284b563fb0
fs_visitor::set_gs_stream_control_data_bits generates some code like "control_data_bits | stream_id << ((2 * (vertex_count - 1)) % 32)" as part of EmitVertex. The first time this (dynamically) occurs in the shader, control_data_bits is zero. Many times we can determine this statically and various optimizations will collaborate to make one of the OR operands literal zero. Converting the OR to a MOV usually allows it to be copy-propagated away. However, this does not happen in at least some shaders (in the assembly output of shaders/closed/UnrealEngine4/EffectsCaveDemo/301.shader_test, search for shl). All of the affected shaders are geometry shaders. Broadwell and Skylake had similar results. (Skylake shown) total instructions in shared programs: 14375452 -> 14375413 (<.01%) instructions in affected programs: 6422 -> 6383 (-0.61%) helped: 39 HURT: 0 helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1 helped stats (rel) min: 0.14% max: 2.56% x̄: 1.91% x̃: 2.56% 95% mean confidence interval for instructions value: -1.00 -1.00 95% mean confidence interval for instructions %-change: -2.26% -1.57% Instructions are helped. total cycles in shared programs: 531981179 -> 531980555 (<.01%) cycles in affected programs: 27493 -> 26869 (-2.27%) helped: 39 HURT: 0 helped stats (abs) min: 16 max: 16 x̄: 16.00 x̃: 16 helped stats (rel) min: 0.60% max: 7.92% x̄: 5.94% x̃: 7.92% 95% mean confidence interval for cycles value: -16.00 -16.00 95% mean confidence interval for cycles %-change: -6.98% -4.90% Cycles are helped. No changes on earlier platforms. Signed-off-by: Ian Romanick <ian.d.romanick@intel.com> |
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| .. | ||
| amd | ||
| broadcom | ||
| compiler | ||
| egl | ||
| gallium | ||
| gbm | ||
| getopt | ||
| glx | ||
| gtest | ||
| hgl | ||
| intel | ||
| loader | ||
| mapi | ||
| mesa | ||
| util | ||
| vulkan | ||
| git_sha1.h.in | ||
| Makefile.am | ||
| meson.build | ||
| SConscript | ||