panfrost,panvk: Make fixed_sysval_ubo < 0 mean compiler-assigned

In 3559efb9bf ("panfrost: Allow passing an explicit UBO index for the
sysval UBO"), an explicit UBO index was added and it was implicitly
assumed that it would be > num_ubos.  This was convenient because it
meant 0, the default for designated initializers, implicitly meant
compiler-assigned.  However, we're about to move the sysval UBO to 0
which breaks this assumption.   Also, we don't want the back-end
compiler to even look at num_ubos since it's meaningless in Vulkan.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16276>

src/gallium/drivers/panfrost/pan_assemble.c

@@ -69,6 +69,7 @@ panfrost_shader_compile(struct pipe_screen *pscreen,
         struct panfrost_compile_inputs inputs = {
                 .gpu_id = dev->gpu_id,
                 .shaderdb = !!(dev->debug & PAN_DBG_PRECOMPILE),
+                .fixed_sysval_ubo = -1,
                 .fixed_varying_mask = state->key.fixed_varying_mask
         };
 

src/panfrost/bifrost/bifrost_compile.c

@@ -503,8 +503,9 @@ static bi_instr *
 bi_load_sysval_to(bi_builder *b, bi_index dest, int sysval,
                 unsigned nr_components, unsigned offset)
 {
-        unsigned sysval_ubo =
-                MAX2(b->shader->inputs->sysval_ubo, b->shader->nir->info.num_ubos);
+        unsigned sysval_ubo = b->shader->inputs->fixed_sysval_ubo >= 0 ?
+                              b->shader->inputs->fixed_sysval_ubo :
+                              b->shader->nir->info.num_ubos;
         unsigned uniform =
                 pan_lookup_sysval(b->shader->sysval_to_id,
                                   b->shader->info.sysvals,

src/panfrost/bifrost/cmdline.c

@@ -193,6 +193,7 @@ compile_shader(int stages, char **files)
 
                 struct panfrost_compile_inputs inputs = {
                         .gpu_id = gpu_id,
+                        .fixed_sysval_ubo = -1,
                 };
                 struct pan_shader_info info = { 0 };
 

src/panfrost/lib/pan_blend.c

@@ -822,6 +822,7 @@ GENX(pan_blend_get_shader_locked)(const struct panfrost_device *dev,
                 .is_blend = true,
                 .blend.rt = shader->key.rt,
                 .blend.nr_samples = key.nr_samples,
+                .fixed_sysval_ubo = -1,
                 .rt_formats = { key.format },
         };
 
@@ -834,6 +835,9 @@ GENX(pan_blend_get_shader_locked)(const struct panfrost_device *dev,
 
         GENX(pan_shader_compile)(nir, &inputs, &variant->binary, &info);
 
+        /* Blend shaders can't have sysvals */
+        assert(info.sysvals.sysval_count == 0);
+
         variant->work_reg_count = info.work_reg_count;
 
 #if PAN_ARCH <= 5

src/panfrost/lib/pan_blitter.c

@@ -604,6 +604,7 @@ pan_blitter_get_blit_shader(struct panfrost_device *dev,
                 .gpu_id = dev->gpu_id,
                 .is_blit = true,
                 .no_idvs = true,
+                .fixed_sysval_ubo = -1,
         };
         struct util_dynarray binary;
 
@@ -619,6 +620,9 @@ pan_blitter_get_blit_shader(struct panfrost_device *dev,
 
         GENX(pan_shader_compile)(b.shader, &inputs, &binary, &shader->info);
 
+        /* Blit shaders shouldn't have sysvals */
+        assert(shader->info.sysvals.sysval_count == 0);
+
         shader->key = *key;
         shader->address =
                 pan_pool_upload_aligned(dev->blitter.shaders.pool,

src/panfrost/lib/pan_indirect_dispatch.c

@@ -216,7 +216,10 @@ GENX(pan_indirect_dispatch_init)(struct panfrost_device *dev)
 
         nir_pop_if(&b, NULL);
 
-        struct panfrost_compile_inputs inputs = { .gpu_id = dev->gpu_id };
+        struct panfrost_compile_inputs inputs = {
+                .gpu_id = dev->gpu_id,
+                .fixed_sysval_ubo = -1,
+        };
         struct pan_shader_info shader_info;
         struct util_dynarray binary;
 

src/panfrost/lib/pan_indirect_draw.c

@@ -1133,7 +1133,10 @@ create_indirect_draw_shader(struct panfrost_device *dev,
         else
                 patch(&builder);
 
-        struct panfrost_compile_inputs inputs = { .gpu_id = dev->gpu_id };
+        struct panfrost_compile_inputs inputs = {
+                .gpu_id = dev->gpu_id,
+                .fixed_sysval_ubo = -1,
+        };
         struct pan_shader_info shader_info;
         struct util_dynarray binary;
 

src/panfrost/lib/pan_shader.c

@@ -312,10 +312,9 @@ GENX(pan_shader_compile)(nir_shader *s,
         info->outputs_written = s->info.outputs_written;
 
         /* Sysvals have dedicated UBO */
-        if (info->sysvals.sysval_count)
-                info->ubo_count = MAX2(s->info.num_ubos + 1, inputs->sysval_ubo + 1);
-        else
-                info->ubo_count = s->info.num_ubos;
+        info->ubo_count = s->info.num_ubos;
+        if (info->sysvals.sysval_count && inputs->fixed_sysval_ubo < 0)
+                info->ubo_count++;
 
         info->attribute_count += BITSET_LAST_BIT(s->info.images_used);
         info->writes_global = s->info.writes_memory;

src/panfrost/midgard/midgard_compile.c

@@ -1575,8 +1575,9 @@ emit_sysval_read(compiler_context *ctx, nir_instr *instr,
         nir_dest nir_dest;
 
         /* Figure out which uniform this is */
-        unsigned sysval_ubo =
-                MAX2(ctx->inputs->sysval_ubo, ctx->nir->info.num_ubos);
+        unsigned sysval_ubo = ctx->inputs->fixed_sysval_ubo >= 0 ?
+                              ctx->inputs->fixed_sysval_ubo :
+                              ctx->nir->info.num_ubos;
         int sysval = panfrost_sysval_for_instr(instr, &nir_dest);
         unsigned dest = nir_dest_index(&nir_dest);
         unsigned uniform =

src/panfrost/util/pan_ir.h

@@ -181,7 +181,7 @@ struct panfrost_compile_inputs {
                 unsigned nr_samples;
                 uint64_t bifrost_blend_desc;
         } blend;
-        unsigned sysval_ubo;
+        int fixed_sysval_ubo;
         bool shaderdb;
         bool no_idvs;
         bool no_ubo_to_push;

src/panfrost/vulkan/panvk_vX_shader.c

@@ -345,7 +345,7 @@ panvk_per_arch(shader_create)(struct panvk_device *dev,
       .gpu_id = pdev->gpu_id,
       .no_ubo_to_push = true,
       .no_idvs = true, /* TODO */
-      .sysval_ubo = sysval_ubo,
+      .fixed_sysval_ubo = sysval_ubo,
    };
 
    NIR_PASS_V(nir, nir_lower_indirect_derefs,