mesa: Add MESA_SHADER_CAPTURE_PATH for writing .shader_test files.

This writes linked shader programs to .shader_test files to
$MESA_SHADER_CAPTURE_PATH in the format used by shader-db
(http://cgit.freedesktop.org/mesa/shader-db).

It supports both GLSL shaders and ARB programs.  All stages that
are linked together are written in a single .shader_test file.

This eliminates the need for shader-db's split-to-files.py, as Mesa
produces the desired format directly.  It's much more reliable than
parsing stdout/stderr, as those may contain extraneous messages, or
simply be closed by the application and unavailable.

We have many similar features already, but this is a bit different:
- MESA_GLSL=dump writes to stdout, not files.
- MESA_GLSL=log writes each stage to separate files (rather than
  all linked shaders in one file), at draw time (not link time),
  with uniform data and state flag info.
- Tapani's shader replacement mechanism (MESA_SHADER_DUMP_PATH and
  MESA_SHADER_READ_PATH) also uses separate files per shader stage,
  but allows reading in files to replace an app's shader code.

v2:  Dump ARB programs too, not just GLSL.
v3:  Don't dump bogus 0.shader_test file.
v4:  Add "GL_ARB_separate_shader_objects" to the [require] block.
v5:  Print "GLSL 4.00" instead of "GLSL 4.0" in the [require] block.
v6:  Don't hardcode /tmp/mesa.
v7:  Fix memoization of getenv().
v8:  Also print "SSO ENABLED" (suggested by Timothy).
v9:  Also handle ES shaders (suggested by Ilia).
v10: Guard against MESA_SHADER_CAPTURE_PATH being too long; add
     _mesa_warning calls on error handling (suggested by Ben).
v11: Fix crash when variable is unset introduced in v10.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/src/mesa/main/shaderapi.c b/src/mesa/main/shaderapi.c
index 167e06f..eb6b1f5 100644
--- a/src/mesa/main/shaderapi.c
+++ b/src/mesa/main/shaderapi.c
@@ -96,6 +96,29 @@ _mesa_get_shader_flags(void)
    return flags;
 }
 
+/**
+ * Memoized version of getenv("MESA_SHADER_CAPTURE_PATH").
+ */
+const char *
+_mesa_get_shader_capture_path(void)
+{
+   static bool read_env_var = false;
+   static const char *path = NULL;
+
+   if (!read_env_var) {
+      path = getenv("MESA_SHADER_CAPTURE_PATH");
+      read_env_var = true;
+      if (path &&
+          strlen(path) > PATH_MAX - strlen("/fp-4294967295.shader_test")) {
+         GET_CURRENT_CONTEXT(ctx);
+         _mesa_warning(ctx, "MESA_SHADER_CAPTURE_PATH too long; ignoring "
+                            "request to capture shaders");
+         path = NULL;
+      }
+   }
+
+   return path;
+}
 
 /**
  * Initialize context's shader state.
@@ -1046,6 +1069,35 @@ _mesa_link_program(struct gl_context *ctx, struct gl_shader_program *shProg)
 
    _mesa_glsl_link_shader(ctx, shProg);
 
+   /* Capture .shader_test files. */
+   const char *capture_path = _mesa_get_shader_capture_path();
+   if (shProg->Name != 0 && capture_path != NULL) {
+      FILE *file;
+      char filename[PATH_MAX];
+
+      _mesa_snprintf(filename, sizeof(filename), "%s/%u.shader_test",
+                     capture_path, shProg->Name);
+
+      file = fopen(filename, "w");
+      if (file) {
+         fprintf(file, "[require]\nGLSL%s >= %u.%02u\n",
+                 shProg->IsES ? " ES" : "",
+                 shProg->Version / 100, shProg->Version % 100);
+         if (shProg->SeparateShader)
+            fprintf(file, "GL_ARB_separate_shader_objects\nSSO ENABLED\n");
+         fprintf(file, "\n");
+
+         for (unsigned i = 0; i < shProg->NumShaders; i++) {
+            fprintf(file, "[%s shader]\n%s\n",
+                    _mesa_shader_stage_to_string(shProg->Shaders[i]->Stage),
+                    shProg->Shaders[i]->Source);
+         }
+         fclose(file);
+      } else {
+         _mesa_warning(ctx, "Failed to open %s", filename);
+      }
+   }
+
    if (shProg->LinkStatus == GL_FALSE &&
        (ctx->_Shader->Flags & GLSL_REPORT_ERRORS)) {
       _mesa_debug(ctx, "Error linking program %u:\n%s\n",