i965: Add lowering pass to fold offset into unnormalized coords

It turns out that nonzero offsets with gsampler2DRect don't work -- they
just return garbage. Work around this by folding the offset into the
coord.

Done as an IR pass rather than yet another hack in the visitors because
it's clear what's going on this way. Can possibly reuse this to replace
the existing txf coord+offset hacks.

V2: Use ir_builder

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/drivers/dri/i965/Makefile.sources

@@ -69,6 +69,7 @@ i965_FILES = \
 	brw_interpolation_map.c \
 	brw_lower_texture_gradients.cpp \
 	brw_lower_offset_array.cpp \
+	brw_lower_unnormalized_offset.cpp \
 	brw_misc_state.c \
 	brw_object_purgeable.c \
 	brw_performance_monitor.c \

src/mesa/drivers/dri/i965/brw_context.h

@@ -1687,6 +1687,7 @@ bool brw_do_cubemap_normalize(struct exec_list *instructions);
 bool brw_lower_texture_gradients(struct brw_context *brw,
                                  struct exec_list *instructions);
 bool brw_do_lower_offset_arrays(struct exec_list *instructions);
+bool brw_do_lower_unnormalized_offset(struct exec_list *instructions);
 
 struct opcode_desc {
     char    *name;

src/mesa/drivers/dri/i965/brw_lower_unnormalized_offset.cpp

@@ -0,0 +1,78 @@
+/*
+ * Copyright © 2013 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 brw_lower_unnormalized_offset.cpp
+ *
+ * IR lower pass to convert a texture offset into an adjusted coordinate,
+ * for use with unnormalized coordinates. At least the gather4* messages
+ * on Ivybridge and Haswell make a mess with nonzero offsets.
+ *
+ * \author Chris Forbes <chrisf@ijw.co.nz>
+ */
+
+#include "glsl/glsl_types.h"
+#include "glsl/ir.h"
+#include "glsl/ir_builder.h"
+
+using namespace ir_builder;
+
+class brw_lower_unnormalized_offset_visitor : public ir_hierarchical_visitor {
+public:
+   brw_lower_unnormalized_offset_visitor()
+   {
+      progress = false;
+   }
+
+   ir_visitor_status visit_leave(ir_texture *ir);
+
+   bool progress;
+};
+
+ir_visitor_status
+brw_lower_unnormalized_offset_visitor::visit_leave(ir_texture *ir)
+{
+   if (ir->sampler->type->sampler_dimensionality != GLSL_SAMPLER_DIM_RECT ||
+       !ir->offset || ir->op != ir_tg4)
+      return visit_continue;
+
+   ir->coordinate = add(ir->coordinate, i2f(ir->offset));
+   ir->offset = NULL;
+
+   progress = true;
+   return visit_continue;
+}
+
+extern "C" {
+
+bool
+brw_do_lower_unnormalized_offset(exec_list *instructions)
+{
+   brw_lower_unnormalized_offset_visitor v;
+
+   visit_list_elements(&v, instructions);
+
+   return v.progress;
+}
+
+}

src/mesa/drivers/dri/i965/brw_shader.cpp

@@ -173,6 +173,7 @@ brw_link_shader(struct gl_context *ctx, struct gl_shader_program *shProg)
       lower_vector_insert(shader->ir, true);
       brw_do_cubemap_normalize(shader->ir);
       brw_do_lower_offset_arrays(shader->ir);
+      brw_do_lower_unnormalized_offset(shader->ir);
       lower_noise(shader->ir);
       lower_quadop_vector(shader->ir, false);