[Mlir-commits] [mlir] [mlir] Do not merge blocks during canonicalization by default (PR #95057)

[Giuseppe Rossini]

giuseros wrote:

> It'd be nice to check if we have some obvious issues with our block argument scaling! Do you have some IR reproducer you could share?

Yes, I am attaching the IRs I used to investigate this issue to this comment. 

If you do:
```
$ ./bin/mlir-opt --canonicalize disable_simplify.mlir
```

The compiler will hang for about 4 seconds and then complete. But if you run:
```
$ ./bin/mlir-opt --canonicalize disable_simplify_hang.mlir
```
The compiler will hang for a long time (I never got it to finish). If you pass `region-simplify=false` it will finish almost immediately. 

[disable_simplify.zip](https://github.com/user-attachments/files/15801638/disable_simplify.zip)


https://github.com/llvm/llvm-project/pull/95057