[llvm] [SCEV] Strengthen flags for AddRec post-inc (PR #217437)

[via llvm-commits]

github-actions[bot] wrote:

test-suite diff from d28bc6be2903a967a356cabbb7d90597d9c0ead5...b5f94d6df6c0922995919d024c09ea18ec901c23: https://github.com/llvm/llvm-project/actions/runs/32324975832/artifacts/9392896875

Statistics: https://github.com/llvm/llvm-project/actions/runs/32324975832/artifacts/9392897231

## 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/217437