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Topics - nkls

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General Development / Compiling ML with GCC 6
« on: July 29, 2016, 11:12:21 AM »
GCC 6 is released, and the linux distro I'm using (arch linux) has decided to upgrade my compiler. Ignoring the fact that I can downgrade/recompile/use a VM and the risk of using untested GCC versions, there is one major issue with the newest version:

The support for the -fshort-double flag is removed, i.e. demoting all doubles to floats.

As far as I understand, the ABI used by Canon actually has 32-bit doubles instead of 64-bit, so it's not just a flag we are using to make ML faster. I've compiled and tested ML with GCC 6 without the -fshort-double flag and all the basic stuff works, but I suspect that printf("%f") and such are broken, and that the binaries should be larger since there might be extra double precision code in there.

Are there other issues that should be expected? Any way to work around this?

My thought are:
Hope that GCC includes a -m32bit-doubles flag for the ARM architecture in the future.
Create a custom arm-eos ABI and recompile GCC.

It's not a big issue right now since we can use GCC 4/5, but in a few years we might be missing out on any new gcc goodies.

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