agx: switch to demote internally

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29179>

src/asahi/compiler/agx_nir_lower_cull_distance.c

@@ -107,7 +107,7 @@ agx_nir_lower_cull_distance_fs(nir_shader *s, unsigned nr_distances)
    }
 
    /* Emulate primitive culling by discarding fragments */
-   nir_discard_if(b, culled);
+   nir_demote_if(b, culled);
 
    s->info.inputs_read |= BITFIELD64_RANGE(VARYING_SLOT_CULL_PRIMITIVE,
                                            DIV_ROUND_UP(nr_distances, 4));

src/asahi/compiler/agx_nir_lower_discard_zs_emit.c

@@ -84,7 +84,9 @@ static bool
 lower_discard(nir_builder *b, nir_intrinsic_instr *intr, UNUSED void *data)
 {
    if (intr->intrinsic != nir_intrinsic_discard &&
-       intr->intrinsic != nir_intrinsic_discard_if)
+       intr->intrinsic != nir_intrinsic_discard_if &&
+       intr->intrinsic != nir_intrinsic_demote &&
+       intr->intrinsic != nir_intrinsic_demote_if)
       return false;
 
    b->cursor = nir_before_instr(&intr->instr);
@@ -93,7 +95,8 @@ lower_discard(nir_builder *b, nir_intrinsic_instr *intr, UNUSED void *data)
    nir_def *no_samples = nir_imm_intN_t(b, 0, 16);
    nir_def *killed_samples = all_samples;
 
-   if (intr->intrinsic == nir_intrinsic_discard_if)
+   if (intr->intrinsic == nir_intrinsic_discard_if ||
+       intr->intrinsic == nir_intrinsic_demote_if)
       killed_samples = nir_bcsel(b, intr->src[0].ssa, all_samples, no_samples);
 
    /* This will get lowered later as needed */

src/asahi/lib/agx_nir_prolog_epilog.c

@@ -47,7 +47,7 @@ agx_nir_lower_poly_stipple(nir_shader *s)
                                         nir_imm_int(b, 1));
 
    /* Discard fragments where the pattern is 0 */
-   nir_discard_if(b, nir_ieq_imm(b, bit, 0));
+   nir_demote_if(b, nir_ieq_imm(b, bit, 0));
    s->info.fs.uses_discard = true;
 
    nir_metadata_preserve(b->impl,