For now the Archive owns the buffers of the thin archive members.
This makes for a simple API, but all the buffers are destructed
only when the archive is destructed. This should be fine since we
close the files after mmap so we should not hit an open file
limit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242215 91177308-0d34-0410-b5e6-96231b3b80d8
It looks like ld64 requires it. With this we seem to be able to bootstrap using
llvm-ar+/usr/bin/true instead of ar+ranlib (currently on stage2).
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The gnu ar format uses BE numbers. The BSD one uses LE. Add a helper for one or the
other. NFC for now, just removes some noise from the following patch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241808 91177308-0d34-0410-b5e6-96231b3b80d8
It will get another use in the following patch. Also rename the other helper to
printGNUSmallMemberHeader for consistency.
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No support for the symbol table yet (but will hopefully add it today).
We always use the long filename format so that we can align the member,
which is an advantage of the BSD format.
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getSymbolValue now returns a value that in convenient for most callers:
* 0 for undefined
* symbol size for common symbols
* offset/address for symbols the rest
Code that needs something more specific can check getSymbolFlags.
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At least not in the interface exposed by ObjectFile. This matches what ELF and
COFF implement.
Adjust existing code that was expecting them to have values. No overall
functionality change intended.
Another option would be to change the interface and the ELF and COFF
implementations to say that the value of a common symbol is its size.
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They are implemented like that in some object formats, but for the interface
provided by lib/Object, SF_Undefined and SF_Common are different things.
This matches the ELF and COFF implementation and fixes llvm-nm for MachO.
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In these two contexts we really just want the raw n_value. No need to use
getSymbolValue which checks for special cases where, semantically, the symbol
has no value.
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Originally added in r139314.
Back then it didn't actually get the address, it got whatever value the
relocation used: address or offset.
The values in different object formats are:
* MachO: Always an offset.
* COFF: Always an address, but when talking about the virtual address of
sections it says: "for simplicity, compilers should set this to zero".
* ELF: An offset for .o files and and address for .so files. In the case of the
.so, the relocation in not linked to any section (sh_info is 0). We can't
really compute an offset.
Some API mappings would be:
* Use getAddress for everything. It would be quite cumbersome. To compute the
address elf has to follow sh_info, which can be corrupted and therefore the
method has to return an ErrorOr. The address of the section is also the same
for every relocation in a section, so we shouldn't have to check the error
and fetch the value for every relocation.
* Use a getValue and make it up to the user to know what it is getting.
* Use a getOffset and:
* Assert for dynamic ELF objects. That is a very peculiar case and it is
probably fair to ask any tool that wants to support it to use ELF.h. The
only tool we have that reads those (llvm-readobj) already does that. The
only other use case I can think of is a dynamic linker.
* Check that COFF .obj files have sections with zero virtual address spaces. If
it turns out that some assembler/compiler produces these, we can change
COFFObjectFile::getRelocationOffset to subtract it. Given COFF format,
this can be done without the need for ErrorOr.
The getRelocationAddress method was never implemented for COFF. It also
had exactly one use in a very peculiar case: a shortcut for adding the
section value to a pcrel reloc on MachO.
Given that, I don't expect that there is any use out there of the C API. If
that is not the case, let me know and I will add it back with the implementation
inlined and do a proper deprecation.
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When talking about the virtual address of sections the coff spec says:
... for simplicity, compilers should set this to zero. Otherwise, it is an
arbitrary value that is subtracted from offsets during relocation.
We don't currently subtract it, so check that it is zero.
If some producer does create such files, we can change getRelocationOffset
instead.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241447 91177308-0d34-0410-b5e6-96231b3b80d8
SHT_NOBITS sections do not have content in an object file. Now the yaml2obj
tool does not accept `Content` field for such sections, and the obj2yaml
tool does not attempt to read the section content from a file.
Restore r241350 and r241352.
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r241350 broke lld tests.
r241352 depends on r241350.
Original messages:
"[ELFYAML] Fix handling SHT_NOBITS sections by obj2yaml/yaml2obj tools"
"[ELFYAML] Make the Size field for .bss section optional"
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SHT_NOBITS sections do not have content in an object file. Now yaml2obj
tool does not accept `Content` field for such sections, and obj2yaml
tool does not attempt to read the section content from a file.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241350 91177308-0d34-0410-b5e6-96231b3b80d8
This function can really fail since the string table offset can be out of
bounds.
Using ErrorOr makes sure the error is checked.
Hopefully a lot of the boilerplate code in tools/* can go away once we have
a diagnostic manager in Object.
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This also improves the logic of what is an error:
* getSection(uint_32): only return an error if the index is out of bounds. The
index 0 corresponds to a perfectly valid entry.
* getSection(Elf_Sym): Returns null for symbols that normally don't have
sections and error for out of bound indexes.
In many places this just moves the report_fatal_error up the stack, but those
can then be fixed in smaller patches.
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We can probably do better in this method, but this is an improvement and
enables further ErrorOr cleanups.
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If you only need Name and Value fields in the COFF symbol,
you don't need to distinguish 32 bit and 64 bit COFF symbols.
These fields start at the same offsets and have the same size.
This data strucutre is one pointer smaller than COFFSymbolRef
thus slightly efficient. I'll use this class in LLD as we create
millions of LLD symbol objects that currently contain COFFSymbolRef.
Shaving off 8 byte (or 4 byte on 32 bit) from that class actually
matters becasue of the number of objects we create in LLD.
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This moves the error checking for string tables to getStringTable which returns
an ErrorOr<StringRef>.
This improves error checking, makes it uniform across all string tables and
makes it possible to check them once instead of once per name.
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This is still a really odd function. Most calls are in object format specific
contexts and should probably be replaced with a more direct query, but at least
now this is not too obnoxious to use.
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On ELF that was already the case since getting the size of a symbol
never fails.
On MachO and COFF we could fail trying to get the section of a symbol. But
we don't really need the section, just the section number to know if two
symbols are in the same section or not.
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This returns either the symbol offset or address. Since it is not defined which
one, it never has to lookup the section and so never fails.
I will add users in the next commit.
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