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Simon Atanasyan 13f6da1d2c [ELF] Implement infrastructure for thunk code creation 
Some targets might require creation of thunks. For example, MIPS targets
require stubs to call PIC code from non-PIC one. The patch implements
infrastructure for thunk code creation and provides support for MIPS
LA25 stubs. Any MIPS PIC code function is invoked with its address
in register $t9. So if we have a branch instruction from non-PIC code
to the PIC one we cannot make the jump directly and need to create a small
stub to save the target function address.
See page 3-38 ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf

- In relocation scanning phase we ask target about thunk creation necessity
by calling `TagetInfo::needsThunk` method. The `InputSection` class
maintains list of Symbols requires thunk creation.

- Reassigning offsets performed for each input sections after relocation
scanning complete because position of each section might change due
thunk creation.

- The patch introduces new dedicated value for DefinedSynthetic symbols
DefinedSynthetic::SectionEnd. Synthetic symbol with that value always
points to the end of the corresponding output section. That allows to
escape updating synthetic symbols if output sections sizes changes after
relocation scanning due thunk creation.

- In the `InputSection::writeTo` method we write thunks after corresponding
input section. Each thunk is written by calling `TargetInfo::writeThunk` method.

- The patch supports the only type of thunk code for each target. For now,
it is enough.

Differential Revision: http://reviews.llvm.org/D17934

llvm-svn: 265059
 		2016-03-31 21:26:23 +00:00
..
COFF [coff] Accept and ignore another link.exe flag for compatibility 2016-03-25 18:09:29 +00:00
ELF [ELF] Implement infrastructure for thunk code creation 2016-03-31 21:26:23 +00:00
cmake/modules
…
docs Docs: keep copyright years up-to-date. 2016-03-30 22:25:04 +00:00
include/lld Remove unused variants of make_dynamic_error_code. NFC. 2016-03-31 01:21:50 +00:00
lib Revert "Remove useless unreachable. Switch coverage already gives us this. NFC" 2016-03-31 01:23:23 +00:00
test [ELF] Implement infrastructure for thunk code creation 2016-03-31 21:26:23 +00:00
tools/lld Inline a trivial CMakeLists.txt. 2016-03-03 01:56:23 +00:00
unittests Use Expected<T> instead of ErrorOr<T>in yaml reader. NFC 2016-03-31 01:13:04 +00:00
.arcconfig Update Phabricator server. 2014-04-07 04:52:24 +00:00
.clang-format Remove redundant "Standard: Cpp11" tag. The LLVM style has used the 2014-07-04 12:08:03 +00:00
.gitignore Update .gitignore to ignore hidden MacOSX Finder droppings 2014-07-16 21:01:17 +00:00
CMakeLists.txt Inline a trivial CMakeLists.txt. 2016-03-03 01:56:23 +00:00
CODE_OWNERS.TXT Add initial CODE_OWNERS.TXT file 2015-07-25 00:44:37 +00:00
LICENSE.TXT Update copyright year to 2016. 2016-03-30 22:40:59 +00:00
README.md
…

README.md

LLVM Linker (lld)

This directory and its subdirectories contain source code for the LLVM Linker, a modular cross platform linker which is built as part of the LLVM compiler infrastructure project.

lld is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.