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authorTimothy Arceri <[email protected]>2015-12-22 10:14:45 +1100
committerTimothy Arceri <[email protected]>2016-01-07 09:06:12 +1100
commit30991d7389b6b475625ccce2aaae2f3f8cf8e95f (patch)
treeddc87be120d68f455aa433074685dd637ab0f3dd /src/glsl/link_varyings.cpp
parent0d7477a2899fe74134cd3e12e7adf1eec0c77f7e (diff)
glsl: remove unused varyings before packing them
Previously we would pack varyings before trying to remove them, this relied on the packing pass not packing varyings with a location of -1 to avoid packing varyings that should be removed. However this meant unused varyings with an explicit location would be packed before they could be removed when we enable packing of them in a later patch. V2: fix regression in V1 removing unused varyings in multi-stage SSO, fix regression with single stage programs. Reviewed-by: Anuj Phogat <[email protected]> Reviewed-by: Edward O'Callaghan <[email protected]>
Diffstat (limited to 'src/glsl/link_varyings.cpp')
-rw-r--r--src/glsl/link_varyings.cpp45
1 files changed, 45 insertions, 0 deletions
diff --git a/src/glsl/link_varyings.cpp b/src/glsl/link_varyings.cpp
index c43abbcc6a5..a80a1b5660d 100644
--- a/src/glsl/link_varyings.cpp
+++ b/src/glsl/link_varyings.cpp
@@ -309,6 +309,41 @@ cross_validate_outputs_to_inputs(struct gl_shader_program *prog,
}
}
+/**
+ * Demote shader inputs and outputs that are not used in other stages, and
+ * remove them via dead code elimination.
+ */
+void
+remove_unused_shader_inputs_and_outputs(bool is_separate_shader_object,
+ gl_shader *sh,
+ enum ir_variable_mode mode)
+{
+ if (is_separate_shader_object)
+ return;
+
+ foreach_in_list(ir_instruction, node, sh->ir) {
+ ir_variable *const var = node->as_variable();
+
+ if ((var == NULL) || (var->data.mode != int(mode)))
+ continue;
+
+ /* A shader 'in' or 'out' variable is only really an input or output if
+ * its value is used by other shader stages. This will cause the
+ * variable to have a location assigned.
+ */
+ if (var->data.is_unmatched_generic_inout) {
+ assert(var->data.mode != ir_var_temporary);
+ var->data.mode = ir_var_auto;
+ }
+ }
+
+ /* Eliminate code that is now dead due to unused inputs/outputs being
+ * demoted.
+ */
+ while (do_dead_code(sh->ir, false))
+ ;
+
+}
/**
* Initialize this object based on a string that was passed to
@@ -1671,6 +1706,16 @@ assign_varying_locations(struct gl_context *ctx,
}
}
}
+
+ /* Now that validation is done its safe to remove unused varyings. As
+ * we have both a producer and consumer its safe to remove unused
+ * varyings even if the program is a SSO because the stages are being
+ * linked together i.e. we have a multi-stage SSO.
+ */
+ remove_unused_shader_inputs_and_outputs(false, producer,
+ ir_var_shader_out);
+ remove_unused_shader_inputs_and_outputs(false, consumer,
+ ir_var_shader_in);
}
if (!disable_varying_packing) {