[llvm-dev] [RFC] Compiled regression tests.

[Hal Finkel via llvm-dev]

On 7/2/20 1:07 PM, Michael Kruse wrote:
> Am Do., 2. Juli 2020 um 12:41 Uhr schrieb Hal Finkel <hfinkel at anl.gov>:
>> I think that, to a large extent, we're on the same page on this aspect.
>> It's a question of reuse and stability. If there's a principled way to
>> design an output that will be reused across many tests and can
>> reasonably be believed will remain relatively stable, then we should do
>> that. If not, then unit tests are better. The question is: do we have so
>> many such unit tests that we want a special way to construct them from
>> IR files (instead of, I suppose, just having the IR in a string in the
>> code)? I don't know.
> Implementing another print mechanism and justifying its presence
> significantly adds to the burden of writing robust and understandable
> tests that  often could be simple call of an already existing API
> function in a unittest.
> Inserting a layer of text representations and matching it using
> FileCheck feels like "unittesting with extra steps", adding the
> previously mentioned shortcoming of FileCheck-based testing to the
> system.
>
> Another example from Polly:
>
>      Arrays {
>          i32 MemRef0[*]; // Element size 4
>      }
>      Arrays (Bounds as pw_affs) {
>          i32 MemRef0[*]; // Element size 4
>      }
>
> This emits the same information twice. The latter is the more
> high-level representation that should be more useful to users, but the
> former is still printed as well because there are existing regression
> tests that expect the former format. For humans trying to understand
> this it makes the output more verbose.


Someone should have updated the tests instead? The interesting question 
is: What about the format made it difficult to update the tests?

Aside from that, as you point out, the textual output is also useful for 
humans. My hypothesis is that this is the general case, and all things 
considered, this utility pays for the price of the extra steps in the 
"unit testing with extra steps."

  -Hal


>
> Michael

-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory