[Mesa-dev] [PATCH v2] glsl: Add link time checks for GLSL precision qualifiers
Iago Toral Quiroga
itoral at igalia.com
Fri Feb 6 06:03:09 PST 2015
Currently, we only consider precision qualifiers at compile-time. This patch
adds precision information to ir_variable so we can also do link time checks.
Specifically, from the GLSL ES3 spec, 4.5.3 Precision Qualifiers:
"The same uniform declared in different shaders that are linked together
must have the same precision qualification."
Notice that this patch will check the above also for GLSL ES globals that are
not uniforms. This is not explicitly stated in the spec, but seems to be
the only consistent choice: since we can only have one definition of a global
all its declarations should be identical, including precision qualifiers.
v2 (Ian Romanick):
- Remove unused precision field from glsl_type.
- Fix comments stating that desktop OpenGL ignores precision qualifiers.
- Make the precision field in ir_variable a bitfield and use pahole to
place it in an available hole so we don't increase memory storage
requirements for ir_variable.
No piglit regressions.
Fixes the following 4 dEQP tests:
dEQP-GLES3.functional.shaders.linkage.uniform.struct.precision_conflict_1
dEQP-GLES3.functional.shaders.linkage.uniform.struct.precision_conflict_2
dEQP-GLES3.functional.shaders.linkage.uniform.struct.precision_conflict_3
dEQP-GLES3.functional.shaders.linkage.uniform.struct.precision_conflict_4
---
src/glsl/ast_to_hir.cpp | 12 ++++++++++++
src/glsl/glsl_types.cpp | 4 ++++
src/glsl/glsl_types.h | 12 ++++++++++++
src/glsl/ir.h | 13 +++++++++++++
src/glsl/linker.cpp | 48 ++++++++++++++++++++++++++++++++++++++++--------
5 files changed, 81 insertions(+), 8 deletions(-)
According to pahole there was exactly a 2-bit hole after the index:1 bitfield:
unsigned int from_named_ifc_block_nonarray:1; /* 0: 5 4 */
unsigned int from_named_ifc_block_array:1; /* 0: 4 4 */
unsigned int must_be_shader_input:1; /* 0: 3 4 */
unsigned int index:1; /* 0: 2 4 */
/* XXX 2 bits hole, try to pack */
enum ir_depth_layout depth_layout:3; /* 4:29 4 */
unsigned int image_read_only:1; /* 4:28 4 */
Making precision a 2-bit bitfield right after index:1 fills the hole
without adding any additional storage requirements:
unsigned int from_named_ifc_block_nonarray:1; /* 0: 5 4 */
unsigned int from_named_ifc_block_array:1; /* 0: 4 4 */
unsigned int must_be_shader_input:1; /* 0: 3 4 */
unsigned int index:1; /* 0: 2 4 */
unsigned int precision:2; /* 0: 0 4 */
enum ir_depth_layout depth_layout:3; /* 4:29 4 */
unsigned int image_read_only:1; /* 4:28 4 */
unsigned int image_write_only:1; /* 4:27 4 */
diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index ed0eb09..39957ad 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -2458,6 +2458,10 @@ apply_type_qualifier_to_variable(const struct ast_type_qualifier *qual,
if (qual->flags.q.sample)
var->data.sample = 1;
+ /* Precision qualifiers do not hold any meaning in Desktop GLSL */
+ if (state->es_shader && qual->precision)
+ var->data.precision = qual->precision;
+
if (state->stage == MESA_SHADER_GEOMETRY &&
qual->flags.q.out && qual->flags.q.stream) {
var->data.stream = qual->stream;
@@ -5218,6 +5222,10 @@ ast_process_structure_or_interface_block(exec_list *instructions,
fields[i].centroid = qual->flags.q.centroid ? 1 : 0;
fields[i].sample = qual->flags.q.sample ? 1 : 0;
+ /* Precision qualifiers do not hold any meaning in Desktop GLSL */
+ fields[i].precision = state->es_shader ? qual->precision :
+ GLSL_PRECISION_NONE;
+
/* Only save explicitly defined streams in block's field */
fields[i].stream = qual->flags.q.explicit_stream ? qual->stream : -1;
@@ -5715,6 +5723,10 @@ ast_interface_block::hir(exec_list *instructions,
var->data.sample = fields[i].sample;
var->init_interface_type(block_type);
+ /* Precision qualifiers do not hold any meaning in Desktop GLSL */
+ var->data.precision = state->es_shader ? fields[i].precision :
+ GLSL_PRECISION_NONE;
+
if (fields[i].matrix_layout == GLSL_MATRIX_LAYOUT_INHERITED) {
var->data.matrix_layout = matrix_layout == GLSL_MATRIX_LAYOUT_INHERITED
? GLSL_MATRIX_LAYOUT_COLUMN_MAJOR : matrix_layout;
diff --git a/src/glsl/glsl_types.cpp b/src/glsl/glsl_types.cpp
index b4223f4..e35c2aa 100644
--- a/src/glsl/glsl_types.cpp
+++ b/src/glsl/glsl_types.cpp
@@ -122,6 +122,7 @@ glsl_type::glsl_type(const glsl_struct_field *fields, unsigned num_fields,
this->fields.structure[i].centroid = fields[i].centroid;
this->fields.structure[i].sample = fields[i].sample;
this->fields.structure[i].matrix_layout = fields[i].matrix_layout;
+ this->fields.structure[i].precision = fields[i].precision;
}
mtx_unlock(&glsl_type::mutex);
@@ -668,6 +669,9 @@ glsl_type::record_compare(const glsl_type *b) const
if (this->fields.structure[i].sample
!= b->fields.structure[i].sample)
return false;
+ if (this->fields.structure[i].precision
+ != b->fields.structure[i].precision)
+ return false;
}
return true;
diff --git a/src/glsl/glsl_types.h b/src/glsl/glsl_types.h
index 441015c..d521f3d 100644
--- a/src/glsl/glsl_types.h
+++ b/src/glsl/glsl_types.h
@@ -100,6 +100,13 @@ enum glsl_matrix_layout {
GLSL_MATRIX_LAYOUT_ROW_MAJOR
};
+enum {
+ GLSL_PRECISION_NONE = 0,
+ GLSL_PRECISION_HIGH,
+ GLSL_PRECISION_MEDIUM,
+ GLSL_PRECISION_LOW
+};
+
#ifdef __cplusplus
#include "GL/gl.h"
#include "util/ralloc.h"
@@ -741,6 +748,11 @@ struct glsl_struct_field {
* streams (as in ir_variable::stream). -1 otherwise.
*/
int stream;
+
+ /**
+ * Precission qualifier
+ */
+ unsigned precision;
};
static inline unsigned int
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index a0f48b2..9fe05ab 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -740,6 +740,19 @@ public:
unsigned index:1;
/**
+ * Precision qualifier.
+ *
+ * In desktop GLSL we do not care about precision qualifiers at all, in
+ * fact, the spec says that precision qualifiers are ignored.
+ *
+ * To make things easy, we make it so that this field is always
+ * GLSL_PRECISION_NONE on desktop shaders. This way all the variables
+ * have the same precision value and the checks we add in the compiler
+ * for this field will never break a desktop shader compile.
+ */
+ unsigned precision:2;
+
+ /**
* \brief Layout qualifier for gl_FragDepth.
*
* This is not equal to \c ir_depth_layout_none if and only if this
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 3f5eac1..091f00f 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -756,14 +756,23 @@ cross_validate_globals(struct gl_shader_program *prog,
&& existing->type->is_record()
&& existing->type->record_compare(var->type)) {
existing->type = var->type;
- } else {
- linker_error(prog, "%s `%s' declared as type "
- "`%s' and type `%s'\n",
- mode_string(var),
- var->name, var->type->name,
- existing->type->name);
- return;
- }
+ } else if (strcmp(var->type->name, existing->type->name)) {
+ linker_error(prog, "%s `%s' declared as type "
+ "`%s' and type `%s'\n",
+ mode_string(var),
+ var->name, var->type->name,
+ existing->type->name);
+ return;
+ } else {
+ /* The global is declared with the same type name but the type
+ * declarations mismatch (e.g. the same struct type name, but
+ * the actual struct declarations mismatch).
+ */
+ linker_error(prog, "%s `%s' declared with mismatching definitions "
+ "of type `%s'\n",
+ mode_string(var), var->name, var->type->name);
+ return;
+ }
}
if (var->data.explicit_location) {
@@ -918,6 +927,29 @@ cross_validate_globals(struct gl_shader_program *prog,
mode_string(var), var->name);
return;
}
+ /* From the GLSL ES3 spec, 4.5.3 Precision qualifiers:
+ *
+ * "The same uniform declared in different shaders that are linked
+ * together must have the same precision qualification."
+ *
+ * In the GLSL ES2 spec this was resolved in the issue amendments
+ * (10.3 Precision Qualifiers). The GLSL ES1 spec overlooked this,
+ * but seems like an obvious error since we can only have one
+ * consistent definition of a global.
+ *
+ * The desktop GLSL spec does not include this reference
+ * because precision qualifiers are ignored. We will never
+ * hit this scenario in desktop GLSL though because we always set
+ * the precision of variables to GLSL_PRECISION_NONE.
+ */
+ if (var->data.mode == ir_var_uniform) {
+ if (existing->data.precision != var->data.precision) {
+ linker_error(prog, "declarations for %s `%s` have "
+ "mismatching precision qualifiers\n",
+ mode_string(var), var->name);
+ return;
+ }
+ }
} else
variables.add_variable(var);
}
--
1.9.1
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