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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 bool is_patch_generic
= var
->data
.patch
&&
107 idx
!= VARYING_SLOT_TESS_LEVEL_INNER
&&
108 idx
!= VARYING_SLOT_TESS_LEVEL_OUTER
;
109 GLbitfield64 bitfield
;
111 if (is_patch_generic
) {
112 assert(idx
>= VARYING_SLOT_PATCH0
&& idx
< VARYING_SLOT_TESS_MAX
);
113 bitfield
= BITFIELD64_BIT(idx
- VARYING_SLOT_PATCH0
);
116 assert(idx
< VARYING_SLOT_MAX
);
117 bitfield
= BITFIELD64_BIT(idx
);
120 if (var
->data
.mode
== ir_var_shader_in
) {
121 if (is_patch_generic
)
122 prog
->PatchInputsRead
|= bitfield
;
124 prog
->InputsRead
|= bitfield
;
127 prog
->DoubleInputsRead
|= bitfield
;
128 if (is_fragment_shader
) {
129 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
130 fprog
->InterpQualifier
[idx
] =
131 (glsl_interp_qualifier
) var
->data
.interpolation
;
132 if (var
->data
.centroid
)
133 fprog
->IsCentroid
|= bitfield
;
134 if (var
->data
.sample
)
135 fprog
->IsSample
|= bitfield
;
137 } else if (var
->data
.mode
== ir_var_system_value
) {
138 prog
->SystemValuesRead
|= bitfield
;
140 assert(var
->data
.mode
== ir_var_shader_out
);
141 if (is_patch_generic
)
142 prog
->PatchOutputsWritten
|= bitfield
;
144 prog
->OutputsWritten
|= bitfield
;
150 * Mark an entire variable as used. Caller must ensure that the variable
151 * represents a shader input or output.
154 ir_set_program_inouts_visitor::mark_whole_variable(ir_variable
*var
)
156 const glsl_type
*type
= var
->type
;
157 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
158 var
->data
.mode
== ir_var_shader_in
&& type
->is_array()) {
159 type
= type
->fields
.array
;
162 if (this->shader_stage
== MESA_SHADER_TESS_CTRL
&&
163 var
->data
.mode
== ir_var_shader_in
) {
164 assert(type
->is_array());
165 type
= type
->fields
.array
;
168 if (this->shader_stage
== MESA_SHADER_TESS_CTRL
&&
169 var
->data
.mode
== ir_var_shader_out
&& !var
->data
.patch
) {
170 assert(type
->is_array());
171 type
= type
->fields
.array
;
174 if (this->shader_stage
== MESA_SHADER_TESS_EVAL
&&
175 var
->data
.mode
== ir_var_shader_in
&& !var
->data
.patch
) {
176 assert(type
->is_array());
177 type
= type
->fields
.array
;
180 mark(this->prog
, var
, 0, type
->count_attribute_slots(),
181 this->shader_stage
== MESA_SHADER_FRAGMENT
);
184 /* Default handler: Mark all the locations in the variable as used. */
186 ir_set_program_inouts_visitor::visit(ir_dereference_variable
*ir
)
188 if (!is_shader_inout(ir
->var
))
189 return visit_continue
;
191 mark_whole_variable(ir
->var
);
193 return visit_continue
;
197 * Try to mark a portion of the given variable as used. Caller must ensure
198 * that the variable represents a shader input or output which can be indexed
199 * into in array fashion (an array or matrix). For the purpose of geometry
200 * shader inputs (which are always arrays*), this means that the array element
201 * must be something that can be indexed into in array fashion.
203 * *Except gl_PrimitiveIDIn, as noted below.
205 * For tessellation control shaders all inputs and non-patch outputs are
206 * arrays. For tessellation evaluation shaders non-patch inputs are arrays.
208 * If the index can't be interpreted as a constant, or some other problem
209 * occurs, then nothing will be marked and false will be returned.
212 ir_set_program_inouts_visitor::try_mark_partial_variable(ir_variable
*var
,
215 const glsl_type
*type
= var
->type
;
217 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
218 var
->data
.mode
== ir_var_shader_in
) {
219 /* The only geometry shader input that is not an array is
220 * gl_PrimitiveIDIn, and in that case, this code will never be reached,
221 * because gl_PrimitiveIDIn can't be indexed into in array fashion.
223 assert(type
->is_array());
224 type
= type
->fields
.array
;
227 if (this->shader_stage
== MESA_SHADER_TESS_CTRL
&&
228 var
->data
.mode
== ir_var_shader_in
) {
229 assert(type
->is_array());
230 type
= type
->fields
.array
;
233 if (this->shader_stage
== MESA_SHADER_TESS_CTRL
&&
234 var
->data
.mode
== ir_var_shader_out
&& !var
->data
.patch
) {
235 assert(type
->is_array());
236 type
= type
->fields
.array
;
239 if (this->shader_stage
== MESA_SHADER_TESS_EVAL
&&
240 var
->data
.mode
== ir_var_shader_in
&& !var
->data
.patch
) {
241 assert(type
->is_array());
242 type
= type
->fields
.array
;
245 /* The code below only handles:
247 * - Indexing into matrices
248 * - Indexing into arrays of (matrices, vectors, or scalars)
250 * All other possibilities are either prohibited by GLSL (vertex inputs and
251 * fragment outputs can't be structs) or should have been eliminated by
252 * lowering passes (do_vec_index_to_swizzle() gets rid of indexing into
253 * vectors, and lower_packed_varyings() gets rid of structs that occur in
256 if (!(type
->is_matrix() ||
258 (type
->fields
.array
->is_numeric() ||
259 type
->fields
.array
->is_boolean())))) {
260 assert(!"Unexpected indexing in ir_set_program_inouts");
262 /* For safety in release builds, in case we ever encounter unexpected
263 * indexing, give up and let the caller mark the whole variable as used.
268 ir_constant
*index_as_constant
= index
->as_constant();
269 if (!index_as_constant
)
274 if (type
->is_array()) {
275 num_elems
= type
->length
;
276 if (type
->fields
.array
->is_matrix())
277 elem_width
= type
->fields
.array
->matrix_columns
;
281 num_elems
= type
->matrix_columns
;
285 if (index_as_constant
->value
.u
[0] >= num_elems
) {
286 /* Constant index outside the bounds of the matrix/array. This could
287 * arise as a result of constant folding of a legal GLSL program.
289 * Even though the spec says that indexing outside the bounds of a
290 * matrix/array results in undefined behaviour, we don't want to pass
291 * out-of-range values to mark() (since this could result in slots that
292 * don't exist being marked as used), so just let the caller mark the
293 * whole variable as used.
298 mark(this->prog
, var
, index_as_constant
->value
.u
[0] * elem_width
,
299 elem_width
, this->shader_stage
== MESA_SHADER_FRAGMENT
);
304 is_multiple_vertices(gl_shader_stage stage
, ir_variable
*var
)
309 if (var
->data
.mode
== ir_var_shader_in
)
310 return stage
== MESA_SHADER_GEOMETRY
||
311 stage
== MESA_SHADER_TESS_CTRL
||
312 stage
== MESA_SHADER_TESS_EVAL
;
313 if (var
->data
.mode
== ir_var_shader_out
)
314 return stage
== MESA_SHADER_TESS_CTRL
;
320 ir_set_program_inouts_visitor::visit_enter(ir_dereference_array
*ir
)
322 /* Note: for geometry shader inputs, lower_named_interface_blocks may
323 * create 2D arrays, so we need to be able to handle those. 2D arrays
324 * shouldn't be able to crop up for any other reason.
326 if (ir_dereference_array
* const inner_array
=
327 ir
->array
->as_dereference_array()) {
329 * inner_array => foo[i]
331 if (ir_dereference_variable
* const deref_var
=
332 inner_array
->array
->as_dereference_variable()) {
333 if (is_multiple_vertices(this->shader_stage
, deref_var
->var
)) {
334 /* foo is a geometry or tessellation shader input, so i is
335 * the vertex, and j the part of the input we're accessing.
337 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
339 /* We've now taken care of foo and j, but i might contain a
340 * subexpression that accesses shader inputs. So manually
341 * visit i and then continue with the parent.
343 inner_array
->array_index
->accept(this);
344 return visit_continue_with_parent
;
348 } else if (ir_dereference_variable
* const deref_var
=
349 ir
->array
->as_dereference_variable()) {
350 /* ir => foo[i], where foo is a variable. */
351 if (is_multiple_vertices(this->shader_stage
, deref_var
->var
)) {
352 /* foo is a geometry or tessellation shader input, so i is
353 * the vertex, and we're accessing the entire input.
355 mark_whole_variable(deref_var
->var
);
356 /* We've now taken care of foo, but i might contain a subexpression
357 * that accesses shader inputs. So manually visit i and then
358 * continue with the parent.
360 ir
->array_index
->accept(this);
361 return visit_continue_with_parent
;
362 } else if (is_shader_inout(deref_var
->var
)) {
363 /* foo is a shader input/output, but not a geometry shader input,
364 * so i is the part of the input we're accessing.
366 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
367 return visit_continue_with_parent
;
371 /* The expression is something we don't recognize. Just visit its
374 return visit_continue
;
378 ir_set_program_inouts_visitor::visit_enter(ir_function_signature
*ir
)
380 /* We don't want to descend into the function parameters and
381 * consider them as shader inputs or outputs.
383 visit_list_elements(this, &ir
->body
);
384 return visit_continue_with_parent
;
388 ir_set_program_inouts_visitor::visit_enter(ir_expression
*ir
)
390 if (this->shader_stage
== MESA_SHADER_FRAGMENT
&&
391 (ir
->operation
== ir_unop_dFdy
||
392 ir
->operation
== ir_unop_dFdy_coarse
||
393 ir
->operation
== ir_unop_dFdy_fine
)) {
394 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
395 fprog
->UsesDFdy
= true;
397 return visit_continue
;
401 ir_set_program_inouts_visitor::visit_enter(ir_discard
*)
403 /* discards are only allowed in fragment shaders. */
404 assert(this->shader_stage
== MESA_SHADER_FRAGMENT
);
406 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
407 fprog
->UsesKill
= true;
409 return visit_continue
;
413 ir_set_program_inouts_visitor::visit_enter(ir_texture
*ir
)
415 if (ir
->op
== ir_tg4
)
416 prog
->UsesGather
= true;
417 return visit_continue
;
421 do_set_program_inouts(exec_list
*instructions
, struct gl_program
*prog
,
422 gl_shader_stage shader_stage
)
424 ir_set_program_inouts_visitor
v(prog
, shader_stage
);
426 prog
->InputsRead
= 0;
427 prog
->OutputsWritten
= 0;
428 prog
->PatchInputsRead
= 0;
429 prog
->PatchOutputsWritten
= 0;
430 prog
->SystemValuesRead
= 0;
431 if (shader_stage
== MESA_SHADER_FRAGMENT
) {
432 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
433 memset(fprog
->InterpQualifier
, 0, sizeof(fprog
->InterpQualifier
));
434 fprog
->IsCentroid
= 0;
436 fprog
->UsesDFdy
= false;
437 fprog
->UsesKill
= false;
439 visit_list_elements(&v
, instructions
);