We were using the default getScalarizationOverhead expansion for extraction costs, which adds up all the individual element extraction costs.
This is fine for 128-bit vectors, but for 256/512-bit vectors each element extraction also has to account for extracting the upper 128-bit subvector extraction before it can handle the element. For scalarization costs we only need to extract each demanded subvector once.
Differential Revision: https://reviews.llvm.org/D125527
Apparently my methodology was suboptimal, and not only did miss all the +VL tuples,
i also missed some plain tuples. I believe, this adds everything missing.
Indeed, these manual costmodels are just not okay long-term.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D114334
Much like the VPMOVM2[BW] / VPMOV[BW]2M from AVX512BW,
these either sign-extent the mask register into a vector,
or pack the mask from vector register.
Apparently, we didn't even have MCA tests for these,
added in rG2f364f6f0d3a2420ca78cbd80abb186657180e05,
so i'm just guessing that their perf characteristics
are optimal.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D114314
Note that there are many other missing costs, i'm *only* adding the ones that are queried
from `getReplicationShuffleCost()` for the existing (quite exhaustive) test coverage.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D114070
Some of the costs get larger here,
but i suppose that makes sense since we'd previously query
scalarization costs that may not be really representative of the reality.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D113852
While this one is trivial and identical to the previous patch,
there is a weird cost change in a follow-up patch that i'm not sure about.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D113851
While this one is trivial and identical to the previous patch,
there is a weird cost change in a follow-up patch that i'm not sure about.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D113850
This was noticed in D113609, hopefully it unblocks that patch.
There are likely other similar problems.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D113842
Update truncation costs based on the worst case costs from the script in D103695.
Move to using legalized types wherever possible, which allows us to prune the cost tables.
Based off the worse case numbers generated by D103695, we were overestimating the cost of a number of vector truncations:
AVX2: v2i32->v2i8, v2i64->v2i16 + v4i64->v4i32
AVX1: v2i32->v2i8, v4i64->v4i16 + v16i16->v16i8
Once we have a working set of conversion costs, the intention is to cleanup the tables and use legalized types a lot more to reduce the number of entries we currently have.
The SkylakeServer model (and later IceLake/TigerLake targets according to Agner) have the PMOV truncations as uops=2, rthroughput=2 instructions.
Noticed while trying to reduce the diffs between cost tables and llvm-mca analysis.
Noticed while investigating PR50364, the truncation costs for v4i64->v4i16/v4i8 and v8i32->v8i8 were way too optimistic for a shuffle sequence that usually matches the AVX1 codegen (they matched AVX512 numbers which have actual truncation instructions!).
If both the source and the destination need to be split then the two halves of the split operation are completely independent and don't need to be split or joined. So we don't need to assess a cost for the split or join.
Differential Revision: https://reviews.llvm.org/D79111
Also fix some cost tables for vXi1 types to match the costs entries for the types they will be promoted to.
Differential Revision: https://reviews.llvm.org/D79045
We generate much better code these days than we used to. And we use the same sequence for AVX1 and AVX2 for these
For v4i64->v4i32 we generate:
vextractf128 xmm1, ymm0, 1
vshufps xmm0, xmm0, xmm1, 136 # xmm0 = xmm0[0,2],xmm1[0,2]
And for v8i64->v8i32 we generate:
vperm2f128 ymm2, ymm0, ymm1, 49 # ymm2 = ymm0[2,3],ymm1[2,3]
vinsertf128 ymm0, ymm0, xmm1, 1
vshufps ymm0, ymm0, ymm2, 136 # ymm0 = ymm0[0,2],ymm2[0,2],ymm0[4,6],ymm2[4,6]
Differential Revision: https://reviews.llvm.org/D79109
I've modified isTruncateFree to get an accurate cost for types that need to be split. I'm planning to look into fixing it for all vectors, but need more cost cleanups first.
Differential Revision: https://reviews.llvm.org/D78973
All avx512 truncate instructions except vXi64->vXi32 are 2 uops
on port 5. So raise their costs to 2. Except when we have an
earlier faster sequence like pshufb for 128 bit input vectors.
Add a lower cost of 3 v16i16->v16i8 with avx512f where we can
extend to v16i32 then truncate. And a cost of 2 for avx512bw with
and without avx512vl. There we can use vpmovwb with either a ymm
or zmm input. Both of these beat masking, splitting, and using
packuswb which is our avx/avx2 codegen.
This moves v32i16/v64i8 to a model consistent with how we
treat integer types with avx1.
This does change the ABI for types vXi16/vXi8 vectors larger than
512 bits to pass in multiple zmms instead of multiple ymms. We'd
already hacked some code to make v64i8/v32i16 pass in zmm.
Cost model is still a bit of a mess. In some place I tried to
match existing behavior. But really we need to account for
splitting and concating costs. Cost model for shuffles is
especially pessimistic.
Differential Revision: https://reviews.llvm.org/D76212
We are missing costs for a lot of truncation cases, I'm hoping to address all the 'zero cost' cases in trunc.ll
I thought this was a vector widening side effect, but even before this we had some interesting LV decisions (notably over indvars) being made due to these zero costs.
llvm-svn: 372498
Our sext/zext cost modeling was somewhat incomplete. And had no coverage for the fact that avx512bw v32i16/v64i8 types return a scalarization cost.
Truncates are a whole different mess because isTruncateFree is returning true for vectors when it shouldn't and that's the fall back for anything not in the tables.
llvm-svn: 347719
Simon Pilgrim