From 4f22db5fbbe59eacb762aa410f18c3078e85c2b7 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Sat, 26 Apr 2014 00:18:54 -0700 Subject: glsl: Lower constant arrays to uniform arrays. Consider GLSL code such as: const ivec2 offsets[] = ivec2[](ivec2(-1, -1), ivec2(-1, 0), ivec2(-1, 1), ivec2(0, -1), ivec2(0, 0), ivec2(0, 1), ivec2(1, -1), ivec2(1, 0), ivec2(1, 1)); ivec2 offset = offsets[]; Both i965 and nv50 currently handle this very poorly. On i965, this becomes a pile of MOVs to load the immediate constants into registers, a pile of scratch writes to move the whole array to memory, and one scratch read to actually access the value - effectively the same as if it were a non-constant array. We'd much rather upload large blocks of constant data as uniform data, so drivers can simply upload the data via constbufs, and not have to populate it via shader instructions. This is currently non-optional because both i965 and nouveau benefit from it, and according to Marek radeonsi would benefit today as well. (According to Tom, radeonsi may want to handle this itself in the long term, but we can always add a flag when it becomes useful.) Improves performance in a terrain rendering microbenchmark by about 2x, and cuts the number of instructions in about half. Helps a lot of "Natural Selection 2" shaders, as well as one "HOARD" shader. total instructions in shared programs: 5473459 -> 5471765 (-0.03%) instructions in affected programs: 5880 -> 4186 (-28.81%) v2: Use ir_var_hidden to avoid exposing the new uniform via the GL uniform introspection API. v3: Alphabetize Makefile.sources properly. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77957 Signed-off-by: Kenneth Graunke --- src/glsl/Makefile.sources | 1 + 1 file changed, 1 insertion(+) (limited to 'src/glsl/Makefile.sources') diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources index 85280eeb297..676fa0d7a6b 100644 --- a/src/glsl/Makefile.sources +++ b/src/glsl/Makefile.sources @@ -59,6 +59,7 @@ LIBGLSL_FILES = \ $(GLSL_SRCDIR)/loop_controls.cpp \ $(GLSL_SRCDIR)/loop_unroll.cpp \ $(GLSL_SRCDIR)/lower_clip_distance.cpp \ + $(GLSL_SRCDIR)/lower_const_arrays_to_uniforms.cpp \ $(GLSL_SRCDIR)/lower_discard.cpp \ $(GLSL_SRCDIR)/lower_discard_flow.cpp \ $(GLSL_SRCDIR)/lower_if_to_cond_assign.cpp \ -- cgit v1.2.3