nir: Add a pass for gathering transform feedback info

This is different from the GL_ARB_spirv pass because it generates a much
simpler data structure that isn't tied to OpenGL and mtypes.h.

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

src/compiler/Makefile.sources

@@ -216,6 +216,7 @@ NIR_FILES = \
 	nir/nir_format_convert.h \
 	nir/nir_from_ssa.c \
 	nir/nir_gather_info.c \
+	nir/nir_gather_xfb_info.c \
 	nir/nir_gs_count_vertices.c \
 	nir/nir_inline_functions.c \
 	nir/nir_instr_set.c \
@@ -308,7 +309,8 @@ NIR_FILES = \
 	nir/nir_validate.c \
 	nir/nir_vla.h \
 	nir/nir_worklist.c \
-	nir/nir_worklist.h
+	nir/nir_worklist.h \
+	nir/nir_xfb_info.h
 
 SPIRV_GENERATED_FILES = \
 	spirv/spirv_info.c \

src/compiler/nir/meson.build

@@ -100,6 +100,7 @@ files_libnir = files(
   'nir_format_convert.h',
   'nir_from_ssa.c',
   'nir_gather_info.c',
+  'nir_gather_xfb_info.c',
   'nir_gs_count_vertices.c',
   'nir_inline_functions.c',
   'nir_instr_set.c',
@@ -193,6 +194,7 @@ files_libnir = files(
   'nir_vla.h',
   'nir_worklist.c',
   'nir_worklist.h',
+  'nir_xfb_info.h',
   '../spirv/GLSL.ext.AMD.h',
   '../spirv/GLSL.std.450.h',
   '../spirv/gl_spirv.c',

src/compiler/nir/nir_gather_xfb_info.c

@@ -0,0 +1,150 @@
+/*
+ * Copyright © 2018 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.
+ */
+
+#include "nir_xfb_info.h"
+
+#include <util/u_math.h>
+
+static void
+add_var_xfb_outputs(nir_xfb_info *xfb,
+                    nir_variable *var,
+                    unsigned *location,
+                    unsigned *offset,
+                    const struct glsl_type *type)
+{
+   if (glsl_type_is_array(type) || glsl_type_is_matrix(type)) {
+      unsigned length = glsl_get_length(type);
+      const struct glsl_type *child_type = glsl_get_array_element(type);
+      for (unsigned i = 0; i < length; i++)
+         add_var_xfb_outputs(xfb, var, location, offset, child_type);
+   } else if (glsl_type_is_struct(type)) {
+      unsigned length = glsl_get_length(type);
+      for (unsigned i = 0; i < length; i++) {
+         const struct glsl_type *child_type = glsl_get_struct_field(type, i);
+         add_var_xfb_outputs(xfb, var, location, offset, child_type);
+      }
+   } else {
+      assert(var->data.xfb_buffer < NIR_MAX_XFB_BUFFERS);
+      if (xfb->buffers_written & (1 << var->data.xfb_buffer)) {
+         assert(xfb->strides[var->data.xfb_buffer] == var->data.xfb_stride);
+         assert(xfb->buffer_to_stream[var->data.xfb_buffer] == var->data.stream);
+      } else {
+         xfb->buffers_written |= (1 << var->data.xfb_buffer);
+         xfb->strides[var->data.xfb_buffer] = var->data.xfb_stride;
+         xfb->buffer_to_stream[var->data.xfb_buffer] = var->data.stream;
+      }
+
+      assert(var->data.stream < NIR_MAX_XFB_STREAMS);
+      xfb->streams_written |= (1 << var->data.stream);
+
+      unsigned comp_slots = glsl_get_component_slots(type);
+      unsigned attrib_slots = DIV_ROUND_UP(comp_slots, 4);
+      assert(attrib_slots == glsl_count_attribute_slots(type, false));
+
+      /* Ensure that we don't have, for instance, a dvec2 with a location_frac
+       * of 2 which would make it crass a location boundary even though it
+       * fits in a single slot.  However, you can have a dvec3 which crosses
+       * the slot boundary with a location_frac of 2.
+       */
+      assert(DIV_ROUND_UP(var->data.location_frac + comp_slots, 4) == attrib_slots);
+
+      assert(var->data.location_frac + comp_slots <= 8);
+      uint8_t comp_mask = ((1 << comp_slots) - 1) << var->data.location_frac;
+
+      assert(attrib_slots <= 2);
+      for (unsigned s = 0; s < attrib_slots; s++) {
+         nir_xfb_output_info *output = &xfb->outputs[xfb->output_count++];
+
+         output->buffer = var->data.xfb_buffer;
+         output->offset = *offset;
+         output->location = *location;
+         output->component_mask = (comp_mask >> (s * 4)) & 0xf;
+
+         (*location)++;
+         *offset += comp_slots * 4;
+      }
+   }
+}
+
+static int
+compare_xfb_output_offsets(const void *_a, const void *_b)
+{
+   const nir_xfb_output_info *a = _a, *b = _b;
+   return a->offset - b->offset;
+}
+
+nir_xfb_info *
+nir_gather_xfb_info(const nir_shader *shader, void *mem_ctx)
+{
+   assert(shader->info.stage == MESA_SHADER_VERTEX ||
+          shader->info.stage == MESA_SHADER_TESS_EVAL ||
+          shader->info.stage == MESA_SHADER_GEOMETRY);
+
+   /* Compute the number of outputs we have.  This is simply the number of
+    * cumulative locations consumed by all the variables.  If a location is
+    * represented by multiple variables, then they each count separately in
+    * number of outputs.
+    */
+   unsigned num_outputs = 0;
+   nir_foreach_variable(var, &shader->outputs) {
+      if (var->data.explicit_xfb_buffer ||
+          var->data.explicit_xfb_stride) {
+         assert(var->data.explicit_xfb_buffer &&
+                var->data.explicit_xfb_stride &&
+                var->data.explicit_offset);
+         num_outputs += glsl_count_attribute_slots(var->type, false);
+      }
+   }
+   if (num_outputs == 0)
+      return NULL;
+
+   nir_xfb_info *xfb = rzalloc_size(mem_ctx, nir_xfb_info_size(num_outputs));
+
+   /* Walk the list of outputs and add them to the array */
+   nir_foreach_variable(var, &shader->outputs) {
+      if (var->data.explicit_xfb_buffer ||
+          var->data.explicit_xfb_stride) {
+         unsigned location = var->data.location;
+         unsigned offset = var->data.offset;
+         add_var_xfb_outputs(xfb, var, &location, &offset, var->type);
+      }
+   }
+   assert(xfb->output_count == num_outputs);
+
+   /* Everything is easier in the state setup code if the list is sorted in
+    * order of output offset.
+    */
+   qsort(xfb->outputs, xfb->output_count, sizeof(xfb->outputs[0]),
+         compare_xfb_output_offsets);
+
+   /* Finally, do a sanity check */
+   unsigned max_offset[NIR_MAX_XFB_BUFFERS] = { };
+   for (unsigned i = 0; i < xfb->output_count; i++) {
+      assert(xfb->outputs[i].offset >= max_offset[xfb->outputs[i].buffer]);
+      assert(xfb->outputs[i].component_mask != 0);
+      unsigned slots = util_bitcount(xfb->outputs[i].component_mask);
+      max_offset[xfb->outputs[i].buffer] = xfb->outputs[i].offset + slots * 4;
+   }
+
+   return xfb;
+}

src/compiler/nir/nir_xfb_info.h

@@ -0,0 +1,59 @@
+/*
+ * Copyright © 2018 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.
+ */
+
+#ifndef NIR_XFB_INFO_H
+#define NIR_XFB_INFO_H
+
+#include "nir.h"
+
+#define NIR_MAX_XFB_BUFFERS 4
+#define NIR_MAX_XFB_STREAMS 4
+
+typedef struct {
+   uint8_t buffer;
+   uint16_t offset;
+   uint8_t location;
+   uint8_t component_mask;
+} nir_xfb_output_info;
+
+typedef struct {
+   uint8_t buffers_written;
+   uint8_t streams_written;
+
+   uint16_t strides[NIR_MAX_XFB_BUFFERS];
+   uint8_t buffer_to_stream[NIR_MAX_XFB_STREAMS];
+
+   uint16_t output_count;
+   nir_xfb_output_info outputs[0];
+} nir_xfb_info;
+
+static inline size_t
+nir_xfb_info_size(uint16_t output_count)
+{
+   return sizeof(nir_xfb_info) + sizeof(nir_xfb_output_info) * output_count;
+}
+
+nir_xfb_info *
+nir_gather_xfb_info(const nir_shader *shader, void *mem_ctx);
+
+#endif /* NIR_XFB_INFO_H */