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glsl: don't attempt to link empty program

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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.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Timothy Arceri
2016-01-25 21:56:18 +11:00
parent 371c4b3c48
commit 76cfb47207
1 changed files with 23 additions and 23 deletions
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46
src/compiler/glsl/linker.cpp
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@@ -4106,15 +4106,34 @@ disable_varying_optimizations_for_sso(struct gl_shader_program *prog)
void
link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
{
prog->LinkStatus = true; /* All error paths will set this to false */
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;
}
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;
/* Separate the shaders into groups based on their type.
@@ -4163,25 +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 &&