If a section is rw, it is irrelevant if the dynamic linker will write to
it or not.
It looks like llvm implemented this because gcc was doing it. It looks
like gcc implemented this in the hope that it would put all the
relocated items close together and speed up the dynamic linker.
There are two problem with this:
* It doesn't work. Both bfd and gold will map .data.rel to .data and
concatenate the input sections in the order they are seen.
* If we want a feature like that, it can be implemented directly in the
linker since it knowns where the dynamic relocations are.
llvm-svn: 253436
The way prelink used to work was
* The compiler decides if a given section only has relocations that
are know to point to the same DSO. If so, it names it
.data.rel.ro.local<something>.
* The static linker puts all of these together.
* The prelinker program assigns addresses to each library and resolves
the local relocations.
There are many problems with this:
* It is incompatible with address space randomization.
* The information passed by the compiler is redundant. The linker
knows if a given relocation is in the same DSO or not. If could sort
by that if so desired.
* There are newer ways of speeding up DSO (gnu hash for example).
* Even if we want to implement this again in the compiler, the previous
implementation is pretty broken. It talks about relocations that are
"resolved by the static linker". If they are resolved, there are none
left for the prelinker. What one needs to track is if an expression
will require only dynamic relocations that point to the same DSO.
At this point it looks like the prelinker is an historical curiosity.
For example, fedora has retired it because it failed to build for two
releases
(http://pkgs.fedoraproject.org/cgit/prelink.git/commit/?id=eb43100a8331d91c801ee3dcdb0a0bb9babfdc1f)
This patch removes support for it. That is, it stops printing the
".local" sections.
llvm-svn: 253280
The AArch32 assembler parses the '@' as a comment symbol, so the error message shouldn't suggest
that '@<type>' is a valid replacement when assembling for AArch32 target.
Differential Revision: http://reviews.llvm.org/D10651
llvm-svn: 241149
The patch is generated using this command:
tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
llvm/lib/
Thanks to Eugene Kosov for the original patch!
llvm-svn: 240137
This create a MCSymbolELF class and moves SymbolSize since only ELF
needs a size expression.
This reduces the size of MCSymbol from 56 to 48 bytes.
llvm-svn: 238801
Both MCStreamer and MCObjectStreamer were maintaining a current section
variable and they were slightly out of sync. I don't think this was observable,
but was inefficient and error prone.
Changing this requires a few cascading changes:
* SwitchSection has to call ChangeSection earlier for ChangeSection to see
the old section.
* With that change, ChangeSection cannot call EmitLabel, since during
ChangeSection we are still in the old section.
* When the object streamer requires a begin label, just reused the existing
generic support for begin labels instead of calling EmitLabel directly.
llvm-svn: 238357
This starts merging MCSection and MCSectionData.
There are a few issues with the current split between MCSection and
MCSectionData.
* It optimizes the the not as important case. We want the production
of .o files to be really fast, but the split puts the information used
for .o emission in a separate data structure.
* The ELF/COFF/MachO hierarchy is not represented in MCSectionData,
leading to some ad-hoc ways to represent the various flags.
* It makes it harder to remember where each item is.
The attached patch starts merging the two by moving the alignment from
MCSectionData to MCSection.
Most of the patch is actually just dropping 'const', since
MCSectionData is mutable, but MCSection was not.
llvm-svn: 237936
This allows the compiler/assembly programmer to switch back to a
section. This in turn fixes the bootstrap failure on powerpc (tested
on gcc110) without changing the ppc codegen at all.
I will try to cleanup the various getELFSection overloads in a followup patch.
Just using a default argument now would lead to ambiguities.
llvm-svn: 234099
Add support for having multiple sections with the same name and comdat.
Using this in combination with -ffunction-sections allows LLVM to output a .o
file with mulitple sections named .text. This saves space by avoiding long
unique names of the form .text.<C++ mangled name>.
llvm-svn: 229541
regressions for LLDB on Linux. Rafael indicated on lldb-dev that we
should just go ahead and revert these but that he wasn't at a computer.
The patches backed out are as follows:
r228980: Add support for having multiple sections with the name and ...
r228889: Invert the section relocation map.
r228888: Use the existing SymbolTableIndex intsead of doing a lookup.
r228886: Create the Section -> Rel Section map when it is first needed.
These patches look pretty nice to me, so hoping its not too hard to get
them re-instated. =D
llvm-svn: 229080
Using this in combination with -ffunction-sections allows LLVM to output a .o
file with mulitple sections named .text. This saves space by avoiding long
unique names of the form .text.<C++ mangled name>.
llvm-svn: 228980
Any code creating an MCSectionELF knows ELF and already provides the flags.
SectionKind is an abstraction used by common code that uses a plain
MCSection.
Use the flags to compute the SectionKind. This removes a lot of
guessing and boilerplate from the MCSectionELF construction.
llvm-svn: 227476
We currently emit an error when trying to assemble a file with more
than one section using DWARF2 debug info. This should be a warning
instead, as the resulting file will still be usable, but with a
degraded debug illusion.
llvm-svn: 218241
Currently, when using llvm as an assembler, DWARF debug information is only
generated for the .text section. This patch modifies this so that DWARF info
is emitted for all executable sections.
llvm-svn: 211273
GAS documents the .type directive as having an optional comma following the key
symbol name when using the STT_<TYPE_IN_UPPER_CASE> form. However, it treats
the comma as optional in all cases. This makes the IAS support both forms of
inputs. Furthermore, the prefixed forms take either the upper case name or the
lower case alias.
The tests are split into two separate sets as the hash character serves as a
comment character on x86, which is tested in the second set by using arm-elf
which uses the at symbol as a comment character.
llvm-svn: 210407
ARM assembly syntax uses @ for a comment, execpt for the second
parameter of the .symver directive which requires @ as part of the
symbol name. This commit fixes the parsing of this directive by
adding a special case for ARM for this one argumnet.
To make the change we had to move the AllowAtInIdentifier variable
to the MCAsmLexer interface (from AsmLexer) and expose a setter for
the value. The ELFAsmParser then toggles this value when parsing
the second argument to the .symver directive for a target that
uses @ as a comment symbol
llvm-svn: 199339
Summary:
The '?' flag uses the last section group if the last had a section
group. We treat combining an explicit section group and the '?' as a
hard error.
This fixes PR17198.
Reviewers: rafael, bkramer
Reviewed By: bkramer
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1686
llvm-svn: 190768
The .local, .hidden, .internal, and .protected are not legal for all supported
file formats (in particular, they're invalid for MachO). Move the parsing for
them into the ELF assembly parser since that's the format they're for.
Similarly, .weak is used by COFF and ELF, but not MachO, so move the parsing
to the COFF and ELF asm parsers. Previously, using any of these directives
on Darwin would result in an assertion failure in the parser; now we get
a diagnostic as we should.
rdar://9827089
llvm-svn: 135921
Introduce a variable in the AsmParserExtension whether [] is valid in an
expression. If it is true, parse them like (). Enable this for ELF only.
llvm-svn: 126443
Rafael Espindola