Since MarkLive.cpp is the place where we set Live flags for
other sections, it looks correct to do that there.
Benefit is that we stop spreading GC logic outsize of MarkLive.cpp.
Differential revision: https://reviews.llvm.org/D40454
llvm-svn: 319435
This includes a fix to mark copy reloc aliases as used.
Original message:
[ELF] Do not keep symbols if they referenced only from discarded sections.
This patch also ensures that in case of "--as-needed" is used,
DT_NEEDED entries are not created if they are required only by
these eliminated symbols.
llvm-svn: 319215
This patch also ensures that in case of "--as-needed" is used,
DT_NEEDED entries are not created if they are required only by
these eliminated symbols.
Differential Revision: https://reviews.llvm.org/D38790
llvm-svn: 319008
Now that DefinedRegular is the only remaining derived class of
Defined, we can merge the two classes.
Differential Revision: https://reviews.llvm.org/D39667
llvm-svn: 317448
Now that we have only SymbolBody as the symbol class. So, "SymbolBody"
is a bit strange name now. This is a mechanical change generated by
perl -i -pe s/SymbolBody/Symbol/g $(git grep -l SymbolBody lld/ELF lld/COFF)
nd clang-format-diff.
Differential Revision: https://reviews.llvm.org/D39459
llvm-svn: 317370
SymbolBody and Symbol were separated classes due to a historical reason.
Symbol used to be a pointer to a SymbolBody, and the relationship
between Symbol and SymbolBody was n:1.
r2681780 changed that. Since that patch, SymbolBody and Symbol are
allocated next to each other to improve memory locality, and they have
1:1 relationship now. So, the separation of Symbol and SymbolBody no
longer makes sense.
This patch merges them into one class. In order to avoid updating too
many places, I chose SymbolBody as a unified name. I'll rename it Symbol
in a follow-up patch.
Differential Revision: https://reviews.llvm.org/D39406
llvm-svn: 317006
DSO is short for dynamic shared object, so the function name was a
little confusing because it sounded like it didn't work when we were
a creating statically-linked executable or something.
What we mean by "DSO" here is the current output file that we are
creating. Thus the new name. Alternatively, we could call it the current
ELF module, but "module" is a overloaded word, so I avoided that.
llvm-svn: 316809
This moves reporting of garbage collected sections right after
we do GC. That simplifies things.
Differential revision: https://reviews.llvm.org/D39058
llvm-svn: 316759
This is "Bug 34836 - --gc-sections remove relocations from --emit-relocs",
When --emit-relocs is used, LLD currently always drops SHT_REL[A] sections from
output if --gc-sections is present. Patch fixes the issue.
Differential revision: https://reviews.llvm.org/D38724
llvm-svn: 316418
ScriptConfiguration was a class to contain parsed results of
linker scripts. LinkerScript is a class to interpret it.
That ditinction was needed because we haven't instantiated
LinkerScript early (because, IIRC, LinkerScript class was a
ELFT template function). So, when we parse linker scripts,
we couldn't directly store the result to a LinkerScript instance.
Now, that limitation is gone. We instantiate LinkerScript
at the very beginning of our main function. We can directly
store parse results to a LinkerScript instance.
llvm-svn: 315403
The condition whether a section is alive or not by default
is becoming increasingly complex, so the decision of garbage
collection is spreading over InputSection.h and MarkLive.cpp,
which is not a good state.
This moves the code to MarkLive.cpp, to keep the file the central
place to make decisions about garbage collection.
llvm-svn: 315384
Convert all common symbols to regular symbols after scan.
This means that the downstream code does not to handle common symbols as a special case.
Differential Revision: https://reviews.llvm.org/D38137
llvm-svn: 314495
EhSectionPiece used to have a pointer to a section, but that pointer was
mostly redundant because we almost always know what the section is without
using that pointer. This patch removes the pointer from the struct.
This patch also use uint32_t/int32_t instead of size_t to represent
offsets that are hardly be larger than 4 GiB. At the moment, I think it is
OK even if we cannot handle .eh_frame sections larger than 4 GiB.
Differential Revision: https://reviews.llvm.org/D38012
llvm-svn: 313697
ResolvedReloc struct is always passed to a callback function and not
stored anywhere. That is, in effect, we use the struct to pack multiple
arguments to one argument, which doesn't make much sense. This patch
removes the struct and passes the members to the callback directly.
llvm-svn: 310620
Liveness is usually a notion of input sections, but this patch adds
"liveness" bit to common symbols because they don't belong to any
input section.
This patch is based on https://reviews.llvm.org/D36520
Differential Revision: https://reviews.llvm.org/D36546
llvm-svn: 310617
This is necessary to ensure that sections containing symbols referenced
from linker scripts (e.g. in data commands) don't get GC'd.
Differential Revision: https://reviews.llvm.org/D34195
llvm-svn: 305452
We had a few Config member functions that returns configuration values.
For example, we had is64() which returns true if the target is 64-bit.
The return values of these functions are constant and never change.
This patch is to compute them only once to make it clear that they'll
never change.
llvm-svn: 298168
__start_xxx symbol keeps section xxx alive only if it is not
SHF_LINK_ORDER. Such sections can be used for user metadata, when
__start_xxx is used to iterate over section contents at runtime, and
the liveness is determined solely by the linked (associated) section.
This was earlier implemented in r294592, and broken in r296723.
Differential Revision: https://reviews.llvm.org/D30964
llvm-svn: 298154
With this we have a single section hierarchy. It is a bit less code,
but the main advantage will be in a future patch being able to handle
foo = symbol_in_obj;
in a linker script. Currently that fails since we try to find the
output section of symbol_in_obj. With this we should be able to just
return an InputSection from the expression.
llvm-svn: 297313
This puts us at parity with bfd, which could already gc this case.
I noticed the sections not being gced when linking a modified freebsd
kernel. A section that was not gced and not mentioned in the linker
script would end up breaking the expected layout. Since fixing the gc
is relatively simple and an improvement, that seems better than trying
to hack the orphan placement code.
There are 173 input section in the entire link whose names are valid C
identifiers, so this is probably not too performance critical.
llvm-svn: 297049
We were not gcing any section whose name was a C identifier. Both gold
and bfd only keep those if they are used.
To avoid having to create the __start/__stop symbols early or doing
string lookups in resolvedReloc, this patch just looks for undefined
symbols __start/__stop to decide if a section is needed or not.
llvm-svn: 296723
The list of all input sections was defined in SymbolTable class for a
historical reason. The list itself is not a template. However, because
SymbolTable class is a template, we needed to pass around ELFT to access
the list. This patch moves the list out of the class so that it doesn't
need ELFT.
llvm-svn: 296309
With the current design an InputSection is basically anything that
goes directly in a OutputSection. That includes plain input section
but also synthetic sections, so this should probably not be a
template.
llvm-svn: 295993
That fixes a case when section has more than one metadata
section. Previously GC would collect one of such sections
because we had implementation that stored only last one as
dependent.
Differential revision: https://reviews.llvm.org/D29981
llvm-svn: 295298
Relocations are the last thing that we wore storing a raw section
pointer to and parsing on demand.
With this patch we parse it only once and store a pointer to the
actual data.
The patch also changes where we store it. It is now in
InputSectionBase. Not all sections have relocations, but most do and
this simplifies the logic. It also means that we now only support one
relocation section per section. Given that that constraint is
maintained even with -r with gold bfd and lld, I think it is OK.
llvm-svn: 286459
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
George Rimar