[GOLD] PowerPC recreate eh_frame for stubs on each relax pass
authorAlan Modra <amodra@gmail.com>
Tue, 1 Aug 2017 04:38:53 +0000 (14:08 +0930)
committerAlan Modra <amodra@gmail.com>
Tue, 1 Aug 2017 04:38:53 +0000 (14:08 +0930)
commitbe897fb774abfb0a44b3b87fe77bccafa336e638
tree8b607740dccdbe530d2c1a87680c35b2320d354c
parent51b69c74c6464c59a5621d6f3d3967a576043fa8
[GOLD] PowerPC recreate eh_frame for stubs on each relax pass

There is a very small but non-zero probability that a stub group
contains stubs on one relax pass, but does not on the next.  In that
case we would get an FDE covering a zero length address range.
(Actually, it's even worse.  Alignment padding for stubs can mean the
address for the non-existent stubs is past the end of the original
section to which stubs are attached, and due to the way
do_plt_fde_location calculates the length we can get a negative
length.)  Fixing this properly requires removing the FDE.

Also, I have been implementing the __tls_get_addr_opt support for
gold, and that stub needs something other than the default FDE.  The
necessary FDE will depend on the offset to the __tls_get_addr_opt
stub, which of course can change during relaxation.  That means at the
very least, rewriting the FDE on each pass, possibly changing the FDE
size.  I think that is better done by completely recreating PLT
eh_frame FDEs.

* ehframe.cc (Fde::operator==): New.
(Cie::remove_fde, Eh_frame::remove_ehframe_for_plt): New.
* ehframe.h (Fde::operator==): Declare.
(Cie::remove_fde, Eh_frame::remove_ehframe_for_plt): Likewise.
* layout.cc (Layout::remove_eh_frame_for_plt): New.
* layout.h (Layout::remove_eh_frame_for_plt): Declare.
* powerpc.cc (Target_powerpc::do_relax): Remove old eh_frame FDEs.
(Stub_table::add_eh_frame): Delete eh_frame_added_ condition.
Don't add eh_frame for empty stub section.
(Stub_table::remove_eh_frame): New.
gold/ChangeLog
gold/ehframe.cc
gold/ehframe.h
gold/layout.cc
gold/layout.h
gold/powerpc.cc