[Mesa-stable] [PATCH 10/13] glsl: Add a lowering pass for gl_VertexID

Ian Romanick idr at freedesktop.org
Fri Jun 20 18:01:00 PDT 2014


From: Ian Romanick <ian.d.romanick at intel.com>

Converts gl_VertexID to (gl_VertexIDMESA + gl_BaseVertex). gl_VertexIDMESA
is backed by SYSTEM_VALUE_VERTEX_ID_ZERO_BASE, and gl_BaseVertex is backed
by a built-in uniform from {STATE_INTERNAL, STATE_BASE_VERTEX}.

NOTE: The enum has to be declared outside the struct or C++ just cannot
find the values.  I tried many variations of scope resolution in
linker.cpp, but could not make it do-the-right-thing.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Cc: "10.2" <mesa-stable at lists.freedesktop.org>
---
 src/glsl/Makefile.sources    |   1 +
 src/glsl/ir_optimization.h   |   2 +
 src/glsl/linker.cpp          |   7 ++
 src/glsl/lower_vertex_id.cpp | 152 +++++++++++++++++++++++++++++++++++++++++++
 src/mesa/main/context.c      |   5 ++
 src/mesa/main/mtypes.h       |  14 ++++
 6 files changed, 181 insertions(+)
 create mode 100644 src/glsl/lower_vertex_id.cpp

diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
index b54eae7..b884d66 100644
--- a/src/glsl/Makefile.sources
+++ b/src/glsl/Makefile.sources
@@ -77,6 +77,7 @@ LIBGLSL_FILES = \
 	$(GLSL_SRCDIR)/lower_vec_index_to_swizzle.cpp \
 	$(GLSL_SRCDIR)/lower_vector.cpp \
 	$(GLSL_SRCDIR)/lower_vector_insert.cpp \
+	$(GLSL_SRCDIR)/lower_vertex_id.cpp \
 	$(GLSL_SRCDIR)/lower_output_reads.cpp \
 	$(GLSL_SRCDIR)/lower_ubo_reference.cpp \
 	$(GLSL_SRCDIR)/opt_algebraic.cpp \
diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index b83c225..2892dc2 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -125,6 +125,8 @@ bool optimize_redundant_jumps(exec_list *instructions);
 bool optimize_split_arrays(exec_list *instructions, bool linked);
 bool lower_offset_arrays(exec_list *instructions);
 
+bool lower_vertex_id(gl_shader *shader);
+
 ir_rvalue *
 compare_index_block(exec_list *instructions, ir_variable *index,
 		    unsigned base, unsigned components, void *mem_ctx);
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 813108c..2e9a0b6 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1623,6 +1623,13 @@ link_intrastage_shaders(void *mem_ctx,
       }
    }
 
+   if (ctx->Const.VertexID != gl_VertexID_native) {
+      /* FINISHME: The other lowering method is not yet implemented.
+       */
+      assert(ctx->Const.VertexID == gl_VertexID_using_uniform_gl_BaseVertex);
+      lower_vertex_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_vertex_id.cpp b/src/glsl/lower_vertex_id.cpp
new file mode 100644
index 0000000..c9cced1
--- /dev/null
+++ b/src/glsl/lower_vertex_id.cpp
@@ -0,0 +1,152 @@
+/*
+ * Copyright © 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_vertex_id.cpp
+ *
+ * There exists hardware, such as i965, that does not implement the OpenGL
+ * semantic for gl_VertexID.  Instead, that hardware does not include the
+ * value of basevertex in the gl_VertexID value.  To implement the OpenGL
+ * semantic, we'll have to convert gl_Vertex_ID to
+ * gl_VertexIDMESA+gl_BaseVertexMESA.
+ */
+
+#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_vertex_id_visitor : public ir_hierarchical_visitor {
+public:
+   explicit lower_vertex_id_visitor(ir_function_signature *main_sig,
+                                    exec_list *ir_list)
+      : progress(false), VertexID(NULL), gl_VertexID(NULL),
+        gl_BaseVertex(NULL), main_sig(main_sig), ir_list(ir_list)
+   {
+      foreach_list(node, ir_list) {
+         ir_instruction *const ir = (ir_instruction *) node;
+         ir_variable *const var = ir->as_variable();
+
+         if (var != NULL && strcmp(var->name, "gl_BaseVertex") == 0) {
+            gl_BaseVertex = var;
+            break;
+         }
+      }
+   }
+
+   virtual ir_visitor_status visit(ir_dereference_variable *);
+
+   bool progress;
+
+private:
+   ir_variable *VertexID;
+   ir_variable *gl_VertexID;
+   ir_variable *gl_BaseVertex;
+
+   ir_function_signature *main_sig;
+   exec_list *ir_list;
+};
+
+} /* anonymous namespace */
+
+ir_visitor_status
+lower_vertex_id_visitor::visit(ir_dereference_variable *ir)
+{
+   if (strcmp(ir->var->name, "gl_VertexID") != 0)
+      return visit_continue;
+
+   if (VertexID == NULL) {
+      const glsl_type *const int_t = glsl_type::int_type;
+      void *const mem_ctx = ralloc_parent(ir);
+
+      VertexID = new(mem_ctx) ir_variable(int_t, "__VertexID",
+                                          ir_var_temporary);
+      ir_list->push_head(VertexID);
+
+      gl_VertexID = new(mem_ctx) ir_variable(int_t, "gl_VertexIDMESA",
+                                             ir_var_system_value);
+      gl_VertexID->data.how_declared = ir_var_declared_implicitly;
+      gl_VertexID->data.read_only = true;
+      gl_VertexID->data.location = SYSTEM_VALUE_VERTEX_ID_ZERO_BASE;
+      gl_VertexID->data.explicit_location = true;
+      gl_VertexID->data.explicit_index = 0;
+      ir_list->push_head(gl_VertexID);
+
+      if (gl_BaseVertex == NULL) {
+         static const int slots[STATE_LENGTH] = {
+            STATE_INTERNAL,
+            STATE_BASE_VERTEX,
+            0,
+            0,
+            0
+         };
+
+         gl_BaseVertex = new(mem_ctx) ir_variable(int_t, "gl_BaseVertex",
+                                                  ir_var_uniform);
+         gl_BaseVertex->num_state_slots = 1;
+         gl_BaseVertex->state_slots =
+            ralloc_array(gl_BaseVertex, ir_state_slot,
+                         gl_BaseVertex->num_state_slots);
+         memcpy(gl_BaseVertex->state_slots, slots, sizeof(slots));
+
+         ir_list->push_head(gl_BaseVertex);
+      }
+
+      ir_instruction *const inst =
+         ir_builder::assign(VertexID,
+                            ir_builder::add(gl_VertexID, gl_BaseVertex));
+
+      main_sig->body.push_head(inst);
+   }
+
+   ir->var = VertexID;
+   progress = true;
+
+   return visit_continue;
+}
+
+bool
+lower_vertex_id(gl_shader *shader)
+{
+   /* gl_VertexID only exists in the vertex shader.
+    */
+   if (shader->Stage != MESA_SHADER_VERTEX)
+      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_vertex_id_visitor v(main_sig, shader->ir);
+
+   v.run(shader->ir);
+
+   return v.progress;
+}
diff --git a/src/mesa/main/context.c b/src/mesa/main/context.c
index 244e63e..40a3a2c 100644
--- a/src/mesa/main/context.c
+++ b/src/mesa/main/context.c
@@ -622,6 +622,11 @@ _mesa_init_constants(struct gl_context *ctx)
    ctx->Const.MaxProgramMatrices = MAX_PROGRAM_MATRICES;
    ctx->Const.MaxProgramMatrixStackDepth = MAX_PROGRAM_MATRIX_STACK_DEPTH;
 
+   /* Assume that if GLSL 1.30+ (or GLSL ES 3.00+) is supported that
+    * gl_VertexID is implemented using a native hardware register.
+    */
+   ctx->Const.VertexID = gl_VertexID_native;
+
    /* CheckArrayBounds is overriden by drivers/x11 for X server */
    ctx->Const.CheckArrayBounds = GL_FALSE;
 
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index c66a16a..e581008 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -3335,6 +3335,11 @@ struct gl_program_constants
    GLuint MaxImageUniforms;
 };
 
+enum _mesa_VertexID_mode {
+   gl_VertexID_native,
+   gl_VertexID_using_system_gl_BaseVertex,
+   gl_VertexID_using_uniform_gl_BaseVertex
+};
 
 /**
  * Constants which may be overridden by device driver during context creation
@@ -3444,6 +3449,15 @@ struct gl_constants
    GLboolean NativeIntegers;
 
    /**
+    * Method used to implement gl_VertexID
+    *
+    * \note
+    * If desktop GLSL 1.30 or GLSL ES 3.00 are not supported, this field is
+    * ignored and need not be set.
+    */
+   enum _mesa_VertexID_mode VertexID;
+
+   /**
     * If the driver supports real 32-bit integers, what integer value should be
     * used for boolean true in uniform uploads?  (Usually 1 or ~0.)
     */
-- 
1.8.1.4



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