[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Bug ld/12608] TLS relocations issues on alpha

From: mcree at orcon dot net.nz
Subject: [Bug ld/12608] TLS relocations issues on alpha
Date: Thu, 31 Mar 2011 23:08:36 +0000


Michael Cree <mcree at orcon dot net.nz> changed:

           What    |Removed                     |Added
                 CC|                            |mcree at orcon dot net.nz

--- Comment #8 from Michael Cree <mcree at orcon dot net.nz> 2011-03-31 
23:08:24 UTC ---
I see the bug compiling just as Aurelien describes.  This is using Debian
unstable binutils (  The bug does not appear if one compiles
with the "-Wl,--no-relax" option.  

I think the bug is likely to be in the elf64_alpha_relax_tls_get_addr()
function of bfd/elf64-alpha.c which is the function that implements the
transformation of code of the specific example.

The particular register that is loaded into the x of the instruction "ldq   
x,-32680(gp)" in the examples given by Aurelien is at line 3500 of the
bfd/elf64-alpha.c  code and is:

 tlsgd_reg = bfd_get_32 (info->abfd, pos[0]);
 tlsgd_reg = (tlsgd_reg >> 21) & 31;

For some reason it can pick up the wrong register, i.e., it seems to be getting
the register of the first instruction in the sequence transformation always,
and if the first two instructions are swapped in order it then gets the wrong
register.  I am not yet sure why this occurs, as there seems to be code above
to deal with this exact situation.  At line 3429 is the following:

  /* Generally, the positions are not allowed to be out of order, lest the
     modified insn sequence have different register lifetimes.  We can make
     an exception when pos 1 is adjacent to pos 0.  */
  if (pos[1] + 4 == pos[0])
      bfd_byte *tmp = pos[0];
      pos[0] = pos[1];
      pos[1] = tmp;

This is far as my analysis has got with the limited time I have had to look at
this so far.

Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]