[llvm] [VPlan][RISCV] Perform a simple version of LSR for EVL tail folded loops (PR #218987)

[via llvm-commits]

github-actions[bot] wrote:

test-suite diff from 8452e5eef125cd26de9b228a40c661001f8acea1...73e5e59a9f48f2272a67868dbeed5c846d85ec6d: https://github.com/llvm/llvm-project/actions/runs/32992963344/artifacts/9618882359

Statistics: https://github.com/llvm/llvm-project/actions/runs/32992963344/artifacts/9618883346

## riscv64-linux-gnu `-march=rva23u64 -O3`
| ('Program', '')                             |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:--------------------------------------------|-------------------------:|-------------------------:|-------------------------:|
| SingleSour...marks/Shootout/Shootout-matrix |                     3260 |                     4444 |               0.36319    |
| MultiSourc.../Benchmarks/VersaBench/bmm/bmm |                     1340 |                     1408 |               0.0507463  |
| SingleSour...near-algebra/kernels/bicg/bicg |                     2114 |                     2164 |               0.0236518  |
| SingleSour...nchmarks/Adobe-C++/loop_unroll |                   305722 |                   311294 |               0.0182257  |
| SingleSour...linear-algebra/kernels/mvt/mvt |                     3114 |                     3166 |               0.0166988  |
| MultiSourc...ks/ASCI_Purple/SMG2000/smg2000 |                   141758 |                   143414 |               0.0116819  |
| MultiSourc...enchmarks/mafft/pairlocalalign |                   262270 |                   264754 |               0.00947116 |
| MultiSource/Benchmarks/McCat/05-eks/eks     |                     9890 |                     9974 |               0.00849343 |
| MultiSourc...hmarks/Rodinia/hotspot/hotspot |                     3928 |                     3956 |               0.00712831 |
| SingleSour...-algebra/solvers/ludcmp/ludcmp |                     2734 |                     2746 |               0.00438917 |
| SingleSource/Benchmarks/Stanford/Oscar      |                     3178 |                     3188 |               0.00314663 |
| MultiSourc...chmarks/Prolangs-C/gnugo/gnugo |                    16832 |                    16882 |               0.00297053 |
| MultiSource/Benchmarks/sim/sim              |                    11250 |                    11274 |               0.00213333 |
| MultiSourc...arks/Rodinia/backprop/backprop |                     4742 |                     4750 |               0.00168705 |
| MultiSourc...reeBench/pcompress2/pcompress2 |                     4352 |                     4358 |               0.00137868 |
| Geomean difference                          |                      nan |                      nan |              -0.00562095 |
## aarch64-linux-gnu `-march=armv9-a -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |                        0 |
## x86_64-linux-gnu `-march=x86-64-v3 -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |                        0 |


https://github.com/llvm/llvm-project/pull/218987