v3d: implement tile buffer color read intrinsic

We will be emitting this intrinsic to signal TLB color loads when we implement
OpenGL logic operations, where we need to blend the fragment shader color
output with the existing color in the render target.

Per-sample TLB reads are not supported yet.

v2: fix the offset into the color_reads array (Eric).

Reviewed-by: Eric Anholt <eric@anholt.net>

diff --git a/src/broadcom/compiler/nir_to_vir.c b/src/broadcom/compiler/nir_to_vir.c
index b05c892bba617100b83af8645317602d472bbab1..75622338aa2063759b8947f90e690925a870123d 100644 (file)
--- a/src/broadcom/compiler/nir_to_vir.c
+++ b/src/broadcom/compiler/nir_to_vir.c
@@ -1632,6 +1632,102 @@ ntq_emit_image_size(struct v3d_compile *c, nir_intrinsic_instr *instr)
         }
 }
 
+static void
+vir_emit_tlb_color_read(struct v3d_compile *c, nir_intrinsic_instr *instr)
+{
+        assert(c->s->info.stage == MESA_SHADER_FRAGMENT);
+
+        int rt = nir_src_as_uint(instr->src[0]);
+        assert(rt < V3D_MAX_DRAW_BUFFERS);
+
+        int sample_index = nir_intrinsic_base(instr) ;
+        assert(sample_index == 0); /* XXX: multisample */
+
+        int component = nir_intrinsic_component(instr);
+        assert(component < 4);
+
+        struct qreg *color_reads =
+                &c->color_reads[(rt * V3D_MAX_SAMPLES + sample_index) * 4];
+
+        if (color_reads[component].file == QFILE_NULL) {
+                enum pipe_format rt_format = c->fs_key->color_fmt[rt].format;
+                int num_components =
+                        util_format_get_nr_components(rt_format);
+
+                const bool swap_rb = c->fs_key->swap_color_rb & (1 << rt);
+                if (swap_rb)
+                        num_components = MAX2(num_components, 3);
+
+                bool is_int_format = (c->fs_key->int_color_rb & (1 << rt)) ||
+                                     (c->fs_key->uint_color_rb & (1 << rt));
+
+                bool is_32b_tlb_format = is_int_format ||
+                                         (c->fs_key->f32_color_rb & (1 << rt));
+
+                uint32_t conf = 0xffffff00;
+                conf |= TLB_SAMPLE_MODE_PER_PIXEL; /* XXX: multisample */
+                conf |= (7 - rt) << TLB_RENDER_TARGET_SHIFT;
+
+                if (is_32b_tlb_format) {
+                        /* The F32 vs I32 distinction was dropped in 4.2. */
+                        conf |= (c->devinfo->ver < 42 && is_int_format) ?
+                                TLB_TYPE_I32_COLOR : TLB_TYPE_F32_COLOR;
+
+                        conf |= ((num_components - 1) <<
+                                 TLB_VEC_SIZE_MINUS_1_SHIFT);
+                } else {
+                        conf |= TLB_TYPE_F16_COLOR;
+                        conf |= TLB_F16_SWAP_HI_LO;
+
+                        if (num_components >= 3)
+                                conf |= TLB_VEC_SIZE_4_F16;
+                        else
+                                conf |= TLB_VEC_SIZE_2_F16;
+                }
+
+                struct qreg r, g, b, a;
+                if (is_32b_tlb_format) {
+                        r = conf != 0xffffffff ? vir_TLBU_COLOR_READ(c, conf) :
+                                                 vir_TLB_COLOR_READ(c);
+                        if (num_components >= 2)
+                                g = vir_TLB_COLOR_READ(c);
+                        if (num_components >= 3)
+                                b = vir_TLB_COLOR_READ(c);
+                        if (num_components >= 4)
+                                a = vir_TLB_COLOR_READ(c);
+                } else {
+                        struct qreg rg = conf != 0xffffffff ?
+                                vir_TLBU_COLOR_READ(c, conf) :
+                                vir_TLB_COLOR_READ(c);
+                        r = vir_FMOV(c, rg);
+                        vir_set_unpack(c->defs[r.index], 0, V3D_QPU_UNPACK_L);
+                        g = vir_FMOV(c, rg);
+                        vir_set_unpack(c->defs[g.index], 0, V3D_QPU_UNPACK_H);
+
+                        if (num_components > 2) {
+                            struct qreg ba = vir_TLB_COLOR_READ(c);
+                            b = vir_FMOV(c, ba);
+                            vir_set_unpack(c->defs[b.index], 0,
+                                           V3D_QPU_UNPACK_L);
+                            a = vir_FMOV(c, ba);
+                            vir_set_unpack(c->defs[a.index], 0,
+                                           V3D_QPU_UNPACK_H);
+                        }
+                }
+
+                color_reads[0] = swap_rb ? b : r;
+                if (num_components >= 2)
+                        color_reads[1] = g;
+                if (num_components >= 3)
+                        color_reads[2] = swap_rb ? r : b;
+                if (num_components >= 4)
+                        color_reads[3] = a;
+        }
+
+        assert(color_reads[component].file != QFILE_NULL);
+        ntq_store_dest(c, &instr->dest, 0, vir_MOV(c, color_reads[component]));
+}
+
 static void
 ntq_emit_intrinsic(struct v3d_compile *c, nir_intrinsic_instr *instr)
 {
@@ -1774,6 +1870,10 @@ ntq_emit_intrinsic(struct v3d_compile *c, nir_intrinsic_instr *instr)
                 ntq_store_dest(c, &instr->dest, 0, vir_MOV(c, c->vid));
                 break;
 
+        case nir_intrinsic_load_tlb_color_v3d:
+                vir_emit_tlb_color_read(c, instr);
+                break;
+
         case nir_intrinsic_load_input:
                 /* Use ldvpmv (uniform offset) or ldvpmd (non-uniform offset)
                  * and enable PIPE_SHADER_CAP_INDIRECT_INPUT_ADDR.