ppc64 and building with newer gcc?

[barracuda156]

@classilla Do you know if it is hard to allow building TFF with a newer version of gcc than 4.8? @kencu confirms here that later versions failed, at least for Intel: iains/gcc-10-branch#7 (comment)
At the moment, we got gcc10 and gcc11 available for PPC, via Macports (not yet officially supported, but they work perfectly) or standalone (from @iains branches). Would be nice if TFF builds with these.

The second question is re ppc64 support, raised here: https://forums.macrumors.com/threads/llvm-and-ld64-for-ppc64-on-leopard.2336740/?post=31178811#post-31178811
From what I understand, TFF is 32-bit for PPC? Is there some inherent issue preventing ppc64 build, or it simply has not been tested?

[kencu]

the newer gcc issues were being tracked here #464 but we stopped a few years ago, so nobody tried gcc10 or gcc11.

[iains]

note that TFF has "10.4" in the title, and 10.4 has very little support for ppc64 (essentially nothing beyond the base libs; no frameworks, no objc .. ) so I would not expect something targeting 10.4 to be useful for a ppc64 case.

[barracuda156]

note that TFF has "10.4" in the title, and 10.4 has very little support for ppc64 (essentially nothing beyond the base libs; no frameworks, no objc .. ) so I would not expect something targeting 10.4 to be useful for a ppc64 case.

@iains Honestly I don’t know if support for 10.4 implies that ppc64 variant should be impossible. Included profiles to be used for the build have dedicated G5 versions: https://github.com/classilla/tenfourfox/blob/master/G5.mozcfg
But those nevertheless use -m32 flags.

[classilla]

I don't know, I've never tried personally. The reason the G5 version is built in 32-bit mode is because of the JIT, which definitely won't work in 64-bit mode (also, assuming you're building this for Mac OS X, TenFourFox has some legacy Carbon code).

[barracuda156]

I don't know, I've never tried personally. The reason the G5 version is built in 32-bit mode is because of the JIT, which definitely won't work in 64-bit mode (also, assuming you're building this for Mac OS X, TenFourFox has some legacy Carbon code).

@classilla Thank you! The JIT is this one? js/src/jit/osxppc
Given that neighboring mips has both 32- and 64-bit versions, I would imagine ppc64 to be feasible, though I dunno how much effort that could require.

[classilla]

It would need to be written from scratch. The one I'm writing for POWER9 is little-endian and specific to that ISA level.

[barracuda156]

It would need to be written from scratch. The one I'm writing for POWER9 is little-endian and specific to that ISA level.

@classilla Oh… I had an impression that as far as Darwin goes, ppc and ppc64 aren’t hugely different. Few assembler instructions should be replaced, in a predictable fashion, and maybe handling of 64-bit numbers (takes more instructions on ppc32?). ABI documentation does not seem to suggest huge differences. Well, r13 is used for some thread-related stuff on ppc64.

But @iains noted earlier that Apple documentation is incomplete, so I guess I miss something here.

[kencu]

it’s not the toolchain exactly, or Apple documentation, or ABI.

the code itself has conditional compilation for systems, endianness, and bit depth. All different paths.

a pathway for darwin big endian 64bit was never written into the code, far as I recall it.

[iains]

it’s not the toolchain exactly, or Apple documentation, or ABI.

the code itself has conditional compilation for systems, endianness, and bit depth. All different paths.

a pathway for darwin big endian 64bit was never written into the code, far as I recall it.

To avoid any confusion : PowerPC Darwin is always Big Endian (32 and 64B),

AFAIK the only LE Power systems are ELF (v2) and for Power >= 9 (ICBW, maybe Power 8 is also covered).

[kencu]

yeah, pre-coffee brainfart after reading Cameron's comment; I changed it to BE 10 seconds after I wrote that, and went 'What -- no'. :>

[classilla]

By 'from scratch' I mean it's probably a bit more than a few tweaks or other trivial changes. Yes, the code runs on the 970 except for things like mcrxr. However, it is inherently 32-bit, all calling conventions are 32-bit, JIT entry and exit uses 32-bit, etc. There are also relatively few 64-bit operations that the JIT performs that would benefit. Even current versions of Firefox mostly deal in 32-bit ints other than bignums, which TenFourFox's JavaScript doesn't support.

The POWER9 JIT (for the record, POWER8 also supports LE, POWER7 sort of) is fully 64-bit. Some code was used as a template, but it's been almost completely redone to make it 64-bit clean. Even then I'm still banging bugs out of it, mostly with sign extension and 32-bit thunking.

[barracuda156]

The POWER9 JIT (for the record, POWER8 also supports LE, POWER7 sort of) is fully 64-bit. Some code was used as a template, but it's been almost completely redone to make it 64-bit clean. Even then I'm still banging bugs out of it, mostly with sign extension and 32-bit thunking.

@classilla Why a choice of LE btw? All POWER CPUs support BE.

[classilla]

Largely convenience. There are relatively few Linux distros that still offer spins with BE support, and they tend to be more fringe. Plus, TenFourFox has a lot of hacks for a Web that now assumes little-endian (little endian typed array emulation being the most notable). I like BE personally and when I upgrade my server to POWER whatever-is-current I'll probably try to run it big with FreeBSD or something, but the desktop experience is better with Linux IMHO, and it's just simpler to run it LE.

[barracuda156]

I like BE personally and when I upgrade my server to POWER whatever-is-current I'll probably try to run it big with FreeBSD or something, but the desktop experience is better with Linux IMHO, and it's just simpler to run it LE.

I am planning to install FreeBSD 13 as a second system into my G5 Quad in fact. There is a nice GUI for FreeBSD, quite MacOS-like: https://github.com/helloSystem

P. S. From what I understand, even ELF2 can be used in BE mode. No good reason to downgrade to LE.

[barracuda156]

@classilla Not to create a separate topic: does TFF use v8-related or similar code? I am trying to fix nodejs12 for Darwin PPC :)