[Mesa-dev] [PATCH v2 1/9] vc4: Do all uniform loads with byte offsets

[Jason Ekstrand]

On Sat, Dec 5, 2015 at 2:33 AM, Michael Schellenberger Costa
<mschellenbergercosta at googlemail.com> wrote:
> Hi Jason,
>
> Am 05/12/2015 um 00:11 schrieb Jason Ekstrand:
>> Previously, we lowered direct uniform loads to dword offsets and indirect
>> loads to byte offsets in vc4_nir_lower_io.  However, it simplifies things a
>> bit if we just use byte offsets for everything and then divide by 4 when we
>> handle the direct uniform load.
>>
>> Cc: Eric Anholt <eric at anholt.net>
>> ---
>>  src/gallium/drivers/vc4/vc4_nir_lower_io.c | 17 +++++------------
>>  src/gallium/drivers/vc4/vc4_program.c      | 11 +++++++----
>>  2 files changed, 12 insertions(+), 16 deletions(-)
>>
>> diff --git a/src/gallium/drivers/vc4/vc4_nir_lower_io.c b/src/gallium/drivers/vc4/vc4_nir_lower_io.c
>> index 1afe52a..e2581c8 100644
>> --- a/src/gallium/drivers/vc4/vc4_nir_lower_io.c
>> +++ b/src/gallium/drivers/vc4/vc4_nir_lower_io.c
>> @@ -338,8 +338,8 @@ static void
>>  vc4_nir_lower_uniform(struct vc4_compile *c, nir_builder *b,
>>                        nir_intrinsic_instr *intr)
>>  {
>> -        /* All TGSI-to-NIR uniform loads are vec4, but we may create dword
>> -         * loads in our lowering passes.
>> +        /* All TGSI-to-NIR uniform loads are vec4, but we need byte offsets
>> +         * byte offsets in the backend.
> there is one to many "byte offsets" here

Thanks!  Fixed locally.
--Jason

> All the best
> Michael
>
>>           */
>>          if (intr->num_components == 1)
>>                  return;
>> @@ -355,6 +355,9 @@ vc4_nir_lower_uniform(struct vc4_compile *c, nir_builder *b,
>>                  intr_comp->num_components = 1;
>>                  nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1, NULL);
>>
>> +                /* Convert the base offset to bytes and add the component */
>> +                intr_comp->const_index[0] = (intr->const_index[0] * 16 + i * 4);
>> +
>>                  if (intr->intrinsic == nir_intrinsic_load_uniform_indirect) {
>>                          /* Convert the variable TGSI register index to a byte
>>                           * offset.
>> @@ -363,16 +366,6 @@ vc4_nir_lower_uniform(struct vc4_compile *c, nir_builder *b,
>>                                  nir_src_for_ssa(nir_ishl(b,
>>                                                           intr->src[0].ssa,
>>                                                           nir_imm_int(b, 4)));
>> -
>> -                        /* Convert the offset to be a byte index, too. */
>> -                        intr_comp->const_index[0] = (intr->const_index[0] * 16 +
>> -                                                     i * 4);
>> -                } else {
>> -                        /* We want a dword index for non-indirect uniform
>> -                         * loads.
>> -                         */
>> -                        intr_comp->const_index[0] = (intr->const_index[0] * 4 +
>> -                                                     i);
>>                  }
>>
>>                  dests[i] = &intr_comp->dest.ssa;
>> diff --git a/src/gallium/drivers/vc4/vc4_program.c b/src/gallium/drivers/vc4/vc4_program.c
>> index 197577b..1a45bac 100644
>> --- a/src/gallium/drivers/vc4/vc4_program.c
>> +++ b/src/gallium/drivers/vc4/vc4_program.c
>> @@ -1433,6 +1433,7 @@ static void
>>  ntq_emit_intrinsic(struct vc4_compile *c, nir_intrinsic_instr *instr)
>>  {
>>          const nir_intrinsic_info *info = &nir_intrinsic_infos[instr->intrinsic];
>> +        int dword_offset;
>>          struct qreg *dest = NULL;
>>
>>          if (info->has_dest) {
>> @@ -1442,11 +1443,13 @@ ntq_emit_intrinsic(struct vc4_compile *c, nir_intrinsic_instr *instr)
>>          switch (instr->intrinsic) {
>>          case nir_intrinsic_load_uniform:
>>                  assert(instr->num_components == 1);
>> -                if (instr->const_index[0] < VC4_NIR_STATE_UNIFORM_OFFSET) {
>> -                        *dest = qir_uniform(c, QUNIFORM_UNIFORM,
>> -                                            instr->const_index[0]);
>> +                /* The offset is in bytes, but we need dwords */
>> +                assert(instr->const_index[0] % 4 == 0);
>> +                dword_offset = instr->const_index[0] / 4;
>> +                if (dword_offset < VC4_NIR_STATE_UNIFORM_OFFSET) {
>> +                        *dest = qir_uniform(c, QUNIFORM_UNIFORM, dword_offset);
>>                  } else {
>> -                        *dest = qir_uniform(c, instr->const_index[0] -
>> +                        *dest = qir_uniform(c, dword_offset -
>>                                              VC4_NIR_STATE_UNIFORM_OFFSET,
>>                                              0);
>>                  }
>>