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25 * \file ir_set_program_inouts.cpp
27 * Sets the InputsRead and OutputsWritten of Mesa programs.
29 * Additionally, for fragment shaders, sets the InterpQualifier array, the
30 * IsCentroid and IsSample bitfields, and the UsesDFdy flag.
32 * Mesa programs (gl_program, not gl_shader_program) have a set of
33 * flags indicating which varyings are read and written. Computing
34 * which are actually read from some sort of backend code can be
35 * tricky when variable array indexing involved. So this pass
36 * provides support for setting InputsRead and OutputsWritten right
40 #include "main/core.h" /* for struct gl_program */
42 #include "ir_visitor.h"
43 #include "glsl_types.h"
47 class ir_set_program_inouts_visitor
: public ir_hierarchical_visitor
{
49 ir_set_program_inouts_visitor(struct gl_program
*prog
,
50 gl_shader_stage shader_stage
)
53 this->shader_stage
= shader_stage
;
55 ~ir_set_program_inouts_visitor()
59 virtual ir_visitor_status
visit_enter(ir_dereference_array
*);
60 virtual ir_visitor_status
visit_enter(ir_function_signature
*);
61 virtual ir_visitor_status
visit_enter(ir_expression
*);
62 virtual ir_visitor_status
visit_enter(ir_discard
*);
63 virtual ir_visitor_status
visit_enter(ir_texture
*);
64 virtual ir_visitor_status
visit(ir_dereference_variable
*);
67 void mark_whole_variable(ir_variable
*var
);
68 bool try_mark_partial_variable(ir_variable
*var
, ir_rvalue
*index
);
70 struct gl_program
*prog
;
71 gl_shader_stage shader_stage
;
74 } /* anonymous namespace */
77 is_shader_inout(ir_variable
*var
)
79 return var
->data
.mode
== ir_var_shader_in
||
80 var
->data
.mode
== ir_var_shader_out
||
81 var
->data
.mode
== ir_var_system_value
;
85 mark(struct gl_program
*prog
, ir_variable
*var
, int offset
, int len
,
86 bool is_fragment_shader
)
88 /* As of GLSL 1.20, varyings can only be floats, floating-point
89 * vectors or matrices, or arrays of them. For Mesa programs using
90 * InputsRead/OutputsWritten, everything but matrices uses one
91 * slot, while matrices use a slot per column. Presumably
92 * something doing a more clever packing would use something other
93 * than InputsRead/OutputsWritten.
96 for (int i
= 0; i
< len
; i
++) {
97 GLbitfield64 bitfield
=
98 BITFIELD64_BIT(var
->data
.location
+ var
->data
.index
+ offset
+ i
);
99 if (var
->data
.mode
== ir_var_shader_in
) {
100 prog
->InputsRead
|= bitfield
;
101 if (is_fragment_shader
) {
102 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
103 fprog
->InterpQualifier
[var
->data
.location
+
104 var
->data
.index
+ offset
+ i
] =
105 (glsl_interp_qualifier
) var
->data
.interpolation
;
106 if (var
->data
.centroid
)
107 fprog
->IsCentroid
|= bitfield
;
108 if (var
->data
.sample
)
109 fprog
->IsSample
|= bitfield
;
111 } else if (var
->data
.mode
== ir_var_system_value
) {
112 prog
->SystemValuesRead
|= bitfield
;
114 assert(var
->data
.mode
== ir_var_shader_out
);
115 prog
->OutputsWritten
|= bitfield
;
121 * Mark an entire variable as used. Caller must ensure that the variable
122 * represents a shader input or output.
125 ir_set_program_inouts_visitor::mark_whole_variable(ir_variable
*var
)
127 const glsl_type
*type
= var
->type
;
128 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
129 var
->data
.mode
== ir_var_shader_in
&& type
->is_array()) {
130 type
= type
->fields
.array
;
133 mark(this->prog
, var
, 0, type
->count_attribute_slots(),
134 this->shader_stage
== MESA_SHADER_FRAGMENT
);
137 /* Default handler: Mark all the locations in the variable as used. */
139 ir_set_program_inouts_visitor::visit(ir_dereference_variable
*ir
)
141 if (!is_shader_inout(ir
->var
))
142 return visit_continue
;
144 mark_whole_variable(ir
->var
);
146 return visit_continue
;
150 * Try to mark a portion of the given variable as used. Caller must ensure
151 * that the variable represents a shader input or output which can be indexed
152 * into in array fashion (an array or matrix). For the purpose of geometry
153 * shader inputs (which are always arrays*), this means that the array element
154 * must be something that can be indexed into in array fashion.
156 * *Except gl_PrimitiveIDIn, as noted below.
158 * If the index can't be interpreted as a constant, or some other problem
159 * occurs, then nothing will be marked and false will be returned.
162 ir_set_program_inouts_visitor::try_mark_partial_variable(ir_variable
*var
,
165 const glsl_type
*type
= var
->type
;
167 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
168 var
->data
.mode
== ir_var_shader_in
) {
169 /* The only geometry shader input that is not an array is
170 * gl_PrimitiveIDIn, and in that case, this code will never be reached,
171 * because gl_PrimitiveIDIn can't be indexed into in array fashion.
173 assert(type
->is_array());
174 type
= type
->fields
.array
;
177 /* The code below only handles:
179 * - Indexing into matrices
180 * - Indexing into arrays of (matrices, vectors, or scalars)
182 * All other possibilities are either prohibited by GLSL (vertex inputs and
183 * fragment outputs can't be structs) or should have been eliminated by
184 * lowering passes (do_vec_index_to_swizzle() gets rid of indexing into
185 * vectors, and lower_packed_varyings() gets rid of structs that occur in
188 if (!(type
->is_matrix() ||
190 (type
->fields
.array
->is_numeric() ||
191 type
->fields
.array
->is_boolean())))) {
192 assert(!"Unexpected indexing in ir_set_program_inouts");
194 /* For safety in release builds, in case we ever encounter unexpected
195 * indexing, give up and let the caller mark the whole variable as used.
200 ir_constant
*index_as_constant
= index
->as_constant();
201 if (!index_as_constant
)
206 if (type
->is_array()) {
207 num_elems
= type
->length
;
208 if (type
->fields
.array
->is_matrix())
209 elem_width
= type
->fields
.array
->matrix_columns
;
213 num_elems
= type
->matrix_columns
;
217 if (index_as_constant
->value
.u
[0] >= num_elems
) {
218 /* Constant index outside the bounds of the matrix/array. This could
219 * arise as a result of constant folding of a legal GLSL program.
221 * Even though the spec says that indexing outside the bounds of a
222 * matrix/array results in undefined behaviour, we don't want to pass
223 * out-of-range values to mark() (since this could result in slots that
224 * don't exist being marked as used), so just let the caller mark the
225 * whole variable as used.
230 mark(this->prog
, var
, index_as_constant
->value
.u
[0] * elem_width
,
231 elem_width
, this->shader_stage
== MESA_SHADER_FRAGMENT
);
236 ir_set_program_inouts_visitor::visit_enter(ir_dereference_array
*ir
)
238 /* Note: for geometry shader inputs, lower_named_interface_blocks may
239 * create 2D arrays, so we need to be able to handle those. 2D arrays
240 * shouldn't be able to crop up for any other reason.
242 if (ir_dereference_array
* const inner_array
=
243 ir
->array
->as_dereference_array()) {
245 * inner_array => foo[i]
247 if (ir_dereference_variable
* const deref_var
=
248 inner_array
->array
->as_dereference_variable()) {
249 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
250 deref_var
->var
->data
.mode
== ir_var_shader_in
) {
251 /* foo is a geometry shader input, so i is the vertex, and j the
252 * part of the input we're accessing.
254 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
256 /* We've now taken care of foo and j, but i might contain a
257 * subexpression that accesses shader inputs. So manually
258 * visit i and then continue with the parent.
260 inner_array
->array_index
->accept(this);
261 return visit_continue_with_parent
;
265 } else if (ir_dereference_variable
* const deref_var
=
266 ir
->array
->as_dereference_variable()) {
267 /* ir => foo[i], where foo is a variable. */
268 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
269 deref_var
->var
->data
.mode
== ir_var_shader_in
) {
270 /* foo is a geometry shader input, so i is the vertex, and we're
271 * accessing the entire input.
273 mark_whole_variable(deref_var
->var
);
274 /* We've now taken care of foo, but i might contain a subexpression
275 * that accesses shader inputs. So manually visit i and then
276 * continue with the parent.
278 ir
->array_index
->accept(this);
279 return visit_continue_with_parent
;
280 } else if (is_shader_inout(deref_var
->var
)) {
281 /* foo is a shader input/output, but not a geometry shader input,
282 * so i is the part of the input we're accessing.
284 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
285 return visit_continue_with_parent
;
289 /* The expression is something we don't recognize. Just visit its
292 return visit_continue
;
296 ir_set_program_inouts_visitor::visit_enter(ir_function_signature
*ir
)
298 /* We don't want to descend into the function parameters and
299 * consider them as shader inputs or outputs.
301 visit_list_elements(this, &ir
->body
);
302 return visit_continue_with_parent
;
306 ir_set_program_inouts_visitor::visit_enter(ir_expression
*ir
)
308 if (this->shader_stage
== MESA_SHADER_FRAGMENT
&&
309 ir
->operation
== ir_unop_dFdy
) {
310 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
311 fprog
->UsesDFdy
= true;
313 return visit_continue
;
317 ir_set_program_inouts_visitor::visit_enter(ir_discard
*)
319 /* discards are only allowed in fragment shaders. */
320 assert(this->shader_stage
== MESA_SHADER_FRAGMENT
);
322 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
323 fprog
->UsesKill
= true;
325 return visit_continue
;
329 ir_set_program_inouts_visitor::visit_enter(ir_texture
*ir
)
331 if (ir
->op
== ir_tg4
)
332 prog
->UsesGather
= true;
333 return visit_continue
;
337 do_set_program_inouts(exec_list
*instructions
, struct gl_program
*prog
,
338 gl_shader_stage shader_stage
)
340 ir_set_program_inouts_visitor
v(prog
, shader_stage
);
342 prog
->InputsRead
= 0;
343 prog
->OutputsWritten
= 0;
344 prog
->SystemValuesRead
= 0;
345 if (shader_stage
== MESA_SHADER_FRAGMENT
) {
346 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
347 memset(fprog
->InterpQualifier
, 0, sizeof(fprog
->InterpQualifier
));
348 fprog
->IsCentroid
= 0;
350 fprog
->UsesDFdy
= false;
351 fprog
->UsesKill
= false;
353 visit_list_elements(&v
, instructions
);