Coverage mapping data is not referenced by runtime, and they won't be dumped
into profile data. There is no need to allocate memory for covmap sections.
A good side effect of this change is that the coverage map data won't be mistakenly
garbage collected by the linker (for Gold linker only, BFD linker has an issue where the a bug is filed).
Tested with clang build with instrumentation and -fcoverage-mapping and linker GC. The size of
covmap section is ~17.6M so the text segment size will be reduced by this amount with this change.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257781 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253436 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253280 91177308-0d34-0410-b5e6-96231b3b80d8
A profile of an LTO link of Chrome revealed that we were spending some
~30-50% of execution time in the function Constant::getRelocationInfo(),
which is called from TargetLoweringObjectFile::getKindForGlobal() and in turn
from TargetMachine::getNameWithPrefix().
It turns out that we only need the result of getKindForGlobal() when
targeting Mach-O, so this change moves the relevant part of the logic to
TargetLoweringObjectFileMachO.
NFCI.
Differential Revision: http://reviews.llvm.org/D14168
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252014 91177308-0d34-0410-b5e6-96231b3b80d8
This prevents MC clients from getting COFF.h, which conflicts with
winnt.h macros. Also a minor IWYU cleanup. Now the only public headers
including COFF.h are in Object, and they actually need it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246784 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.
Reviewers: echristo
Subscribers: yaron.keren, rafael, llvm-commits, jholewinski
Differential Revision: http://reviews.llvm.org/D11079
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242385 91177308-0d34-0410-b5e6-96231b3b80d8
It is mandatory to specify a comdat in order to receive comdat semantics
for a symbol. We were previously getting this wrong in -function-sections
mode; linker-weak symbols were being emitted in a selectany comdat. This
change causes such symbols to use a noduplicates comdat instead, fixing
the inconsistency.
Also correct an inaccuracy in the docs.
Differential Revision: http://reviews.llvm.org/D10828
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241103 91177308-0d34-0410-b5e6-96231b3b80d8
This change unifies how LTOModule and the backend obtain linker flags
for globals: via a new TargetLoweringObjectFile member function named
emitLinkerFlagsForGlobal. A new function LTOModule::getLinkerOpts() returns
the list of linker flags as a single concatenated string.
This change affects the C libLTO API: the function lto_module_get_*deplibs now
exposes an empty list, and lto_module_get_*linkeropts exposes a single element
which combines the contents of all observed flags. libLTO should never have
tried to parse the linker flags; it is the linker's job to do so. Because
linkers will need to be able to parse flags in regular object files, it
makes little sense for libLTO to have a redundant mechanism for doing so.
The new API is compatible with the old one. It is valid for a user to specify
multiple linker flags in a single pragma directive like this:
#pragma comment(linker, "/defaultlib:foo /defaultlib:bar")
The previous implementation would not have exposed
either flag via lto_module_get_*deplibs (as the test in
TargetLoweringObjectFileCOFF::getDepLibFromLinkerOpt was case sensitive)
and would have exposed "/defaultlib:foo /defaultlib:bar" as a single flag via
lto_module_get_*linkeropts. This may have been a bug in the implementation,
but it does give us a chance to fix the interface.
Differential Revision: http://reviews.llvm.org/D10548
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241010 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238801 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237936 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234099 91177308-0d34-0410-b5e6-96231b3b80d8
COFF COMDATs (for selection kinds other than 'select any') require at
least one non-section symbol in the symbol table.
Satisfy this by morally enhancing the linkage from private to internal.
Differential Revision: http://reviews.llvm.org/D8394
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232570 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
COFF COMDATs (for selection kinds other than 'select any') require at
least one non-section symbol in the symbol table.
Satisfy this by morally enhancing the linkage from private to internal.
Reviewers: rafael
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D8374
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232539 91177308-0d34-0410-b5e6-96231b3b80d8
If a function is going in an unique section (because of -ffunction-sections
for example), putting a jump table in .rodata will keep .rodata alive and
that will keep alive any other function that also has a jump table.
Instead, put the jump table in a unique section that is associated with the
function.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231961 91177308-0d34-0410-b5e6-96231b3b80d8
Add MachO 32-bit (i.e. arm and x86) support for replacing global GOT equivalent
symbol accesses. Unlike 64-bit targets, there's no GOTPCREL relocation, and
access through a non_lazy_symbol_pointers section is used instead.
-- before
_extgotequiv:
.long _extfoo
_delta:
.long _extgotequiv-_delta
-- after
_delta:
.long L_extfoo$non_lazy_ptr-_delta
.section __IMPORT,__pointers,non_lazy_symbol_pointers
L_extfoo$non_lazy_ptr:
.indirect_symbol _extfoo
.long 0
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231475 91177308-0d34-0410-b5e6-96231b3b80d8
This patch unifies the comdat and non-comdat code paths. By doing this
it add missing features to the comdat side and removes the fixed
section assumptions from the non-comdat side.
In ELF there is no one true section for "4 byte mergeable" constants.
We are better off computing the required properties of the section
and asking the context for it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230411 91177308-0d34-0410-b5e6-96231b3b80d8
The problem in the original patch was not switching back to .text after printing
an eh table.
Original message:
On ELF, put PIC jump tables in a non executable section.
Fixes PR22558.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229586 91177308-0d34-0410-b5e6-96231b3b80d8
Xinliang David Li
Rafael Espindola
Peter Collingbourne
Reid Kleckner
Benjamin Kramer
Mehdi Amini
Jim Grosbach
David Majnemer
Bruno Cardoso Lopes