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pan/bi: Handle nir_tex_src_lod 

We need to emit some lowering code to convert it to the 8:8 format
expected by the hardware.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7081>
This commit is contained in:
Alyssa Rosenzweig 2020-10-06 11:46:50 -04:00
parent f8151312af
commit 4836366ede
1 changed files with 85 additions and 0 deletions
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85
src/panfrost/bifrost/bifrost_compile.c
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@ -1030,6 +1030,77 @@ bi_texture_format(nir_alu_type T, enum bifrost_outmod outmod)
}
}
/* TEXC's explicit and bias LOD modes requires the LOD to be transformed to a
* 16-bit 8:8 fixed-point format. We lower as:
*
* F32_TO_S32(clamp(x, -16.0, +16.0) * 256.0) & 0xFFFF =
* MKVEC(F32_TO_S32(clamp(x * 1.0/16.0, -1.0, 1.0) * (16.0 * 256.0)), #0)
*/
static unsigned
bi_emit_lod_88(bi_context *ctx, unsigned lod, bool fp16)
{
nir_alu_type T = fp16 ? nir_type_float16 : nir_type_float32;
/* Sort of arbitrary. Must be less than 128.0, greater than or equal to
* the max LOD (16 since we cap at 2^16 texture dimensions), and
* preferably small to minimize precision loss */
const float max_lod = 16.0;
/* FMA.f16/f32.sat_signed, saturated, lod, #1.0/max_lod, #0 */
bi_instruction fsat = {
.type = BI_FMA,
.dest = bi_make_temp(ctx),
.dest_type = nir_type_float32,
.src = { lod, BIR_INDEX_CONSTANT, BIR_INDEX_ZERO },
.src_types = { T, nir_type_float32, nir_type_float32 },
.outmod = BIFROST_SAT_SIGNED,
.roundmode = BIFROST_RTE,
.constant = {
.u64 = fui(1.0 / max_lod)
},
};
/* FMA.f32 scaled, saturated, lod, #(max_lod * 256.0), #0 */
bi_instruction fmul = {
.type = BI_FMA,
.dest = bi_make_temp(ctx),
.dest_type = T,
.src = { fsat.dest, BIR_INDEX_CONSTANT, BIR_INDEX_ZERO },
.src_types = { nir_type_float32, nir_type_float32, nir_type_float32 },
.roundmode = BIFROST_RTE,
.constant = {
.u64 = fui(max_lod * 256.0)
},
};
/* F32_TO_S32 s32, scaled */
bi_instruction f2i = {
.type = BI_CONVERT,
.dest = bi_make_temp(ctx),
.dest_type = nir_type_int32,
.src = { fmul.dest },
.src_types = { T },
.roundmode = BIFROST_RTZ
};
/* MKVEC.v2i16 s32.h0, #0 */
bi_instruction mkvec = {
.type = BI_SELECT,
.dest = bi_make_temp(ctx),
.dest_type = nir_type_int16,
.src = { f2i.dest, BIR_INDEX_ZERO },
.src_types = { nir_type_int16, nir_type_int16 },
};
bi_emit(ctx, fsat);
bi_emit(ctx, fmul);
bi_emit(ctx, f2i);
bi_emit(ctx, mkvec);
return mkvec.dest;
}
/* Data registers required by texturing in the order they appear. All are
* optional, the texture operation descriptor determines which are present.
* Note since 3D arrays are not permitted at an API level, Z_COORD and
@ -1095,6 +1166,8 @@ emit_texc(bi_context *ctx, nir_tex_instr *instr)
for (unsigned i = 0; i < instr->num_srcs; ++i) {
unsigned index = pan_src_index(&instr->src[i].src);
unsigned sz = nir_src_bit_size(instr->src[i].src);
ASSERTED nir_alu_type base = nir_tex_instr_src_type(instr, i);
switch (instr->src[i].src_type) {
case nir_tex_src_coord:
@ -1103,6 +1176,18 @@ emit_texc(bi_context *ctx, nir_tex_instr *instr)
tex.src[2] = index;
tex.swizzle[1][0] = 0;
tex.swizzle[2][0] = 1;
break;
case nir_tex_src_lod:
if (nir_src_is_const(instr->src[i].src) && nir_src_as_uint(instr->src[i].src) == 0) {
desc.lod_mode = BIFROST_LOD_MODE_ZERO;
} else {
assert(base == nir_type_float);
assert(sz == 16 || sz == 32);
dregs[BIFROST_TEX_DREG_LOD] =
bi_emit_lod_88(ctx, index, sz == 16);
desc.lod_mode = BIFROST_LOD_MODE_EXPLICIT;
}
break;
default:
unreachable("Unhandled src type in texc emit");