glsl/shader_cache: restore evicted shader keys

Even though the programs themselves stay in cache and are loaded, the
shader keys can be evicted separately. If that happens, unnecessary
compiles are caused that waste time, and no matter how many times the
program is re-run, performance never recovers to the levels of first
hot cache run. To deal with this, we need to refresh the shader keys
of shaders that were recompiled.

An easy way to currently observe this is running Deux Ex, then piglit
and Deux Ex again, or deleting just the cache index. The later is
causing over a minute of lost time on all later Deux Ex runs, with this
patch it returns to normal after 1 run.

Signed-off-by: Grazvydas Ignotas <[email protected]>
Reviewed-by: Timothy Arceri <[email protected]>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/compiler/glsl/shader_cache.cpp b/src/compiler/glsl/shader_cache.cpp
index dd8c6c0b408..274bb8c91e7 100644
--- a/src/compiler/glsl/shader_cache.cpp
+++ b/src/compiler/glsl/shader_cache.cpp
@@ -1409,6 +1409,23 @@ shader_cache_read_program_metadata(struct gl_context *ctx,
    /* This is used to flag a shader retrieved from cache */
    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) {
+         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);
 
    return true;