[llvm-dev] Improve LLVM IR dumps

[Fedor Sergeev via llvm-dev]

On 07/03/2018 03:02 AM, Damian Bodnar via llvm-dev wrote:
> Hi all,
>
> I have been thinking about an improvement to -print-(before/after)-all 
> feature. In some situations you want to check how code changes between 
> different passes. This is already available in GCC using 
> -fdump-tree-cfg. It would be great to have a similar way of dumping 
> code in LLVM, possibly with Godbolt integration that makes it able to 
> watch the differences.
>
> The way how it is available now is nice, but quite inconvenient, so 
> the idea is to:
>
> 1) Dump IR from each pass to separate file.
> 2) Make dumps complete. For now, dumps from some passes are partial, 
> e. g. they contain only loop body.
Already available with -print-module-scope (and -print-after-all).

> 3) Integrate with Godbolt.
>
> Why to do this?
> It helps to debug optimizations and other passes that change IR. It 
> also makes compiler easier to be understood.
>
> Your comments are greatly appreciated. What do you think about utility 
> of the improvement?
There was a relatively recent patch by Alexandre Isoard on 
-git-commit-after-all (not accepted/integrated):
   https://reviews.llvm.org/D44244

As was discussed earlier on the list, implementation for it should be 
closer to what you describe here.
However I still sometimes find this patch rather useful as it is.

regards,
   Fedor.