commit 685d45ff938f004aebffb06e8766ee9027030167
author Boris Brezillon <boris.brezillon@collabora.com> Wed Oct 14 14:11:52 2020 +0200
committer Boris Brezillon <boris.brezillon@collabora.com> Thu Oct 15 08:05:23 2020 +0200
tree 803f85ee088c97441098b5094a39edc1505dee6d
parent 0d40460757b809c8c28ee78f79e87a01e79bc518

pan/bi: Special-case load_input for blend shaders

Blend shaders are passed blend inputs through r0-r3. Let's emit a MOV
from those register when we see a load_input intrinsic.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7151>

src/panfrost/bifrost/bifrost_compile.c

diff --git a/src/panfrost/bifrost/bifrost_compile.c b/src/panfrost/bifrost/bifrost_compile.c
index 07a4bfe..c8f9762 100644
--- a/src/panfrost/bifrost/bifrost_compile.c
+++ b/src/panfrost/bifrost/bifrost_compile.c
@@ -166,6 +166,38 @@
 }
 
 static void
+bi_emit_ld_blend_input(bi_context *ctx, nir_intrinsic_instr *instr)
+{
+        ASSERTED nir_io_semantics sem = nir_intrinsic_io_semantics(instr);
+
+        /* We don't support dual-source blending yet. */
+        assert(sem.location == VARYING_SLOT_COL0);
+
+        bi_instruction ins = {
+                .type = BI_COMBINE,
+                .dest_type = nir_type_uint32,
+                .dest = pan_dest_index(&instr->dest),
+                .src_types = {
+                        nir_type_uint32, nir_type_uint32,
+                        nir_type_uint32, nir_type_uint32,
+                },
+
+                /* Source color is passed through r0-r3.
+                 * TODO: We should probably find a way to avoid this
+                 * combine/mov and use r0-r3 directly.
+                 */
+                .src = {
+                        BIR_INDEX_REGISTER | 0,
+                        BIR_INDEX_REGISTER | 1,
+                        BIR_INDEX_REGISTER | 2,
+                        BIR_INDEX_REGISTER | 3,
+                },
+        };
+
+        bi_emit(ctx, ins);
+}
+
+static void
 bi_emit_frag_out(bi_context *ctx, nir_intrinsic_instr *instr)
 {
         if (!ctx->emitted_atest && !ctx->is_blend) {
@@ -512,7 +544,9 @@
                 break;
         case nir_intrinsic_load_interpolated_input:
         case nir_intrinsic_load_input:
-                if (ctx->stage == MESA_SHADER_FRAGMENT)
+                if (ctx->is_blend)
+                        bi_emit_ld_blend_input(ctx, instr);
+                else if (ctx->stage == MESA_SHADER_FRAGMENT)
                         bi_emit_ld_vary(ctx, instr);
                 else if (ctx->stage == MESA_SHADER_VERTEX)
                         bi_emit(ctx, bi_load_with_r61(BI_LOAD_ATTR, instr));