Nitpicks aside, I don't think this is a great idea now that you've got
the SKL PI working.
I also think it's broken -- you need to arrange to have the centroid
barycentric coords delivered to the FS thread, which won't be
happening if this is the *only* use of them. Masked in the tests,
because they compare with a centroid-qualified input. [I'm assuming
you don't always get these delivered to the FS in SKL, but no docs
access...]
- Chris
On Sat, Jul 11, 2015 at 11:18 AM, Chris Forbes <chr...@ijw.co.nz> wrote:
> s/interpolater/interpolator/g
>
> On Fri, Jul 10, 2015 at 1:31 AM, Neil Roberts <n...@linux.intel.com> wrote:
>> For centroid interpolation we can just directly use the values set up
>> in the shader payload instead of querying the pixel interpolator. To
>> do this we need to modify brw_compute_barycentric_interp_modes to
>> detect when interpolateAtCentroid is called.
>>
>> v2: Rebase on top of changes to set the pulls bary bit on SKL
>> ---
>>
>> As an aside, I was deliberating over whether to call the function
>> set_up_blah instead of setup_blah because I think the former is more
>> correct. The rest of Mesa seems to use setup so maybe it's more
>> important to be consistent than correct.
>>
>> src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 52 +++++++++++++++++++-----------
>> src/mesa/drivers/dri/i965/brw_wm.c | 55
>> ++++++++++++++++++++++++++++++++
>> 2 files changed, 88 insertions(+), 19 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> index 5d1ea21..fd7f1b8 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> @@ -1238,6 +1238,25 @@ fs_visitor::emit_percomp(const fs_builder &bld, const
>> fs_inst &inst,
>> }
>> }
>>
>> +/* For most messages, we need one reg of ignored data; the hardware requires
>> + * mlen==1 even when there is no payload. in the per-slot offset case, we'll
>> + * replace this with the proper source data.
>> + */
>> +static void
>> +setup_pixel_interpolater_instruction(fs_visitor *v,
>> + nir_intrinsic_instr *instr,
>> + fs_inst *inst,
>> + int mlen = 1)
>> +{
>> + inst->mlen = mlen;
>> + inst->regs_written = 2 * v->dispatch_width / 8;
>> + inst->pi_noperspective = instr->variables[0]->var->data.interpolation
>> ==
>> + INTERP_QUALIFIER_NOPERSPECTIVE;
>> +
>> + assert(v->stage == MESA_SHADER_FRAGMENT);
>> + ((struct brw_wm_prog_data *) v->prog_data)->pulls_bary = true;
>> +}
>> +
>> void
>> fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr
>> *instr)
>> {
>> @@ -1482,25 +1501,23 @@ fs_visitor::nir_emit_intrinsic(const fs_builder
>> &bld, nir_intrinsic_instr *instr
>> case nir_intrinsic_interp_var_at_centroid:
>> case nir_intrinsic_interp_var_at_sample:
>> case nir_intrinsic_interp_var_at_offset: {
>> - assert(stage == MESA_SHADER_FRAGMENT);
>> -
>> - ((struct brw_wm_prog_data *) prog_data)->pulls_bary = true;
>> -
>> fs_reg dst_xy = bld.vgrf(BRW_REGISTER_TYPE_F, 2);
>>
>> - /* For most messages, we need one reg of ignored data; the hardware
>> - * requires mlen==1 even when there is no payload. in the per-slot
>> - * offset case, we'll replace this with the proper source data.
>> - */
>> fs_reg src = vgrf(glsl_type::float_type);
>> - int mlen = 1; /* one reg unless overriden */
>> fs_inst *inst;
>>
>> switch (instr->intrinsic) {
>> - case nir_intrinsic_interp_var_at_centroid:
>> - inst = bld.emit(FS_OPCODE_INTERPOLATE_AT_CENTROID,
>> - dst_xy, src, fs_reg(0u));
>> + case nir_intrinsic_interp_var_at_centroid: {
>> + enum brw_wm_barycentric_interp_mode interp_mode;
>> + if (instr->variables[0]->var->data.interpolation ==
>> + INTERP_QUALIFIER_NOPERSPECTIVE)
>> + interp_mode = BRW_WM_NONPERSPECTIVE_CENTROID_BARYCENTRIC;
>> + else
>> + interp_mode = BRW_WM_PERSPECTIVE_CENTROID_BARYCENTRIC;
>> + uint8_t reg = payload.barycentric_coord_reg[interp_mode];
>> + dst_xy = fs_reg(brw_vec16_grf(reg, 0));
>> break;
>> + }
>>
>> case nir_intrinsic_interp_var_at_sample: {
>> /* XXX: We should probably handle non-constant sample id's */
>> @@ -1509,6 +1526,7 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld,
>> nir_intrinsic_instr *instr
>> unsigned msg_data = const_sample ? const_sample->i[0] << 4 : 0;
>> inst = bld.emit(FS_OPCODE_INTERPOLATE_AT_SAMPLE, dst_xy, src,
>> fs_reg(msg_data));
>> + setup_pixel_interpolater_instruction(this, instr, inst);
>> break;
>> }
>>
>> @@ -1521,6 +1539,7 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld,
>> nir_intrinsic_instr *instr
>>
>> inst = bld.emit(FS_OPCODE_INTERPOLATE_AT_SHARED_OFFSET, dst_xy,
>> src,
>> fs_reg(off_x | (off_y << 4)));
>> + setup_pixel_interpolater_instruction(this, instr, inst);
>> } else {
>> src = vgrf(glsl_type::ivec2_type);
>> fs_reg offset_src = retype(get_nir_src(instr->src[0]),
>> @@ -1550,9 +1569,10 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld,
>> nir_intrinsic_instr *instr
>> bld.SEL(offset(src, bld, i), itemp, fs_reg(7)));
>> }
>>
>> - mlen = 2 * dispatch_width / 8;
>> inst = bld.emit(FS_OPCODE_INTERPOLATE_AT_PER_SLOT_OFFSET,
>> dst_xy, src,
>> fs_reg(0u));
>> + setup_pixel_interpolater_instruction(this, instr, inst,
>> + 2 * dispatch_width / 8);
>> }
>> break;
>> }
>> @@ -1561,12 +1581,6 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld,
>> nir_intrinsic_instr *instr
>> unreachable("Invalid intrinsic");
>> }
>>
>> - inst->mlen = mlen;
>> - /* 2 floats per slot returned */
>> - inst->regs_written = 2 * dispatch_width / 8;
>> - inst->pi_noperspective = instr->variables[0]->var->data.interpolation
>> ==
>> - INTERP_QUALIFIER_NOPERSPECTIVE;
>> -
>> for (unsigned j = 0; j < instr->num_components; j++) {
>> fs_reg src = interp_reg(instr->variables[0]->var->data.location,
>> j);
>> src.type = dest.type;
>> diff --git a/src/mesa/drivers/dri/i965/brw_wm.c
>> b/src/mesa/drivers/dri/i965/brw_wm.c
>> index 592a729..f7fe1e0 100644
>> --- a/src/mesa/drivers/dri/i965/brw_wm.c
>> +++ b/src/mesa/drivers/dri/i965/brw_wm.c
>> @@ -40,9 +40,62 @@
>> #include "program/prog_parameter.h"
>> #include "program/program.h"
>> #include "intel_mipmap_tree.h"
>> +#include "brw_nir.h"
>>
>> #include "util/ralloc.h"
>>
>> +static bool
>> +compute_modes_in_block(nir_block *block,
>> + void *state)
>> +{
>> + unsigned *interp_modes = state;
>> + nir_intrinsic_instr *intrin;
>> + enum brw_wm_barycentric_interp_mode interp_mode;
>> +
>> + nir_foreach_instr(block, instr) {
>> + if (instr->type != nir_instr_type_intrinsic)
>> + continue;
>> +
>> + intrin = nir_instr_as_intrinsic(instr);
>> +
>> + if (intrin->intrinsic != nir_intrinsic_interp_var_at_centroid)
>> + continue;
>> +
>> + if (intrin->variables[0]->var->data.interpolation ==
>> + INTERP_QUALIFIER_NOPERSPECTIVE)
>> + interp_mode = BRW_WM_NONPERSPECTIVE_CENTROID_BARYCENTRIC;
>> + else
>> + interp_mode = BRW_WM_PERSPECTIVE_CENTROID_BARYCENTRIC;
>> +
>> + *interp_modes |= 1 << interp_mode;
>> + }
>> +
>> + return true;
>> +}
>> +
>> +/**
>> + * Looks for calls to interpolateAtCentroid within the program and returns a
>> + * mask of the additional interpolation modes that they require.
>> + */
>> +static unsigned
>> +compute_interpolate_at_centroid_modes(const struct gl_fragment_program
>> *fprog)
>> +{
>> + unsigned interp_modes = 0;
>> + struct nir_shader *shader = fprog->Base.nir;
>> +
>> + if (shader == NULL)
>> + return 0;
>> +
>> + nir_foreach_overload(shader, overload) {
>> + if (overload->impl == NULL)
>> + continue;
>> +
>> + nir_foreach_block(overload->impl, compute_modes_in_block,
>> &interp_modes);
>> + }
>> +
>> + return interp_modes;
>> +}
>> +
>> /**
>> * Return a bitfield where bit n is set if barycentric interpolation mode n
>> * (see enum brw_wm_barycentric_interp_mode) is needed by the fragment
>> shader.
>> @@ -114,6 +167,8 @@ brw_compute_barycentric_interp_modes(struct brw_context
>> *brw,
>> }
>> }
>>
>> + barycentric_interp_modes |= compute_interpolate_at_centroid_modes(fprog);
>> +
>> return barycentric_interp_modes;
>> }
>>
>> --
>> 1.9.3
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
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