[Mesa-stable] [PATCH V3 3/4] glsl: Link error if fs defines conflicting qualifiers for gl_FragCoord
Anuj Phogat
anuj.phogat at gmail.com
Fri Feb 28 11:53:08 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.
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()
{
}
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 | 86 +++++++++++++++++++++++++++++++++++++++++
src/mesa/main/mtypes.h | 8 ++++
5 files changed, 116 insertions(+)
diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index 0234339..784f5cf 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..b5dd996 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1195,6 +1195,91 @@ private:
};
/**
+ * 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];
+ bool linked_shader_gl_fragcoord_layout_qualifiers_present =
+ linked_shader->origin_upper_left || linked_shader->pixel_center_integer;
+
+ bool shader_gl_fragcoord_layout_qualifiers_present =
+ shader->origin_upper_left || shader->pixel_center_integer;
+
+ /* 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."
+ *
+ * Make an exception to allow the linking to happen if:
+ * One of the shaders ('linked_shader' or 'shader') redeclares
+ * gl_FragCoord with no layout qualifiers and the other one doesn't
+ * redeclare but uses 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 already working applications.
+ */
+ if ((linked_shader->redeclares_gl_fragcoord
+ && linked_shader_gl_fragcoord_layout_qualifiers_present
+ && !shader->redeclares_gl_fragcoord
+ && shader->uses_gl_fragcoord)
+ || (shader->redeclares_gl_fragcoord
+ && shader_gl_fragcoord_layout_qualifiers_present
+ && !linked_shader->redeclares_gl_fragcoord
+ && linked_shader->uses_gl_fragcoord)) {
+ linker_error(prog, "fragment shader defined with missing "
+ "redeclaration 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->uses_gl_fragcoord) {
+ linked_shader->uses_gl_fragcoord = linked_shader->uses_gl_fragcoord
+ || shader->uses_gl_fragcoord;
+ }
+ if (shader->redeclares_gl_fragcoord) {
+ linked_shader->redeclares_gl_fragcoord =
+ shader->redeclares_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 +1556,7 @@ 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 7246b1e..c27dc2d 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2430,6 +2430,14 @@ 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.
--
1.8.3.1
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