Now that we are trying to use the linker script representation as the
canonycal one, there are a few loops looking for just OutputSectionCommands.
Create a vector with just the OutputSectionCommands once that is
stable to simplify the rest of the code.
llvm-svn: 304181
On SPARC, .plt is both writeable and executable. The current way
sections are sorted means that lld puts it after .data/.bss. but it
really needs to be close to .test to make sure branches into .plt
don't overflow. I'd argue that because .bss is supposed to come last
on all architectures, we should change the default sort order such
that writable and executable sections come before sections that are
just writeable. read-only executable sections should still come after
sections that are just read-only of course. This diff makes this
change.
llvm-svn: 304008
In this way, the content and the flag is always consistent, which I
think better than removing the bit when input sections reaches the Writer.
llvm-svn: 303926
This reduces how many times we have to map from OutputSection to
OutputSectionCommand. It is a required step to moving
clearOutputSections earlier.
In order to always use writeTo in OutputSectionCommand we have to call
fabricateDefaultCommands for -r links and move section compression
after it.
llvm-svn: 303784
Once the dummy linker script is created, we want it to be used for
everything to avoid having two redundant representations that can get
out of sync.
We were already clearing OutputSections. With this patch we clear the
Sections vector of every OutputSection.
llvm-svn: 303703
This converts the last (chronologically) user of OutputSections to use
the linker script commands instead.
The idea is to convert all uses after fabricateDefaultCommands, so
that we have a single representation.
llvm-svn: 303384
GetSection is a template because write calls relocate.
relocate has two parts. The non alloc code really has to be a
template, as it is looking a raw input file data.
The alloc part is only a template because of getSize.
This patch folds the value of getSize early, detemplates
getRelocTargetVA and splits relocate into a templated non alloc case
and a regular function for the alloc case. This has the nice advantage
of making sure we collect all the information we need for relocations
before getting to InputSection::relocateNonAlloc.
Since we know got is alloc, it can just call the function directly and
avoid the template.
llvm-svn: 303355
Nothing special here, just detemplates code that became possible
to detemplate after recent commits in a straghtforward way.
Differential revision: https://reviews.llvm.org/D33234
llvm-svn: 303237
SymbolTableBaseSection was introduced.
Detemplation of SymbolTableSection should allow to detemplate more things.
Differential revision: https://reviews.llvm.org/D33124
llvm-svn: 303150
Switch to llvm::to_integer() everywhere in LLD instead of
StringRef::getAsInteger() because API of latter is confusing.
It returns true on error and false otherwise what makes reading
the code incomfortable.
Differential revision: https://reviews.llvm.org/D33187
llvm-svn: 303149
We used to place orphans by just using compareSectionsNonScript.
Then we noticed that since linker scripts can use another order, we
should first try match the section to a given PT_LOAD. But there is
nothing special about PT_LOAD. The same issue can show up for
PT_GNU_RELRO for example.
In general, we have to search for the most similar section and put the
orphan next to it. Most similar being defined as how long they follow
the same code path in compareSecitonsNonScript.
That is what this patch does. We now compute a rank for each output
section, with a bit for each branch in what was
compareSectionsNonScript.
With this findOrphanPos is now fully general and orphan placement can
be optimized by placing every section with the same rank at once.
The included testcase is a variation of many-sections.s that uses
allocatable sections to avoid the fast path in the existing
code. Without threads it goes form 46 seconds to 0.9 seconds.
llvm-svn: 302903
This behavior differs from the semantics implemented by GNU linkers
which only define this symbol iff ELF headers are in the memory
mapped segment.
Differential Revision: https://reviews.llvm.org/D33019
llvm-svn: 302687
This is a bit easier to read and a lot faster in some cases. A version
of many-sections.s with linker scripts goes from 0m41.232s to
0m19.575s.
llvm-svn: 302528
The code following this one already considers every possible insertion
point for orphan sections, there is no point in sorting them before.
llvm-svn: 302441
We can set SectionIndex tentatively as we process the linker script
instead of looking it repeatedly.
In general we should try to have as few name lookups as possible.
llvm-svn: 302299
In the non linker script case we would try very early to find out if
we could allocate the headers. Failing to do that would add extra
alignment to the first ro section, since we would set PageAlign
thinking it was the first section in the PT_LOAD.
In the linker script case the header allocation must be done in the
end, causing some duplication.
We now tentatively add the headers to the first PT_LOAD and if it
turns out they don't fit, remove them. With this we only need to
allocate the headers in one place in the code.
llvm-svn: 302186
The --section-start <name>=<address> needs to be translated into equivalent
linker script commands. There are a couple of problems with the existing
implementation:
- The --section-start with the lowest address is assumed to be at the start
of the map. This assumption is incorrect, we have to iterate through the
SectionStartMap to find the lowest address.
- The addresses in --section-start were being over-aligned when the
sections were marked as PageAlign. This is inconsistent with the use of
SectionStartMap in fixHeaders(), and can cause problems when the PageAlign
causes an "unable to move location counter backward" error when the
--section-start with PageAlign is aligned to an address higher than the next
--section-start. The ld.bfd and ld.gold seem to be more consistent with this
approach but this is not a well specified area.
This change fixes the problems above and also corrects a typo in which
fabricateDefaultCommands() is called with the wrong parameter, it should be
called with AllocateHeader not Config->MaxPageSize.
Differential Revision: https://reviews.llvm.org/D32749
llvm-svn: 302007
This version uses a set to speed up the synchronize method.
Original message:
Remove LinkerScript::flush.
This patch replaces flush with a last ditch attempt at synchronizing
the section list with the linker script "AST".
The synchronization is a bit of a hack and should in time be avoided
by creating the AST earlier so that modifications can be made directly
to it instead of modifying the section list and synchronizing it back.
This is the main step for fixing
https://bugs.llvm.org/show_bug.cgi?id=32816. With this in place I
think the only missing thing would be to have processCommands assign
section indexes as dummy offsets so that the sort in
OutputSection::finalize works.
With this LinkerScript::assignAddresses becomes much simpler, which
should help with the thunk work.
llvm-svn: 301745
This reverts commit r301678 since that change significantly slowed
down the linker. Before this patch, LLD could link clang in 8 seconds,
but with this patch it took 40 seconds.
llvm-svn: 301709
This patch replaces flush with a last ditch attempt at synchronizing
the section list with the linker script "AST".
The synchronization is a bit of a hack and should in time be avoided
by creating the AST earlier so that modifications can be made directly
to it instead of modifying the section list and synchronizing it back.
This is the main step for fixing
https://bugs.llvm.org/show_bug.cgi?id=32816. With this in place I
think the only missing thing would be to have processCommands assign
section indexes as dummy offsets so that the sort in
OutputSection::finalize works.
With this LinkerScript::assignAddresses becomes much simpler, which
should help with the thunk work.
llvm-svn: 301678
addIgnored defines a given symbol even if there is no existing
symbol with the same name. So, even if libc provides __tls_get_addr,
we should still be able to call addIgnored.
Differential Revision: https://reviews.llvm.org/D32053
llvm-svn: 301290
This change fabricates linker script commands for the case where there is
no linker script SECTIONS to control address assignment. This permits us
to have a single Script->assignAddresses() function.
There is a small change in user-visible-behavior with respect to the
handling of .tbss SHT_NOBITS, SHF_TLS as the Script->assignAddresses()
requires setDot() to be called with monotically increasing addresses.
The tls-offset.s test has been updated so that the script and non-script
results match.
This change should make the non-script behavior of lld closer to an
equivalent linker script.
Differential Revision: https://reviews.llvm.org/D31888
llvm-svn: 300687
Patch implements --compress-debug-sections=zlib.
In compare with D20211 (a year old patch, abandoned), it implementation
uses streaming and fully reimplemented, does not support zlib-gnu for
simplification.
This is PR32308.
Differential revision: https://reviews.llvm.org/D31941
llvm-svn: 300444
RELRO is a feature to make segments read-only after dynamic relocations
are applied. It is different from read-only segments because RELRO is
initially writable. And of course RELRO is different from writable
segments.
RELRO is not a very well known feature. We have a series of checks to
make a decision whether a section should be in a RELRO segment or not,
but we didn't describe why. This patch adds comments to explain how
that decision is made.
llvm-svn: 300176
Executable sections should not be padded with zero by default. On some
architectures, 0x00 is the start of a valid instruction sequence, so can confuse
disassembly between InputSections (and indeed the start of the next InputSection
in some situations). Further, in the case of misjumps into padding, padding may
start to be executed silently.
On x86, the "0xcc" byte represents the int3 trap instruction. It is a single
byte long so can serve well as padding. This change switches x86 (and x86_64) to
use this value for padding in executable sections, if no linker script directive
overrides it. It also puts the behaviour into place making it easy to change the
behaviour of other targets when desired. I do not know the relevant instruction
sequences for trap instructions on other targets however, so somebody should add
this separately.
Because the old behaviour simply wrote padding in the whole section before
overwriting most of it, this change also modifies the padding algorithm to write
padding only where needed. This in turn has caused a small behaviour change with
regards to what values are written via Fill commands in linker scripts, bringing
it into line with ld.bfd. The fill value is now written starting from the end of
the previous block, which means that it always starts from the first byte of the
fill, whereas the old behaviour meant that the padding sometimes started mid-way
through the fill value. See the test changes for more details.
Reviewed by: ruiu
Differential Revision: https://reviews.llvm.org/D30886
Bugzilla: http://bugs.llvm.org/show_bug.cgi?id=32227
llvm-svn: 299635
For range extension thunks we will need to repeatedly call createThunks()
until no more thunks are created. We will need to retain the state of
Thunks that we have created so far to avoid recreating them on later
passes. This change does not change the functionality of createThunks().
Differential Revision: https://reviews.llvm.org/D31654
llvm-svn: 299530
GNU linkers define __bss_start symbol.
Patch teaches LLD to do that. This is PR32051.
Below is part of standart ld.bfd script:
.data1 : { *(.data1) }
_edata = .; PROVIDE (edata = .);
. = .;
__bss_start = .;
.bss :
{
Currently LLD can emit up to 3 .bss* sections as one of testcase shows.
Implementation inserts this symbol before first .bss* output section.
Differential revision: https://reviews.llvm.org/D30419
llvm-svn: 299528
LinkerScript used to be a template class, so we couldn't instantiate
that class in elf::link. We instantiated ScriptConfig class earlier
instead so that the linker script parser can store configurations to
the object.
Now that LinkerScript is not a template, it doesn't make sense to
separate ScriptConfig from LinkerScript. This patch merges them.
llvm-svn: 298457
Patch moves Sections array to
InputFile (root class for input files).
That allows to detemplate GdbIndexSection.
Differential revision: https://reviews.llvm.org/D30976
llvm-svn: 298345
The patch introduces two new relocations expressions R_MIPS_GOT_GP and
R_MIPS_GOT_GP_PC. The first one represents a current value of `_gp`
pointer and used to calculate relocations against the `__gnu_local_gp`
symbol. The second one represents the offset between the beginning of
the function and the `_gp` pointer's value.
There are two motivations for introducing new expressions:
- It's better to keep all non-trivial relocation calculations in the
single place - `getRelocTargetVA` function.
- Relocations against both `_gp_disp` and `__gnu_local_gp` symbols
depend on the `_gp` value. It's a magical value points to the "middle"
of GOT. Now all relocations use a common `_gp` value. But in fact,
under some conditions each input file might require its own `_gp`
value. I'm going to implement it in the future patches. So it's
better to make `MipsGotSection` responsible for calculation of
the `_gp` value.
llvm-svn: 298306
This continues detemplation process.
Detemplating MipsGotSection<ELFT> is helpfull because can
help to detemplate getRelocTargetVA. (one more change is required)
It opens road to detemplation of GotSection<ELFT> and probably
something else after that.
Differential revision: https://reviews.llvm.org/D31090
llvm-svn: 298272
Does not introduce anything new,
just performs detemplate, using methods we
already have.
Differential revision: https://reviews.llvm.org/D30935
llvm-svn: 298269
We had a few Config member functions that returns configuration values.
For example, we had is64() which returns true if the target is 64-bit.
The return values of these functions are constant and never change.
This patch is to compute them only once to make it clear that they'll
never change.
llvm-svn: 298168
With fix of next warning:
Writer.cpp:361:3: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
Original commit message:
Patch reuses BssSection section to simplify creation of
COMMON section.
Differential revision: https://reviews.llvm.org/D30690
llvm-svn: 298086
Was fixed, details on review page.
Original commit message:
That removes CopyRelSection class completely, making
Bss/BssRelRo to be just regular synthetics.
This is splitted from D30541 and polished.
Difference from D30541 that all logic of SharedSymbol
converting to DefinedRegular was removed for now and
probably will be posted as separate patch.
Differential revision: https://reviews.llvm.org/D30892
llvm-svn: 298062
After introducing Config->is64Bit() and
recent changes in LinkerScriptBase, some
sections can be detemplated trivially. This
is one of such cases.
llvm-svn: 297825
StringTableSection was <ELFT> templated previously,
It disallow to de-template code that uses it,
for example LinkerScript<ELFT>::discard uses it as:
if (S == In<ELFT>::ShStrTab)
error("discarding .shstrtab section is not allowed");
It seems we can try to detemplate some of synthetic sections
and somehow make them available for non-templated calls.
(move out of In<ELFT> struct probably).
Differential revision: https://reviews.llvm.org/D30933
llvm-svn: 297815
That removes CopyRelSection class completely, making
Bss/BssRelRo to be just regular synthetics.
This is splitted from D30541 and polished.
Difference from D30541 that all logic of SharedSymbol
converting to DefinedRegular was removed for now and
probably will be posted as separate patch.
Differential revision: https://reviews.llvm.org/D30892
llvm-svn: 297814
Patch introduces Config->is64Bit() and with help of that detemplates
GotPltSection and IgotPltSection sections
Differential revision: https://reviews.llvm.org/D30944
llvm-svn: 297813
This also requires postponing the assignment the assignment of
symbols defined in input linker scripts since those can refer to
output sections and in case we don't have a SECTIONS command, we
need to wait until all output sections have been created and
assigned addresses.
Differential Revision: https://reviews.llvm.org/D30851
llvm-svn: 297802
We can move all not templated functionality to LinkerScriptBase.
Patch do that for hasPhdrsCommands() and shows how it helps to detemplate
things in other places.
Probably we should be able to merge these 2 classes into single one after such steps.
Even if not, it still looks as reasonable cleanup for me.
Differential revision: https://reviews.llvm.org/D30895
llvm-svn: 297714
lld crashes when .eh_frame or .eh_frame_hdr section is discarded
in linker script and there is no PHDRS directive.
Differential revision: https://reviews.llvm.org/D30885
llvm-svn: 297712
Fix a bug introduced in r297313 which caused them to resolve to the end
of the ELF header in PIEs and DSOs.
Differential Revision: https://reviews.llvm.org/D30843
llvm-svn: 297638
Using .eh_frame input section pattern in linker script currently
causes a crash; this is because .eh_frame input sections require
special handling since they're all combined into a synthetic
section rather than regular output section.
Differential Revision: https://reviews.llvm.org/D30627
llvm-svn: 297501
.eh_frame_hdr is a header constructed for .eh_frame sections.
We do not proccess .eh_frame when doing relocatable output,
so should not try to create .eh_frame_hdr too.
Previous behavior without this patch is segfault.
Fixes PR32118.
Differential revision: https://reviews.llvm.org/D30566
llvm-svn: 297365
With this we have a single section hierarchy. It is a bit less code,
but the main advantage will be in a future patch being able to handle
foo = symbol_in_obj;
in a linker script. Currently that fails since we try to find the
output section of symbol_in_obj. With this we should be able to just
return an InputSection from the expression.
llvm-svn: 297313
This change moves the calls to finalizeContent() for each synthetic section
before createThunks(). This will allow us to assign addresses prior to
calling createThunks(). As addition of thunks may add to the static
symbol table and may affect the size of the mips got section we introduce a
couple of additional member functions to update these values.
Differential revision: https://reviews.llvm.org/D29983
llvm-svn: 297277
In compare with D30458, this makes Bss/BssRelRo to be pure
synthetic sections.
That removes CopyRelSection class completely, making
Bss/BssRelRo to be just regular synthetics.
SharedSymbols involved in creating copy relocations are
converted to DefinedRegular, what also simplifies things.
Differential revision: https://reviews.llvm.org/D30541
llvm-svn: 297008
In many places we reset Size to 0 before calling assignOffsets()
manually. Sometimes we don't do that.
It looks we can just always do that inside.
Previous code had:
template <class ELFT> void OutputSection::assignOffsets() {
uint64_t Off = Size;
And tests feels fine with Off = 0.
I think Off = Size make no sence.
Differential revision: https://reviews.llvm.org/D30463
llvm-svn: 296609
Previously, these two functions put their symbols in different queues.
Now that the queues have been merged. So there's no point to keep two
separate functions.
llvm-svn: 296435
The list of all input sections was defined in SymbolTable class for a
historical reason. The list itself is not a template. However, because
SymbolTable class is a template, we needed to pass around ELFT to access
the list. This patch moves the list out of the class so that it doesn't
need ELFT.
llvm-svn: 296309
__ehdr_start should be pointing to ELF file headers, not program
headers.
This is a reland of D30319.
Differential Revision: https://reviews.llvm.org/D30323
llvm-svn: 296085
With this we complete the transition out of special output sections,
and with the previous patches it should be possible to merge
OutputSectionBase and OuputSection.
llvm-svn: 296023
With the current design an InputSection is basically anything that
goes directly in a OutputSection. That includes plain input section
but also synthetic sections, so this should probably not be a
template.
llvm-svn: 295993
This change moves the SymbolBodies with isLocal() == true before the global
symbols then calculating NumLocals rather than assuming all locals are
added before globals and the first NumLocals have isLocal() == true. This
permits Thunks to be moved after the pass that adds global symbols from
synthetics to the symbol table.
Differential revision: https://reviews.llvm.org/D30085
llvm-svn: 295650
This is a small difference I noticed to gold and bfd. When given
--print-gc-sections, we print sections a linkerscript marks
DISCARD. The other linkers don't.
llvm-svn: 295467
Without this we would produce two relocation sections pointing to the
same section, which gnu tools reject.
This fixes pr31986.
The implementation of -r/--emit-reloc is getting fairly
complicated. But lets get the test passing before trying to refactor
it.
llvm-svn: 295385
Previously, space in a BSS section for copy relocations are reserved
in a special way. We directly manipulated size of the BSS section.
r294577 changed the way of doing it. Now, we create an instance of
CopyRelSection (which is a synthetic input section) for each copy
relocation.
This patch removes the remains of the old way and add CopyRelSections
to BSS sections using `addSections` function, which is the usual
way to add an input section to an output section.
llvm-svn: 295278
For CloudABI I'm only interested in generating non-PIC/PIE executables
on armv6 and i686, as PIE introduces larger overhead than on aarch64 and
x86_64. Still, I want to be able to instruct the linker to generate a
dynamic symbol table if requested. One example use for this is that
dynamic symbol tables can be used by programs to print nicely formatted
stacktraces, including symbol names.
Right now there seems to be some logic in LLD that it only wants to emit
dynamic symbol tables when either linking against libraries or when
building PIC. Let's extend this to also take --export-dynamic into
account.
Reviewed by: ruiu
Differential Revision: https://reviews.llvm.org/D29982
llvm-svn: 295240
Unfortunately some consumers of our .o files produced with -r expect
only one section symbol per section. That is true of at least of go's
own linker.
Combining them is a somewhat convoluted process. We have to create a
symbol for every section since we don't know which ones will be
needed. The relocation sections also have to be written first to
handle the Elf_Rel addend.
I did consider a completely different approach:
We could remove the -r special case of relocation sections when
reading. We would instead have a copyRelocs function that is used
instead of scanRelocs. It would create a DynamicReloc for each
relocation and a RelocationSection for each input relocation section.
A complication of such change is that DynamicReloc would have to take
a section index and a input section instead of a symbol since with
-emit-relocs some DynamicReloc would hold relocations referring to the
dynamic symbol table and other to the static symbol table.
That would be a pretty big change, and if we do it it is probably
better to do it as a refactoring.
llvm-svn: 294816
Much of the code in PltSection and IPltSection is similar, we identify
the IPlt by a HeaderSize of 0 and alter our behaviour in the member
functions appropriately:
-Iplt does not have a header
-Iplt always follows after the Plt
Differential Revision: https://reviews.llvm.org/D29664
llvm-svn: 294579
with temporarily file name fix in testcase.
Original commit message:
-q, --emit-relocs - Generate relocations in output
Simplest implementation:
* no GC case,
* no "/DISCARD/" linkerscript command support.
This patch is extracted from D28612 / D29636,
Relative to PR31579.
Differential revision: https://reviews.llvm.org/D29663
llvm-svn: 294469
-q, --emit-relocs - Generate relocations in output
Simplest implementation:
* no GC case,
* no "/DISCARD/" linkerscript command support.
This patch is extracted from D28612 / D29636,
Relative to PR31579.
Differential revision: https://reviews.llvm.org/D29663
llvm-svn: 294464
With a synthetic merge section we can have, for example, a single
.rodata section with stings, fixed sized constants and non merge
constants.
I can be simplified further by not setting Entsize, but that is
probably better done is a followup patch.
This should allow some cleanup in the linker script code now that
every output section command maps to just one output section.
llvm-svn: 294005
Instead of creating multiple PHDRs in a single loop, this patch
runs one for loop for each PHDR type. I think this improves code
readability.
llvm-svn: 293832
There could be multiple discontiguous output .note sections in which
case we need to put these into separate PT_NOTE segments rather then
placing them into a single segment. Where possible, we could reorder
the input sections to make sure that all .note are layed out next to
each other to avoid creation multiple PT_NOTE segments, but even in
that case, it's still possible to construct a discontiguous case e.g.
by using a linker script.
Differential Revision: https://reviews.llvm.org/D29364
llvm-svn: 293811
Thunks are now implemented by redirecting the relocation to the
symbol S, to a symbol TS in a Thunk. The Thunk will transfer control
to S. This has the following implications:
- All the side-effects of Thunks happen within createThunks()
- Thunks are no longer stored in InputSections and Symbols no longer
need to hold a pointer to a Thunk
- The synthetic Thunk sections need to be merged into OutputSections
This implementation is almost a direct conversion of the existing
Thunks with the following exceptions:
- Mips LA25 Thunks are placed before the InputSection that defines
the symbol that needs a Thunk.
- All ARM Thunks are placed at the end of the OutputSection of the
first caller to the Thunk.
Range extension Thunks are not supported yet so it is optimistically
assumed that all Thunks can be reused.
This is a recommit of r293283 with a fixed comparison predicate as
std::merge requires a strict weak ordering.
Differential revision: https://reviews.llvm.org/D29327
llvm-svn: 293757
If no bss sections appear after the relro segment, the loader will round
the r/w segment size to the target's page size. Align the relro size in the
same way to ensure that it does not extend past the end of the program's
own memory region.
Differential Revision: https://reviews.llvm.org/D29242
llvm-svn: 293519
Rafael Espindola