[Mesa-dev] [PATCH 4/7] i965/disasm: Split opcode tables by the generation they were introduced in.

Francisco Jerez currojerez at riseup.net
Thu Apr 28 19:46:44 UTC 2016


Matt Turner <mattst88 at gmail.com> writes:

> On Thu, Apr 28, 2016 at 12:19 AM, Francisco Jerez <currojerez at riseup.net> wrote:
>> ---
>>  src/mesa/drivers/dri/i965/brw_disasm.c | 90 ++++++++++++++++++++++++++--------
>>  1 file changed, 69 insertions(+), 21 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_disasm.c b/src/mesa/drivers/dri/i965/brw_disasm.c
>> index 15d9383..0125434 100644
>> --- a/src/mesa/drivers/dri/i965/brw_disasm.c
>> +++ b/src/mesa/drivers/dri/i965/brw_disasm.c
>> @@ -30,9 +30,8 @@
>>  #include "brw_inst.h"
>>  #include "brw_eu.h"
>>
>> -static const struct opcode_desc opcode_descs[128] = {
>> +static const struct opcode_desc gen4_opcode_descs[128] = {
>>     [BRW_OPCODE_MOV]      = { .name = "mov",     .nsrc = 1, .ndst = 1 },
>> -   [BRW_OPCODE_MOVI]     = { .name = "movi",    .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_FRC]      = { .name = "frc",     .nsrc = 1, .ndst = 1 },
>>     [BRW_OPCODE_RNDU]     = { .name = "rndu",    .nsrc = 1, .ndst = 1 },
>>     [BRW_OPCODE_RNDD]     = { .name = "rndd",    .nsrc = 1, .ndst = 1 },
>> @@ -40,27 +39,17 @@ static const struct opcode_desc opcode_descs[128] = {
>>     [BRW_OPCODE_RNDZ]     = { .name = "rndz",    .nsrc = 1, .ndst = 1 },
>>     [BRW_OPCODE_NOT]      = { .name = "not",     .nsrc = 1, .ndst = 1 },
>>     [BRW_OPCODE_LZD]      = { .name = "lzd",     .nsrc = 1, .ndst = 1 },
>> -   [BRW_OPCODE_F32TO16]  = { .name = "f32to16", .nsrc = 1, .ndst = 1 },
>> -   [BRW_OPCODE_F16TO32]  = { .name = "f16to32", .nsrc = 1, .ndst = 1 },
>> -   [BRW_OPCODE_BFREV]    = { .name = "bfrev",   .nsrc = 1, .ndst = 1 },
>> -   [BRW_OPCODE_FBH]      = { .name = "fbh",     .nsrc = 1, .ndst = 1 },
>> -   [BRW_OPCODE_FBL]      = { .name = "fbl",     .nsrc = 1, .ndst = 1 },
>> -   [BRW_OPCODE_CBIT]     = { .name = "cbit",    .nsrc = 1, .ndst = 1 },
>>
>>     [BRW_OPCODE_MUL]      = { .name = "mul",     .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_MAC]      = { .name = "mac",     .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_MACH]     = { .name = "mach",    .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_LINE]     = { .name = "line",    .nsrc = 2, .ndst = 1 },
>> -   [BRW_OPCODE_PLN]      = { .name = "pln",     .nsrc = 2, .ndst = 1 },
>> -   [BRW_OPCODE_MAD]      = { .name = "mad",     .nsrc = 3, .ndst = 1 },
>> -   [BRW_OPCODE_LRP]      = { .name = "lrp",     .nsrc = 3, .ndst = 1 },
>>     [BRW_OPCODE_SAD2]     = { .name = "sad2",    .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_SADA2]    = { .name = "sada2",   .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_DP4]      = { .name = "dp4",     .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_DPH]      = { .name = "dph",     .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_DP3]      = { .name = "dp3",     .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_DP2]      = { .name = "dp2",     .nsrc = 2, .ndst = 1 },
>> -   [BRW_OPCODE_MATH]     = { .name = "math",    .nsrc = 2, .ndst = 1 },
>>
>>     [BRW_OPCODE_AVG]      = { .name = "avg",     .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_ADD]      = { .name = "add",     .nsrc = 2, .ndst = 1 },
>> @@ -73,17 +62,9 @@ static const struct opcode_desc opcode_descs[128] = {
>>     [BRW_OPCODE_ASR]      = { .name = "asr",     .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_CMP]      = { .name = "cmp",     .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_CMPN]     = { .name = "cmpn",    .nsrc = 2, .ndst = 1 },
>> -   [BRW_OPCODE_CSEL]     = { .name = "csel",    .nsrc = 3, .ndst = 1 },
>> -   [BRW_OPCODE_BFE]      = { .name = "bfe",     .nsrc = 3, .ndst = 1 },
>> -   [BRW_OPCODE_BFI1]     = { .name = "bfi1",    .nsrc = 2, .ndst = 1 },
>> -   [BRW_OPCODE_BFI2]     = { .name = "bfi2",    .nsrc = 3, .ndst = 1 },
>> -   [BRW_OPCODE_ADDC]     = { .name = "addc",    .nsrc = 2, .ndst = 1 },
>> -   [BRW_OPCODE_SUBB]     = { .name = "subb",    .nsrc = 2, .ndst = 1 },
>>
>>     [BRW_OPCODE_SEND]     = { .name = "send",    .nsrc = 1, .ndst = 1 },
>>     [BRW_OPCODE_SENDC]    = { .name = "sendc",   .nsrc = 1, .ndst = 1 },
>> -   [BRW_OPCODE_SENDS]    = { .name = "sends",   .nsrc = 2, .ndst = 1 },
>> -   [BRW_OPCODE_SENDSC]   = { .name = "sendsc",  .nsrc = 2, .ndst = 1 },
>>     [BRW_OPCODE_ILLEGAL]  = { .name = "illegal", .nsrc = 0, .ndst = 0 },
>>     [BRW_OPCODE_NOP]      = { .name = "nop",     .nsrc = 0, .ndst = 0 },
>>     [BRW_OPCODE_NENOP]    = { .name = "nenop",   .nsrc = 0, .ndst = 0 },
>> @@ -104,6 +85,70 @@ static const struct opcode_desc opcode_descs[128] = {
>>     [BRW_OPCODE_ENDIF]    = { .name = "endif",   .nsrc = 0, .ndst = 0 },
>>  };
>>
>> +static const struct opcode_desc g45_opcode_descs[128] = {
>> +   [BRW_OPCODE_MOVI]     = { .name = "movi",    .nsrc = 2, .ndst = 1 },
>> +   [BRW_OPCODE_PLN]      = { .name = "pln",     .nsrc = 2, .ndst = 1 },
>> +};
>> +
>> +static const struct opcode_desc gen6_opcode_descs[128] = {
>> +   [BRW_OPCODE_MATH]     = { .name = "math",    .nsrc = 2, .ndst = 1 },
>> +   [BRW_OPCODE_MAD]      = { .name = "mad",     .nsrc = 3, .ndst = 1 },
>> +   [BRW_OPCODE_LRP]      = { .name = "lrp",     .nsrc = 3, .ndst = 1 },
>> +};
>> +
>> +static const struct opcode_desc gen7_opcode_descs[128] = {
>> +   [BRW_OPCODE_F32TO16]  = { .name = "f32to16", .nsrc = 1, .ndst = 1 },
>> +   [BRW_OPCODE_F16TO32]  = { .name = "f16to32", .nsrc = 1, .ndst = 1 },
>> +   [BRW_OPCODE_BFREV]    = { .name = "bfrev",   .nsrc = 1, .ndst = 1 },
>> +   [BRW_OPCODE_BFE]      = { .name = "bfe",     .nsrc = 3, .ndst = 1 },
>> +   [BRW_OPCODE_BFI1]     = { .name = "bfi1",    .nsrc = 2, .ndst = 1 },
>> +   [BRW_OPCODE_BFI2]     = { .name = "bfi2",    .nsrc = 3, .ndst = 1 },
>> +   [BRW_OPCODE_FBH]      = { .name = "fbh",     .nsrc = 1, .ndst = 1 },
>> +   [BRW_OPCODE_FBL]      = { .name = "fbl",     .nsrc = 1, .ndst = 1 },
>> +   [BRW_OPCODE_CBIT]     = { .name = "cbit",    .nsrc = 1, .ndst = 1 },
>> +   [BRW_OPCODE_ADDC]     = { .name = "addc",    .nsrc = 2, .ndst = 1 },
>> +   [BRW_OPCODE_SUBB]     = { .name = "subb",    .nsrc = 2, .ndst = 1 },
>> +};
>> +
>> +static const struct opcode_desc gen8_opcode_descs[128] = {
>> +   [BRW_OPCODE_CSEL]     = { .name = "csel",    .nsrc = 3, .ndst = 1 },
>> +};
>> +
>> +static const struct opcode_desc gen9_opcode_descs[128] = {
>> +   [BRW_OPCODE_SENDS]    = { .name = "sends",   .nsrc = 2, .ndst = 1 },
>> +   [BRW_OPCODE_SENDSC]   = { .name = "sendsc",  .nsrc = 2, .ndst = 1 },
>
> A 128*16-byte array for each differing generation seems really bad to
> me, especially when they add 1-3 opcodes. A half a page for... one
> opcode.
>
No, it's not, an array bounded by 128*16B for each major hardware
generation is a tiny amount of memory by (even not so) modern standards.
I have the suspicion you're trying to optimize prematurely, or do you
have any evidence that your suggestion can substantially improve
performance?

> Your idea to order the array by opcode (but not index by opcode) and
> then by generation seems more appealing to me than this. Especially
> since you could make an initial guess that the opcode you want lives
> at opcode_desc[opcode] and start your (linear) search from there.
>
> For the common case (accessing an opcode that always exists) I think
> that's actually fewer operations than searching five  opcode_descs
> arrays before finding it.
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