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author | Jason Ekstrand <[email protected]> | 2017-03-02 17:10:24 -0800 |
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committer | Jason Ekstrand <[email protected]> | 2017-03-14 07:36:20 -0700 |
commit | 3c312be7b3e95ec7540e98abed1b6f3cc8d31b2a (patch) | |
tree | 77461dca97a8af61c35a4c0b9200ad6fbbf9d977 /src/hgl | |
parent | 60d1aac28a1f44ac166e72262e378e063155d6fd (diff) |
nir/copy_prop: Respect the source's number of components
In the near future we are going to require that the num_components in a
src dereference match the num_components of the SSA value being
dereferenced. To do that, we need copy_prop to not remove our MOVs from
a larger SSA value into an instruction that uses fewer channels.
Because we suddenly have to know how many components each source has,
this makes the pass a bit more complicated. Fortunately, copy
propagation is the only pass that cares about the number of components
are read by any given source so it's fairly contained.
Shader-db results on Sky Lake:
total instructions in shared programs: 13318947 -> 13320265 (0.01%)
instructions in affected programs: 260633 -> 261951 (0.51%)
helped: 324
HURT: 1027
Looking through the hurt programs, about a dozen are hurt by 3
instructions and the rest are all hurt by 2 instructions. From a
spot-check of the shaders, the story is always the same: They get a
vec4 from somewhere (frequently an input) and use the first two or three
components as a texture coordinate. Because of the vector component
mismatch, we have a mov or, more likely, a vecN sitting between the
texture instruction and the input. This means that the back-end inserts
a bunch of MOVs and split_virtual_grfs() goes to town. Because the
texture coordinate is also used by some other calculation, register
coalesce can't combine them back together and we end up with an extra 2
MOV instructions in our shader.
Reviewed-by: Eric Anholt <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>
Reviewed-by: Connor Abbott <[email protected]>
Diffstat (limited to 'src/hgl')
0 files changed, 0 insertions, 0 deletions