On Thu, Nov 13, 2014 at 8:46 PM, H.J. Lu <hjl.to...@gmail.com> wrote: > On Thu, Nov 13, 2014 at 9:36 AM, Jeff Law <l...@redhat.com> wrote: >> On 11/12/14 03:02, Alexander Ivchenko wrote: >>> >>> Hi, >>> >>> Bionic - Android libc - supports indirect functions right now, but >>> they are disabled in gcc; >>> >>> We cannot do the configure-time check for that, because there is only >>> one version of each compiler shipped in ndk for all Android platforms. >>> On the other hand, having different runtime targets like -mandroid-19, >>> -mandroid-20 would be a nightmare. But, keeping in mind that the last >>> version of Android is a priority, I think that enabling ifuncs >>> unconditionally would be the right thing. >>> >>> Is the patch ok? Bootstrapped/regtested on x86_64-unknown-linux-gnu + >>> checked that the behavior of i686-linux-android is correct. >>> >>> >>> diff --git a/gcc/ChangeLog b/gcc/ChangeLog >>> index eac19cf..9932323 100644 >>> --- a/gcc/ChangeLog >>> +++ b/gcc/ChangeLog >>> @@ -1,3 +1,8 @@ >>> +2014-11-11 Alexander Ivchenko <alexander.ivche...@intel.com> >>> + >>> + * config/linux.c (linux_has_ifunc_p): Remove. >>> + * config/linux.h (TARGET_HAS_IFUNC_P): Use the default version. >> >> This feels like a bad idea to me simply because a new compiler with an old >> runtime will generate code that fails, right? >> >> If you can't do a configure-time test, then the way to go is either a >> compile-time option, or to use a different target. If there's some minimum >> version of android that has this capability, then this isn't terribly hard. >> You may not even need a config file for this since you could define >> LIBC_BIONIC_USE_IFUNCS or something like that when configured for a suitably >> new android version. > > Hi Jeff, > > I believe the patch is correct. Not all glibcs support IFUNC. It doesn't mean > we should disable IFUNC for all glibcs. By default, we do a configure time > check for IFUNC. We DO want to use configure time check for IFUNC for > Android NDK. > > Alexander, configure time check for IFUNC should work for Android. If > it doesn't, > please let me know and I will fix it. > >
Jeff, another thing. Alexander original message: --- We cannot do the configure-time check for that, because there is only one version of each compiler shipped in ndk for all Android platforms. On the other hand, having different runtime targets like -mandroid-19, -mandroid-20 would be a nightmare. But, keeping in mind that the last version of Android is a priority, I think that enabling ifuncs unconditionally would be the right thing. --- isn't precise. That isn't what his patch does. All his patch does is to check IFUNC support at GCC configure-time when targetting Android. His patch alone won't "enabling ifuncs unconditionally" for any targets, Android or not. -- H.J.
