Add command line option --polly={yes|no}

[MatthiasJReisinger]

When this option is passed @polly declarations will be ignored. This facilitates debugging or evaluating performance differences between using/not using Polly without having to manually remove @polly declarations from functions.

I also wanted to ask you for some advice on the following issues: The polly field in the JLOptions type will also be present in a non-Polly build (USE_POLLY := 0) because I don't know how I could hide it in this case. Do you think that there would be a better alternative for this or would that be acceptable?

Furthermore, I also wanted to add according test cases to test/cmdlineargs.jl:

@test readchomp(`$exename -E "Bool(Base.JLOptions().polly)"`) == "true"
@test readchomp(`$exename --disable-polly -E "Bool(Base.JLOptions().polly)"`) == "false"

But the problem for the second test case is that in a non-Polly build --disable-polly would not be available which would make this test fail. A possible solution would be to add the following to the build_h.jl.phy target in base/Makefile:

ifeq ($(USE_POLLY), 1)
    @echo "const USE_POLLY = true" >> $@
else
    @echo "const USE_POLLY = false" >> $@
endif

Then it should be possible to make the above test cases conditional by adding:

if Base.USE_POLLY
    @test readchomp(`$exename -E "Bool(Base.JLOptions().polly)"`) == "true"
    @test readchomp(`$exename --disable-polly -E "Bool(Base.JLOptions().polly)"`) == "false"
end

Do you think that this would be a convenient solution?

Thank you in advance for your help!

Best,
Matthias

@tobig @vtjnash @timholy

[tkelman]

probably simpler to always have the option (--polly=no would be more consistent with others) but have it not do anything in a non polly build

[MatthiasJReisinger]

Thank you for the feedback @tkelman! I updated the PR accordingly.

Best,
Matthias

[vtjnash]

I think we should put #ifdef USE_POLLY around this

[vtjnash]

lgtm. if we add another similar option in the future, maybe we should transition to a feature list (e.g. --features=with-polly,with-other,without-that, but I think it would be premature to build that without knowing what the other cases look like).

is this still WIP, or can we merge it?

[MatthiasJReisinger]

Thank you for the feedback! It's no longer WIP.

[tkelman]

New command-line flags should be mentioned in NEWS.md