[Bug target/99783] relocation truncated to fit: R_OR1K_GOT16 on OpenRISC, building libgeos

["shorne at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99783

--- Comment #7 from shorne at gmail dot com ---
On Thu, Dec 30, 2021 at 09:59:57PM +0000, shorne at gmail dot com wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99783
> 
> --- Comment #6 from shorne at gmail dot com ---
> Ok, let me have a look.
> 

OK, I can reproduce, but I am not sure what is going on I will need to debug a
bit more.  This is what I have so far.

ERROR:

  I am seeing the same error you report.

   
buildroot/output/host/lib/gcc/or1k-buildroot-linux-uclibc/11.2.0/crtbeginS.o:
in function `deregister_tm_clones':
    crtstuff.c:(.text+0x44): relocation truncated to fit: R_OR1K_GOT16 against
undefined symbol `_ITM_deregisterTMCloneTable'
   
buildroot/output/host/lib/gcc/or1k-buildroot-linux-uclibc/11.2.0/crtbeginS.o:
in function `register_tm_clones':
    crtstuff.c:(.text+0xcc): relocation truncated to fit: R_OR1K_GOT16 against
undefined symbol `_ITM_registerTMCloneTable'
   
buildroot/output/host/lib/gcc/or1k-buildroot-linux-uclibc/11.2.0/crtbeginS.o:
in function `__do_global_dtors_aux':
    crtstuff.c:(.text+0x12c): relocation truncated to fit: R_OR1K_GOT16 against
symbol `__cxa_finalize' defined in .text section in
buildroot/output/host/or1k-buildroot-linux-uclibc/sysroot/lib/libc.so.1
    crtstuff.c:(.text+0x15c): relocation truncated to fit: R_OR1K_GOT16 against
symbol `__deregister_frame_info@@GLIBC_2.0' defined in .text section in
buildroot/output/host/lib/gcc/or1k-buildroot-linux-uclibc/11.2.0/../../../../or1k-buildroot-linux-uclibc/lib/libgcc_s.so
   
buildroot/output/host/lib/gcc/or1k-buildroot-linux-uclibc/11.2.0/crtbeginS.o:
in function `frame_dummy':


Actual Code patterns:

  Looking at the generated object file.
  We can see R_OR1K_GOT_AHI16 followed by R_OR1K_GOT16.  This confirms the
  cmodel=large is ON.

    or1k-elf-objdump -dr
buildroot/output/host/lib/gcc/or1k-buildroot-linux-uclibc/11.2.0/crtbeginS.o

    deregister_tm_clones:

      38:   1a 20 00 00     l.movhi r17,0x0
                            38: R_OR1K_GOT_AHI16    _ITM_deregisterTMCloneTable
      3c:   e2 31 98 00     l.add r17,r17,r19
      40:   1a 60 00 00     l.movhi r19,0x0
      44:   86 31 00 00     l.lwz r17,0(r17)
                            44: R_OR1K_GOT16        _ITM_deregisterTMCloneTable
      48:   e4 11 98 00     l.sfeq r17,r19
      4c:   10 00 00 04     l.bf 5c <deregister_tm_clones+0x5c>
      50:   85 21 00 00     l.lwz r9,0(r1)

    register_tm_clones:

      c0:   10 00 00 09     l.bf e4 <register_tm_clones+0x7c>
      c4:   1a 20 00 00     l.movhi r17,0x0
                            c4: R_OR1K_GOT_AHI16    _ITM_registerTMCloneTable
      c8:   e2 31 98 00     l.add r17,r17,r19
      cc:   86 31 00 00     l.lwz r17,0(r17)
                            cc: R_OR1K_GOT16        _ITM_registerTMCloneTable
      d0:   e4 11 a8 00     l.sfeq r17,r21

    __do_global_dtors_aux:

     150:   1a 20 00 00     l.movhi r17,0x0
                            150: R_OR1K_GOT_AHI16   __deregister_frame_info
     154:   e2 31 80 00     l.add r17,r17,r16
     158:   1a 60 00 00     l.movhi r19,0x0
     15c:   86 31 00 00     l.lwz r17,0(r17)
                            15c: R_OR1K_GOT16       __deregister_frame_info
     160:   e4 11 98 00     l.sfeq r17,r19
     164:   10 00 00 07     l.bf 180 <__do_global_dtors_aux+0x90>

IN buildroot/output/build/host-binutils-2.37/bfd/elf32-or1k.c:

   We have this bit of code which confirms we have the correct patches
   available in binutils.  This code shows we should be avoiding this
truncation
   if we have R_OR1K_GOT_AHI16 followed by R_OR1K_GOT16 which is what we have.

   Note, the comment above if (r_type == R_OR1K_GOT16 && saw_gotha) seems
   backwards.

            if (r_type == R_OR1K_GOT_AHI16)
              saw_gotha = true;

            /* If we have a R_OR1K_GOT16 followed by a R_OR1K_GOT_AHI16
               relocation we assume the code is doing the right thing to avoid
               overflows.  Here we mask the lower 16-bit of the relocation to
               avoid overflow validation failures.  */
            if (r_type == R_OR1K_GOT16 && saw_gotha)
              relocation &= 0xffff;

I will have to look at this more.