The code to handle symbol versions is getting tricky and hard to
understand, so it is probably time to simplify it. This patch does
the following.
- Add `DemangledSyms` variable to SymbolTable so that we don't
need to pass it around to findDemangled.
- Define `initDemangledSyms` to initialize the variable lazily.
- hasExternCpp is removed because we no longer have to initialize
the map eagerly.
- scanScriptVersion is split.
- Comments are updated.
llvm-svn: 287002
Patch adds a filename to that error message.
I faced next error when debugged one of FreeBSD port:
error: relocation R_X86_64_PLT32 cannot refer to absolute symbol __tls_get_addr
error message was poor and this patch improves it to show the locations
of symbol declaration and using.
Differential revision: https://reviews.llvm.org/D26508
llvm-svn: 286940
The disadvantage is that we use uint64_t instad of uint32_t for some
value in 32 bit files. The advantage is a substantially simpler code,
faster builds and less code duplication.
llvm-svn: 286414
Previously, we do this piece of code to iterate over all input sections.
for (elf::ObjectFile<ELFT> *F : Symtab.getObjectFiles())
for (InputSectionBase<ELFT> *S : F->getSections())
It turned out that this mechanisms doesn't work well with synthetic
input sections because synthetic input sections don't belong to any
input file.
This patch defines a vector that contains all input sections including
synthetic ones.
llvm-svn: 286051
Previously, it didn't support the character class, so we couldn't
eliminate the use fo llvm::Regex. Now that it is supported, we
can remove compileGlobPattern, which converts a glob pattern to
a regex.
This patch contains optimization for exact/prefix/suffix matches.
Differential Revision: https://reviews.llvm.org/D26284
llvm-svn: 285949
Previously, we have a lot of BumpPtrAllocators, but all these
allocators virtually have the same lifetime because they are
not freed until the linker finishes its job. This patch aggregates
them into a single allocator.
Differential revision: https://reviews.llvm.org/D26042
llvm-svn: 285452
Summary:
This uses one less word on 64-bit platforms, so should be a strict
improvement. This change also lets us get rid of llvm::CachedHash.
Reviewers: rafael, timshen
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D25646
llvm-svn: 284502
Previouly bot was failing:
http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu/builds/413/steps/test-stage1-compiler/logs/stdio
Fixed possible segfault, so commit should bix the buildbot.
Initial commit message:
This is PR30312. Info from bug page:
Both of these symbols demangle to abc::abc():
_ZN3abcC1Ev
_ZN3abcC2Ev
(These would be abc's complete object constructor and base object constructor, respectively.)
however with "abc::abc()" in the version script only one of the two receives the symbol version.
Patch fixes that.
It uses testcase created by Ed Maste (D24306).
Differential revision: https://reviews.llvm.org/D24336
llvm-svn: 281605
Previously, all input files were owned by the symbol table.
Files were created at various places, such as the Driver, the lazy
symbols, or the bitcode compiler, and the ownership of new files
was transferred to the symbol table using std::unique_ptr.
All input files were then free'd when the symbol table is freed
which is on program exit.
I think we don't have to transfer ownership just to free all
instance at once on exit.
In this patch, all instances are automatically collected to a
vector and freed on exit. In this way, we no longer have to
use std::unique_ptr.
Differential Revision: https://reviews.llvm.org/D24493
llvm-svn: 281425
Something broked BBots:
281318 failed on step 9:
http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu/builds/413
r281317 built step 9 green:
http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu/builds/415
Initial revision commits were:
This is PR30312. Info from bug page:
Both of these symbols demangle to abc::abc():
_ZN3abcC1Ev
_ZN3abcC2Ev
(These would be abc's complete object constructor and base object constructor, respectively.)
however with "abc::abc()" in the version script only one of the two receives the symbol version.
Patch fixes that.
It uses testcase created by Ed Maste (D24306).
Differential revision: https://reviews.llvm.org/D24336
llvm-svn: 281411
This is PR30312. Info from bug page:
Both of these symbols demangle to abc::abc():
_ZN3abcC1Ev
_ZN3abcC2Ev
(These would be abc's complete object constructor and base object constructor, respectively.)
however with "abc::abc()" in the version script only one of the two receives the symbol version.
Patch fixes that.
It uses testcase created by Ed Maste (D24306).
Differential revision: https://reviews.llvm.org/D24336
llvm-svn: 281318
Use std::regex instead of hand written matcher.
Patch based on code and ideas of Rui Ueyama.
Differential revision: https://reviews.llvm.org/D23829
llvm-svn: 280544
This patch is opposite to D19024, which made this symbols to be hidden by default.
Unfortunately FreeBSD loader wants to see
start_set_modmetadata_set/stop_set_modmetadata_set in the dynamic symbol table.
They were not placed there because had hidden visibility.
Patch makes them to have default visibility again.
Differential revision: https://reviews.llvm.org/D23552
llvm-svn: 279262
r275711 for "speedng up symbol version handling" was committed
by misunderstanding; the benchmark number was measured with
a debug build. The number with a release build didn't actually change.
This patch removes false optimizations added in that patch.
llvm-svn: 276267
Under MSVS 2015 I observed integral constant overflow warning when aggregate initialization was used
to init the bit field. Patch fixes that.
llvm-svn: 276118
In the last patch for --trace-symbol, I introduced a new symbol type
PlaceholderKind and store it to SymVector storage. It made all code
that iterates over SymVector to recognize and skip PlaceholderKind
symbols. I found that that's annoying.
In this patch, I removed PlaceholderKind and stop storing them to SymVector.
Now the information whether a symbol is being watched by --trace-symbol
is stored to the Symtab hash table.
llvm-svn: 275747
--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
Versions can be assigned to symbols in two different ways.
One is the usual version scripts, and the other is special
symbol suffix '@'. If a symbol contains '@', the string after
that is considered to specify a version name.
Previously, we look for '@' for all symbols.
Anything that works on every symbol can be expensive because
the linker has to handle a lot of symbols. The search for '@'
was not an exception.
In this patch, I made two optimizations.
The first optimization is to handle '@' only when at least one
version is defined. If no versions are defined, no versions can
be assigned to any symbols, so it's waste of time to search for '@'.
The second optimization is to scan only suffixes of symbol names
instead of entire symbol names. Symbol names can be very long, but
symbol versions are usually short, so scanning entire symbol names
is waste of time, too.
There are some error cases which we no longer be able to detect
with this patch. I don't think it's a major drawback because they
are minor errors. Speed is more important.
This change improves LLD with debug info self-link time from
6.6993 seconds to 6.3426 seconds (or -5.3%).
Differential Revision: https://reviews.llvm.org/D22433
llvm-svn: 275711
Patch implements 'extern' version script tag.
Currently only values in quotes(") are supported.
Matching of externs is performed in the same pass as exact match of globals.
Differential revision: http://reviews.llvm.org/D21930
llvm-svn: 275257
Example:
VERSION_1.0 {
global: foo*;
local: *; }
now correctly matches all the symbols which name starts with
`foo`.
Differential Revision: http://reviews.llvm.org/D21732
llvm-svn: 274091
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
Weak undefined symbols resolve to the image base. This is a little strange,
but it allows us to link function calls to such symbols. Normally such a
call will be guarded with a comparison, which will load a zero from the GOT.
There's one example of such a function call in crti.o in Linux's CRT.
As part of this change, I also needed to make the synthetic start and end
symbols image base relative in the case where their sections were empty,
so that PC-relative references to those symbols would continue to work.
Differential Revision: http://reviews.llvm.org/D19844
llvm-svn: 268350
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
The semantics of the -u flag are to load the lazy symbol named by the flag. We
were previously relying on this behavior falling out of symbol resolution
against a synthetic undefined symbol, but that didn't quite give us the
correct behavior, so we needed a flag to mark symbols created with -u so
we could treat them specially in the writer. However, it's simpler and less
error prone to implement the required behavior directly and remove the flag.
This fixes an issue where symbols loaded with -u would receive hidden
visibility even when the definition in an object file had wider visibility.
Differential Revision: http://reviews.llvm.org/D19560
llvm-svn: 267639
This patch only implements support for version scripts of the form:
{ [ global: symbol1; symbol2; [...]; symbolN; ] local: *; };
No wildcards are supported, other than for the local entry. Symbol versioning
is also not supported.
It works by introducing a new Symbol flag which tracks whether a symbol
appears in the global section of a version script.
This patch also simplifies the logic in SymbolBody::isPreemptible(), and
teaches it to handle the case where symbols with default visibility in DSOs
do not appear in the dynamic symbol table because of a version script.
Fixes PR27482.
Differential Revision: http://reviews.llvm.org/D19430
llvm-svn: 267208
We never need to iterate over the K,V pairs, so we can avoid copying the
key as MapVector does.
This is a small speedup on most benchmarks.
llvm-svn: 266364
Rui Ueyama