[Mesa-stable] [PATCH 2/3] glsl: Link error if fs defines conflicting qualifiers for gl_FragCoord
Anuj Phogat
anuj.phogat at gmail.com
Mon Feb 10 17:29:57 PST 2014
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;
}
Cc: <mesa-stable at lists.freedesktop.org>
Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
---
src/glsl/ast_to_hir.cpp | 5 ++++
src/glsl/glsl_parser_extras.cpp | 14 +++++++++
src/glsl/glsl_parser_extras.h | 1 +
src/glsl/linker.cpp | 63 +++++++++++++++++++++++++++++++++++++++++
src/mesa/main/mtypes.h | 7 +++++
5 files changed, 90 insertions(+)
diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index 7d7d89b..3b2e05a 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->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 b06337e..07fd1c7 100644
--- a/src/glsl/glsl_parser_extras.cpp
+++ b/src/glsl/glsl_parser_extras.cpp
@@ -193,6 +193,7 @@ _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->uses_gl_fragcoord = false;
this->fs_origin_upper_left = false;
this->fs_pixel_center_integer = false;
@@ -1350,6 +1351,13 @@ 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->uses_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;
@@ -1379,6 +1387,12 @@ set_shader_inout_layout(struct gl_shader *shader,
}
break;
+ case MESA_SHADER_FRAGMENT:
+ shader->uses_gl_fragcoord = state->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 674dae5..eddcf77 100644
--- a/src/glsl/glsl_parser_extras.h
+++ b/src/glsl/glsl_parser_extras.h
@@ -393,6 +393,7 @@ struct _mesa_glsl_parse_state {
const struct gl_extensions *extensions;
bool uses_builtin_functions;
+ bool 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 bcd7394..f8564ca 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1194,6 +1194,68 @@ 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);
+
+ if ((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))
+ return true;
+
+ return false;
+}
+
+/**
+ * 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 qualifier for gl_FragCoord\n");
+ return;
+ } else if (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,
@@ -1453,6 +1515,7 @@ 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 205b2f2..bbb6231 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2412,6 +2412,13 @@ struct gl_shader
struct glsl_symbol_table *symbols;
bool uses_builtin_functions;
+ bool uses_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.
--
1.8.3.1
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