glsl/cs: Lower gl_GlobalInvocationID variable

We lower this based on the extension spec formula:
    gl_GlobalInvocationID =
        gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID

Suggested-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>

4 files changed, 182 insertions, 0 deletions

diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
index d784a81072..368c4845cf 100644
--- a/src/glsl/Makefile.sources
+++ b/src/glsl/Makefile.sources
@@ -143,6 +143,7 @@ LIBGLSL_FILES = \
 	loop_unroll.cpp \
 	lower_clip_distance.cpp \
 	lower_const_arrays_to_uniforms.cpp \
+	lower_cs_global_id.cpp \
 	lower_discard.cpp \
 	lower_discard_flow.cpp \
 	lower_if_to_cond_assign.cpp \
diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index e6939f3fe1..f377835a72 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -134,6 +134,7 @@ void optimize_dead_builtin_variables(exec_list *instructions,
                                      enum ir_variable_mode other);
 
 bool lower_vertex_id(gl_shader *shader);
+bool lower_cs_global_id(gl_shader *shader);
 
 ir_rvalue *
 compare_index_block(exec_list *instructions, ir_variable *index,
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index b7a783c098..0a2bf9d90e 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1825,6 +1825,8 @@ link_intrastage_shaders(void *mem_ctx,
    if (ctx->Const.VertexID_is_zero_based)
       lower_vertex_id(linked);
 
+   lower_cs_global_id(linked);
+
    /* Make a pass over all variable declarations to ensure that arrays with
     * unspecified sizes have a size specified.  The size is inferred from the
     * max_array_access field.
diff --git a/src/glsl/lower_cs_global_id.cpp b/src/glsl/lower_cs_global_id.cpp
new file mode 100644
index 0000000000..8a00880d2f
--- /dev/null
+++ b/src/glsl/lower_cs_global_id.cpp
@@ -0,0 +1,178 @@
+/*
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file lower_cs_global_id.cpp
+ *
+ *  We lower this based on the extension spec formula:
+ *      gl_GlobalInvocationID =
+ *          gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID
+ */
+
+#include "glsl_symbol_table.h"
+#include "ir_hierarchical_visitor.h"
+#include "ir.h"
+#include "ir_builder.h"
+#include "linker.h"
+#include "program/prog_statevars.h"
+
+namespace {
+
+class lower_cs_global_id_visitor : public ir_hierarchical_visitor {
+public:
+   explicit lower_cs_global_id_visitor(ir_function_signature *main_sig,
+                                    exec_list *ir_list)
+      : progress(false), GlobalInvocationID(NULL), gl_WorkGroupID(NULL),
+        gl_WorkGroupSize(NULL), gl_LocalInvocationID(NULL),
+        main_sig(main_sig), ir_list(ir_list)
+   {
+      foreach_in_list(ir_instruction, ir, ir_list) {
+         ir_variable *const var = ir->as_variable();
+
+         if (var == NULL)
+            continue;
+
+         if (var->data.mode == ir_var_system_value) {
+            if (var->data.location == SYSTEM_VALUE_WORK_GROUP_ID)
+               gl_WorkGroupID = var;
+            if (var->data.location == SYSTEM_VALUE_LOCAL_INVOCATION_ID)
+               gl_LocalInvocationID = var;
+         } else if (gl_WorkGroupSize == NULL &&
+                    /* FIXME: Clean this up */
+                    /*var->data.mode == ir_var_auto &&
+                    var->data.read_only &&
+                    var->data.how_declared == ir_var_declared_implicitly &&*/
+                    var->name != NULL &&
+                    strcmp(var->name, "gl_WorkGroupSize") == 0) {
+            gl_WorkGroupSize = var;
+         } else
+            continue;
+         if (gl_WorkGroupID != NULL && gl_LocalInvocationID != NULL &&
+             gl_WorkGroupSize != NULL)
+            break;
+      }
+   }
+
+   virtual ir_visitor_status visit(ir_dereference_variable *);
+
+   bool progress;
+
+private:
+   ir_variable *GlobalInvocationID;
+   ir_variable *gl_WorkGroupID;
+   ir_variable *gl_WorkGroupSize;
+   ir_variable *gl_LocalInvocationID;
+
+   ir_function_signature *main_sig;
+   exec_list *ir_list;
+};
+
+} /* anonymous namespace */
+
+ir_visitor_status
+lower_cs_global_id_visitor::visit(ir_dereference_variable *ir)
+{
+   if (ir->var->data.mode != ir_var_system_value ||
+       ir->var->data.location != SYSTEM_VALUE_GLOBAL_INVOCATION_ID)
+      return visit_continue;
+
+   if (GlobalInvocationID == NULL) {
+      const glsl_type *const uvec3_t = glsl_type::uvec3_type;
+      void *const mem_ctx = ralloc_parent(ir);
+
+      GlobalInvocationID =
+         new(mem_ctx) ir_variable(uvec3_t, "__GlobalInvocationID",
+                                  ir_var_temporary);
+      ir_list->push_head(GlobalInvocationID);
+
+      if (gl_WorkGroupID == NULL) {
+         gl_WorkGroupID = new(mem_ctx) ir_variable(uvec3_t, "gl_WorkGroupID",
+                                                   ir_var_system_value);
+         gl_WorkGroupID->data.how_declared = ir_var_declared_implicitly;
+         gl_WorkGroupID->data.read_only = true;
+         gl_WorkGroupID->data.location = SYSTEM_VALUE_GLOBAL_INVOCATION_ID;
+         gl_WorkGroupID->data.explicit_location = true;
+         gl_WorkGroupID->data.explicit_index = 0;
+         ir_list->push_head(gl_WorkGroupID);
+      }
+
+      if (gl_WorkGroupSize == NULL) {
+         gl_WorkGroupSize = new(mem_ctx) ir_variable(uvec3_t, "gl_WorkGroupSize",
+                                                     ir_var_auto);
+         gl_WorkGroupSize->data.how_declared = ir_var_declared_implicitly;
+         gl_WorkGroupSize->data.read_only = true;
+         ir_list->push_head(gl_WorkGroupSize);
+      }
+
+      if (gl_LocalInvocationID == NULL) {
+         gl_LocalInvocationID =
+            new(mem_ctx) ir_variable(uvec3_t, "gl_LocalInvocationID",
+                                     ir_var_system_value);
+         gl_LocalInvocationID->data.how_declared = ir_var_declared_implicitly;
+         gl_LocalInvocationID->data.read_only = true;
+         gl_LocalInvocationID->data.location = SYSTEM_VALUE_LOCAL_INVOCATION_ID;
+         gl_LocalInvocationID->data.explicit_location = true;
+         gl_LocalInvocationID->data.explicit_index = 0;
+         ir_list->push_head(gl_LocalInvocationID);
+      }
+
+      /**
+       *  gl_GlobalInvocationID =
+       *     gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID
+       */
+      ir_instruction *const inst =
+         ir_builder::assign(GlobalInvocationID,
+                            ir_builder::add(ir_builder::mul(gl_WorkGroupID,
+                                                            gl_WorkGroupSize),
+                                            gl_LocalInvocationID));
+
+      main_sig->body.push_head(inst);
+   }
+
+   ir->var = GlobalInvocationID;
+   progress = true;
+
+   return visit_continue;
+}
+
+bool
+lower_cs_global_id(gl_shader *shader)
+{
+   /* gl_GlobalInvocationID only exists in the compute shader.
+    */
+   if (shader->Stage != MESA_SHADER_COMPUTE)
+      return false;
+
+   ir_function_signature *const main_sig =
+      link_get_main_function_signature(shader);
+   if (main_sig == NULL) {
+      assert(main_sig != NULL);
+      return false;
+   }
+
+   lower_cs_global_id_visitor v(main_sig, shader->ir);
+
+   v.run(shader->ir);
+
+   return v.progress;
+}