Arrange .ctors/.dtors sections in the following order:
.ctors from crtbegin.o or crtbegin?.o
.ctors from regular object files
.ctors.* (sorted) from regular object files
.ctors from crtend.o or crtend?.o
This order is specific for MIPS traget. For example, on X86
the .ctors.* sections are merged into the .init_array section.
llvm-svn: 209987
The main problem is in the predicate passed to the `std::stable_sort()`.
This predicate always returns false if **both** section's names do not
start with `.init_array` or `.fini_array` prefixes. In short, it does not
define a strict weak orderng. Suppose we have the following sections:
.A .init_array.1 .init_array.2
The predicate states that:
not .init_array.1 < .A
not .A < .init_array.2
but .init_array.1 < .init_array.2 !!!
The second problem is that `.init_array` section without number should
go last in the list. Not it has the lowest priority '0' and goes first.
The patch fixes both of the problems.
llvm-svn: 209875
In r205566, I made a change to Resolver so that Resolver revisit
only archive files in --start-group and --end-group pair. That's
not correct, as it also has to revisit DSO files.
This patch is to fix the issue.
Added a test to demonstrate the fix. I confirmed that it succeeded
before r205566, failed after r205566, and is ok with this patch.
Differential Revision: http://reviews.llvm.org/D3734
llvm-svn: 208797
If one or more dynamic relocation might modify a read-only section,
dynamic table should contain DT_TEXTREL tag.
The patch introduces new `RelocationTable::canModifyReadonlySection()`
method. This method checks through the relocations to see if any modifies
a read-only section. The DynamicTable class calls this method and emits
the DT_TEXTREL tag if necessary.
The patch reviewed by Rui Ueyama and Shankar Easwaran.
llvm-svn: 208670
In general the linker scripts's GROUP command works like a pair
of command line options --start-group/--end-group. But there is
a difference in the files look up algorithm.
The --start-group/--end-group commands use a trivial approach:
a) If the path has '-l' prefix, add 'lib' prefix and '.a'/'.so'
suffix and search the path through library search directories.
b) Otherwise, use the path 'as-is'.
The GROUP command implements more compicated approach:
a) If the path has '-l' prefix, add 'lib' prefix and '.a'/'.so'
suffix and search the path through library search directories.
b) If the path does not have '-l' prefix, and sysroot is configured,
and the path starts with the / character, and the script being
processed is located inside the sysroot, search the path under
the sysroot. Otherwise, try to open the path in the current
directory. If it is not found, search through library search
directories.
https://www.sourceware.org/binutils/docs-2.24/ld/File-Commands.html
The patch reviewed by Shankar Easwaran, Rui Ueyama.
llvm-svn: 207769
1. Re-implement PLT entries and dynamic relocations emitting to keep PLT
and relocations table in a consistent state.
2. Initialize st_value and st_other fields for dynamic symbols table
entry if this entry corresponds to an external function which address is
taken in a non-PIC executable. In that case the st_value field holds an
address of the function's PLT entry. Also set STO_MIPS_PLT bit in the
st_other field.
llvm-svn: 207494
Currently LLD supports --defsym only in the form of
--defsym=<symbol>=<integer>, where the integer is interpreted as the
absolute address of the symbol. This patch extends it to allow other
symbol name to be given as an RHS value. If a RHS value is a symbol
name, the LHS symbol will be defined as an alias for the RHS symbol.
Internally, a LHS symbol is represented as a zero-size defined atom
who has an LayoutAfter reference to an undefined atom, whose name is
the RHS value. Everything else is already implemented -- Resolver
will resolve the undefined symbol, and the layout pass will layout
the two atoms at the same location. Looks like it's working fine.
Note that GNU LD supports --defsym=<symbol>=<symbol>+<addend>. That
feature is out of scope of this patch.
Differential Revision: http://reviews.llvm.org/D3332
llvm-svn: 206417
a couple of new virtual functions.
Follow-up to the rL203408. Two virtual functions `createRelocationReference()`
responsible for creation of `ELFReference` have been replaced by a couple of
new virtual functions `createRelocationReferences()` (plural). Each former
function creates a //single// ELFReference for a specified `Elf_Rela`
or `Elf_Rel` relocation records. The new functions responsible for creation
of //all// relocation references for provided symbol.
For all targets except MIPS there are no functional changes.
MIPS ABI has a notion of //paired// relocations. An effective addend of such
relocations are calculated using addends of both pair's members.
Each `R_MIPS_HI16` and `R_MIPS_GOT16` (for local symbols) relocations must have
an associated `R_MIPS_LO16` entry immediately following it in the list
of relocations. Immediately does not mean "next record" in relocations section
but "next record referenced the same symbol". Moreover a single `R_MIPS_LO16`
relocation can be paired with multiple preceding `R_MIPS_HI16/R_MIPS_GOT16`
relocations.
The paired relocation can have offsets belong to the different symbols.
That is why we need to have access to list of all relocations during
construction of `ELFReference` for MIPS target.
The patch reviewed by Shankar Easwaran.
llvm-svn: 206102
On these tests llvm-mc will convert got relocations with a symbol to section
relocations. This is invalid, since the relocation doesn't reference the symbol
itself, so its offset in a section in irrelevant.
Given the object files, these are still valid lld tests, so just run the
tests directly on the binaries.
Found by running check-lld after fixing the relocation handling in llvm-mc.
llvm-svn: 205077
Response file is a command line argument in the form of @file. The GNU-
compatible driver expands the file contents, replacing @file argument.
Differential Revision: http://llvm-reviews.chandlerc.com/D3210
llvm-svn: 205038
This patch is to support --defsym option for ELF file format/GNU-compatible
driver. Currently it takes a symbol name followed by '=' and a number. If such
option is given, the driver sets up an absolute symbol with the specified
address. You can specify multiple --defsym options to define multiple symbols.
GNU LD's --defsym provides many more features. For example, it allows users to
specify another symbol name instead of a number to define a symbol alias, or it
even allows a symbol plus an offset (e.g. --defsym=foo+3) to define symbol-
relative alias. This patch does not support that, but will be supported in
subsequent patches.
Differential Revision: http://llvm-reviews.chandlerc.com/D3208
llvm-svn: 205029
If --allow-multiple-definition option is given, LLD does not treat duplicate
symbol error as a fatal error. GNU LD supports this option.
Differential Revision: http://llvm-reviews.chandlerc.com/D3211
llvm-svn: 205015
of GOT.
* Read addend for R_MIPS_GOT16 relocation.
* Put only high 16 bits of symbol + addend into GOT entries for
locally visible symbols.
llvm-svn: 204247
The sections .rela/.rel.(*) have a alignment of 2 in the final image created by
the linker. This needs to be properly set to the right alignment depending on
the architecture(32/64bits).
llvm-svn: 201740
Add new virtual virtual function `isRelaOutputFormat` to the
`ELFLinkingContext` class. Call this function everywhere we need to
select a relocation table format.
Patch reviewed by Shankar Easwaran and Rui Ueyama.
llvm-svn: 199973
The main changes are in:
include/lld/Core/Reference.h
include/lld/ReaderWriter/Reader.h
Everything else is details to support the main change.
1) Registration based Readers
Previously, lld had a tangled interdependency with all the Readers. It would
have been impossible to make a streamlined linker (say for a JIT) which
just supported one file format and one architecture (no yaml, no archives, etc).
The old model also required a LinkingContext to read an object file, which
would have made .o inspection tools awkward.
The new model is that there is a global Registry object. You programmatically
register the Readers you want with the registry object. Whenever you need to
read/parse a file, you ask the registry to do it, and the registry tries each
registered reader.
For ease of use with the existing lld code base, there is one Registry
object inside the LinkingContext object.
2) Changing kind value to be a tuple
Beside Readers, the registry also keeps track of the mapping for Reference
Kind values to and from strings. Along with that, this patch also fixes
an ambiguity with the previous Reference::Kind values. The problem was that
we wanted to reuse existing relocation type values as Reference::Kind values.
But then how can the YAML write know how to convert a value to a string? The
fix is to change the 32-bit Reference::Kind into a tuple with an 8-bit namespace
(e.g. ELF, COFFF, etc), an 8-bit architecture (e.g. x86_64, PowerPC, etc), and
a 16-bit value. This tuple system allows conversion to and from strings with
no ambiguities.
llvm-svn: 197727
The following are the most significant peculiarities of MIPS target:
- MIPS ABI requires some special tags in the dynamic table.
- GOT consists of two parts local and global. The local part contains
entries refer locally visible symbols. The global part contains entries
refer global symbols.
- Entries in the .dynsym section which have corresponded entries in the
GOT should be:
* Emitted at the end of .dynsym section
* Sorted accordingly to theirs GOT counterparts
- There are "paired" relocations. One or more R_MIPS_HI16 and R_MIPS_GOT16
relocations should be followed by R_MIPS_LO16 relocation. To calculate
result of R_MIPS_HI16 and R_MIPS_GOT16 relocations we need to combine
addends from these relocations and paired R_MIPS_LO16 relocation.
The patch reviewed by Michael Spencer, Shankar Easwaran, Rui Ueyama.
http://llvm-reviews.chandlerc.com/D2156
llvm-svn: 197342
Simon Atanasyan