glsl: add initial implementation of shader cache

This uses disk_cache.c to write out a serialization of various
state that's required in order to successfully load and use a
binary written out by a drivers backend, this state is referred to as
"metadata" throughout the implementation.

This initial version is intended to work with all stages beside
compute.

This patch is based on the initial work done by Carl.

V2: extend the file's doxygen comment to cover some of the
design decisions.

V3:
- skip cache for fixed function shaders
- add int64 support
- fix glsl IR program parameter caching/restore and cache the
  parameter values which are used by gallium backends.
- use new link status enum

V4:
- add compute program support

Reviewed-by: Nicolai Hähnle <[email protected]>

4 files changed, 633 insertions, 1 deletions

diff --git a/src/compiler/Makefile.glsl.am b/src/compiler/Makefile.glsl.am
index f67319622a0..41edb3cf4d9 100644
--- a/src/compiler/Makefile.glsl.am
+++ b/src/compiler/Makefile.glsl.am
@@ -131,7 +131,8 @@ glsl_libglsl_la_LIBADD = \
 
 glsl_libglsl_la_SOURCES =				\
 	$(LIBGLSL_GENERATED_FILES)			\
-	$(LIBGLSL_FILES)
+	$(LIBGLSL_FILES)				\
+	$(LIBGLSL_SHADER_CACHE_FILES)
 
 glsl_libstandalone_la_SOURCES = \
 	$(GLSL_COMPILER_CXX_FILES)
diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index a8bb4d3dda6..1e8edc08743 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -142,6 +142,10 @@ LIBGLSL_FILES = \
 	glsl/s_expression.cpp \
 	glsl/s_expression.h
 
+LIBGLSL_SHADER_CACHE_FILES = \
+	glsl/shader_cache.cpp \
+	glsl/shader_cache.h
+
 # glsl_compiler
 
 GLSL_COMPILER_CXX_FILES = \
diff --git a/src/compiler/glsl/shader_cache.cpp b/src/compiler/glsl/shader_cache.cpp
new file mode 100644
index 00000000000..5064dc308d6
--- /dev/null
+++ b/src/compiler/glsl/shader_cache.cpp
@@ -0,0 +1,589 @@
+/*
+ * 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 shader_cache.cpp
+ *
+ * GLSL shader cache implementation
+ *
+ * This uses disk_cache.c to write out a serialization of various
+ * state that's required in order to successfully load and use a
+ * binary written out by a drivers backend, this state is referred to as
+ * "metadata" throughout the implementation.
+ *
+ * The hash key for glsl metadata is a hash of the hashes of each GLSL
+ * source string as well as some API settings that change the final program
+ * such as SSO, attribute bindings, frag data bindings, etc.
+ *
+ * In order to avoid caching any actual IR we use the put_key/get_key support
+ * in the disk_cache to put the SHA-1 hash for each successfully compiled
+ * shader into the cache, and optimisticly return early from glCompileShader
+ * (if the identical shader had been successfully compiled in the past),
+ * in the hope that the final linked shader will be found in the cache.
+ * If anything goes wrong (shader variant not found, backend cache item is
+ * corrupt, etc) we will use a fallback path to compile and link the IR.
+ */
+
+#include "blob.h"
+#include "compiler/shader_info.h"
+#include "glsl_symbol_table.h"
+#include "glsl_parser_extras.h"
+#include "ir.h"
+#include "ir_optimization.h"
+#include "ir_rvalue_visitor.h"
+#include "ir_uniform.h"
+#include "linker.h"
+#include "link_varyings.h"
+#include "main/core.h"
+#include "nir.h"
+#include "program.h"
+#include "util/disk_cache.h"
+#include "util/mesa-sha1.h"
+#include "util/string_to_uint_map.h"
+
+extern "C" {
+#include "main/enums.h"
+#include "main/shaderobj.h"
+#include "program/program.h"
+}
+
+static void
+compile_shaders(struct gl_context *ctx, struct gl_shader_program *prog) {
+   for (unsigned i = 0; i < prog->NumShaders; i++) {
+      _mesa_glsl_compile_shader(ctx, prog->Shaders[i], false, false, true);
+   }
+}
+
+static void
+encode_type_to_blob(struct blob *blob, const glsl_type *type)
+{
+   uint32_t encoding;
+
+   switch (type->base_type) {
+   case GLSL_TYPE_UINT:
+   case GLSL_TYPE_INT:
+   case GLSL_TYPE_FLOAT:
+   case GLSL_TYPE_BOOL:
+   case GLSL_TYPE_DOUBLE:
+   case GLSL_TYPE_UINT64:
+   case GLSL_TYPE_INT64:
+      encoding = (type->base_type << 24) |
+         (type->vector_elements << 4) |
+         (type->matrix_columns);
+      break;
+   case GLSL_TYPE_SAMPLER:
+      encoding = (type->base_type) << 24 |
+         (type->sampler_dimensionality << 4) |
+         (type->sampler_shadow << 3) |
+         (type->sampler_array << 2) |
+         (type->sampled_type);
+      break;
+   case GLSL_TYPE_SUBROUTINE:
+      encoding = type->base_type << 24;
+      blob_write_uint32(blob, encoding);
+      blob_write_string(blob, type->name);
+      return;
+   case GLSL_TYPE_IMAGE:
+      encoding = (type->base_type) << 24 |
+         (type->sampler_dimensionality << 3) |
+         (type->sampler_array << 2) |
+         (type->sampled_type);
+      break;
+   case GLSL_TYPE_ATOMIC_UINT:
+      encoding = (type->base_type << 24);
+      break;
+   case GLSL_TYPE_ARRAY:
+      blob_write_uint32(blob, (type->base_type) << 24);
+      blob_write_uint32(blob, type->length);
+      encode_type_to_blob(blob, type->fields.array);
+      return;
+   case GLSL_TYPE_STRUCT:
+   case GLSL_TYPE_INTERFACE:
+      blob_write_uint32(blob, (type->base_type) << 24);
+      blob_write_string(blob, type->name);
+      blob_write_uint32(blob, type->length);
+      blob_write_bytes(blob, type->fields.structure,
+                       sizeof(glsl_struct_field) * type->length);
+      for (unsigned i = 0; i < type->length; i++) {
+         encode_type_to_blob(blob, type->fields.structure[i].type);
+         blob_write_string(blob, type->fields.structure[i].name);
+      }
+
+      if (type->base_type == GLSL_TYPE_INTERFACE) {
+         blob_write_uint32(blob, type->interface_packing);
+         blob_write_uint32(blob, type->interface_row_major);
+      }
+      return;
+   case GLSL_TYPE_VOID:
+   case GLSL_TYPE_ERROR:
+   default:
+      assert(!"Cannot encode type!");
+      encoding = 0;
+      break;
+   }
+
+   blob_write_uint32(blob, encoding);
+}
+
+static const glsl_type *
+decode_type_from_blob(struct blob_reader *blob)
+{
+   uint32_t u = blob_read_uint32(blob);
+   glsl_base_type base_type = (glsl_base_type) (u >> 24);
+
+   switch (base_type) {
+   case GLSL_TYPE_UINT:
+   case GLSL_TYPE_INT:
+   case GLSL_TYPE_FLOAT:
+   case GLSL_TYPE_BOOL:
+   case GLSL_TYPE_DOUBLE:
+   case GLSL_TYPE_UINT64:
+   case GLSL_TYPE_INT64:
+      return glsl_type::get_instance(base_type, (u >> 4) & 0x0f, u & 0x0f);
+   case GLSL_TYPE_SAMPLER:
+      return glsl_type::get_sampler_instance((enum glsl_sampler_dim) ((u >> 4) & 0x07),
+                                             (u >> 3) & 0x01,
+                                             (u >> 2) & 0x01,
+                                             (glsl_base_type) ((u >> 0) & 0x03));
+   case GLSL_TYPE_SUBROUTINE:
+      return glsl_type::get_subroutine_instance(blob_read_string(blob));
+   case GLSL_TYPE_IMAGE:
+      return glsl_type::get_image_instance((enum glsl_sampler_dim) ((u >> 3) & 0x07),
+                                             (u >> 2) & 0x01,
+                                             (glsl_base_type) ((u >> 0) & 0x03));
+   case GLSL_TYPE_ATOMIC_UINT:
+      return glsl_type::atomic_uint_type;
+   case GLSL_TYPE_ARRAY: {
+      unsigned length = blob_read_uint32(blob);
+      return glsl_type::get_array_instance(decode_type_from_blob(blob),
+                                           length);
+   }
+   case GLSL_TYPE_STRUCT:
+   case GLSL_TYPE_INTERFACE: {
+      char *name = blob_read_string(blob);
+      unsigned num_fields = blob_read_uint32(blob);
+      glsl_struct_field *fields = (glsl_struct_field *)
+         blob_read_bytes(blob, sizeof(glsl_struct_field) * num_fields);
+      for (unsigned i = 0; i < num_fields; i++) {
+         fields[i].type = decode_type_from_blob(blob);
+         fields[i].name = blob_read_string(blob);
+      }
+
+      if (base_type == GLSL_TYPE_INTERFACE) {
+         enum glsl_interface_packing packing =
+            (glsl_interface_packing) blob_read_uint32(blob);
+         bool row_major = blob_read_uint32(blob);
+         return glsl_type::get_interface_instance(fields, num_fields,
+                                                  packing, row_major, name);
+      } else {
+         return glsl_type::get_record_instance(fields, num_fields, name);
+      }
+   }
+   case GLSL_TYPE_VOID:
+   case GLSL_TYPE_ERROR:
+   default:
+      assert(!"Cannot decode type!");
+      return NULL;
+   }
+}
+
+static void
+write_uniforms(struct blob *metadata, struct gl_shader_program *prog)
+{
+   blob_write_uint32(metadata, prog->SamplersValidated);
+   blob_write_uint32(metadata, prog->data->NumUniformStorage);
+   blob_write_uint32(metadata, prog->data->NumUniformDataSlots);
+
+   for (unsigned i = 0; i < prog->data->NumUniformStorage; i++) {
+      encode_type_to_blob(metadata, prog->data->UniformStorage[i].type);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].array_elements);
+      blob_write_string(metadata, prog->data->UniformStorage[i].name);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].storage -
+                                  prog->data->UniformDataSlots);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].remap_location);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].block_index);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].atomic_buffer_index);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].offset);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].array_stride);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].matrix_stride);
+      blob_write_uint32(metadata, prog->data->UniformStorage[i].row_major);
+      blob_write_uint32(metadata,
+                        prog->data->UniformStorage[i].num_compatible_subroutines);
+      blob_write_uint32(metadata,
+                        prog->data->UniformStorage[i].top_level_array_size);
+      blob_write_uint32(metadata,
+                        prog->data->UniformStorage[i].top_level_array_stride);
+   }
+}
+
+static void
+read_uniforms(struct blob_reader *metadata, struct gl_shader_program *prog)
+{
+   struct gl_uniform_storage *uniforms;
+   union gl_constant_value *data;
+
+   prog->SamplersValidated = blob_read_uint32(metadata);
+   prog->data->NumUniformStorage = blob_read_uint32(metadata);
+   prog->data->NumUniformDataSlots = blob_read_uint32(metadata);
+
+   uniforms = rzalloc_array(prog, struct gl_uniform_storage,
+                            prog->data->NumUniformStorage);
+   prog->data->UniformStorage = uniforms;
+
+   data = rzalloc_array(uniforms, union gl_constant_value,
+                        prog->data->NumUniformDataSlots);
+   prog->data->UniformDataSlots = data;
+
+   prog->UniformHash = new string_to_uint_map;
+
+   for (unsigned i = 0; i < prog->data->NumUniformStorage; i++) {
+      uniforms[i].type = decode_type_from_blob(metadata);
+      uniforms[i].array_elements = blob_read_uint32(metadata);
+      uniforms[i].name = ralloc_strdup(prog, blob_read_string (metadata));
+      uniforms[i].storage = data + blob_read_uint32(metadata);
+      uniforms[i].remap_location = blob_read_uint32(metadata);
+      uniforms[i].block_index = blob_read_uint32(metadata);
+      uniforms[i].atomic_buffer_index = blob_read_uint32(metadata);
+      uniforms[i].offset = blob_read_uint32(metadata);
+      uniforms[i].array_stride = blob_read_uint32(metadata);
+      uniforms[i].matrix_stride = blob_read_uint32(metadata);
+      uniforms[i].row_major = blob_read_uint32(metadata);
+      uniforms[i].num_compatible_subroutines = blob_read_uint32(metadata);
+      uniforms[i].top_level_array_size = blob_read_uint32(metadata);
+      uniforms[i].top_level_array_stride = blob_read_uint32(metadata);
+      prog->UniformHash->put(i, uniforms[i].name);
+   }
+}
+
+
+static void
+write_uniform_remap_table(struct blob *metadata,
+                          struct gl_shader_program *prog)
+{
+   blob_write_uint32(metadata, prog->NumUniformRemapTable);
+
+   for (unsigned i = 0; i < prog->NumUniformRemapTable; i++) {
+      blob_write_uint32(metadata, prog->UniformRemapTable[i] -
+                           prog->data->UniformStorage);
+   }
+}
+
+static void
+read_uniform_remap_table(struct blob_reader *metadata,
+                         struct gl_shader_program *prog)
+{
+   prog->NumUniformRemapTable = blob_read_uint32(metadata);
+
+   prog->UniformRemapTable =rzalloc_array(prog, struct gl_uniform_storage *,
+                                          prog->NumUniformRemapTable);
+
+   for (unsigned i = 0; i < prog->NumUniformRemapTable; i++) {
+      prog->UniformRemapTable[i] =
+         prog->data->UniformStorage + blob_read_uint32(metadata);
+   }
+}
+
+static void
+write_shader_parameters(struct blob *metadata,
+                        struct gl_program_parameter_list *params)
+{
+   blob_write_uint32(metadata, params->NumParameters);
+   uint32_t i = 0;
+
+   while (i < params->NumParameters) {
+      struct gl_program_parameter *param = &params->Parameters[i];
+
+      blob_write_uint32(metadata, param->Type);
+      blob_write_string(metadata, param->Name);
+      blob_write_uint32(metadata, param->Size);
+      blob_write_uint32(metadata, param->DataType);
+      blob_write_bytes(metadata, param->StateIndexes,
+                       sizeof(param->StateIndexes));
+
+      i += (param->Size + 3) / 4;
+   }
+
+   blob_write_bytes(metadata, params->ParameterValues,
+                    sizeof(gl_constant_value) * 4 * params->NumParameters);
+
+   blob_write_uint32(metadata, params->StateFlags);
+}
+
+static void
+read_shader_parameters(struct blob_reader *metadata,
+                       struct gl_program_parameter_list *params)
+{
+   gl_state_index state_indexes[STATE_LENGTH];
+   uint32_t i = 0;
+   uint32_t num_parameters = blob_read_uint32(metadata);
+
+   while (i < num_parameters) {
+      gl_register_file type = (gl_register_file) blob_read_uint32(metadata);
+      const char *name = blob_read_string(metadata);
+      unsigned size = blob_read_uint32(metadata);
+      unsigned data_type = blob_read_uint32(metadata);
+      blob_copy_bytes(metadata, (uint8_t *) state_indexes,
+                      sizeof(state_indexes));
+
+      _mesa_add_parameter(params, type, name, size, data_type,
+                          NULL, state_indexes);
+
+      i += (size + 3) / 4;
+   }
+
+   blob_copy_bytes(metadata, (uint8_t *) params->ParameterValues,
+                    sizeof(gl_constant_value) * 4 * params->NumParameters);
+
+   params->StateFlags = blob_read_uint32(metadata);
+}
+
+static void
+write_shader_metadata(struct blob *metadata, gl_linked_shader *shader)
+{
+   assert(shader->Program);
+   struct gl_program *glprog = shader->Program;
+
+   blob_write_bytes(metadata, glprog->TexturesUsed,
+                    sizeof(glprog->TexturesUsed));
+   blob_write_uint64(metadata, glprog->SamplersUsed);
+
+   write_shader_parameters(metadata, glprog->Parameters);
+}
+
+static void
+read_shader_metadata(struct blob_reader *metadata,
+                     struct gl_program *glprog,
+                     gl_linked_shader *linked)
+{
+   blob_copy_bytes(metadata, (uint8_t *) glprog->TexturesUsed,
+                   sizeof(glprog->TexturesUsed));
+   glprog->SamplersUsed = blob_read_uint64(metadata);
+
+   glprog->Parameters = _mesa_new_parameter_list();
+   read_shader_parameters(metadata, glprog->Parameters);
+}
+
+static void
+create_binding_str(const char *key, unsigned value, void *closure)
+{
+   char **bindings_str = (char **) closure;
+   ralloc_asprintf_append(bindings_str, "%s:%u,", key, value);
+}
+
+static void
+create_linked_shader_and_program(struct gl_context *ctx,
+                                 gl_shader_stage stage,
+                                 struct gl_shader_program *prog,
+                                 struct blob_reader *metadata)
+{
+   struct gl_program *glprog;
+
+   struct gl_linked_shader *linked = rzalloc(NULL, struct gl_linked_shader);
+   linked->Stage = stage;
+
+   glprog = ctx->Driver.NewProgram(ctx, _mesa_shader_stage_to_program(stage),
+                                   prog->Name, false);
+   glprog->info.stage = stage;
+   linked->Program = glprog;
+
+   read_shader_metadata(metadata, glprog, linked);
+
+   /* Restore shader info */
+   blob_copy_bytes(metadata, (uint8_t *) &glprog->info, sizeof(shader_info));
+   if (glprog->info.name)
+      glprog->info.name = ralloc_strdup(glprog, blob_read_string(metadata));
+   if (glprog->info.label)
+      glprog->info.label = ralloc_strdup(glprog, blob_read_string(metadata));
+
+   _mesa_reference_shader_program_data(ctx, &glprog->sh.data, prog->data);
+   _mesa_reference_program(ctx, &linked->Program, glprog);
+   prog->_LinkedShaders[stage] = linked;
+}
+
+void
+shader_cache_write_program_metadata(struct gl_context *ctx,
+                                    struct gl_shader_program *prog)
+{
+   struct disk_cache *cache = ctx->Cache;
+   if (!cache)
+      return;
+
+   /* Exit early when we are dealing with a ff shader with no source file to
+    * generate a source from.
+    *
+    * TODO: In future we should use another method to generate a key for ff
+    * programs.
+    */
+   if (*prog->data->sha1 == 0)
+      return;
+
+   struct blob *metadata = blob_create(NULL);
+
+   write_uniforms(metadata, prog);
+
+   blob_write_uint32(metadata, prog->data->Version);
+   blob_write_uint32(metadata, prog->data->linked_stages);
+
+   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
+      struct gl_linked_shader *sh = prog->_LinkedShaders[i];
+      if (sh) {
+         write_shader_metadata(metadata, sh);
+
+         /* Store nir shader info */
+         blob_write_bytes(metadata, &sh->Program->info, sizeof(shader_info));
+
+         if (sh->Program->info.name)
+            blob_write_string(metadata, sh->Program->info.name);
+
+         if (sh->Program->info.label)
+            blob_write_string(metadata, sh->Program->info.label);
+      }
+   }
+
+   write_uniform_remap_table(metadata, prog);
+
+   char sha1_buf[41];
+   for (unsigned i = 0; i < prog->NumShaders; i++) {
+      disk_cache_put_key(cache, prog->Shaders[i]->sha1);
+      if (ctx->_Shader->Flags & GLSL_CACHE_INFO) {
+         fprintf(stderr, "marking shader: %s\n",
+                 _mesa_sha1_format(sha1_buf, prog->Shaders[i]->sha1));
+      }
+   }
+
+   disk_cache_put(cache, prog->data->sha1, metadata->data, metadata->size);
+
+   ralloc_free(metadata);
+
+   if (ctx->_Shader->Flags & GLSL_CACHE_INFO) {
+      fprintf(stderr, "putting program metadata in cache: %s\n",
+              _mesa_sha1_format(sha1_buf, prog->data->sha1));
+   }
+}
+
+bool
+shader_cache_read_program_metadata(struct gl_context *ctx,
+                                   struct gl_shader_program *prog)
+{
+   /* Fixed function programs generated by Mesa are not cached. So don't
+    * try to read metadata for them from the cache.
+    */
+   if (prog->Name == 0)
+      return false;
+
+   struct disk_cache *cache = ctx->Cache;
+   if (!cache)
+      return false;
+
+   /* Include bindings when creating sha1. These bindings change the resulting
+    * binary so they are just as important as the shader source.
+    */
+   char *buf = ralloc_strdup(NULL, "vb: ");
+   prog->AttributeBindings->iterate(create_binding_str, &buf);
+   ralloc_strcat(&buf, "fb: ");
+   prog->FragDataBindings->iterate(create_binding_str, &buf);
+   ralloc_strcat(&buf, "fbi: ");
+   prog->FragDataIndexBindings->iterate(create_binding_str, &buf);
+
+   /* SSO has an effect on the linked program so include this when generating
+    * the sha also.
+    */
+   ralloc_asprintf_append(&buf, "sso: %s\n",
+                          prog->SeparateShader ? "T" : "F");
+
+   char sha1buf[41];
+   for (unsigned i = 0; i < prog->NumShaders; i++) {
+      struct gl_shader *sh = prog->Shaders[i];
+      ralloc_asprintf_append(&buf, "%s: %s\n",
+                             _mesa_shader_stage_to_abbrev(sh->Stage),
+                             _mesa_sha1_format(sha1buf, sh->sha1));
+   }
+   _mesa_sha1_compute(buf, strlen(buf), prog->data->sha1);
+   ralloc_free(buf);
+
+   size_t size;
+   uint8_t *buffer = (uint8_t *) disk_cache_get(cache, prog->data->sha1,
+                                                &size);
+   if (buffer == NULL) {
+      /* Cached program not found. We may have seen the individual shaders
+       * before and skipped compiling but they may not have been used together
+       * in this combination before. Fall back to linking shaders but first
+       * re-compile the shaders.
+       *
+       * We could probably only compile the shaders which were skipped here
+       * but we need to be careful because the source may also have been
+       * changed since the last compile so for now we just recompile
+       * everything.
+       */
+      compile_shaders(ctx, prog);
+      return false;
+   }
+
+   if (ctx->_Shader->Flags & GLSL_CACHE_INFO) {
+      fprintf(stderr, "loading shader program meta data from cache: %s\n",
+              _mesa_sha1_format(sha1buf, prog->data->sha1));
+   }
+
+   struct blob_reader metadata;
+   blob_reader_init(&metadata, buffer, size);
+
+   assert(prog->data->UniformStorage == NULL);
+
+   read_uniforms(&metadata, prog);
+
+   prog->data->Version = blob_read_uint32(&metadata);
+   prog->data->linked_stages = blob_read_uint32(&metadata);
+
+   unsigned mask = prog->data->linked_stages;
+   while (mask) {
+      const int j = u_bit_scan(&mask);
+      create_linked_shader_and_program(ctx, (gl_shader_stage) j, prog,
+                                       &metadata);
+   }
+
+   read_uniform_remap_table(&metadata, prog);
+
+   if (metadata.current != metadata.end || metadata.overrun) {
+      /* Something has gone wrong discard the item from the cache and rebuild
+       * from source.
+       */
+      assert(!"Invalid GLSL shader disk cache item!");
+
+      if (ctx->_Shader->Flags & GLSL_CACHE_INFO) {
+         fprintf(stderr, "Error reading program from cache (invalid GLSL "
+                 "cache item)\n");
+      }
+
+      disk_cache_remove(cache, prog->data->sha1);
+      compile_shaders(ctx, prog);
+      free(buffer);
+      return false;
+   }
+
+   /* This is used to flag a shader retrieved from cache */
+   prog->data->LinkStatus = linking_skipped;
+
+   free (buffer);
+
+   return true;
+}
diff --git a/src/compiler/glsl/shader_cache.h b/src/compiler/glsl/shader_cache.h
new file mode 100644
index 00000000000..8bd0a3ce282
--- /dev/null
+++ b/src/compiler/glsl/shader_cache.h
@@ -0,0 +1,38 @@
+/*
+ * 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.
+ */
+
+#pragma once
+#ifndef SHADER_CACHE
+#define SHADER_CACHE
+
+#include "util/disk_cache.h"
+
+void
+shader_cache_write_program_metadata(struct gl_context *ctx,
+                                    struct gl_shader_program *prog);
+
+bool
+shader_cache_read_program_metadata(struct gl_context *ctx,
+                                   struct gl_shader_program *prog);
+
+#endif /* GLSL_SYMBOL_TABLE */