On 01/25/2016 04:46 PM, Timothy Arceri wrote:
> Previously an empty program would go through the entire
> link_shaders() function and we would have to be careful
> not to cause a segfault.
>
> In core profile also now set link_status to false by
> generating an error, it was previously set to true.
>
>>From Section 7.3 (PROGRAM OBJECTS) of the OpenGL 4.5 spec:
>
> "Linking can fail for a variety of reasons as specified in the
> OpenGL Shading Language Specification, as well as any of the
> following reasons:
>
> - No shader objects are attached to program."
>
> V2: Only generate an error in core profile and add spec quote (Ian)
>
> V3: generate error in ES too, remove previous check which was only
> applying the rule to GL 4.5/ES 3.1 and above. My understand is that
> this spec change is clarifying previously undefined behaviour and
> therefore should be applied retrospectively. The ES CTS tests for
> this are in ES 2 I suspect it was passing because it would have
> generated an error for not having both a vertex and fragment shader.
>
> Cc: Ian Romanick <i...@freedesktop.org>
> Cc: Tapani Pälli <tapani.pa...@intel.com>
> Cc: Ilia Mirkin <imir...@alum.mit.edu>
> ---
> src/glsl/linker.cpp | 43 ++++++++++++++++++++++---------------------
> 1 file changed, 22 insertions(+), 21 deletions(-)
>
> diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
> index 6657777..79039a0 100644
> --- a/src/glsl/linker.cpp
> +++ b/src/glsl/linker.cpp
> @@ -4105,14 +4105,34 @@ disable_varying_optimizations_for_sso(struct
> gl_shader_program *prog)
> void
> link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
> {
> + prog->Validated = false;
> + prog->_Used = false;
> +
> + /* Section 7.3 (Program Objects) of the OpenGL 4.5 Core Profile spec says:
> + *
> + * "Linking can fail for a variety of reasons as specified in the
> + * OpenGL Shading Language Specification, as well as any of the
> + * following reasons:
> + *
> + * - No shader objects are attached to program."
> + *
> + * The Compatibility Profile specification does not list the error. In
> + * Compatibility Profile missing shader stages are replaced by
> + * fixed-function. This applies to the case where all stages are
> + * missing.
> + */
> + if (prog->NumShaders == 0) {
> + if (ctx->API != API_OPENGL_COMPAT)
> + linker_error(prog, "no shaders attached to the program\n");
> + return;
Does glsl-link-empty-prog-02 still pass? Since prog->LinkStatus is
false, I think that will cause problems. Won't glUseProgram generate
GL_INVALID_OPERATION?
> + }
> +
> tfeedback_decl *tfeedback_decls = NULL;
> unsigned num_tfeedback_decls = prog->TransformFeedback.NumVarying;
>
> void *mem_ctx = ralloc_context(NULL); // temporary linker context
>
> prog->LinkStatus = true; /* All error paths will set this to false */
> - prog->Validated = false;
> - prog->_Used = false;
>
> prog->ARB_fragment_coord_conventions_enable = false;
>
> @@ -4162,25 +4182,6 @@ link_shaders(struct gl_context *ctx, struct
> gl_shader_program *prog)
> prog->Version = max_version;
> prog->IsES = is_es_prog;
>
> - /* From OpenGL 4.5 Core specification (7.3 Program Objects):
> - * "Linking can fail for a variety of reasons as specified in the
> OpenGL
> - * Shading Language Specification, as well as any of the following
> - * reasons:
> - *
> - * * No shader objects are attached to program.
> - *
> - * ..."
> - *
> - * Same rule applies for OpenGL ES >= 3.1.
> - */
> -
> - if (prog->NumShaders == 0 &&
> - ((ctx->API == API_OPENGL_CORE && ctx->Version >= 45) ||
> - (ctx->API == API_OPENGLES2 && ctx->Version >= 31))) {
> - linker_error(prog, "No shader objects are attached to program.\n");
> - goto done;
> - }
> -
> /* Some shaders have to be linked with some other shaders present.
> */
> if (num_shaders[MESA_SHADER_GEOMETRY] > 0 &&
>
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