build: add support for 64-bit AIX

[richardlau]

Support building 64-bit binaries on AIX via gyp. At the moment there's no automatic detection as platform.machine()/uname -m on AIX is a bit useless (e.g., on an AIX system I have access to uname -m outputs 00F460A94C00) so you need to pass -Dtarget_arch=ppc64 to gyp_uv.py to activate.

Note however that #1795 actually fails to compile on 64-bit AIX due to incorrect assumptions about the size of uv_sem_t, see nodejs/node#20129 (comment).

[richardlau]

With regards to automatic host/target arch detection, at least one place in V8 appears to assume that if you're on AIX you want ppc64: https://github.com/nodejs/node/blob/82e475dc75751df08d80bd6e25926bd25c1794f2/deps/v8/third_party/binutils/detect_v8_host_arch.py#L63-L68

[richardlau]

I assume I also need to make an equivalent change for autotools? Anyone able to point me at where I should be editing?

[santigimeno]

Probably around here: https://github.com/libuv/libuv/blob/v1.x/Makefile.am#L330

[mhdawson]

The -Dtarget_arch=ppc64 must be what is allowing the 64 bit Node.js builds.

If we have to choose either 32 or 64 bit it should be 64 bit as we have only every shipped 64 bit node.js community builds, however, is it possible for us to update the CI job to set the target arch for AIX ?

[richardlau]

@mhdawson Node.js has it's own version of common.gypi that adds the correct flags for target_arch=ppc64: https://github.com/nodejs/node/blob/94596560c2556fae614ef237ed0ff2f749b14651/common.gypi#L371-L393

There's no such equivalent (until this PR) in the libuv version of common.gypi (so you can set -Dtarget_arch=ppc64 in the CI but it won't actually change any of the compile/link flags).

[richardlau]

Probably around here: https://github.com/libuv/libuv/blob/v1.x/Makefile.am#L330

I don't see any equivalents for the equivalent -m32 flags for ia32:

libuv/common.gypi

Lines 146 to 149 in 1e4823c

	[ 'host_arch != target_arch and target_arch=="ia32"', {
	'cflags': [ '-m32' ],
	'ldflags': [ '-m32' ],
	}],

Do we want to hardcode -maix64 into https://github.com/libuv/libuv/blob/v1.x/Makefile.am, or is the convention to pass such flags through to make using environment variables?

[mhdawson]

@richardlau got it.

[santigimeno]

@richardlau from other similar changes such as this it seems that for some architectures the support is only added to gyp build system. I'm sure @bnoordhuis knows better.

[bnoordhuis]

LGTM. CI: https://ci.nodejs.org/job/libuv-test-commit/797/

[bnoordhuis]

from other similar changes such as this it seems that for some architectures the support is only added to gyp build system

Yes. If someone needs aix+autotools, they'll open an issue.

[mhdawson]

LGTM

[cjihrig]

Landed in 4f77a23. Thanks!

[richardlau]

from other similar changes such as this it seems that for some architectures the support is only added to gyp build system

Yes. If someone needs aix+autotools, they'll open an issue.

So to follow up it appears that the libuv CI is using autotools on AIX 😆 . I think I've figured out the steps you need to build 64-bit AIX binaries via autotools in nodejs/build#1245 (comment).