[Mesa-dev] [PATCH 07/40] glsl: make use of on disk shader cache

[Nicolai Hähnle]

On 07.02.2017 04:42, Timothy Arceri wrote:
> From: Timothy Arceri <timothy.arceri at collabora.com>
>
> The hash key for glsl metadata is a hash of the hashes of each GLSL
> source string.
>
> This commit uses the put_key/get_key support in the cache put the SHA-1
> hash of the source string for each successfully compiled shader into the
> cache. This allows for early, optimistic returns from glCompileShader
> (if the identical source string had been successfully compiled in the past),
> in the hope that the final, linked shader will be found in the cache.
>
> This is based on the intial patch by Carl.

Okay, here I actually think you may need some fallback handling around 
the shader source. I'm thinking of the following sequence:

glShaderSource
glCompileShader <-- deferred due to cache hit of shader

glShaderSource

glAttachShader
glLinkProgram <-- no cache hit for program

At that point, we have to actually compile the shader, but the true 
shader source has been thrown away.

Or maybe I'm reading all of this code wrong?

Thanks,
Nicolai

> ---
>  src/compiler/glsl/glsl_parser_extras.cpp | 16 ++++++++++++++++
>  src/compiler/glsl/linker.cpp             |  5 +++++
>  src/mesa/program/ir_to_mesa.cpp          |  8 ++++++++
>  3 files changed, 29 insertions(+)
>
> diff --git a/src/compiler/glsl/glsl_parser_extras.cpp b/src/compiler/glsl/glsl_parser_extras.cpp
> index 6fe1dd9..e16d543 100644
> --- a/src/compiler/glsl/glsl_parser_extras.cpp
> +++ b/src/compiler/glsl/glsl_parser_extras.cpp
> @@ -33,6 +33,8 @@
>  #include "main/shaderobj.h"
>  #include "util/u_atomic.h" /* for p_atomic_cmpxchg */
>  #include "util/ralloc.h"
> +#include "util/disk_cache.h"
> +#include "util/mesa-sha1.h"
>  #include "ast.h"
>  #include "glsl_parser_extras.h"
>  #include "glsl_parser.h"
> @@ -1924,6 +1926,20 @@ _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader,
>     state->error = glcpp_preprocess(state, &source, &state->info_log,
>                               add_builtin_defines, state, ctx);
>
> +   if (!force_recompile) {
> +      char buf[41];
> +      _mesa_sha1_compute(source, strlen(source), shader->sha1);
> +      if (ctx->Cache && disk_cache_has_key(ctx->Cache, shader->sha1)) {
> +         /* We've seen this shader before and know it compiles */
> +         if (ctx->_Shader->Flags & GLSL_CACHE_INFO) {
> +            fprintf(stderr, "deferring compile of shader: %s\n",
> +                    _mesa_sha1_format(buf, shader->sha1));
> +         }
> +         shader->CompileStatus = true;
> +         return;
> +      }
> +   }
> +
>     if (!state->error) {
>       _mesa_glsl_lexer_ctor(state, source);
>       _mesa_glsl_parse(state);
> diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
> index 720c22b..b5745ba 100644
> --- a/src/compiler/glsl/linker.cpp
> +++ b/src/compiler/glsl/linker.cpp
> @@ -73,6 +73,7 @@
>  #include "program.h"
>  #include "program/prog_instruction.h"
>  #include "program/program.h"
> +#include "util/mesa-sha1.h"
>  #include "util/set.h"
>  #include "util/string_to_uint_map.h"
>  #include "linker.h"
> @@ -81,6 +82,7 @@
>  #include "ir_rvalue_visitor.h"
>  #include "ir_uniform.h"
>  #include "builtin_functions.h"
> +#include "shader_cache.h"
>
>  #include "main/shaderobj.h"
>  #include "main/enums.h"
> @@ -4651,6 +4653,9 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
>        return;
>     }
>
> +   if (shader_cache_read_program_metadata(ctx, prog))
> +      return;
> +
>     void *mem_ctx = ralloc_context(NULL); // temporary linker context
>
>     prog->ARB_fragment_coord_conventions_enable = false;
> diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
> index ce58fbb..67c9267 100644
> --- a/src/mesa/program/ir_to_mesa.cpp
> +++ b/src/mesa/program/ir_to_mesa.cpp
> @@ -46,6 +46,7 @@
>  #include "compiler/glsl_types.h"
>  #include "compiler/glsl/linker.h"
>  #include "compiler/glsl/program.h"
> +#include "compiler/glsl/shader_cache.h"
>  #include "program/prog_instruction.h"
>  #include "program/prog_optimize.h"
>  #include "program/prog_print.h"
> @@ -3114,6 +3115,10 @@ _mesa_glsl_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
>        }
>     }
>
> +   /* Return early if we are loading the shader from on-disk cache */
> +   if (prog->data->LinkStatus == linking_skipped)
> +      return;
> +
>     if (ctx->_Shader->Flags & GLSL_DUMP) {
>        if (!prog->data->LinkStatus) {
>  	 fprintf(stderr, "GLSL shader program %d failed to link\n", prog->Name);
> @@ -3124,6 +3129,9 @@ _mesa_glsl_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
>           fprintf(stderr, "%s\n", prog->data->InfoLog);
>        }
>     }
> +
> +   if (prog->data->LinkStatus)
> +      shader_cache_write_program_metadata(ctx, prog);
>  }
>
>  } /* extern "C" */
>