[Mesa-dev] [PATCH 24/26] radeonsi: add si_vs_prolog_bits::unpack_instance_id_from_vertex_id:1

[Marek Olšák]

From: Marek Olšák <marek.ol...@amd.com>

The prim discard compute shader bakes InstanceID into the output index buffer.
---
 src/gallium/drivers/radeonsi/si_shader.c | 25 ++++++++++++++++++++++--
 src/gallium/drivers/radeonsi/si_shader.h |  1 +
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_shader.c 
b/src/gallium/drivers/radeonsi/si_shader.c
index 6e3019a9f6c..ba43f0ff902 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -5788,6 +5788,8 @@ static void si_dump_shader_key_vs(const struct 
si_shader_key *key,
                prefix, prolog->instance_divisor_is_one);
        fprintf(f, "  %s.instance_divisor_is_fetched = %u\n",
                prefix, prolog->instance_divisor_is_fetched);
+       fprintf(f, "  %s.unpack_instance_id_from_vertex_id = %u\n",
+               prefix, prolog->unpack_instance_id_from_vertex_id);
        fprintf(f, "  %s.ls_vgpr_fix = %u\n",
                prefix, prolog->ls_vgpr_fix);
 
@@ -7214,8 +7216,21 @@ static void si_build_vs_prolog_function(struct 
si_shader_context *ctx,
                }
        }
 
-       ctx->abi.vertex_id = input_vgprs[first_vs_vgpr];
-       ctx->abi.instance_id = input_vgprs[first_vs_vgpr + 
(key->vs_prolog.as_ls ? 2 : 1)];
+       unsigned vertex_id_vgpr = first_vs_vgpr;
+       unsigned instance_id_vgpr = first_vs_vgpr + (key->vs_prolog.as_ls ? 2 : 
1);
+
+       ctx->abi.vertex_id = input_vgprs[vertex_id_vgpr];
+       ctx->abi.instance_id = input_vgprs[instance_id_vgpr];
+
+       /* InstanceID = VertexID >> 16;
+        * VertexID   = VertexID & 0xffff;
+        */
+       if (key->vs_prolog.states.unpack_instance_id_from_vertex_id) {
+               ctx->abi.instance_id = LLVMBuildLShr(ctx->ac.builder, 
ctx->abi.vertex_id,
+                                                    LLVMConstInt(ctx->i32, 16, 
0), "");
+               ctx->abi.vertex_id = LLVMBuildAnd(ctx->ac.builder, 
ctx->abi.vertex_id,
+                                                 LLVMConstInt(ctx->i32, 
0xffff, 0), "");
+       }
 
        /* Copy inputs to outputs. This should be no-op, as the registers match,
         * but it will prevent the compiler from overwriting them 
unintentionally.
@@ -7227,6 +7242,12 @@ static void si_build_vs_prolog_function(struct 
si_shader_context *ctx,
        }
        for (i = 0; i < num_input_vgprs; i++) {
                LLVMValueRef p = input_vgprs[i];
+
+               if (i == vertex_id_vgpr)
+                       p = ctx->abi.vertex_id;
+               else if (i == instance_id_vgpr)
+                       p = ctx->abi.instance_id;
+
                p = ac_to_float(&ctx->ac, p);
                ret = LLVMBuildInsertValue(ctx->ac.builder, ret, p,
                                           key->vs_prolog.num_input_sgprs + i, 
"");
diff --git a/src/gallium/drivers/radeonsi/si_shader.h 
b/src/gallium/drivers/radeonsi/si_shader.h
index f9f81a7bc1e..28f32be30c8 100644
--- a/src/gallium/drivers/radeonsi/si_shader.h
+++ b/src/gallium/drivers/radeonsi/si_shader.h
@@ -412,6 +412,7 @@ struct si_vs_prolog_bits {
        uint16_t        instance_divisor_is_one;     /* bitmask of inputs */
        uint16_t        instance_divisor_is_fetched; /* bitmask of inputs */
        unsigned        ls_vgpr_fix:1;
+       unsigned        unpack_instance_id_from_vertex_id:1;
 };
 
 /* Common TCS bits between the shader key and the epilog key. */
-- 
2.17.1

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