Avoid allocations due to usage of broadcasting operation

[DanielDoehring]

This caused CI tests to fail, see for instance https://github.com/trixi-framework/Trixi.jl/pull/1650/checks

[github-actions]

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[ranocha]

Thanks! Did you also have the bandwidth to investigate what's going on? We had some problems like this already earlier, e.g., #1626

[jlchan]

Agreed with Hendrik's suggestions.

Can you also make a note that the loops were introduced to avoid allocations due to broadcasting? If it's possible to link to the test failure that would also be good.

Hopefully we can eventually figure out what is causing this.

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (adce486) 96.11% compared to head (3453511) 96.11%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1656   +/-   ##
=======================================
  Coverage   96.11%   96.11%           
=======================================
  Files         418      418           
  Lines       34238    34240    +2     
=======================================
+ Hits        32907    32909    +2     
  Misses       1331     1331           

Flag	Coverage Δ
unittests	96.11% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/solvers/dgmulti/dg.jl	94.31% <100.00%> (+0.04%)	⬆️

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[DanielDoehring]

Thanks! Did you also have the bandwidth to investigate what's going on? We had some problems like this already earlier, e.g., #1626

Not really - this is quite a mystery to me, as

Trixi.jl/src/solvers/dgmulti/dg.jl

Line 305 in adce486

flux_values .= flux.(view(u_values, :, e), i, equations)

is allocating while

Trixi.jl/src/solvers/dgmulti/dg.jl

Line 330 in adce486

flux_values[i] .= flux.(view(u_values, :, e), i, equations)

is not...