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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 gl_shader_stage stage
)
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 int idx
= var
->data
.location
+ var
->data
.index
+ offset
+ i
;
98 bool is_patch_generic
= var
->data
.patch
&&
99 idx
!= VARYING_SLOT_TESS_LEVEL_INNER
&&
100 idx
!= VARYING_SLOT_TESS_LEVEL_OUTER
;
101 GLbitfield64 bitfield
;
103 if (is_patch_generic
) {
104 assert(idx
>= VARYING_SLOT_PATCH0
&& idx
< VARYING_SLOT_TESS_MAX
);
105 bitfield
= BITFIELD64_BIT(idx
- VARYING_SLOT_PATCH0
);
108 assert(idx
< VARYING_SLOT_MAX
);
109 bitfield
= BITFIELD64_BIT(idx
);
112 if (var
->data
.mode
== ir_var_shader_in
) {
113 if (is_patch_generic
)
114 prog
->PatchInputsRead
|= bitfield
;
116 prog
->InputsRead
|= bitfield
;
118 /* double inputs read is only for vertex inputs */
119 if (stage
== MESA_SHADER_VERTEX
&&
120 var
->type
->without_array()->is_dual_slot_double())
121 prog
->DoubleInputsRead
|= bitfield
;
123 if (stage
== MESA_SHADER_FRAGMENT
) {
124 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
125 fprog
->InterpQualifier
[idx
] =
126 (glsl_interp_qualifier
) var
->data
.interpolation
;
127 if (var
->data
.centroid
)
128 fprog
->IsCentroid
|= bitfield
;
129 if (var
->data
.sample
)
130 fprog
->IsSample
|= bitfield
;
132 } else if (var
->data
.mode
== ir_var_system_value
) {
133 prog
->SystemValuesRead
|= bitfield
;
135 assert(var
->data
.mode
== ir_var_shader_out
);
136 if (is_patch_generic
)
137 prog
->PatchOutputsWritten
|= bitfield
;
139 prog
->OutputsWritten
|= bitfield
;
145 * Mark an entire variable as used. Caller must ensure that the variable
146 * represents a shader input or output.
149 ir_set_program_inouts_visitor::mark_whole_variable(ir_variable
*var
)
151 const glsl_type
*type
= var
->type
;
152 bool vertex_input
= false;
153 if (this->shader_stage
== MESA_SHADER_GEOMETRY
&&
154 var
->data
.mode
== ir_var_shader_in
&& type
->is_array()) {
155 type
= type
->fields
.array
;
158 if (this->shader_stage
== MESA_SHADER_TESS_CTRL
&&
159 var
->data
.mode
== ir_var_shader_in
) {
160 assert(type
->is_array());
161 type
= type
->fields
.array
;
164 if (this->shader_stage
== MESA_SHADER_TESS_CTRL
&&
165 var
->data
.mode
== ir_var_shader_out
&& !var
->data
.patch
) {
166 assert(type
->is_array());
167 type
= type
->fields
.array
;
170 if (this->shader_stage
== MESA_SHADER_TESS_EVAL
&&
171 var
->data
.mode
== ir_var_shader_in
&& !var
->data
.patch
) {
172 assert(type
->is_array());
173 type
= type
->fields
.array
;
176 if (this->shader_stage
== MESA_SHADER_VERTEX
&&
177 var
->data
.mode
== ir_var_shader_in
)
180 mark(this->prog
, var
, 0, type
->count_attribute_slots(vertex_input
),
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 /* TODO: implement proper arrays of arrays support
246 * for now let the caller mark whole variable as used.
248 if (type
->is_array() && type
->fields
.array
->is_array())
251 /* The code below only handles:
253 * - Indexing into matrices
254 * - Indexing into arrays of (matrices, vectors, or scalars)
256 * All other possibilities are either prohibited by GLSL (vertex inputs and
257 * fragment outputs can't be structs) or should have been eliminated by
258 * lowering passes (do_vec_index_to_swizzle() gets rid of indexing into
259 * vectors, and lower_packed_varyings() gets rid of structs that occur in
262 if (!(type
->is_matrix() ||
264 (type
->fields
.array
->is_numeric() ||
265 type
->fields
.array
->is_boolean())))) {
266 assert(!"Unexpected indexing in ir_set_program_inouts");
268 /* For safety in release builds, in case we ever encounter unexpected
269 * indexing, give up and let the caller mark the whole variable as used.
274 ir_constant
*index_as_constant
= index
->as_constant();
275 if (!index_as_constant
)
280 if (type
->is_array()) {
281 num_elems
= type
->length
;
282 if (type
->fields
.array
->is_matrix())
283 elem_width
= type
->fields
.array
->matrix_columns
;
287 num_elems
= type
->matrix_columns
;
291 if (index_as_constant
->value
.u
[0] >= num_elems
) {
292 /* Constant index outside the bounds of the matrix/array. This could
293 * arise as a result of constant folding of a legal GLSL program.
295 * Even though the spec says that indexing outside the bounds of a
296 * matrix/array results in undefined behaviour, we don't want to pass
297 * out-of-range values to mark() (since this could result in slots that
298 * don't exist being marked as used), so just let the caller mark the
299 * whole variable as used.
304 /* double element width for double types that takes two slots */
305 if (this->shader_stage
!= MESA_SHADER_VERTEX
||
306 var
->data
.mode
!= ir_var_shader_in
) {
307 if (type
->without_array()->is_dual_slot_double())
311 mark(this->prog
, var
, index_as_constant
->value
.u
[0] * elem_width
,
312 elem_width
, this->shader_stage
);
317 is_multiple_vertices(gl_shader_stage stage
, ir_variable
*var
)
322 if (var
->data
.mode
== ir_var_shader_in
)
323 return stage
== MESA_SHADER_GEOMETRY
||
324 stage
== MESA_SHADER_TESS_CTRL
||
325 stage
== MESA_SHADER_TESS_EVAL
;
326 if (var
->data
.mode
== ir_var_shader_out
)
327 return stage
== MESA_SHADER_TESS_CTRL
;
333 ir_set_program_inouts_visitor::visit_enter(ir_dereference_array
*ir
)
335 /* Note: for geometry shader inputs, lower_named_interface_blocks may
336 * create 2D arrays, so we need to be able to handle those. 2D arrays
337 * shouldn't be able to crop up for any other reason.
339 if (ir_dereference_array
* const inner_array
=
340 ir
->array
->as_dereference_array()) {
342 * inner_array => foo[i]
344 if (ir_dereference_variable
* const deref_var
=
345 inner_array
->array
->as_dereference_variable()) {
346 if (is_multiple_vertices(this->shader_stage
, deref_var
->var
)) {
347 /* foo is a geometry or tessellation shader input, so i is
348 * the vertex, and j the part of the input we're accessing.
350 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
352 /* We've now taken care of foo and j, but i might contain a
353 * subexpression that accesses shader inputs. So manually
354 * visit i and then continue with the parent.
356 inner_array
->array_index
->accept(this);
357 return visit_continue_with_parent
;
361 } else if (ir_dereference_variable
* const deref_var
=
362 ir
->array
->as_dereference_variable()) {
363 /* ir => foo[i], where foo is a variable. */
364 if (is_multiple_vertices(this->shader_stage
, deref_var
->var
)) {
365 /* foo is a geometry or tessellation shader input, so i is
366 * the vertex, and we're accessing the entire input.
368 mark_whole_variable(deref_var
->var
);
369 /* We've now taken care of foo, but i might contain a subexpression
370 * that accesses shader inputs. So manually visit i and then
371 * continue with the parent.
373 ir
->array_index
->accept(this);
374 return visit_continue_with_parent
;
375 } else if (is_shader_inout(deref_var
->var
)) {
376 /* foo is a shader input/output, but not a geometry shader input,
377 * so i is the part of the input we're accessing.
379 if (try_mark_partial_variable(deref_var
->var
, ir
->array_index
))
380 return visit_continue_with_parent
;
384 /* The expression is something we don't recognize. Just visit its
387 return visit_continue
;
391 ir_set_program_inouts_visitor::visit_enter(ir_function_signature
*ir
)
393 /* We don't want to descend into the function parameters and
394 * consider them as shader inputs or outputs.
396 visit_list_elements(this, &ir
->body
);
397 return visit_continue_with_parent
;
401 ir_set_program_inouts_visitor::visit_enter(ir_expression
*ir
)
403 if (this->shader_stage
== MESA_SHADER_FRAGMENT
&&
404 (ir
->operation
== ir_unop_dFdy
||
405 ir
->operation
== ir_unop_dFdy_coarse
||
406 ir
->operation
== ir_unop_dFdy_fine
)) {
407 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
408 fprog
->UsesDFdy
= true;
410 return visit_continue
;
414 ir_set_program_inouts_visitor::visit_enter(ir_discard
*)
416 /* discards are only allowed in fragment shaders. */
417 assert(this->shader_stage
== MESA_SHADER_FRAGMENT
);
419 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
420 fprog
->UsesKill
= true;
422 return visit_continue
;
426 ir_set_program_inouts_visitor::visit_enter(ir_texture
*ir
)
428 if (ir
->op
== ir_tg4
)
429 prog
->UsesGather
= true;
430 return visit_continue
;
434 do_set_program_inouts(exec_list
*instructions
, struct gl_program
*prog
,
435 gl_shader_stage shader_stage
)
437 ir_set_program_inouts_visitor
v(prog
, shader_stage
);
439 prog
->InputsRead
= 0;
440 prog
->OutputsWritten
= 0;
441 prog
->PatchInputsRead
= 0;
442 prog
->PatchOutputsWritten
= 0;
443 prog
->SystemValuesRead
= 0;
444 if (shader_stage
== MESA_SHADER_FRAGMENT
) {
445 gl_fragment_program
*fprog
= (gl_fragment_program
*) prog
;
446 memset(fprog
->InterpQualifier
, 0, sizeof(fprog
->InterpQualifier
));
447 fprog
->IsCentroid
= 0;
449 fprog
->UsesDFdy
= false;
450 fprog
->UsesKill
= false;
452 visit_list_elements(&v
, instructions
);