glsl: Add a pass to flip matrix/vector multiplies to use dot products.

This pass flips (matrix * vector) operations to (vector *
matrixTranspose) for certain built-in matrices (currently
gl_ModelViewProjectionMatrix and gl_TextureMatrix).

This is equivalent, but results in dot products rather than multiplies
and adds.  On some hardware, this is more efficient.

This pass is conditionalized on ctx->mvp_with_dp4, the flag drivers set
to indicate they prefer dot products.

Improves performance in Lightsmark by 1.01131% +/- 0.162069% (n = 10)
on a Haswell GT2 system.  Passes Piglit on Ivybridge.

v2: Use struct gl_shader_compiler_options instead of plumbing through
    another boolean flag for this purpose.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index 9d28e9166e9..28093cfe1a1 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -80,6 +80,7 @@ bool do_dead_code(exec_list *instructions, bool uniform_locations_assigned);
 bool do_dead_code_local(exec_list *instructions);
 bool do_dead_code_unlinked(exec_list *instructions);
 bool do_dead_functions(exec_list *instructions);
+bool opt_flip_matrices(exec_list *instructions);
 bool do_function_inlining(exec_list *instructions);
 bool do_lower_jumps(exec_list *instructions, bool pull_out_jumps = true, bool lower_sub_return = true, bool lower_main_return = false, bool lower_continue = false, bool lower_break = false);
 bool do_lower_texture_projection(exec_list *instructions);