There are two ways one could implement hiding of linkonce_odr symbols in LTO:
* LLVM tells the linker which symbols can be hidden if not used from native
files.
* The linker tells LLVM which symbols are not used from other object files,
but will be put in the dso symbol table if present.
GOLD's API is the second option. It was implemented almost 1:1 in llvm by
passing the list down to internalize.
LLVM already had partial support for the first option. It is also very similar
to how ld64 handles hiding these symbols when *not* doing LTO.
This patch then
* removes the APIs for the DSO list.
* marks LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN all linkonce_odr unnamed_addr
global values and other linkonce_odr whose address is not used.
* makes the gold plugin responsible for handling the API mismatch.
llvm-svn: 193800
This reverts commit r193255 and instead creates an lto_bool_t typedef
that points to bool, _Bool, or unsigned char depending on what is
available. Only recent versions of MSVC provide a stdbool.h header.
Reviewers: rafael.espindola
Differential Revision: http://llvm-reviews.chandlerc.com/D2019
llvm-svn: 193377
Generalize the API so we can distinguish symbols that are needed just for a DSO
symbol table from those that are used from some native .o.
The symbols that are only wanted for the dso symbol table can be dropped if
llvm can prove every other dso has a copy (linkonce_odr) and the address is not
important (unnamed_addr).
llvm-svn: 191922
----
Add new API lto_codegen_compile_parallel().
This API is proposed by Nick Kledzik. The semantic is:
--------------------------------------------------------------------------
Generate code for merged module into an array of native object files. On
success returns a pointer to an array of NativeObjectFile. The count
parameter returns the number of elements in the array. Each element is
a pointer/length for a generated mach-o/ELF buffer. The buffer is owned
by the lto_code_gen_t and will be freed when lto_codegen_dispose() is called,
or lto_codegen_compile() is called again. On failure, returns NULL
(check lto_get_error_message() for details).
extern const struct NativeObjectFile*
lto_codegen_compile_parallel(lto_code_gen_t cg, size_t *count);
---------------------------------------------------------------------------
This API is currently only called on OSX platform. Linux or other Unixes
using GNU gold are not supposed to call this function, because on these systems,
object files are fed back to linker via disk file instead of memory buffer.
In this commit, lto_codegen_compile_parallel() simply calls
lto_codegen_compile() to return a single object file. In the near future,
this function is the entry point for compilation with partition. Linker can
blindly call this function even if partition is turned off; in this case,
compiler will return only one object file.
llvm-svn: 189386
This API is proposed by Nick Kledzik. The semantic is:
--------------------------------------------------------------------------
Generate code for merged module into an array of native object files. On
success returns a pointer to an array of NativeObjectFile. The count
parameter returns the number of elements in the array. Each element is
a pointer/length for a generated mach-o/ELF buffer. The buffer is owned
by the lto_code_gen_t and will be freed when lto_codegen_dispose() is called,
or lto_codegen_compile() is called again. On failure, returns NULL
(check lto_get_error_message() for details).
extern const struct NativeObjectFile*
lto_codegen_compile_parallel(lto_code_gen_t cg, size_t *count);
---------------------------------------------------------------------------
This API is currently only called on OSX platform. Linux or other Unixes
using GNU gold are not supposed to call this function, because on these systems,
object files are fed back to linker via disk file instead of memory buffer.
In this commit, lto_codegen_compile_parallel() simply calls
lto_codegen_compile() to return a single object file. In the near future,
this function is the entry point for compilation with partition. Linker can
blindly call this function even if partition is turned off; in this case,
compiler will return only one object file.
llvm-svn: 189297
In order to appease people (in Apple) who accuse me for committing "huge change" (?) without proper review.
Thank Eric for fixing a compile-warning.
llvm-svn: 188204
1. Add some helper classes for partitions. They are designed in a
way such that the top-level LTO driver will not see much difference
with or without partitioning.
2. Introduce work-dir. Now all intermediate files generated during
LTO phases will be saved under work-dir. User can specify the workdir
via -lto-workdir=/path/to/dir. By default the work-dir will be
erased before linker exit. To keep the workdir, do -lto-keep, or -lto-keep=1.
TODO: Erase the workdir, if the linker exit prematurely.
We are currently not able to remove directory on signal. The support
routines simply ignore directory.
3. Add one new API lto_codegen_get_files_need_remove().
Linker and LTO plugin will communicate via this API about which files
(including directories) need to removed before linker exit.
llvm-svn: 188188
The linker will call `lto_codegen_add_must_preserve_symbol' on all globals that
should be kept around. The linker will pretend that a dylib is being created.
<rdar://problem/12528059>
llvm-svn: 169770
This function sets the `_exportDynamic' ivar. When that's set, we export all
symbols (e.g. we don't run the internalize pass). This is equivalent to the
`--export-dynamic' linker flag in GNU land:
--export-dynamic
When creating a dynamically linked executable, add all symbols to the dynamic
symbol table. The dynamic symbol table is the set of symbols which are visible
from dynamic objects at run time. If you do not use this option, the dynamic
symbol table will normally contain only those symbols which are referenced by
some dynamic object mentioned in the link. If you use dlopen to load a dynamic
object which needs to refer back to the symbols defined by the program, rather
than some other dynamic object, then you will probably need to use this option
when linking the program itself.
The Darwin linker will support this via the `-export_dynamic' flag. We should
modify clang to support this via the `-rdynamic' flag.
llvm-svn: 169656
Necessary to give disassembler users (like darwin's otool) a possibility to
dlopen libLTO and still initialize the required LLVM bits. This used to go
through libMCDisassembler but that's a gross layering violation, the MC layer
can't pull in functions from the targets. Adding a function to libLTO is a bit
of a hack but not worse than exposing other disassembler bits from libLTO.
Fixes PR14362.
llvm-svn: 168545
so we don't want it to show up in the stable 3.1 interface.
While at it, add a comment about why LTOCodeGenerator manually creates the
internalize pass.
llvm-svn: 154807
This gives a lot of love to the docs for the C API. Like Clang's
documentation, the C API is now organized into a Doxygen "module"
(LLVMC). Each C header file is a child of the main module. Some modules
(like Core) have a hierarchy of there own. The produced documentation is
thus better organized (before everything was in one monolithic list).
This patch also includes a lot of new documentation for APIs in Core.h.
It doesn't document them all, but is better than none. Function docs are
missing @param and @return annotation, but the documentation body now
commonly provides help details (like the expected llvm::Value sub-type
to expect).
llvm-svn: 153157
Add lto_codegen_set_assembler_path() API which allows the linker to specify the
path to the assembler tool to run. When assembler is used (instead of compiler)
different command line options are used.
Add LTO_API_VERSION #define so clients (linkers) can conditionalize use of new APIs.
llvm-svn: 72823
