Section symbols exist as an optimization: instead of having multiple relocations
point to different symbols, many of them can point to a single section symbol.
When that optimization is unused, a section symbol is also unused and adds no
extra information to the object file.
This saves a bit of space on the object files and makes the output of
llvm-objdump -t easier to read and consequently some tests get quite a bit
simpler.
llvm-svn: 239045
Normally an ELF .o has two string tables, one for symbols, one for section
names.
With the scheme of naming sections like ".text.foo" where foo is a symbol,
there is a big potential saving in using a single one.
Building llvm+clang+lld with master and with this patch the results were:
master: 193,267,008 bytes
patch: 186,107,952 bytes
master non unique section names: 183,260,192 bytes
patch non unique section names: 183,118,632 bytes
So using non usique saves 10,006,816 bytes, and the patch saves 7,159,056 while
still using distinct names for the sections.
llvm-svn: 238073
Summary:
The object format can be set to something other than MachO, e.g.
to use ELF-on-Darwin for MCJIT. This already works on Windows, so
there's no reason it shouldn't on Darwin.
Reviewers: lhames, grosbach
Subscribers: rafael, grosbach, t.p.northover, llvm-commits
Differential Revision: http://reviews.llvm.org/D6185
llvm-svn: 236455
Instead of accumulating the content in a fragment first, just write it
to the output stream.
Also put it first in the section table, so that we never have to worry
about its index being >= SHN_LORESERVE.
llvm-svn: 236145
The failures in r116753 r116756 were caused by a python issue -
Python likes to append 'L' suffix to stringified numbers if the number
is larger than a machine int. Unfortunately, this causes a divergence of
behavior between 32 and 64 bit python versions.
I re-crafted elf-dump/common_dump to take care of these issues by:
1. always printing 0x (makes for easy sed/regex)
2. always print fixed length (exactly 2 + numBits/4 digits long)
by mod ((2^numBits) - 1)
3. left-padded with '0'
There is a residual common routine that is also used by
macho-dump (dataToHex) , so I left the 'section_data' test values alone.
llvm-svn: 116823
The ELF implementation now creates text, data and bss to match the gnu as
behavior.
The text streamer still has the old MachO specific behavior since
the testsuite checks that it will error when a directive is given
before a setting the current section for example.
A nice benefit is that -n is not required anymore when producing
ELF files.
llvm-svn: 114027
Rafael Espindola