radeonsi: eliminate trivial constant VS outputs
These constant value VS PARAM exports:
- 0,0,0,0
- 0,0,0,1
- 1,1,1,0
- 1,1,1,1
can be loaded into PS inputs using the DEFAULT_VAL field, and the VS exports
can be removed from the IR to save export & parameter memory.
After LLVM optimizations, analyze the IR to see which exports are equal to
the ones listed above (or undef) and remove them if they are.
Targeted use cases:
- All DX9 eON ports always clear 10 VS outputs to 0.0 even if most of them
are unused by PS (such as Witcher 2 below).
- VS output arrays with unused elements that the GLSL compiler can't
eliminate (such as Batman below).
The shader-db deltas are quite interesting:
(not from upstream si-report.py, it won't be upstreamed)
PERCENTAGE DELTAS Shaders PARAM exports (affected only)
batman_arkham_origins 589 -67.17 %
bioshock-infinite 1769 -0.47 %
dirt-showdown 548 -2.68 %
dota2 1747 -3.36 %
f1-2015 776 -4.94 %
left_4_dead_2 1762 -0.07 %
metro_2033_redux 2670 -0.43 %
portal 474 -0.22 %
talos_principle 324 -3.63 %
warsow 176 -2.20 %
witcher2 1040 -73.78 %
----------------------------------------
All affected 991 -65.37 % ... 9681 -> 3353
----------------------------------------
Total 26725 -10.82 % ... 58490 -> 52162
v2: treat Undef as both 0 and 1
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com> (v1)
Tested-by: Edmondo Tommasina <edmondo.tommasina@gmail.com> (v1)
3 files changed