[llvm] [VPlan] Extend cse to eliminate redundant widened loads (PR #212543)

[via llvm-commits]

github-actions[bot] wrote:

test-suite diff from 26d08c22c68bbb9e644012c4e5cae32f68d897cb...4fb4f5e1a14870fc650ac7e73261d840144d8453: https://github.com/llvm/llvm-project/actions/runs/30526859691/artifacts/8755758631

Statistics: https://github.com/llvm/llvm-project/actions/runs/30526859691/artifacts/8755759596

## riscv64-linux-gnu `-march=rva23u64 -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |                        0 |
## 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/212543