[Mesa-dev] [PATCH V2 3/4] glsl: Link error if fs defines conflicting qualifiers for gl_FragCoord
Ian Romanick
idr at freedesktop.org
Tue Feb 25 09:14:24 PST 2014
On 02/24/2014 05:34 PM, Anuj Phogat wrote:
> 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. For example:
>
> fragment shader 1:
> layout(origin_upper_left, pixel_center_integer) in vec4 gl_FragCoord;
>
> void foo();
> void main()
> {
> gl_FragColor = vec4(gl_FragCoord.xyz, 1.0);
> foo();
> }
>
> fragment shader 2:
> layout(origin_upper_left) in vec4 gl_FragCoord;
> void foo()
> {
> gl_FragColor.a = gl_FragCoord.z;
> }
>
> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> Cc: <mesa-stable at lists.freedesktop.org>
> ---
> src/glsl/ast_to_hir.cpp | 5 ++++
> src/glsl/glsl_parser_extras.cpp | 16 +++++++++++
> src/glsl/glsl_parser_extras.h | 1 +
> src/glsl/linker.cpp | 60 +++++++++++++++++++++++++++++++++++++++++
> src/mesa/main/mtypes.h | 8 ++++++
> 5 files changed, 90 insertions(+)
>
> diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
> index f5dacfd..b639f98 100644
> --- a/src/glsl/ast_to_hir.cpp
> +++ b/src/glsl/ast_to_hir.cpp
> @@ -120,6 +120,11 @@ _mesa_ast_to_hir(exec_list *instructions, struct _mesa_glsl_parse_state *state)
> instructions->push_head(var);
> }
>
> + /* Figure out if gl_FragCoord is actually used in fragment shader */
> + ir_variable *const var = state->symbols->get_variable("gl_FragCoord");
> + if (var != NULL)
> + state->fs_uses_gl_fragcoord = var->data.used;
> +
> /* From section 7.1 (Built-In Language Variables) of the GLSL 4.10 spec:
> *
> * If multiple shaders using members of a built-in block belonging to
> diff --git a/src/glsl/glsl_parser_extras.cpp b/src/glsl/glsl_parser_extras.cpp
> index fcbbf44..f953713 100644
> --- a/src/glsl/glsl_parser_extras.cpp
> +++ b/src/glsl/glsl_parser_extras.cpp
> @@ -201,6 +201,7 @@ _mesa_glsl_parse_state::_mesa_glsl_parse_state(struct gl_context *_ctx,
> this->default_uniform_qualifier->flags.q.shared = 1;
> this->default_uniform_qualifier->flags.q.column_major = 1;
>
> + this->fs_uses_gl_fragcoord = false;
> this->fs_redeclares_gl_fragcoord = false;
> this->fs_origin_upper_left = false;
> this->fs_pixel_center_integer = false;
> @@ -1363,6 +1364,14 @@ set_shader_inout_layout(struct gl_shader *shader,
> assert(!state->cs_input_local_size_specified);
> }
>
> + if (shader->Stage != MESA_SHADER_FRAGMENT) {
> + /* Should have been prevented by the parser. */
> + assert(!state->fs_uses_gl_fragcoord);
> + assert(!state->fs_redeclares_gl_fragcoord);
> + assert(!state->fs_pixel_center_integer);
> + assert(!state->fs_origin_upper_left);
> + }
> +
> switch (shader->Stage) {
> case MESA_SHADER_GEOMETRY:
> shader->Geom.VerticesOut = 0;
> @@ -1396,6 +1405,13 @@ set_shader_inout_layout(struct gl_shader *shader,
> }
> break;
>
> + case MESA_SHADER_FRAGMENT:
> + shader->redeclares_gl_fragcoord = state->fs_redeclares_gl_fragcoord;
> + shader->uses_gl_fragcoord = state->fs_uses_gl_fragcoord;
> + shader->pixel_center_integer = state->fs_pixel_center_integer;
> + shader->origin_upper_left = state->fs_origin_upper_left;
> + break;
> +
> default:
> /* Nothing to do. */
> break;
> diff --git a/src/glsl/glsl_parser_extras.h b/src/glsl/glsl_parser_extras.h
> index 2017913..511ca48 100644
> --- a/src/glsl/glsl_parser_extras.h
> +++ b/src/glsl/glsl_parser_extras.h
> @@ -427,6 +427,7 @@ struct _mesa_glsl_parse_state {
> const struct gl_extensions *extensions;
>
> bool uses_builtin_functions;
> + bool fs_uses_gl_fragcoord;
>
> /**
> * For geometry shaders, size of the most recently seen input declaration
> diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
> index f6b2661..1268aef 100644
> --- a/src/glsl/linker.cpp
> +++ b/src/glsl/linker.cpp
> @@ -1194,6 +1194,65 @@ private:
> hash_table *unnamed_interfaces;
> };
>
> +static bool
> +fs_uses_conflicting_layout_qualifiers(struct gl_shader *shader,
> + struct gl_shader *linked_shader)
> +{
> + bool qual_absent_in_shader_but_present_in_linked_shader =
> + (!shader->origin_upper_left && linked_shader->origin_upper_left) ||
> + (!shader->pixel_center_integer && linked_shader->pixel_center_integer);
> +
> + bool qual_present_in_shader_but_absent_in_linked_shader =
> + (shader->origin_upper_left && !linked_shader->origin_upper_left) ||
> + (shader->pixel_center_integer && !linked_shader->pixel_center_integer);
> +
> + return ((qual_absent_in_shader_but_present_in_linked_shader &&
> + shader->uses_gl_fragcoord) ||
> + (qual_present_in_shader_but_absent_in_linked_shader &&
> + linked_shader->uses_gl_fragcoord));
I don't think this logic catches the redefined-but-not-used cases.
layout(origin_upper_left) in vec4 gl_FragCoord;
void main()
{
foo();
gl_FragColor = gl_FragData;
}
---
layout(pixel_center_integer) in vec4 gl_FragCoord;
void foo()
{
}
I think in the loop in link_fs_input_layout_qualifiers you want:
/* 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.
*/
if ((linked_shader->redeclares_gl_fragcoord
&& !shader->redeclares_gl_fragcoord
&& shader->uses_gl_fragcoord)
|| (shader->redeclares_gl_fragcoord
&& !linked_shader->redeclares_gl_fragcoord
&& linked_shader->uses_gl_fragcoord)) {
// error
}
/* 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)){
// error
}
/* 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) {
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 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->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;
> +
> + /* 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. All redeclarations of
> + * gl_FragCoord in all fragment shaders in a single program must have
> + * the same set of qualifiers."
> + */
> +
> + for (unsigned i = 0; i < num_shaders; i++) {
> + struct gl_shader *shader = shader_list[i];
> +
> + if (fs_uses_conflicting_layout_qualifiers(shader, linked_shader)) {
> + linker_error(prog, "fragment shader defined with conflicting "
> + "layout qualifiers for gl_FragCoord\n");
> + return;
> + } else if (shader->redeclares_gl_fragcoord || 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,
> @@ -1471,6 +1530,7 @@ link_intrastage_shaders(void *mem_ctx,
> 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);
>
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index fbbca55..dd2ee82 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -2414,6 +2414,14 @@ struct gl_shader
> struct glsl_symbol_table *symbols;
>
> bool uses_builtin_functions;
> + bool uses_gl_fragcoord;
> + bool redeclares_gl_fragcoord;
> +
> + /**
> + * Fragment shader state from GLSL 1.50 layout qualifiers.
> + */
> + bool origin_upper_left;
> + bool pixel_center_integer;
>
> /**
> * Geometry shader state from GLSL 1.50 layout qualifiers.
>
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