Implement the TLS relocation optimization for 32-bit x86 that is described in
"ELF Handling For Thread-Local Storage" by Ulrich Drepper, chapter 5,
"IA-32 Linker Optimizations". Specifically, this patch implements these
optimizations: LD->LE, GD->IE, GD->LD, and IE->LE.

Differential revision: http://reviews.llvm.org/D15292

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The gcc_except_tab was generating these references to point to the typeinfo in the data section.

gcc_except_tab also had the DW_EH_PE_indirect flag set which means that at runtime we are going
to dereference this entry as if it is in the GOT.

Reviewed by Nick Kledzik in http://reviews.llvm.org/D15360.

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MSVC linker considers PDB files created with this patch valid.
So you don't have to remove PDB files created by lld before
running MSVC linker.

This patch has no test since llvm-pdbdump dislikes PDB files
with no metadata streams.

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(per discussion with Michael Spencer)

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All relocations, which cannot be handled by the dynamic linker,
cause a linking error "rebuild with -fPIC".

Differential revision: http://reviews.llvm.org/D15193


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Before this patch, we created an empty PDB file if /debug option is
specified. For MSVC linker, such PDB file is completely broken, and
linker exits without doing anything as soon as it finds an empty PDB
file.

A PDB file created in this patch has the correct file signature.
MSVC linker still thinks that the file is broken, but it then removes
and replaces with its output.

This is an initial patch to support PDB in LLD. We aim to support
PDB in order to make it 100% compatible with MSVC linker. PDB support
is the last missing piece.

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"Ulrich Drepper, ELF Handling For Thread-Local Storage" (5.5 x86-x64 linker optimizations, http://www.akkadia.org/drepper/tls.pdf) shows how GD can be optimized to IE.
This patch implements the optimization.

Differential revision: http://reviews.llvm.org/D15000

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Generate R_AARCH64_COPY relocations for non-GOT relocations,
which reference object symbols from shared libraries.

Differential revision: http://reviews.llvm.org/D15043


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If a section symbol is not external, that COMDAT section should never
be merge with other sections in other compilation unit. Previously,
we didn't take visibility into account.

Note that COMDAT sections with non-external visibility makes sense
because they can be removed by dead-stripping.

Fixes https://llvm.org/bugs/show_bug.cgi?id=25686

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Main aim of the patch to introduce basic support for TLS access models for x86 target.
Models using @tlsgd, @tlsldm and @gotntpoff are implemented.

Differential revision: http://reviews.llvm.org/D15060

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Some MIPS relocations including `R_MIPS_HI16/R_MIPS_LO16` use combined
addends. Such addend is calculated using addends of both paired relocations.
Each `R_MIPS_HI16` relocation is paired with the next `R_MIPS_LO16`
relocation. ABI requires to compute such combined addend in case of REL
relocation record format only.

For details see p. 4-17 at
ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf

This patch implements lookup of the next paired relocation suing new
`InputSectionBase::findPairedRelocLocation` method. The primary
disadvantage of this approach is that we put MIPS specific logic into
the common code. The next disadvantage is that we lookup `R_MIPS_LO16`
for each `R_MIPS_HI16` relocation, while in fact multiple `R_MIPS_HI16`
might be paired with the single `R_MIPS_LO16`. From the other side
this way allows us to keep `MipsTargetInfo` class stateless and implement
later relocation handling in parallel.

This patch does not support `R_MIPS_HI16/R_MIPS_LO16` relocations against
`_gp_disp` symbol. In that case the relocations use a special formula for
the calculation. That will be implemented later.

Differential Revision: http://reviews.llvm.org/D15112

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[ELF] - Fixed bug leading to miss of tls relocation when @tlsgd and @gottpoff relocations were used at the same time.

Combination of @tlsgd and @gottpoff at the same time leads to miss of R_X86_64_TPOFF64 dynamic relocation. Patch fixes that.

@tlsgd(%rip) - Allocate two contiguous entries in the GOT to hold a tls index
structure (for passing to tls get addr).
@gottpoff(%rip) - Allocate one GOT entry to hold a variable offset in initial TLS
block (relative to TLS block end, %fs:0).

The same situation can be observed for x86 (probably others too, not sure) with corresponding for that target relocations: @tlsgd, @gotntpoff.

Differential revision: http://reviews.llvm.org/D15105

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Fix was:
uint32_t getLocalTlsIndexVA() { return getVA() + LocalTlsIndexOff; }
=>
uint32_t getLocalTlsIndexVA() { return Base::getVA() + LocalTlsIndexOff; }
Both works for my MSVS.

Original commit message:
[ELF] - Refactor of tls_index implementation for tls local dynamic model.

Patch contains the next 2 changes:
1) static variable Out<ELFT>::LocalModuleTlsIndexOffset moved to Out<ELFT>::Got. At fact there is no meaning for it to be separated from GOT class because at each place of using it anyways needs to call GOT`s getVA(). Also it is impossible to have that offset and not have GOT.
2) addLocalModuleTlsIndex -> addLocalModelTlsIndex (word "Module" changed to "Model"). Not sure was it a mistype or not but I think that update is closer to Urlich terminology.

Differential revision: http://reviews.llvm.org/D15113


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It failed buildbot:
http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/3782/steps/build/logs/stdio

Target.cpp
In file included from /home/buildbot/Buildbot/Slave/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm.src/tools/lld/ELF/Target.cpp:20:
/home/buildbot/Buildbot/Slave/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm.src/tools/lld/ELF/OutputSections.h:136:42: error: use of undeclared identifier 'getVA'
  uint32_t getLocalTlsIndexVA() { return getVA() + LocalTlsIndexOff; }

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Removes Target::getGotRefReloc() method to simplify Target class a little.

Differential revision: http://reviews.llvm.org/D15107

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Patch contains the next 2 changes:
1) static variable Out<ELFT>::LocalModuleTlsIndexOffset moved to Out<ELFT>::Got. At fact there is no meaning for it to be separated from GOT class because at each place of using it anyways needs to call GOT`s getVA(). Also it is impossible to have that offset and not have GOT.
2) addLocalModuleTlsIndex -> addLocalModelTlsIndex (word "Module" changed to "Model"). Not sure was it a mistype or not but I think that update is closer to Urlich terminology.

Differential revision: http://reviews.llvm.org/D15113

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Differential revision: http://reviews.llvm.org/D15045


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In other places, we don't have the comment. Absence of check{Int,UInt}
is the sign that no overflow check is needed.

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Splitted writeTo to separate tls relocs handling stuff which is too long for one method now. NFC.

Differential revision: http://reviews.llvm.org/D15012

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Incorrect template specialization was used (generic ELFT type was expected but platform specific was used).

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If an argument of the INPUT directive is a regular path, linker should
lookup it in the current folder first.

The fix does not contain any test cases because I think it is not a good
idea to pollute a current folder (which in general might be arbitrary)
by test files.

Differential Revision: http://reviews.llvm.org/D15027

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ABI specifies the allowed range for these relocations as 2^(n-1) <= X < 2^n.

The patch fixes checks and introduces precise tests for these relocations.

Differential revision: http://reviews.llvm.org/D14957


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It helps to standardize common checks and unify error messages.

Differential revision: http://reviews.llvm.org/D14943


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In case a sysroot prefix is configured, and the filename starts with
the '/' character, and the script being processed was located inside
the sysroot prefix, the file's name will be looked for in the sysroot
prefix. Otherwise, the linker falls to the common lookup scheme.

It is slightly modified version of the commit r254031. The problem of
the initial commit was in the `is_absolute` call. On Windows 'C:\' is
absolute path but we do not need to find it under sysroot. In this patch
linker looks up a path under sysroot only if the paths starts with '/'
character.

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Fix is (OutputSections.cpp):
for (std::pair<const SymbolBody *, size_t> &I : Entries) {
 =>
for (std::pair<const SymbolBody *, unsigned> &I : Entries) {

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http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/3555

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Implements @tlsld (LD to LE) and @tlsgd (GD to LE) optimizations.
Patch does not implement the GD->IE case for @tlsgd.

Differential revision: http://reviews.llvm.org/D14870

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Patch implements lazy relocations for x86.
One of features of x86 is that executable files and shared object files have separate procedure linkage tables. So patch implements both cases.

Detailed information about instructions used can be found in http://docs.oracle.com/cd/E19620-01/805-3050/chapter6-1235/index.html (search: x86: Procedure Linkage Table).

Differential revision: http://reviews.llvm.org/D14955

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R_MIPS_CALL16 relocation provides the same result as R_MIPS_GOT16
relocation but does not need to check the result on overflow.

Differential Revision: http://reviews.llvm.org/D14916

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This patch implements next relocations:
R_386_TLS_LE - Negative offset relative to static TLS (GNU version).
R_386_TLS_LE_32 - Offset relative to static TLS block.

These ones are created when using next code sequences:
* @tpoff - The operator must be used to compute an immediate value. The linker will report
an error if the referenced variable is not defined or it is not code for the executable
itself. No GOT entry is created in this case.
* @ntpoff Calculate the negative offset of the variable it is added to relative to the static TLS block.
The operator must be used to compute an immediate value. The linker will report
an error if the referenced variable is not defined or it is not code for the executable
itself. No GOT entry is created in this case.

Information was found in Ulrich Drepper, ELF Handling For Thread-Local Storage, http://www.akkadia.org/drepper/tls.pdf, (6.2, p76)

Differential revision: http://reviews.llvm.org/D14930

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https://docs.oracle.com/cd/E19683-01/817-3677/chapter6-26/index.html says:
R_386_GOTPC
Resembles R_386_PC32, except that it uses the address of the global offset table in its calculation. The symbol referenced in this relocation normally is _GLOBAL_OFFSET_TABLE_, which also instructs the link-editor to create the global offset table.

Currently _GLOBAL_OFFSET_TABLE_ has value == zero. And we use GOT address to calculate the relocation. This patch does not changes that. It just removes the method which is used only for x86. So it is close to non functional change.

Differential revision: http://reviews.llvm.org/D14993

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Implements R_386_COPY relocation for x86 target.
Similar to one for x64 http://reviews.llvm.org/D14090 which did most of job needed.

Differential revision: http://reviews.llvm.org/D14958

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