llvm-project/lld
Fangrui Song c8f0d3e130 [ELF][PPC64] Support long branch thunks with addends
Fixes PPC64 part of PR40438

  // clang -target ppc64le -c a.cc
  // .text.unlikely may be placed in a separate output section (via -z keep-text-section-prefix)
  // The distance between bar in .text.unlikely and foo in .text may be larger than 32MiB.
  static void foo() {}
  __attribute__((section(".text.unlikely"))) static int bar() { foo(); return 0; }
  __attribute__((used)) static int dummy = bar();

This patch makes such thunks with addends work for PPC64.

AArch64: .text -> `__AArch64ADRPThunk_ (adrp x16, ...; add x16, x16, ...; br x16)` -> target
PPC64: .text -> `__long_branch_ (addis 12, 2, ...; ld 12, ...(12); mtctr 12; bctr)` -> target

AArch64 can leverage ADRP to jump to the target directly, but PPC64
needs to load an address from .branch_lt . Before Power ISA v3.0, the
PC-relative ADDPCIS was not available. .branch_lt was invented to work
around the limitation.

Symbol::ppc64BranchltIndex is replaced by
PPC64LongBranchTargetSection::entry_index which take addends into
consideration.

The tests are rewritten: ppc64-long-branch.s tests -no-pie and
ppc64-long-branch-pi.s tests -pie and -shared.

Reviewed By: sfertile

Differential Revision: https://reviews.llvm.org/D70937
2019-12-05 10:17:45 -08:00
..
COFF [LLD] Add a default copy constructor to avoid warnings 2019-11-25 14:09:16 -06:00
Common LLD: Don't use the stderrOS stream in link before it's reassigned. 2019-11-21 10:55:03 -05:00
ELF [ELF][PPC64] Support long branch thunks with addends 2019-12-05 10:17:45 -08:00
MinGW LLD: Don't use the stderrOS stream in link before it's reassigned. 2019-11-21 10:55:03 -05:00
cmake/modules [CMake] Properly conditionalize installation of lld libraries 2018-03-09 13:09:36 +00:00
docs [lld] [ELF] Add '-z nognustack' opt to suppress emitting PT_GNU_STACK 2019-10-29 17:54:23 +01:00
include/lld LLD: Don't use the stderrOS stream in link before it's reassigned. 2019-11-21 10:55:03 -05:00
lib LLD: Don't use the stderrOS stream in link before it's reassigned. 2019-11-21 10:55:03 -05:00
test [ELF][PPC64] Support long branch thunks with addends 2019-12-05 10:17:45 -08:00
tools/lld Make it possible to redirect not only errs() but also outs() 2019-11-18 11:18:06 +09:00
unittests Make it possible to redirect not only errs() but also outs() 2019-11-18 11:18:06 +09:00
utils Python 2/3 compatibility 2019-03-20 07:42:13 +00:00
wasm LLD: Don't use the stderrOS stream in link before it's reassigned. 2019-11-21 10:55:03 -05:00
.arcconfig
.clang-format
.gitignore
CMakeLists.txt [CMake] Don't set Python_ADDITIONAL_VERSIONS 2019-07-18 15:17:42 +00:00
CODE_OWNERS.TXT
LICENSE.TXT Fix typos throughout the license files that somehow I and my reviewers 2019-01-21 09:52:34 +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.

Benchmarking

In order to make sure various developers can evaluate patches over the same tests, we create a collection of self contained programs.

It is hosted at https://s3-us-west-2.amazonaws.com/linker-tests/lld-speed-test.tar.xz

The current sha256 is 10eec685463d5a8bbf08d77f4ca96282161d396c65bd97dc99dbde644a31610f.