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Fangrui Song bc4b159bb1 [ELF][X86] Allow R_386_TLS_LDO_32 and R_X86_64_DTPOFF{32,64} to preemptable local-dynamic symbols 
Summary:
Fixes PR35242. A simplified reproduce:

    thread_local int i; int f() { return i; }

% {g++,clang++} -fPIC -shared -ftls-model=local-dynamic -fuse-ld=lld a.cc
ld.lld: error: can't create dynamic relocation R_X86_64_DTPOFF32 against symbol: i in readonly segment; recompile object files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in the output

In isStaticLinkTimeConstant(), Syn.IsPreemptible is true, so it is not
seen as a constant. The error is then issued in processRelocAux().

A symbol of the local-dynamic TLS model cannot be preempted but it can
preempt symbols of the global-dynamic TLS model in other DSOs.
So it makes some sense that the variable is not static.

This patch fixes the linking error by changing getRelExpr() on
R_386_TLS_LDO_32 and R_X86_64_DTPOFF{32,64} from R_ABS to R_DTPREL.
R_PPC64_DTPREL_* and R_MIPS_TLS_DTPREL_* need similar fixes, but they are not handled in this patch.

As a bonus, we use `if (Expr == R_ABS && !Config->Shared)` to find
ld-to-le opportunities. R_ABS is overloaded here for such STT_TLS symbols.
A dedicated R_DTPREL is clearer.

Differential Revision: https://reviews.llvm.org/D60945

llvm-svn: 358870
 		2019-04-22 03:10:40 +00:00
..
COFF [COFF] Pack Name in Symbol as is done in ELF 2019-04-19 22:51:49 +00:00
Common Fail early if an output file is not writable 2019-03-11 16:30:55 +00:00
ELF [ELF][X86] Allow R_386_TLS_LDO_32 and R_X86_64_DTPOFF{32,64} to preemptable local-dynamic symbols 2019-04-22 03:10:40 +00:00
MinGW [MinGW] Add an --appcontainer flag, passed through to lld-link 2019-04-19 13:50:43 +00:00
cmake/modules [CMake] Properly conditionalize installation of lld libraries 2018-03-09 13:09:36 +00:00
docs [COFF] Link crtend.o as the last object file 2019-04-15 10:57:44 +00:00
include/lld Fail early if an output file is not writable 2019-03-11 16:30:55 +00:00
lib lld: Fix initial Mach-O load commands size calculation omitting LC_FUNCTION_STARTS 2019-04-17 01:47:16 +00:00
test [ELF][X86] Allow R_386_TLS_LDO_32 and R_X86_64_DTPOFF{32,64} to preemptable local-dynamic symbols 2019-04-22 03:10:40 +00:00
tools/lld Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
unittests Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
utils Python 2/3 compatibility 2019-03-20 07:42:13 +00:00
wasm [WebAssembly] Emit the DataCount section when bulk memory is enabled 2019-04-19 23:40:36 +00:00
.arcconfig [lld] Set up .arcconfig to point to new Diffusion LLD repository 2017-12-06 20:56:23 +00:00
.clang-format
…
.gitignore
…
CMakeLists.txt [WebAssembly] Initial wasm linker implementation 2017-11-17 18:14:09 +00:00
CODE_OWNERS.TXT [WebAssembly] Initial wasm linker implementation 2017-11-17 18:14:09 +00:00
LICENSE.TXT Fix typos throughout the license files that somehow I and my reviewers 2019-01-21 09:52:34 +00:00
README.md Note that the test .tar.xz has been updated. 2017-12-22 19:37:32 +00:00

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.