[Mesa-dev] [PATCH 18/22] i965/fs: Add infrastructure for generating CSEL instructions.
Ian Romanick
idr at freedesktop.org
Mon Mar 5 19:17:29 UTC 2018
On 02/28/2018 12:58 AM, Samuel Iglesias Gonsálvez wrote:
> On 24/02/18 00:56, Ian Romanick wrote:
>> From: Kenneth Graunke <kenneth at whitecape.org>
>>
>> v2 (idr): Don't allow CSEL with a non-float src2.
>>
>> v3 (idr): Add CSEL to fs_inst::flags_written. Suggested by Matt.
>>
>> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
>> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
>> ---
>> src/intel/compiler/brw_eu.h | 1 +
>> src/intel/compiler/brw_eu_emit.c | 1 +
>> src/intel/compiler/brw_fs.cpp | 1 +
>> src/intel/compiler/brw_fs_builder.h | 22 +++++++++++++++++++++-
>> src/intel/compiler/brw_fs_generator.cpp | 5 +++++
>> 5 files changed, 29 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/intel/compiler/brw_eu.h b/src/intel/compiler/brw_eu.h
>> index 2d0f56f..3201624 100644
>> --- a/src/intel/compiler/brw_eu.h
>> +++ b/src/intel/compiler/brw_eu.h
>> @@ -171,6 +171,7 @@ ALU2(SHR)
>> ALU2(SHL)
>> ALU1(DIM)
>> ALU2(ASR)
>> +ALU3(CSEL)
>> ALU1(F32TO16)
>> ALU1(F16TO32)
>> ALU2(ADD)
>> diff --git a/src/intel/compiler/brw_eu_emit.c b/src/intel/compiler/brw_eu_emit.c
>> index c25d8d6..305a759 100644
>> --- a/src/intel/compiler/brw_eu_emit.c
>> +++ b/src/intel/compiler/brw_eu_emit.c
>> @@ -953,6 +953,7 @@ ALU2(SHR)
>> ALU2(SHL)
>> ALU1(DIM)
>> ALU2(ASR)
>> +ALU3(CSEL)
>> ALU1(FRC)
>> ALU1(RNDD)
>> ALU2(MAC)
>> diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
>> index bed632d..accae1b 100644
>> --- a/src/intel/compiler/brw_fs.cpp
>> +++ b/src/intel/compiler/brw_fs.cpp
>> @@ -929,6 +929,7 @@ unsigned
>> fs_inst::flags_written() const
>> {
>> if ((conditional_mod && (opcode != BRW_OPCODE_SEL &&
>> + opcode != BRW_OPCODE_CSEL &&
>> opcode != BRW_OPCODE_IF &&
>> opcode != BRW_OPCODE_WHILE)) ||
>> opcode == FS_OPCODE_MOV_DISPATCH_TO_FLAGS) {
>> diff --git a/src/intel/compiler/brw_fs_builder.h b/src/intel/compiler/brw_fs_builder.h
>> index 87394bc..47eac42 100644
>> --- a/src/intel/compiler/brw_fs_builder.h
>> +++ b/src/intel/compiler/brw_fs_builder.h
>> @@ -458,7 +458,6 @@ namespace brw {
>> ALU1(BFREV)
>> ALU1(CBIT)
>> ALU2(CMPN)
>> - ALU3(CSEL)
>> ALU1(DIM)
>> ALU2(DP2)
>> ALU2(DP3)
>> @@ -534,6 +533,27 @@ namespace brw {
>> }
>>
>> /**
>> + * CSEL: dst = src2 <op> 0.0f ? src0 : src1
>> + */
>> + instruction *
>> + CSEL(const dst_reg &dst, const src_reg &src0, const src_reg &src1,
>> + const src_reg &src2, brw_conditional_mod condition) const
>> + {
>> + /* CSEL only operates on floats, so we can't do integer </<=/>=/>
>> + * comparisons. Zero/non-zero (== and !=) comparisons almost work.
>> + * 0x80000000 fails because it is -0.0, and -0.0 == 0.0.
>> + */
>> + assert(src2.type == BRW_REGISTER_TYPE_F);
>> +
>> + return set_condmod(condition,
>> + emit(BRW_OPCODE_CSEL,
>> + retype(dst, BRW_REGISTER_TYPE_F),
>> + retype(src0, BRW_REGISTER_TYPE_F),
>> + retype(src1, BRW_REGISTER_TYPE_F),
>> + src2));
>> + }
>> +
>> + /**
>> * Emit a linear interpolation instruction.
>> */
>> instruction *
>> diff --git a/src/intel/compiler/brw_fs_generator.cpp b/src/intel/compiler/brw_fs_generator.cpp
>> index cd5be05..9157367 100644
>> --- a/src/intel/compiler/brw_fs_generator.cpp
>> +++ b/src/intel/compiler/brw_fs_generator.cpp
>> @@ -1826,6 +1826,11 @@ fs_generator::generate_code(const cfg_t *cfg, int dispatch_width)
>> case BRW_OPCODE_SEL:
>> brw_SEL(p, dst, src[0], src[1]);
>> break;
>> + case BRW_OPCODE_CSEL:
>> + brw_set_default_access_mode(p, BRW_ALIGN_16);
>> + brw_CSEL(p, dst, src[0], src[1], src[2]);
>> + brw_set_default_access_mode(p, BRW_ALIGN_1);
>
> Setting the access mode to ALIGN_1 is not needed, right? It will
> continue with the next instruction in the loop that sets ALIGN1 at the
> beginning of the loop.
This was in Ken's original patch, so I'm not 100% sure. I've seen this
pattern around generating some other instructions, so my gut tells me
that it's done like this to be explicit and more defensive.
> In any case,
>
> Reviewed-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
>
> Sam
>
>
>> + break;
>> case BRW_OPCODE_BFREV:
>> assert(devinfo->gen >= 7);
>> brw_BFREV(p, retype(dst, BRW_REGISTER_TYPE_UD),
>
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