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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 * For compute shaders, gl_GlobalInvocationID has some dependencies, so
66 * we avoid removing these dependencies.
68 * We also avoid removing gl_GlobalInvocationID at this stage because it
69 * might be used by a linked shader. In this case it still needs to be
70 * initialized by the main function.
72 * gl_GlobalInvocationID =
73 * gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID
75 * Similarly, we initialize gl_LocalInvocationIndex in the main function:
77 * gl_LocalInvocationIndex =
78 * gl_LocalInvocationID.z * gl_WorkGroupSize.x * gl_WorkGroupSize.y +
79 * gl_LocalInvocationID.y * gl_WorkGroupSize.x +
80 * gl_LocalInvocationID.x;
82 * Matrix uniforms with "Transpose" are not eliminated because there's
83 * an optimization pass that can turn references to the regular matrix
84 * into references to the transpose matrix. Eliminating the transpose
85 * matrix would cause that pass to generate references to undeclareds
86 * variables (thank you, ir_validate).
88 * It doesn't seem worth the effort to track when the transpose could be
89 * eliminated (i.e., when the non-transpose was eliminated).
91 if (strcmp(var
->name
, "gl_ModelViewProjectionMatrix") == 0
92 || strcmp(var
->name
, "gl_Vertex") == 0
93 || strcmp(var
->name
, "gl_WorkGroupID") == 0
94 || strcmp(var
->name
, "gl_WorkGroupSize") == 0
95 || strcmp(var
->name
, "gl_LocalInvocationID") == 0
96 || strcmp(var
->name
, "gl_GlobalInvocationID") == 0
97 || strcmp(var
->name
, "gl_LocalInvocationIndex") == 0
98 || strstr(var
->name
, "Transpose") != NULL
)