[llvm] [MachinePipeliner] Limit the number of stores in BB (PR #154940)

[via llvm-commits]

aankit-ca wrote:

@kasuga-fj The benchmark that showed the regression had only 2 stores in the innermost loop and your patch should not have caused the regression. I don't want to block the merging for more time.

I feel the patch is good and the default store limit is pretty high already to not cause regressions for most practical usecases. Thanks for fixing the issue

https://github.com/llvm/llvm-project/pull/154940