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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
, GLenum shader_type
)
52 this->shader_type
= shader_type
;
54 ~ir_set_program_inouts_visitor()
58 virtual ir_visitor_status
visit_enter(ir_dereference_array
*);
59 virtual ir_visitor_status
visit_enter(ir_function_signature
*);
60 virtual ir_visitor_status
visit_enter(ir_expression
*);
61 virtual ir_visitor_status
visit_enter(ir_discard
*);
62 virtual ir_visitor_status
visit_enter(ir_texture
*);
63 virtual ir_visitor_status
visit(ir_dereference_variable
*);
66 void mark_whole_variable(ir_variable
*var
);
67 bool try_mark_partial_variable(ir_variable
*var
, ir_rvalue
*index
);
69 struct gl_program
*prog
;
73 } /* anonymous namespace */
76 is_shader_inout(ir_variable
*var
)
78 return var
->mode
== ir_var_shader_in
||
79 var
->mode
== ir_var_shader_out
||
80 var
->mode
== ir_var_system_value
;
84 mark(struct gl_program
*prog
, ir_variable
*var
, int offset
, int len
,
85 bool is_fragment_shader
)
87 /* As of GLSL 1.20, varyings can only be floats, floating-point
88 * vectors or matrices, or arrays of them. For Mesa programs using
89 * InputsRead/OutputsWritten, everything but matrices uses one
90 * slot, while matrices use a slot per column. Presumably
91 * something doing a more clever packing would use something other
92 * than InputsRead/OutputsWritten.
95 for (int i
= 0; i
< len
; i
++) {
96 GLbitfield64 bitfield
= BITFIELD64_BIT(var
->location
+ var
->index
+ offset
+ i
);
97 if (var
->mode
== ir_var_shader_in
) {
98 prog
->InputsRead
|= bitfield
;
99 if (is_fragment_shader
) {
100 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
101 fprog
->InterpQualifier
[var
->location
+ var
->index
+ offset
+ i
] =
102 (glsl_interp_qualifier
) var
->interpolation
;
104 fprog
->IsCentroid
|= bitfield
;
106 fprog
->IsSample
|= bitfield
;
108 } else if (var
->mode
== ir_var_system_value
) {
109 prog
->SystemValuesRead
|= bitfield
;
111 assert(var
->mode
== ir_var_shader_out
);
112 prog
->OutputsWritten
|= bitfield
;
118 * Mark an entire variable as used. Caller must ensure that the variable
119 * represents a shader input or output.
122 ir_set_program_inouts_visitor::mark_whole_variable(ir_variable
*var
)
124 const glsl_type
*type
= var
->type
;
125 if (this->shader_type
== GL_GEOMETRY_SHADER
&&
126 var
->mode
== ir_var_shader_in
&& type
->is_array()) {
127 type
= type
->fields
.array
;
130 mark(this->prog
, var
, 0, type
->count_attribute_slots(),
131 this->shader_type
== GL_FRAGMENT_SHADER
);
134 /* Default handler: Mark all the locations in the variable as used. */
136 ir_set_program_inouts_visitor::visit(ir_dereference_variable
*ir
)
138 if (!is_shader_inout(ir
->var
))
139 return visit_continue
;
141 mark_whole_variable(ir
->var
);
143 return visit_continue
;
147 * Try to mark a portion of the given variable as used. Caller must ensure
148 * that the variable represents a shader input or output which can be indexed
149 * into in array fashion (an array or matrix). For the purpose of geometry
150 * shader inputs (which are always arrays*), this means that the array element
151 * must be something that can be indexed into in array fashion.
153 * *Except gl_PrimitiveIDIn, as noted below.
155 * If the index can't be interpreted as a constant, or some other problem
156 * occurs, then nothing will be marked and false will be returned.
159 ir_set_program_inouts_visitor::try_mark_partial_variable(ir_variable
*var
,
162 const glsl_type
*type
= var
->type
;
164 if (this->shader_type
== GL_GEOMETRY_SHADER
&&
165 var
->mode
== ir_var_shader_in
) {
166 /* The only geometry shader input that is not an array is
167 * gl_PrimitiveIDIn, and in that case, this code will never be reached,
168 * because gl_PrimitiveIDIn can't be indexed into in array fashion.
170 assert(type
->is_array());
171 type
= type
->fields
.array
;
174 /* The code below only handles:
176 * - Indexing into matrices
177 * - Indexing into arrays of (matrices, vectors, or scalars)
179 * All other possibilities are either prohibited by GLSL (vertex inputs and
180 * fragment outputs can't be structs) or should have been eliminated by
181 * lowering passes (do_vec_index_to_swizzle() gets rid of indexing into
182 * vectors, and lower_packed_varyings() gets rid of structs that occur in
185 if (!(type
->is_matrix() ||
187 (type
->fields
.array
->is_numeric() ||
188 type
->fields
.array
->is_boolean())))) {
189 assert(!"Unexpected indexing in ir_set_program_inouts");
191 /* For safety in release builds, in case we ever encounter unexpected
192 * indexing, give up and let the caller mark the whole variable as used.
197 ir_constant
*index_as_constant
= index
->as_constant();
198 if (!index_as_constant
)
203 if (type
->is_array()) {
204 num_elems
= type
->length
;
205 if (type
->fields
.array
->is_matrix())
206 elem_width
= type
->fields
.array
->matrix_columns
;
210 num_elems
= type
->matrix_columns
;
214 if (index_as_constant
->value
.u
[0] >= num_elems
) {
215 /* Constant index outside the bounds of the matrix/array. This could
216 * arise as a result of constant folding of a legal GLSL program.
218 * Even though the spec says that indexing outside the bounds of a
219 * matrix/array results in undefined behaviour, we don't want to pass
220 * out-of-range values to mark() (since this could result in slots that
221 * don't exist being marked as used), so just let the caller mark the
222 * whole variable as used.
227 mark(this->prog
, var
, index_as_constant
->value
.u
[0] * elem_width
,
228 elem_width
, this->shader_type
== GL_FRAGMENT_SHADER
);
233 ir_set_program_inouts_visitor::visit_enter(ir_dereference_array
*ir
)
235 /* Note: for geometry shader inputs, lower_named_interface_blocks may
236 * create 2D arrays, so we need to be able to handle those. 2D arrays
237 * shouldn't be able to crop up for any other reason.
239 if (ir_dereference_array
* const inner_array
=
240 ir
->array
->as_dereference_array()) {
242 * inner_array => foo[i]
244 if (ir_dereference_variable
* const deref_var
=
245 inner_array
->array
->as_dereference_variable()) {
246 if (this->shader_type
== GL_GEOMETRY_SHADER
&&
247 deref_var
->var
->mode
== ir_var_shader_in
) {
248 /* foo is a geometry shader input, so i is the vertex, and j the
249 * part of the input we're accessing.
251 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
253 /* We've now taken care of foo and j, but i might contain a
254 * subexpression that accesses shader inputs. So manually
255 * visit i and then continue with the parent.
257 inner_array
->array_index
->accept(this);
258 return visit_continue_with_parent
;
262 } else if (ir_dereference_variable
* const deref_var
=
263 ir
->array
->as_dereference_variable()) {
264 /* ir => foo[i], where foo is a variable. */
265 if (this->shader_type
== GL_GEOMETRY_SHADER
&&
266 deref_var
->var
->mode
== ir_var_shader_in
) {
267 /* foo is a geometry shader input, so i is the vertex, and we're
268 * accessing the entire input.
270 mark_whole_variable(deref_var
->var
);
271 /* We've now taken care of foo, but i might contain a subexpression
272 * that accesses shader inputs. So manually visit i and then
273 * continue with the parent.
275 ir
->array_index
->accept(this);
276 return visit_continue_with_parent
;
277 } else if (is_shader_inout(deref_var
->var
)) {
278 /* foo is a shader input/output, but not a geometry shader input,
279 * so i is the part of the input we're accessing.
281 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
282 return visit_continue_with_parent
;
286 /* The expression is something we don't recognize. Just visit its
289 return visit_continue
;
293 ir_set_program_inouts_visitor::visit_enter(ir_function_signature
*ir
)
295 /* We don't want to descend into the function parameters and
296 * consider them as shader inputs or outputs.
298 visit_list_elements(this, &ir
->body
);
299 return visit_continue_with_parent
;
303 ir_set_program_inouts_visitor::visit_enter(ir_expression
*ir
)
305 if (this->shader_type
== GL_FRAGMENT_SHADER
&&
306 ir
->operation
== ir_unop_dFdy
) {
307 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
308 fprog
->UsesDFdy
= true;
310 return visit_continue
;
314 ir_set_program_inouts_visitor::visit_enter(ir_discard
*)
316 /* discards are only allowed in fragment shaders. */
317 assert(this->shader_type
== GL_FRAGMENT_SHADER
);
319 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
320 fprog
->UsesKill
= true;
322 return visit_continue
;
326 ir_set_program_inouts_visitor::visit_enter(ir_texture
*ir
)
328 if (ir
->op
== ir_tg4
)
329 prog
->UsesGather
= true;
330 return visit_continue
;
334 do_set_program_inouts(exec_list
*instructions
, struct gl_program
*prog
,
337 ir_set_program_inouts_visitor
v(prog
, shader_type
);
339 prog
->InputsRead
= 0;
340 prog
->OutputsWritten
= 0;
341 prog
->SystemValuesRead
= 0;
342 if (shader_type
== GL_FRAGMENT_SHADER
) {
343 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
344 memset(fprog
->InterpQualifier
, 0, sizeof(fprog
->InterpQualifier
));
345 fprog
->IsCentroid
= 0;
347 fprog
->UsesDFdy
= false;
348 fprog
->UsesKill
= false;
350 visit_list_elements(&v
, instructions
);