glsl: Link error if fs defines conflicting qualifiers for gl_FragCoord
GLSL 1.50 spec says:
"If gl_FragCoord is redeclared in any fragment shader in a program,
it must be redeclared in all the fragment shaders in that
program that have a static use gl_FragCoord. All redeclarations of
gl_FragCoord in all fragment shaders in a single program must
have the same set of qualifiers."
This patch causes the shader link to fail if we have multiple fragment
shaders with conflicting layout qualifiers for gl_FragCoord.
V2: Restructure the code and add conditions to correctly handle the
following case:
fragment shader 1:
layout(origin_upper_left) in vec4 gl_FragCoord;
void main()
{
foo();
gl_FragColor = gl_FragData;
}
fragment shader 2:
layout(pixel_center_integer) in vec4 gl_FragCoord;
void foo()
{
}
V3:
Allow linking in the following case:
fragment shader 1:
void main()
{
foo();
gl_FragColor = gl_FragCoord;
}
fragment shader 2:
in vec4 gl_FragCoord;
void foo()
{
...
}
Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index a2e43073..9a01877 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1195,6 +1195,82 @@
};
/**
+ * Performs the cross-validation of layout qualifiers specified in
+ * redeclaration of gl_FragCoord for the attached fragment shaders,
+ * and propagates them to the linked FS and linked shader program.
+ */
+static void
+link_fs_input_layout_qualifiers(struct gl_shader_program *prog,
+ struct gl_shader *linked_shader,
+ struct gl_shader **shader_list,
+ unsigned num_shaders)
+{
+ linked_shader->redeclares_gl_fragcoord = false;
+ linked_shader->uses_gl_fragcoord = false;
+ linked_shader->origin_upper_left = false;
+ linked_shader->pixel_center_integer = false;
+
+ if (linked_shader->Stage != MESA_SHADER_FRAGMENT || prog->Version < 150)
+ return;
+
+ for (unsigned i = 0; i < num_shaders; i++) {
+ struct gl_shader *shader = shader_list[i];
+ /* From the GLSL 1.50 spec, page 39:
+ *
+ * "If gl_FragCoord is redeclared in any fragment shader in a program,
+ * it must be redeclared in all the fragment shaders in that program
+ * that have a static use gl_FragCoord."
+ *
+ * Exclude the case when one of the 'linked_shader' or 'shader' redeclares
+ * gl_FragCoord with no layout qualifiers but the other one doesn't
+ * redeclare it. If we strictly follow GLSL 1.50 spec's language, it
+ * should be a link error. But, generating link error for this case will
+ * be a wrong behaviour which spec didn't intend to do and it could also
+ * break some applications.
+ */
+ if ((linked_shader->redeclares_gl_fragcoord
+ && !shader->redeclares_gl_fragcoord
+ && shader->uses_gl_fragcoord
+ && (linked_shader->origin_upper_left
+ || linked_shader->pixel_center_integer))
+ || (shader->redeclares_gl_fragcoord
+ && !linked_shader->redeclares_gl_fragcoord
+ && linked_shader->uses_gl_fragcoord
+ && (shader->origin_upper_left
+ || shader->pixel_center_integer))) {
+ linker_error(prog, "fragment shader defined with conflicting "
+ "layout qualifiers for gl_FragCoord\n");
+ }
+
+ /* From the GLSL 1.50 spec, page 39:
+ *
+ * "All redeclarations of gl_FragCoord in all fragment shaders in a
+ * single program must have the same set of qualifiers."
+ */
+ if (linked_shader->redeclares_gl_fragcoord && shader->redeclares_gl_fragcoord
+ && (shader->origin_upper_left != linked_shader->origin_upper_left
+ || shader->pixel_center_integer != linked_shader->pixel_center_integer)) {
+ linker_error(prog, "fragment shader defined with conflicting "
+ "layout qualifiers for gl_FragCoord\n");
+ }
+
+ /* Update the linked shader state. Note that uses_gl_fragcoord should
+ * accumulate the results. The other values should replace. If there
+ * are multiple redeclarations, all the fields except uses_gl_fragcoord
+ * are already known to be the same.
+ */
+ if (shader->redeclares_gl_fragcoord || shader->uses_gl_fragcoord) {
+ linked_shader->redeclares_gl_fragcoord =
+ shader->redeclares_gl_fragcoord;
+ linked_shader->uses_gl_fragcoord = linked_shader->uses_gl_fragcoord
+ || shader->uses_gl_fragcoord;
+ linked_shader->origin_upper_left = shader->origin_upper_left;
+ linked_shader->pixel_center_integer = shader->pixel_center_integer;
+ }
+ }
+}
+
+/**
* Performs the cross-validation of geometry shader max_vertices and
* primitive type layout qualifiers for the attached geometry shaders,
* and propagates them to the linked GS and linked shader program.
@@ -1471,6 +1547,7 @@
linked->NumUniformBlocks = num_uniform_blocks;
ralloc_steal(linked, linked->UniformBlocks);
+ link_fs_input_layout_qualifiers(prog, linked, shader_list, num_shaders);
link_gs_inout_layout_qualifiers(prog, linked, shader_list, num_shaders);
link_cs_input_layout_qualifiers(prog, linked, shader_list, num_shaders);