On Wed, Dec 3, 2014 at 10:35 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
>>>>>> It would probably help reviewers if you pointed to actual path >>>>>> submission [1], which unfortunately contains the explanation in the >>>>>> patch itself [2], which further explains that this functionality is >>>>>> currently only supported with gold, patched with [3]. >>>>>> >>>>>> [1] https://gcc.gnu.org/ml/gcc-patches/2014-09/msg00645.html >>>>>> [2] https://gcc.gnu.org/ml/gcc-patches/2014-09/txt2CHtu81P1O.txt >>>>>> [3] https://sourceware.org/ml/binutils/2014-05/msg00092.html >>>>>> >>>>>> After a bit of the above detective work, I think that new gcc option >>>>>> is not necessary. The configure should detect if new functionality is >>>>>> supported in the linker, and auto-configure gcc to use it when >>>>>> appropriate. >>>>> >>>>> I think GCC option is needed since one can use -fuse-ld= to >>>>> change linker. >>>> >>>> IMO, nobody will use this highly special x86_64-only option. It would >>>> be best for gnu-ld to reach feature parity with gold as far as this >>>> functionality is concerned. In this case, the optimization would be >>>> auto-configured, and would fire automatically, without any user >>>> intervention. >>>> >>> >>> Let's do it. I implemented the same feature in bfd linker on both >>> master and 2.25 branch. >>> >> >> +bool >> +i386_binds_local_p (const_tree exp) >> +{ >> + /* Globals marked extern are treated as local when linker copy relocations >> + support is available with -f{pie|PIE}. */ >> + if (TARGET_64BIT && ix86_copyrelocs && flag_pie >> + && TREE_CODE (exp) == VAR_DECL >> + && DECL_EXTERNAL (exp) && !DECL_WEAK (exp)) >> + return true; >> + return default_binds_local_p (exp); >> +} >> + >> >> It returns true with -fPIE and false without -fPIE. It is lying to compiler. >> Maybe legitimate_pic_address_disp_p is a better place. Agreed. > Something like this? Yes. OK, if Jakub doesn't have any objections here. Please also add Sriraman as author to ChangeLog entry. Thanks, Uros.