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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 is_dual_slot(ir_variable
*var
)
87 const glsl_type
*type
= var
->type
->without_array();
88 return type
== glsl_type::dvec4_type
|| type
== glsl_type::dvec3_type
;
92 mark(struct gl_program
*prog
, ir_variable
*var
, int offset
, int len
,
93 bool is_fragment_shader
)
95 /* As of GLSL 1.20, varyings can only be floats, floating-point
96 * vectors or matrices, or arrays of them. For Mesa programs using
97 * InputsRead/OutputsWritten, everything but matrices uses one
98 * slot, while matrices use a slot per column. Presumably
99 * something doing a more clever packing would use something other
100 * than InputsRead/OutputsWritten.
103 for (int i
= 0; i
< len
; i
++) {
104 bool dual_slot
= is_dual_slot(var
);
105 int idx
= var
->data
.location
+ var
->data
.index
+ offset
+ i
;
106 GLbitfield64 bitfield
= BITFIELD64_BIT(idx
);
108 if (var
->data
.mode
== ir_var_shader_in
) {
109 prog
->InputsRead
|= bitfield
;
111 prog
->DoubleInputsRead
|= bitfield
;
112 if (is_fragment_shader
) {
113 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
114 fprog
->InterpQualifier
[idx
] =
115 (glsl_interp_qualifier
) var
->data
.interpolation
;
116 if (var
->data
.centroid
)
117 fprog
->IsCentroid
|= bitfield
;
118 if (var
->data
.sample
)
119 fprog
->IsSample
|= bitfield
;
121 } else if (var
->data
.mode
== ir_var_system_value
) {
122 prog
->SystemValuesRead
|= bitfield
;
124 assert(var
->data
.mode
== ir_var_shader_out
);
125 prog
->OutputsWritten
|= bitfield
;
131 * Mark an entire variable as used. Caller must ensure that the variable
132 * represents a shader input or output.
135 ir_set_program_inouts_visitor::mark_whole_variable(ir_variable
*var
)
137 const glsl_type
*type
= var
->type
;
138 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
139 var
->data
.mode
== ir_var_shader_in
&& type
->is_array()) {
140 type
= type
->fields
.array
;
143 mark(this->prog
, var
, 0, type
->count_attribute_slots(),
144 this->shader_stage
== MESA_SHADER_FRAGMENT
);
147 /* Default handler: Mark all the locations in the variable as used. */
149 ir_set_program_inouts_visitor::visit(ir_dereference_variable
*ir
)
151 if (!is_shader_inout(ir
->var
))
152 return visit_continue
;
154 mark_whole_variable(ir
->var
);
156 return visit_continue
;
160 * Try to mark a portion of the given variable as used. Caller must ensure
161 * that the variable represents a shader input or output which can be indexed
162 * into in array fashion (an array or matrix). For the purpose of geometry
163 * shader inputs (which are always arrays*), this means that the array element
164 * must be something that can be indexed into in array fashion.
166 * *Except gl_PrimitiveIDIn, as noted below.
168 * If the index can't be interpreted as a constant, or some other problem
169 * occurs, then nothing will be marked and false will be returned.
172 ir_set_program_inouts_visitor::try_mark_partial_variable(ir_variable
*var
,
175 const glsl_type
*type
= var
->type
;
177 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
178 var
->data
.mode
== ir_var_shader_in
) {
179 /* The only geometry shader input that is not an array is
180 * gl_PrimitiveIDIn, and in that case, this code will never be reached,
181 * because gl_PrimitiveIDIn can't be indexed into in array fashion.
183 assert(type
->is_array());
184 type
= type
->fields
.array
;
187 /* The code below only handles:
189 * - Indexing into matrices
190 * - Indexing into arrays of (matrices, vectors, or scalars)
192 * All other possibilities are either prohibited by GLSL (vertex inputs and
193 * fragment outputs can't be structs) or should have been eliminated by
194 * lowering passes (do_vec_index_to_swizzle() gets rid of indexing into
195 * vectors, and lower_packed_varyings() gets rid of structs that occur in
198 if (!(type
->is_matrix() ||
200 (type
->fields
.array
->is_numeric() ||
201 type
->fields
.array
->is_boolean())))) {
202 assert(!"Unexpected indexing in ir_set_program_inouts");
204 /* For safety in release builds, in case we ever encounter unexpected
205 * indexing, give up and let the caller mark the whole variable as used.
210 ir_constant
*index_as_constant
= index
->as_constant();
211 if (!index_as_constant
)
216 if (type
->is_array()) {
217 num_elems
= type
->length
;
218 if (type
->fields
.array
->is_matrix())
219 elem_width
= type
->fields
.array
->matrix_columns
;
223 num_elems
= type
->matrix_columns
;
227 if (index_as_constant
->value
.u
[0] >= num_elems
) {
228 /* Constant index outside the bounds of the matrix/array. This could
229 * arise as a result of constant folding of a legal GLSL program.
231 * Even though the spec says that indexing outside the bounds of a
232 * matrix/array results in undefined behaviour, we don't want to pass
233 * out-of-range values to mark() (since this could result in slots that
234 * don't exist being marked as used), so just let the caller mark the
235 * whole variable as used.
240 mark(this->prog
, var
, index_as_constant
->value
.u
[0] * elem_width
,
241 elem_width
, this->shader_stage
== MESA_SHADER_FRAGMENT
);
246 ir_set_program_inouts_visitor::visit_enter(ir_dereference_array
*ir
)
248 /* Note: for geometry shader inputs, lower_named_interface_blocks may
249 * create 2D arrays, so we need to be able to handle those. 2D arrays
250 * shouldn't be able to crop up for any other reason.
252 if (ir_dereference_array
* const inner_array
=
253 ir
->array
->as_dereference_array()) {
255 * inner_array => foo[i]
257 if (ir_dereference_variable
* const deref_var
=
258 inner_array
->array
->as_dereference_variable()) {
259 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
260 deref_var
->var
->data
.mode
== ir_var_shader_in
) {
261 /* foo is a geometry shader input, so i is the vertex, and j the
262 * part of the input we're accessing.
264 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
266 /* We've now taken care of foo and j, but i might contain a
267 * subexpression that accesses shader inputs. So manually
268 * visit i and then continue with the parent.
270 inner_array
->array_index
->accept(this);
271 return visit_continue_with_parent
;
275 } else if (ir_dereference_variable
* const deref_var
=
276 ir
->array
->as_dereference_variable()) {
277 /* ir => foo[i], where foo is a variable. */
278 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
279 deref_var
->var
->data
.mode
== ir_var_shader_in
) {
280 /* foo is a geometry shader input, so i is the vertex, and we're
281 * accessing the entire input.
283 mark_whole_variable(deref_var
->var
);
284 /* We've now taken care of foo, but i might contain a subexpression
285 * that accesses shader inputs. So manually visit i and then
286 * continue with the parent.
288 ir
->array_index
->accept(this);
289 return visit_continue_with_parent
;
290 } else if (is_shader_inout(deref_var
->var
)) {
291 /* foo is a shader input/output, but not a geometry shader input,
292 * so i is the part of the input we're accessing.
294 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
295 return visit_continue_with_parent
;
299 /* The expression is something we don't recognize. Just visit its
302 return visit_continue
;
306 ir_set_program_inouts_visitor::visit_enter(ir_function_signature
*ir
)
308 /* We don't want to descend into the function parameters and
309 * consider them as shader inputs or outputs.
311 visit_list_elements(this, &ir
->body
);
312 return visit_continue_with_parent
;
316 ir_set_program_inouts_visitor::visit_enter(ir_expression
*ir
)
318 if (this->shader_stage
== MESA_SHADER_FRAGMENT
&&
319 (ir
->operation
== ir_unop_dFdy
||
320 ir
->operation
== ir_unop_dFdy_coarse
||
321 ir
->operation
== ir_unop_dFdy_fine
)) {
322 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
323 fprog
->UsesDFdy
= true;
325 return visit_continue
;
329 ir_set_program_inouts_visitor::visit_enter(ir_discard
*)
331 /* discards are only allowed in fragment shaders. */
332 assert(this->shader_stage
== MESA_SHADER_FRAGMENT
);
334 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
335 fprog
->UsesKill
= true;
337 return visit_continue
;
341 ir_set_program_inouts_visitor::visit_enter(ir_texture
*ir
)
343 if (ir
->op
== ir_tg4
)
344 prog
->UsesGather
= true;
345 return visit_continue
;
349 do_set_program_inouts(exec_list
*instructions
, struct gl_program
*prog
,
350 gl_shader_stage shader_stage
)
352 ir_set_program_inouts_visitor
v(prog
, shader_stage
);
354 prog
->InputsRead
= 0;
355 prog
->OutputsWritten
= 0;
356 prog
->SystemValuesRead
= 0;
357 if (shader_stage
== MESA_SHADER_FRAGMENT
) {
358 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
359 memset(fprog
->InterpQualifier
, 0, sizeof(fprog
->InterpQualifier
));
360 fprog
->IsCentroid
= 0;
362 fprog
->UsesDFdy
= false;
363 fprog
->UsesKill
= false;
365 visit_list_elements(&v
, instructions
);