The final section order in relocatable files was just a side effect
of the atom sorter. This meant that sections like __data were before
__text because __data has RW permissions and __text RX and RW was less
than RX in our enum.
Final linked images had an actual section/segment sorter. There was no
reason for the difference, so simplify a bunch of code and just use the
same sorted for everything.
Reviewed by Lang Hames.
http://reviews.llvm.org/D15868
llvm-svn: 256786
The encoded value should be an offset from the fixup location, which
means that it should take in to account the fixup offset in its section.
We weren't subtracting the base address of the atom, which meant that when
we parsed the file again for a round trip, we had 2x the atom address in our
target address.
I've also improved comments for these to try and describe what is going on.
There's no test case right now, as the bug is only exhibited when __data is at
a non-zero address in a -r link. A commit will soon sort the sections differently
and move __data to after __text. Then these relocations in
test/mach-o/parse-data-relocs-x86_64.yaml will test for this bug.
llvm-svn: 256779
Test did not catch this either, so I`ll improve it and recommit later.
Original commit message:
[ELF] - Optimize .eh_frame section: remove CIE if all FDEs referencing it were removed.
This patch performs little optimization for eh_frame section.
If all FDE`s that referenced CIE are removed then CIE is also removed from output.
That can happen for example when dropping FDEs that point to dropped sections. Testcase showing that is included.
The same optimization was added to ld about 14 years ago: https://sourceware.org/ml/binutils/2001-12/msg00144.html, gold does not do that it seems.
Differential revision: http://reviews.llvm.org/D15564
llvm-svn: 256693
This patch performs little optimization for eh_frame section.
If all FDE`s that referenced CIE are removed then CIE is also removed from output.
That can happen for example when dropping FDEs that point to dropped sections. Testcase showing that is included.
The same optimization was added to ld about 14 years ago: https://sourceware.org/ml/binutils/2001-12/msg00144.html, gold does not do that it seems.
Differential revision: http://reviews.llvm.org/D15564
llvm-svn: 256638
The linker has to create __tls_get_addr, end and _end symbols.
Previously, these symbols were created in createSections().
But they are not actually related to creating output sections.
This patch moves code out of the function.
llvm-svn: 256441
Previously, this code was directly written in createSections()
function. This patch moves some code out of that function to a
new class.
llvm-svn: 256438
The number of output sections is usually limited, so the cost
of allocating them is not a bottleneck. This patch simplifies
the code by removing the allocators.
llvm-svn: 256437
OutputSectionBase already has virtual member functions.
This patch makes addSection() a virtual function to remove code
from Writer::createSections().
llvm-svn: 256436
The R_MIPS_GPREL16 / R_MIPS_GPREL32 relocations use the following
expressions for calculations:
```
local symbol: S + A + GP0 - GP
global symbol: S + A - GP
GP - Represents the final gp value, i.e. _gp symbol
GP0 - Represents the gp value used to create the relocatable object
```
The GP0 value is taken from the .reginfo data section defined by an object
file. To implement that I keep a reference to `MipsReginfoInputSection`
in the `ObjectFile` class. This reference is used by the
`ObjectFile::getMipsGp0` method to return the GP0 value.
Differential Revision: http://reviews.llvm.org/D15760
llvm-svn: 256416
The file crtbeginT.o has relocations pointing to the start of an empty
.eh_frame that is known to be the first in the link. It does that to
identify the start of the output .eh_frame. Handle this special case.
Differential revision: http://reviews.llvm.org/D15610
llvm-svn: 256414
This function was longer than 250 lines, which is way too long
in my own standard. This patch reduces the size. It is still
too long, but this patch should be toward the right direction.
llvm-svn: 256411
There are 3 symbol types that a .bc can provide during lto: defined,
undefined, common.
Defined and undefined symbols have already been refactored. I was
working on common and noticed that absolute symbols would become an
oddity: They would be the only symbol type present in a .o but not in
a.bc.
Looking a bit more, other than the special section number they were only
used for special rules for computing values. In that way they are
similar to TLS, and we don't have a DefinedTLS.
This patch deletes it. With it we have a reasonable rule of the thumb
for having a symbol kind: It exists if it has special resolution
semantics.
llvm-svn: 256383
In FreeBSD, rtld expects .ctors containing -1 (0xffffffff), and a
.ctors section containing the correct bits is provided to the linker as
input (/usr/lib/crtbegin.o).
Contents of section .ctors:
0000 ffffffff ffffffff ........
This section is not stripped even if not referenced or empty, also in
gold or ld.bfd. It would be nice to strip it when not needed but
since existing object files rely on that we can't do better to keep it
around.
Differential Revision: http://reviews.llvm.org/D15767
llvm-svn: 256373
Before this patch sections that go after relro sequence were placed at
the same memory page with relro ones. It caused segmentation fault on
freebsd.
Fixes PR25790.
Patch by George Rimar with some tweaks by myself.
llvm-svn: 256334
Pete Cooper