glsl/standalone: Optimize add-of-neg to subtract

This just makes the output of the standalone compiler a little more
compact.

v2: Fix indexing typo noticed by Iago.  Move the add_neg_to_sub_visitor
to it's own header file.  Add a unit test that exercises the visitor.
Both the neg_a_plus_b and neg_a_plus_neg_b tests reproduced the bug that
Iago discovered.

Signed-off-by: Ian Romanick <[email protected]>
Reviewed-by: Nicolai Hähnle <[email protected]>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/compiler/glsl/standalone.cpp b/src/compiler/glsl/standalone.cpp
index f0964900938..efc6da9d004 100644
--- a/src/compiler/glsl/standalone.cpp
+++ b/src/compiler/glsl/standalone.cpp
@@ -37,6 +37,7 @@
 #include "standalone_scaffolding.h"
 #include "standalone.h"
 #include "util/string_to_uint_map.h"
+#include "opt_add_neg_to_sub.h"
 
 static const struct standalone_options *options;
 
@@ -441,6 +442,9 @@ standalone_compile_shader(const struct standalone_options *_options,
          if (!shader)
             continue;
 
+         add_neg_to_sub_visitor v;
+         visit_list_elements(&v, shader->ir);
+
          shader->Program = rzalloc(shader, gl_program);
          init_gl_program(shader->Program, shader->Stage);
       }