This simplifies error handling as there is now only one place in the
code that needs to consider the possibility that the name is
corrupted. Before we would do it in every access.
llvm-svn: 280937
This approach is not only consistent with UnresolvedPolicy,
but also should help to solve a problem
of options with opposing meanings, mentioned in PR28843
Differential revision: https://reviews.llvm.org/D23869
llvm-svn: 280206
After latest changes we combine input sections with
different attributes into single output section.
Problem here is that regular output sections does not
support adding mergeable input sections (and vise versa).
Patch just temporarily disables merging for now at
the same way we do for -O0 for example.
This change helps for linking FreeBSD kernel.
Differential revision: https://reviews.llvm.org/D23447
llvm-svn: 278555
We found that GNU assembler 2.17.50 [FreeBSD] 2007-07-03
could generate broken objects. STT_SECTION symbols can be
associated with SHT_REL[A]/SHT_SYMTAB/SHT_STRTAB sections.
This is PR28868, patch fixes handling of such files.
Differential revision: https://reviews.llvm.org/D23201
llvm-svn: 278550
This section supersedes .reginfo and .MIPS.options sections. But for now
we have to support all three sections for ABI transition period.
llvm-svn: 278482
Mergeable sections with size zero are useless because they don't
actually contain data, and therefore there's no merit ot merge them.
However, in reality, there are object files in the wild containing
such sections. Currently, LLD can't handle them proerply.
This patch makes LLD to handle such sections as if they are non-
mergeable to fix the issue.
Fixes bug 28822.
llvm-svn: 277568
We already have code for ARM in initializeSections, so this
is more consistent.
Differential Revision: https://reviews.llvm.org/D22833
llvm-svn: 276811
--trace-symbol is a command line option to watch a symbol.
Previosly, we looked up a hash table for a new symbol if the
option is given. Any code that looks up a hash table for each
symbol is expensive because the linker handles a lot of symbols.
In our design, we look up a hash table strictly only once
for a symbol, so --trace-symbol was an exception.
This patch improves efficiency of the option by merging the
hash table into the symbol table.
Instead of looking up a separate hash table with a string,
this patch sets `Traced` flag to symbols specified by --trace-symbol.
So, if you insert a symbol and get a symbol with `Traced` flag on,
you know that you need to print out a log message for the symbol.
This is nearly zero cost.
llvm-svn: 275716
Previously, each subclass of SymbolBody had a pointer to a source
file from which it was created. So, there was no single way to get
a source file for a symbol. We had getSourceFile<ELFT>(), but the
function was a bit inconvenient as it's a template.
This patch makes SymbolBody have a pointer to a source file.
If a symbol is not created from a file, the pointer has a nullptr.
llvm-svn: 275701
Symbol's dtors are not called because they are allocated using
BumpPtrAllocators. So, members of std::unique_ptr type are not
freed when symbols are deallocated.
This patch is to allocate Thunks using BumpPtrAllocators.
llvm-svn: 274896
So that users are not forced to pass `-m` on the command line
when the inputs are all bitcode.
PR: 28268
Differential Revision: http://reviews.llvm.org/D21779
llvm-svn: 274107
Previously, we initialized Config->EKind and Config->EMachine when
we instantiate ELF objects. That was not an ideal location to do that
because the logic was buried too deep inside a concrete logic.
This patch moves the code to the driver so that the initialization
becomes explicit.
Differential Revision: http://reviews.llvm.org/D21784
llvm-svn: 274089
Patch by Shridhar Joshi.
This option provides names of all the link time modules which define and
reference symbols requested by user. This helps to speed up application
development by detecting references causing undefined symbols.
It also helps in detecting symbols being resolved to wrong (unintended)
definitions in case of applications containing multiple definitions for
same symbols with different types, bindings.
Implements PR28226.
llvm-svn: 273536
This should never happen with correct programs, but it is trivial
write a testcase where lld would crash or report duplicated
symbols. We now behave like when an archive is used and include the
file only once.
llvm-svn: 272724
Add support for an ARM Target and the initial set of relocations
and PLT entries that are necessary for an ARM only hello world to
link. This has been tested against an ARM only sysroot from the
4.2.0 CodeSourcery Lite release.
Tests have been added to test/ELF for the support that has been
implemented.
Main limitations:
- No Thumb support
- Relocations incomplete
- No C++ exceptions support
- No TLS support
- No range extension or interworking veneer (thunk) support
- No Build Attribute support
- No Big-endian support
The deprecated relocations R_ARM_PLT32 and R_ARM_PC24 have been
implemented as these are used by the 4.2.0 CodeSourcery Lite release.
llvm-svn: 271993
MIPS N64 ABI introduces .MIPS.options section which specifies miscellaneous
options to be applied to an object/shared/executable file. LLVM as well as
modern versions of GNU tools read and write the only type of the options -
ODK_REGINFO. It is exact copy of .reginfo section used by O32 ABI.
llvm-svn: 268485
We want --reproduce to
* not rewrite scripts and thin archives
* work with absolute paths
Given that, it pretty much has to create a full directory tree. On windows that
is problematic because of the very short maximum path limit. On most cases
users can still work around it with "--repro c:\r", but that is annoying and
not viable for automated testing.
We then need to produce some form of archive with the files. The first option
that comes to mind is .a files since we already have code for writing them.
There are a few problems with them
The format has a dedicated string table, so we cannot start writing it until
all members are known.
Regular implementations don't support creating directories. We could make
llvm-ar support that, but that is probably not a good idea.
The next natural option would be tar. The problem is that to support long path
names (which is how this started) it needs a "pax extended header" making this
an annoying format to write.
The next option I looked at seems a natural fit: cpio files.
They are available on pretty much every unix, support directories and long path
names and are really easy to write. The only slightly annoying part is a
terminator, but at least gnu cpio only prints a warning if it is missing, which
is handy for crashes. This patch still makes an effort to always create it.
llvm-svn: 268404
This patch implements a new design for the symbol table that stores
SymbolBodies within a memory region of the Symbol object. Symbols are mutated
by constructing SymbolBodies in place over existing SymbolBodies, rather
than by mutating pointers. As mentioned in the initial proposal [1], this
memory layout helps reduce the cache miss rate by improving memory locality.
Performance numbers:
old(s) new(s)
Without debug info:
chrome 7.178 6.432 (-11.5%)
LLVMgold.so 0.505 0.502 (-0.5%)
clang 0.954 0.827 (-15.4%)
llvm-as 0.052 0.045 (-15.5%)
With debug info:
scylla 5.695 5.613 (-1.5%)
clang 14.396 14.143 (-1.8%)
Performance counter results show that the fewer required indirections is
indeed the cause of the improved performance. For example, when linking
chrome, stalled cycles decreases from 14,556,444,002 to 12,959,238,310, and
instructions per cycle increases from 0.78 to 0.83. We are also executing
many fewer instructions (15,516,401,933 down to 15,002,434,310), probably
because we spend less time allocating SymbolBodies.
The new mechanism by which symbols are added to the symbol table is by calling
add* functions on the SymbolTable.
In this patch, I handle local symbols by storing them inside "unparented"
SymbolBodies. This is suboptimal, but if we do want to try to avoid allocating
these SymbolBodies, we can probably do that separately.
I also removed a few members from the SymbolBody class that were only being
used to pass information from the input file to the symbol table.
This patch implements the new design for the ELF linker only. I intend to
prepare a similar patch for the COFF linker.
[1] http://lists.llvm.org/pipermail/llvm-dev/2016-April/098832.html
Differential Revision: http://reviews.llvm.org/D19752
llvm-svn: 268178
