe/p_shader_tokens.h
>> +++ b/src/gallium/include/pipe/p_shader_tokens.h
>> @@ -453,7 +453,14 @@ struct tgsi_property_data {
>> #define TGSI_OPCODE_IMUL_HI 180
>> #define TGSI_OPCODE_UMUL_HI 181
>>
>> -#define TGSI_OPCODE_LAST 182
>> +#define TGSI_OPCODE_FMA 182
>> +#define TGSI_OPCODE_POPCNT 183
>> +#define TGSI_OPCODE_IMSB 184
>> +#define TGSI_OPCODE_ILSB 185
>> +#define TGSI_OPCODE_UMSB 186
>> +#define TGSI_OPCODE_ULSB 187
>> +
>> +#define TGSI_OPCODE_LAST 188
>>
>> #define TGSI_SAT_NONE 0 /* do not saturate */
>> #define TGSI_SAT_ZERO_ONE 1 /* clamp to [0,1] */
>> --
>> 1.8.5.2
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
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