glsl: use correct shader source in case of cache fallback

The scenario is:

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

glShaderSource <-- with new source code

glAttachShader
glLinkProgram <-- no cache hit for program

At this point we need to compile the original source when we
fallback.

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

3 files changed, 15 insertions, 3 deletions

diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index efe0cbcad75..e24ee3c0c00 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2397,6 +2397,8 @@ struct gl_shader
 #endif
    const GLchar *Source;  /**< Source code string */
 
+   const GLchar *FallbackSource;  /**< Fallback string used by on-disk cache*/
+
    GLchar *InfoLog;
 
    unsigned Version;       /**< GLSL version used for linking */
diff --git a/src/mesa/main/shaderapi.c b/src/mesa/main/shaderapi.c
index 86ce0bc5fdf..0c38cea2555 100644
--- a/src/mesa/main/shaderapi.c
+++ b/src/mesa/main/shaderapi.c
@@ -1003,9 +1003,18 @@ shader_source(struct gl_shader *sh, const GLchar *source)
 {
    assert(sh);
 
-   /* free old shader source string and install new one */
-   free((void *)sh->Source);
-   sh->Source = source;
+   if (sh->CompileStatus == GL_TRUE && !sh->FallbackSource) {
+      /* If shader was previously compiled back-up the source in case of cache
+       * fallback.
+       */
+      sh->FallbackSource = sh->Source;
+      sh->Source = source;
+   } else {
+      /* free old shader source string and install new one */
+      free((void *)sh->Source);
+      sh->Source = source;
+   }
+
 #ifdef DEBUG
    sh->SourceChecksum = util_hash_crc32(sh->Source, strlen(sh->Source));
 #endif
diff --git a/src/mesa/main/shaderobj.c b/src/mesa/main/shaderobj.c
index b41137fbce3..222efc12c4e 100644
--- a/src/mesa/main/shaderobj.c
+++ b/src/mesa/main/shaderobj.c
@@ -122,6 +122,7 @@ void
 _mesa_delete_shader(struct gl_context *ctx, struct gl_shader *sh)
 {
    free((void *)sh->Source);
+   free((void *)sh->FallbackSource);
    free(sh->Label);
    ralloc_free(sh);
 }