0.194 does not compile on ppc64/ppc64le linux

[belegdol]

Hi all,
mame-0.194 Fedora package has failed to build [1][2] on ppc64 and ppc64le Fedora:

In file included from ../../../../../src/emu/emu.h:31:0:
../../../../../src/mame/drivers/fp200.cpp:28:36:   in constexpr expansion of 'operator""_MHz_XTAL(6.14399999999999999999999999999999e+0l)'
../../../../../src/emu/xtal.h:85:83: error: '(6.14399999999999999999999999999999e+0l * 1.0e+6l)' is not a constant expression
 constexpr XTAL operator ""_MHz_XTAL(long double clock) { return XTAL(double(clock * 1e6)); }
                                                                             ~~~~~~^~~~~
make[2]: *** [casio.make:362: ../../../../linux_gcc/obj/x64/Release/src/mame/drivers/fp200.o] Error 1
make[1]: *** [Makefile:463: casio] Error 2

The builds on s390x, i686, x86_64, aarch64 and armv7hl have completed successfully.
Best regards,
Julian
[1] https://koji.fedoraproject.org/koji/taskinfo?taskID=24590264
[2] https://koji.fedoraproject.org/koji/taskinfo?taskID=24590275

[felipesanches]

I guess you mean 0.194 ?

[belegdol]

Indeed, sorry - comment and title corrected

[galibert]

That compiler is drunk. Find a sober one. OG.

…

On Wed, Jan 31, 2018 at 1:38 PM, Julian Sikorski ***@***.***> wrote: Hi all, mame-0.184 Fedora package has failed to build [1][2] on ppc64 and ppc64le Fedora: In file included from ../../../../../src/emu/emu.h:31:0: ../../../../../src/mame/drivers/fp200.cpp:28:36: in constexpr expansion of 'operator""_MHz_XTAL(6.14399999999999999999999999999999e+0l)' ../../../../../src/emu/xtal.h:85:83: error: '(6.14399999999999999999999999999999e+0l * 1.0e+6l)' is not a constant expression constexpr XTAL operator ""_MHz_XTAL(long double clock) { return XTAL(double(clock * 1e6)); } ~~~~~~^~~~~ make[2]: *** [casio.make:362: ../../../../linux_gcc/obj/x64/Release/src/mame/drivers/fp200.o] Error 1 make[1]: *** [Makefile:463: casio] Error 2 The builds on s390x, i686, x86_64, aarch64 and armv7hl have completed successfully. Best regards, Julian — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#3157>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AI0i8TKliu9eBsGaLfFta5QMGo6d4RaUks5tQF65gaJpZM4Rz509> .

[belegdol]

The drunk compiler is gcc-7.2.1 on both Fedora releases.

[galibert]

That's also what I use, but obviously not on ppc. But seriously, that error message is insane. OG.

…

On Wed, Jan 31, 2018 at 1:50 PM, Julian Sikorski ***@***.***> wrote: The drunk compiler is gcc-7.2.1 on both Fedora releases. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3157 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AI0i8SLl8sHXN6XyNJOM66KKLuCb7lxSks5tQGGOgaJpZM4Rz509> .

[cuavas]

The long double type is a bit weird on PPC - it's a pair of double added together effectively, so you get an increase in precision but not range. You can also get strange effects if the two parts of the double don't line up neatly end-to-end. I suspect what's happening is that it's implicitly relying on a library function to multiply long double values, and the library function isn't constexpr qualified. I don't know what to do about it though - user-defined literal suffixes work on a very limited set of types.

[ajrhacker]

It appears that constant expressions of the PPC long double type have been basically broken for over a decade in GCC, with no fix projected.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26374

[galibert]

Are we using --with-long-double-128 on ppc, and if yes why? There's a clear lack of "long" in the compiled code. OG.

…

On Wed, Jan 31, 2018 at 2:16 PM, ajrhacker ***@***.***> wrote: It appears that constant expressions of the PPC long double type have been basically broken for over a decade in GCC, with no fix projected. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26374 — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3157 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AI0i8S9OYUKaYlNSo89k38P_YFILPFYXks5tQGelgaJpZM4Rz509> .

[ajrhacker]

@galibert: As the OP shows, there are in fact long double overloads in our code now. These were Vas's doing, not yours.

[cuavas]

Floating point user-defined literals need to use long double, so there's no way of avoiding it. I think --with-long-double-128 is default on ppc64/ppc64le so there's not much we can do about it on that side.

[belegdol]

I added ExcludeArch for ppc64 and ppc64le for now, we may be able to get some help from Fedora's ppc team.

[classilla]

The miscompile can be worked around by adding -mlong-double-64 to the compiler flags. This isn't ideal but appears to fix this specific problem. This gets the build further but there is another compilation issue at least on my ppc64le machine which I will try to spin up a PR for.

[classilla]

(obviously -mlong-double-64 is only necessary for ppc64/ppc64le, it could be written into the platform code in the makefile)