[Mesa-dev] [PATCH 1/3] glsl: delay optimisations on individual shaders when cache is available

Timothy Arceri tarceri at itsqueeze.com
Mon Mar 27 03:14:49 UTC 2017


Due to a max limit of 65,536 entries on the index table that we use to
decide if we can skip compiling individual shaders, it is very likely
we will have collisions.

To avoid doing too much work when the linked program may be in the
cache this patch delays calling the optimisations until link time.

Improves cold cache start-up times on Deus Ex by ~20 seconds.

When deleting the cache index to simulate a worst case scenario
of colisions in the index, warm cache start-up time improve by
~45 seconds.
---
 src/compiler/glsl/glsl_parser_extras.cpp | 169 +++++++++++++++++--------------
 src/compiler/glsl/shader_cache.cpp       |   2 +-
 src/mesa/main/mtypes.h                   |   3 +-
 3 files changed, 98 insertions(+), 76 deletions(-)

diff --git a/src/compiler/glsl/glsl_parser_extras.cpp b/src/compiler/glsl/glsl_parser_extras.cpp
index 8b5df3b..7fc35df 100644
--- a/src/compiler/glsl/glsl_parser_extras.cpp
+++ b/src/compiler/glsl/glsl_parser_extras.cpp
@@ -1914,20 +1914,101 @@ static void
 do_late_parsing_checks(struct _mesa_glsl_parse_state *state)
 {
    if (state->stage == MESA_SHADER_COMPUTE && !state->has_compute_shader()) {
       YYLTYPE loc;
       memset(&loc, 0, sizeof(loc));
       _mesa_glsl_error(&loc, state, "Compute shaders require "
                        "GLSL 4.30 or GLSL ES 3.10");
    }
 }
 
+static void
+opt_shader_and_create_symbol_table(struct gl_context *ctx,
+                                  struct gl_shader *shader)
+{
+   assert(shader->CompileStatus != compile_failure &&
+          !shader->ir->is_empty());
+
+   struct gl_shader_compiler_options *options =
+      &ctx->Const.ShaderCompilerOptions[shader->Stage];
+
+   /* Do some optimization at compile time to reduce shader IR size
+    * and reduce later work if the same shader is linked multiple times
+    */
+   if (ctx->Const.GLSLOptimizeConservatively) {
+      /* Run it just once. */
+      do_common_optimization(shader->ir, false, false, options,
+                             ctx->Const.NativeIntegers);
+   } else {
+      /* Repeat it until it stops making changes. */
+      while (do_common_optimization(shader->ir, false, false, options,
+                                    ctx->Const.NativeIntegers))
+         ;
+   }
+
+   validate_ir_tree(shader->ir);
+
+   enum ir_variable_mode other;
+   switch (shader->Stage) {
+   case MESA_SHADER_VERTEX:
+      other = ir_var_shader_in;
+      break;
+   case MESA_SHADER_FRAGMENT:
+      other = ir_var_shader_out;
+      break;
+   default:
+      /* Something invalid to ensure optimize_dead_builtin_uniforms
+       * doesn't remove anything other than uniforms or constants.
+       */
+      other = ir_var_mode_count;
+      break;
+   }
+
+   optimize_dead_builtin_variables(shader->ir, other);
+
+   validate_ir_tree(shader->ir);
+
+   shader->symbols = new(shader->ir) glsl_symbol_table;
+
+   /* Retain any live IR, but trash the rest. */
+   reparent_ir(shader->ir, shader->ir);
+
+   /* Destroy the symbol table.  Create a new symbol table that contains only
+    * the variables and functions that still exist in the IR.  The symbol
+    * table will be used later during linking.
+    *
+    * There must NOT be any freed objects still referenced by the symbol
+    * table.  That could cause the linker to dereference freed memory.
+    *
+    * We don't have to worry about types or interface-types here because those
+    * are fly-weights that are looked up by glsl_type.
+    */
+   foreach_in_list (ir_instruction, ir, shader->ir) {
+      switch (ir->ir_type) {
+      case ir_type_function:
+         shader->symbols->add_function((ir_function *) ir);
+         break;
+      case ir_type_variable: {
+         ir_variable *const var = (ir_variable *) ir;
+
+         if (var->data.mode != ir_var_temporary)
+            shader->symbols->add_variable(var);
+         break;
+      }
+      default:
+         break;
+      }
+   }
+
+   _mesa_glsl_initialize_derived_variables(ctx, shader);
+}
+
 void
 _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader,
                           bool dump_ast, bool dump_hir, bool force_recompile)
 {
    struct _mesa_glsl_parse_state *state =
       new(shader) _mesa_glsl_parse_state(ctx, shader->Stage, shader);
    const char *source = force_recompile && shader->FallbackSource ?
       shader->FallbackSource : shader->Source;
 
    if (ctx->Const.GenerateTemporaryNames)
@@ -1955,20 +2036,26 @@ _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader,
             return;
          }
       }
    } else {
       /* We should only ever end up here if a re-compile has been forced by a
        * shader cache miss. In which case we can skip the compile if its
        * already be done by a previous fallback or the initial compile call.
        */
       if (shader->CompileStatus == compile_success)
          return;
+
+      if (shader->CompileStatus == compiled_no_opts) {
+         opt_shader_and_create_symbol_table(ctx, shader);
+         shader->CompileStatus = compile_success;
+         return;
+      }
    }
 
    if (!state->error) {
      _mesa_glsl_lexer_ctor(state, source);
      _mesa_glsl_parse(state);
      _mesa_glsl_lexer_dtor(state);
      do_late_parsing_checks(state);
    }
 
    if (dump_ast) {
@@ -1985,109 +2072,43 @@ _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader,
 
    if (!state->error) {
       validate_ir_tree(shader->ir);
 
       /* Print out the unoptimized IR. */
       if (dump_hir) {
          _mesa_print_ir(stdout, shader->ir, state);
       }
    }
 
-
-   if (!state->error && !shader->ir->is_empty()) {
-      struct gl_shader_compiler_options *options =
-         &ctx->Const.ShaderCompilerOptions[shader->Stage];
-
-      assign_subroutine_indexes(shader, state);
-      lower_subroutine(shader->ir, state);
-
-      /* Do some optimization at compile time to reduce shader IR size
-       * and reduce later work if the same shader is linked multiple times
-       */
-      if (ctx->Const.GLSLOptimizeConservatively) {
-         /* Run it just once. */
-         do_common_optimization(shader->ir, false, false, options,
-                                ctx->Const.NativeIntegers);
-      } else {
-         /* Repeat it until it stops making changes. */
-         while (do_common_optimization(shader->ir, false, false, options,
-                                       ctx->Const.NativeIntegers))
-            ;
-      }
-
-      validate_ir_tree(shader->ir);
-
-      enum ir_variable_mode other;
-      switch (shader->Stage) {
-      case MESA_SHADER_VERTEX:
-         other = ir_var_shader_in;
-         break;
-      case MESA_SHADER_FRAGMENT:
-         other = ir_var_shader_out;
-         break;
-      default:
-         /* Something invalid to ensure optimize_dead_builtin_uniforms
-          * doesn't remove anything other than uniforms or constants.
-          */
-         other = ir_var_mode_count;
-         break;
-      }
-
-      optimize_dead_builtin_variables(shader->ir, other);
-
-      validate_ir_tree(shader->ir);
-   }
-
    if (shader->InfoLog)
       ralloc_free(shader->InfoLog);
 
    if (!state->error)
       set_shader_inout_layout(shader, state);
 
-   shader->symbols = new(shader->ir) glsl_symbol_table;
    shader->CompileStatus = state->error ? compile_failure : compile_success;
    shader->InfoLog = state->info_log;
    shader->Version = state->language_version;
    shader->IsES = state->es_shader;
 
-   /* Retain any live IR, but trash the rest. */
-   reparent_ir(shader->ir, shader->ir);
-
-   /* Destroy the symbol table.  Create a new symbol table that contains only
-    * the variables and functions that still exist in the IR.  The symbol
-    * table will be used later during linking.
-    *
-    * There must NOT be any freed objects still referenced by the symbol
-    * table.  That could cause the linker to dereference freed memory.
-    *
-    * We don't have to worry about types or interface-types here because those
-    * are fly-weights that are looked up by glsl_type.
-    */
-   foreach_in_list (ir_instruction, ir, shader->ir) {
-      switch (ir->ir_type) {
-      case ir_type_function:
-         shader->symbols->add_function((ir_function *) ir);
-         break;
-      case ir_type_variable: {
-         ir_variable *const var = (ir_variable *) ir;
+   if (!state->error && !shader->ir->is_empty()) {
+      assign_subroutine_indexes(shader, state);
+      lower_subroutine(shader->ir, state);
 
-         if (var->data.mode != ir_var_temporary)
-            shader->symbols->add_variable(var);
-         break;
-      }
-      default:
-         break;
+      if (!ctx->Cache)
+         opt_shader_and_create_symbol_table(ctx, shader);
+      else {
+         reparent_ir(shader->ir, shader->ir);
+         shader->CompileStatus = compiled_no_opts;
       }
    }
 
-   _mesa_glsl_initialize_derived_variables(ctx, shader);
-
    if (!force_recompile) {
       free((void *)shader->FallbackSource);
       shader->FallbackSource = NULL;
    }
 
    delete state->symbols;
    ralloc_free(state);
 }
 
 } /* extern "C" */
diff --git a/src/compiler/glsl/shader_cache.cpp b/src/compiler/glsl/shader_cache.cpp
index 274bb8c..ccc8aaf 100644
--- a/src/compiler/glsl/shader_cache.cpp
+++ b/src/compiler/glsl/shader_cache.cpp
@@ -1410,21 +1410,21 @@ shader_cache_read_program_metadata(struct gl_context *ctx,
    prog->data->LinkStatus = linking_skipped;
 
    /* Since the program load was successful, CompileStatus of all shaders at
     * this point should normally be compile_skipped. However because of how
     * the eviction works, it may happen that some of the individual shader keys
     * have been evicted, resulting in unnecessary recompiles on this load, so
     * mark them again to skip such recompiles next time.
     */
    char sha1_buf[41];
    for (unsigned i = 0; i < prog->NumShaders; i++) {
-      if (prog->Shaders[i]->CompileStatus == compile_success) {
+      if (prog->Shaders[i]->CompileStatus == compiled_no_opts) {
          disk_cache_put_key(cache, prog->Shaders[i]->sha1);
          if (ctx->_Shader->Flags & GLSL_CACHE_INFO) {
             _mesa_sha1_format(sha1_buf, prog->Shaders[i]->sha1);
             fprintf(stderr, "re-marking shader: %s\n", sha1_buf);
          }
       }
    }
 
    free (buffer);
 
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index 91e1948..45e49a6 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2401,21 +2401,22 @@ static inline GLbitfield gl_external_samplers(struct gl_program *prog)
 
 /**
  * Compile status enum. compile_skipped is used to indicate the compile
  * was skipped due to the shader matching one that's been seen before by
  * the on-disk cache.
  */
 enum gl_compile_status
 {
    compile_failure = 0,
    compile_success,
-   compile_skipped
+   compile_skipped,
+   compiled_no_opts
 };
 
 /**
  * A GLSL shader object.
  */
 struct gl_shader
 {
    /** GL_FRAGMENT_SHADER || GL_VERTEX_SHADER || GL_GEOMETRY_SHADER_ARB ||
     *  GL_TESS_CONTROL_SHADER || GL_TESS_EVALUATION_SHADER.
     * Must be the first field.
-- 
2.9.3



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