nir/lower_system_values: Add support for several computed values

Reviewed-by: Rob Clark <robdclark@gmail.com>

src/compiler/nir/nir.h

@@ -1626,6 +1626,9 @@ typedef struct nir_shader_compiler_options {
     * are simulated by floats.)
     */
    bool native_integers;
+
+   /* Indicates that the driver only has zero-based vertex id */
+   bool vertex_id_zero_based;
 } nir_shader_compiler_options;
 
 typedef struct nir_shader_info {

src/compiler/nir/nir_lower_system_values.c

@@ -55,9 +55,76 @@ convert_block(nir_block *block, void *void_state)
 
       b->cursor = nir_after_instr(&load_var->instr);
 
-      nir_intrinsic_op sysval_op =
-         nir_intrinsic_from_system_value(var->data.location);
-      nir_ssa_def *sysval = nir_load_system_value(b, sysval_op, 0);
+      nir_ssa_def *sysval;
+      switch (var->data.location) {
+      case SYSTEM_VALUE_GLOBAL_INVOCATION_ID: {
+         /* From the GLSL man page for gl_GlobalInvocationID:
+          *
+          *    "The value of gl_GlobalInvocationID is equal to
+          *    gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID"
+          */
+
+         nir_const_value local_size;
+         local_size.u32[0] = b->shader->info.cs.local_size[0];
+         local_size.u32[1] = b->shader->info.cs.local_size[1];
+         local_size.u32[2] = b->shader->info.cs.local_size[2];
+
+         nir_ssa_def *group_id =
+            nir_load_system_value(b, nir_intrinsic_load_work_group_id, 0);
+         nir_ssa_def *local_id =
+            nir_load_system_value(b, nir_intrinsic_load_local_invocation_id, 0);
+
+         sysval = nir_iadd(b, nir_imul(b, group_id,
+                                          nir_build_imm(b, 3, local_size)),
+                              local_id);
+         break;
+      }
+
+      case SYSTEM_VALUE_LOCAL_INVOCATION_INDEX: {
+         /* From the GLSL man page for gl_LocalInvocationIndex:
+          *
+          *    "The value of gl_LocalInvocationIndex is equal to
+          *    gl_LocalInvocationID.z * gl_WorkGroupSize.x *
+          *    gl_WorkGroupSize.y + gl_LocalInvocationID.y *
+          *    gl_WorkGroupSize.x + gl_LocalInvocationID.x"
+          */
+         nir_ssa_def *local_id =
+            nir_load_system_value(b, nir_intrinsic_load_local_invocation_id, 0);
+
+         nir_ssa_def *size_x = nir_imm_int(b, b->shader->info.cs.local_size[0]);
+         nir_ssa_def *size_y = nir_imm_int(b, b->shader->info.cs.local_size[1]);
+
+         sysval = nir_imul(b, nir_channel(b, local_id, 2),
+                              nir_imul(b, size_x, size_y));
+         sysval = nir_iadd(b, sysval,
+                              nir_imul(b, nir_channel(b, local_id, 1), size_x));
+         sysval = nir_iadd(b, sysval, nir_channel(b, local_id, 0));
+         break;
+      }
+
+      case SYSTEM_VALUE_VERTEX_ID:
+         if (b->shader->options->vertex_id_zero_based) {
+            sysval = nir_iadd(b,
+               nir_load_system_value(b, nir_intrinsic_load_vertex_id_zero_base, 0),
+               nir_load_system_value(b, nir_intrinsic_load_base_vertex, 0));
+         } else {
+            sysval = nir_load_system_value(b, nir_intrinsic_load_vertex_id, 0);
+         }
+         break;
+
+      case SYSTEM_VALUE_INSTANCE_INDEX:
+         sysval = nir_iadd(b,
+            nir_load_system_value(b, nir_intrinsic_load_instance_id, 0),
+            nir_load_system_value(b, nir_intrinsic_load_base_instance, 0));
+         break;
+
+      default: {
+         nir_intrinsic_op sysval_op =
+            nir_intrinsic_from_system_value(var->data.location);
+         sysval = nir_load_system_value(b, sysval_op, 0);
+         break;
+      } /* default */
+      }
 
       nir_ssa_def_rewrite_uses(&load_var->dest.ssa, nir_src_for_ssa(sysval));
       nir_instr_remove(&load_var->instr);

src/gallium/drivers/freedreno/ir3/ir3_nir.c

@@ -45,6 +45,7 @@ ir3_tgsi_to_nir(const struct tgsi_token *tokens)
 			.lower_flrp = true,
 			.lower_ffract = true,
 			.native_integers = true,
+			.vertex_id_zero_based = true,
 			.lower_extract_byte = true,
 			.lower_extract_word = true,
 	};

src/mesa/drivers/dri/i965/brw_compiler.c

@@ -82,7 +82,8 @@ shader_perf_log_mesa(void *data, const char *fmt, ...)
    .lower_uadd_carry = true,                                                  \
    .lower_usub_borrow = true,                                                 \
    .lower_fdiv = true,                                                        \
-   .native_integers = true
+   .native_integers = true,                                                   \
+   .vertex_id_zero_based = true
 
 static const struct nir_shader_compiler_options scalar_nir_options = {
    COMMON_OPTIONS,