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25 #include "ir_visitor.h"
26 #include "ir_optimization.h"
29 * Pre-linking, optimize unused built-in variables
31 * Uniforms, constants, system values, inputs (vertex shader only), and
32 * outputs (fragment shader only) that are not used can be removed.
35 optimize_dead_builtin_variables(exec_list
*instructions
,
36 enum ir_variable_mode other
)
38 foreach_in_list_safe(ir_variable
, var
, instructions
) {
39 if (var
->ir_type
!= ir_type_variable
|| var
->data
.used
)
42 if (var
->data
.mode
!= ir_var_uniform
43 && var
->data
.mode
!= ir_var_auto
44 && var
->data
.mode
!= ir_var_system_value
45 && var
->data
.mode
!= other
)
48 /* So that linker rules can later be enforced, we cannot elimate
49 * variables that were redeclared in the shader code.
51 if ((var
->data
.mode
== other
|| var
->data
.mode
== ir_var_system_value
)
52 && var
->data
.how_declared
!= ir_var_declared_implicitly
)
55 if (!is_gl_identifier(var
->name
))
58 /* gl_ModelViewProjectionMatrix and gl_Vertex are special because they
59 * are used by ftransform. No other built-in variable is used by a
60 * built-in function. The forward declarations of these variables in
61 * the built-in function shader does not have the "state slot"
62 * information, so removing these variables from the user shader will
63 * cause problems later.
65 * Matrix uniforms with "Transpose" are not eliminated because there's
66 * an optimization pass that can turn references to the regular matrix
67 * into references to the transpose matrix. Eliminating the transpose
68 * matrix would cause that pass to generate references to undeclareds
69 * variables (thank you, ir_validate).
71 * It doesn't seem worth the effort to track when the transpose could be
72 * eliminated (i.e., when the non-transpose was eliminated).
74 if (strcmp(var
->name
, "gl_ModelViewProjectionMatrix") == 0
75 || strcmp(var
->name
, "gl_Vertex") == 0
76 || strstr(var
->name
, "Transpose") != NULL
)