Add a USE_GCC_TOOLCHAINS knob to make universe.
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Authored by jhb on Jul 19 2020, 8:48 PM.

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emaste
imp

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rS364325: Add a USE_GCC_TOOLCHAINS knob to make universe.

Summary

This uses GCC toolchains instead of LLVM on architectures supported by GCC.
Currently this uses GCC 6 on aarch64, amd64, i386, mips, and powerpc.

Test Plan

make tinderbox USE_GCC_TOOLCHAINS=yes, observe much breakage

Diff Detail

Repository

rS FreeBSD src repository - subversion

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Unit

Tests Not Applicable

Event Timeline

jhb requested review of this revision.Jul 19 2020, 8:48 PM

jhb created this revision.

Harbormaster completed remote builds in B32422: Diff 74661.Jul 19 2020, 8:49 PM

jhb added child revisions: D25731: Pass the full CFLAGS to cpp for MKlib_gen.sh., D25730: Disable LTO on aarch64 when using GCC., D25729: Disable errors for -Wsystem-headers for GCC on aarch64., D25728: ld.bfd requires an explicit emulation for MIPS for ld -r., D25727: Disable errors for -Wredundant-decls for GCC 6+., D25726: Turn off errors for -Wmaybe-uninitialized in GCC 6+..Jul 19 2020, 8:49 PM

jhb added inline comments.Jul 19 2020, 8:52 PM

Makefile
521 ↗	(On Diff #74661)	powerpc-gcc6 doesn't exist, so this doesn't really work for powerpc yet. It does exist for GCC 9 (and I might try bumping to GCC9 next after fixing the current fallout)
532 ↗	(On Diff #74661)	This approach is still not ideal as it blocks "powerpc" if you don't have both toolchains installed. However, that is not really fixable without redoing universe entirely to be target_arch driven instead of target driven which seems like too much work.

jhb added a reviewer: imp.Jul 19 2020, 8:52 PM

jhb mentioned this in D25873: vxlan(4): Support for stateless NIC hardware offloads with VXLAN encapsulated traffic..Jul 29 2020, 10:52 PM

Any thoughts? This (and all the fixes needed for GCC 6) have sat in review for 2 weeks with no feedback. I'll probably commit this in the next day or so barring feedback.

lwhsu added a subscriber: lwhsu.Aug 6 2020, 6:15 PM

Seems fine to me, although what do we have to fix wrt powerpc-gcc6 before commit?

In D25732#577022, @emaste wrote:

Seems fine to me, although what do we have to fix wrt powerpc-gcc6 before commit?

We'd have to create the flavor of gcc6. I'd rather spend time getting GCC9 working with it instead to be honest.

In D25732#577973, @jhb wrote:

In D25732#577022, @emaste wrote:

Seems fine to me, although what do we have to fix wrt powerpc-gcc6 before commit?

We'd have to create the flavor of gcc6. I'd rather spend time getting GCC9 working with it instead to be honest.

I agree there's little point in spending effort on gcc6. Does this mean we're just going to hold this change for the foreseeable future?

In D25732#578015, @emaste wrote:

In D25732#577973, @jhb wrote:

In D25732#577022, @emaste wrote:

Seems fine to me, although what do we have to fix wrt powerpc-gcc6 before commit?

We'd have to create the flavor of gcc6. I'd rather spend time getting GCC9 working with it instead to be honest.

I agree there's little point in spending effort on gcc6. Does this mean we're just going to hold this change for the foreseeable future?

I already have another git branch off of this to switch to gcc9 and add more targets. For powerpc-gcc9 I need to back port a patch to the GCC port I think to deal with secure plt issues. However, not all the worlds yet build with GCC 9 though I think I have most of them working.

https://github.com/bsdjhb/freebsd/compare/gcc_universe...bsdjhb:gcc9_universe are the diffs for GCC 9 so far.

This revision was not accepted when it landed; it landed in state Needs Review.Aug 17 2020, 8:11 PM

Closed by commit rS364325: Add a USE_GCC_TOOLCHAINS knob to make universe. (authored by jhb). · Explain Why

This revision was automatically updated to reflect the committed changes.

jhb added a commit: rS364325: Add a USE_GCC_TOOLCHAINS knob to make universe..