api: add printing and parsing of dynamic lists as in MLIR

[superlopuh]

This is used in a few places, notably in memref.subview custom syntax, which is the next PR

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.87%. Comparing base (612c1b2) to head (8c15a86).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2839      +/-   ##
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+ Coverage   89.83%   89.87%   +0.04%     
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  Files         397      398       +1     
  Lines       49203    49590     +387     
  Branches     7551     7621      +70     
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+ Hits        44202    44570     +368     
- Misses       3807     3824      +17     
- Partials     1194     1196       +2     

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[webmiche]

So, the weird thing about this is that MLIR is not fully consistent itself with how this works, AFAIK. In particular, the default "take the operand"-value is different among different dialects (GEP from the LLVM dialect uses INT_MIN, whereas memref uses -1 apparently).

Providing this functionality within the parser feels like we are preferring one version over the other. I guess, one could overwrite the DYNAMIC_INDEX variable, but that feels very forced. What do you think about adding this value as a keyword argument? The default can still be -1, I guess.

[superlopuh]

That's exactly my plan, I'll add it as a parameter, and fix my implementation, turns out that memref actually uses -9223372036854775808, and I ported the wrong function.

[superlopuh]

The PR on top of this one roundrips perfectly with MLIR, so I'm now pretty confident the helper functions have at least that functionality working.