This patch is to use ELFT instead of Is64Bits to template OutputSection
and its subclasses. This increases code size slightly because it creates
two identical functions for some classes, but that's only 20 KB out of
33 MB, so it's negligible.
This is as per discussion with Rafael. He's not fan of the idea but OK
with this. We'll revisit later to this topic.
llvm-svn: 250466
What was done:
1) .got.plt section is created for functions that requires PLT. .got.plt has 3 predefined empty entries now that are required for dynamic linker.
Also other new items created are configured to have correct jump to PLT[N].
2) PLT section now has PLT[0] entry, also others ones are configured to support PLT->GOT(.got.plt) calls.
3) Implemented .rel[a].plt sections (based on patch http://reviews.llvm.org/D13569).
4) Fixed plt relocations types (based on patch http://reviews.llvm.org/D13589).
NOTES:
The .plt.got zero entry is still empty now. According to ELF specification it should hold the address of the dynamic structure, referenced with the symbol
_DYNAMIC. The _DYNAMIC entry points to the .dynamic section which contains information used by the ELF interpreter to setup the binary.
Differential Revision: http://reviews.llvm.org/D13651
llvm-svn: 250169
This patch adds AsNeeded and IsUsed bool fields to SharedFile. AsNeeded bit
is set if the DSO is enclosed with --as-needed and --no-as-needed. IsUsed
bit is off by default. When we adds a symbol to the symbol table for dynamic
linking, we set its SharedFile's IsUsed bit.
If AsNeeded is set but IsUsed is not set, we don't want to write that
file's SO name to DT_NEEDED field.
http://reviews.llvm.org/D13579
llvm-svn: 249998
SymbolTable was not a template class. Instead we had switch-case-based
type dispatch to call desired functions. We had to do that because
SymbolTable was created before we know what ELF type objects had been
passed.
Every time I tried to add a new function to the symbol table, I had to
define a dispatcher which consist of a single switch statement.
It also brought an restriction what the driver can do. For example,
we cannot add undefined symbols before any files are added to the symbol
table. That's because no symbols can be added until the symbol table
knows the ELF type, but when it knows about that, it's too late.
In this patch, the driver makes a decision on what ELF type objects
are being handled. Then the driver creates a SymbolTable object for
an appropriate ELF type.
http://reviews.llvm.org/D13544
llvm-svn: 249902
This reverts commit r249816.
It broke building llvm with lld:
$ ./bin/FileCheck
./bin/FileCheck: error while loading shared libraries: unexpected PLT reloc type 0x06
I think the only thing that is wrong with this patch is that it is too soon.
The plt we create (and its relocs) don't support lazy loading, so they have
to be relocated as ordinary dynamic relocations.
llvm-svn: 249835
.rela.plt contains list of elements in the PLT, which are liable to the relocation during the dynamic linking.
Differential Revision: http://reviews.llvm.org/D13569
llvm-svn: 249816
The size of a .plt entry is different on different targets (it is,
specifically, much larger than 8 on all PPC ABIs). There is no functional
change here (later patches to create .plt entries for PPC64 will depend on this
change).
llvm-svn: 249756
In preparation for making the size of a .plt entry target dependent, use the
existing EntrySize variable when writing (instead of a hard-coded value). NFC.
llvm-svn: 249720
Previously, output sections that are handled specially by the linker
(e.g. PLT or GOT) were created by Writer and passed to other classes
that need them. The problem was that because these special sections
are required by so many classes, the plumbing work became too much
burden.
This patch is to simply make them accessible from anywhere in the
linker to eliminate the plumbing work once and for all.
http://reviews.llvm.org/D13486
llvm-svn: 249590
When generating an executable or shared library, mark it to tell the dynamic linker to resolve all symbols when the program is started, or when the shared library is linked to using dlopen, instead of deferring function call resolution to the point when the function is first called.
Differential Revision: http://reviews.llvm.org/D13468
llvm-svn: 249551
This is a case that requires --start-group --end-group with regular ELF
linkers. Fortunately it is still possible to handle it with lazy symbols without
taking a second look at archives.
Thanks to Michael Spencer for the bug report.
llvm-svn: 249406
Rui Ueyama