This change permits there to be more than one thunk to be associated with
a symbol. For interworking thunks we only require one thunk, but range
extension thunks may require more than one.

Differential Revision: https://reviews.llvm.org/D34037

llvm-svn: 307136

On ARM the interworking thunks are only produced for branch instructions
that can't be changed into a blx instruction so only Thumb callers would
call Thumb thunks and only ARM callers would call ARM thunks. With range
extension thunks branch and link instructions may need a Thunk. These
instructions can be rewritten as a blx and can use either ARM or Thumb
thunks.

We introduce an isCompatibleWith() function so that a caller can check if
an existing Thunk is compatible before reusing it.

Differential Revision: https://reviews.llvm.org/D34035

llvm-svn: 307132

The allocateHeaders() function is called at the end of assignAddresses(), it
decides whether the ELF header and program header table can be allocated to
a PT_LOAD program header. As the function alters state, it prevents
assignAddresses() from being called multiple times.

This change splits out the call to allocateHeaders() from assignAddresses()
this will permit assignAddresses() to be called while processing range
extension thunks without trying to allocateHeaders().

Differential Revision: https://reviews.llvm.org/D34344

llvm-svn: 307131

This is a semantic revert of r306036.

We have to change the names, otherwise dynamic relocations will point
to the wrong name.

llvm-svn: 307110

This is finally getting to the point where output sections are
constructed.

createOrphanCommands and fabricateDefaultCommands are moved out so
they can be merged with existing code in followup commits.

llvm-svn: 307107

Now addSectionSymbols operates on the linker script.

llvm-svn: 307102

Now all of finalizeSections works on the linker script.

llvm-svn: 307101

Now addPredefinedSections operates only on the linker script.

llvm-svn: 307100

Summary:
If the output file is a character file (e.g. /dev/null) unlinking it could
potentially destabilize the user's system.  For example,
unlinking causes `lld %input -o /dev/null` to replace /dev/null with a
regular file, which will lead to unexpected behavior in other programs
that read from /dev/null, and worse than expected peformance for
programs that write to /dev/null.

This makes it possible to run the test-release.sh script as root.
Prior to this patch, the ELF/basic.s test would replace
/dev/null with a regular file, which would cause crashes in llvm
test-suite programs that piped /dev/null to stdin.

For example, if you run the test-relase.sh script as root,

Reviewers: ruiu

Reviewed By: ruiu

Subscribers: emaste, llvm-commits

Differential Revision: https://reviews.llvm.org/D34917

llvm-svn: 307092

Before we would sometimes not mention that the relocation was in a ro
area before.

llvm-svn: 307089

llvm-svn: 307083

This is PR28414. 
Previously LLD was unable to link following:
(failed with undefined symbol bar)

Version script:
SOME_VERSION { global: *; };

.global _start
.global bar
.symver _start, bar@@SOME_VERSION
_start:
  jmp bar
Manual has next description:

.symver name, name2@@nodename
In this case, the symbol name must exist and be defined within the file being assembled. It is similar to name2@nodename. 
The difference is name2@@nodename will also be used to resolve references to name2 by the linker
https://sourceware.org/binutils/docs/as/Symver.html

Patch implements that. If we have name@@ver symbol and name is undefined, name@@ver is used to resolve references to name.
If name is defined then multiple definition error is emited, that is consistent with what bfd do.

Differential revision: https://reviews.llvm.org/D33680

llvm-svn: 307077

Two more places.

llvm-svn: 307076

llvm-svn: 307044

Now removeUnusedSyntheticSections operates entirely on the linker
script.

llvm-svn: 307043

* Return type changed to void, because it was unused.
* std::find_if -> llvm::find_if

llvm-svn: 307039

Script commands are processed before unused synthetic sections are
removed. Therefore, if a linker script matches one of these sections
it'll get emitted as an empty output section because the logic for
removing unused synthetic sections ignores script commands which
could have already matched and captured one of these sections. This
patch fixes that by also removing the unused synthetic sections from
the script commands.

Differential Revision: https://reviews.llvm.org/D34800

llvm-svn: 307037

This patch makes changes to allow sections without the SHF_ALLOC bit to be
assigned to segments in a linker script.

The assignment of output sections to segments is performed in
LinkerScript::createPhdrs. Previously, this function would bail as soon as it
encountered an output section which did not have the SHF_ALLOC bit set, thus
preventing any output section without SHF_ALLOC from being assigned to a
segment.

This restriction has now been removed from LinkerScript::createPhdrs and instead
a check for SHF_ALLOC has been added to LinkerScript::adjustSectionsAfterSorting
to not propagate program headers to sections without SHF_ALLOC which matches the
behaviour of bfd linker scripts.

Differential Revision: https://reviews.llvm.org/D34204

llvm-svn: 307013

This reverts commit r306813 because it broke linking of the
FreeBSD base system.

llvm-svn: 306996

This is PR28414. 
Previously LLD was unable to link following:
(failed with undefined symbol bar)

```
Version script:
SOME_VERSION { global: *; };

.global _start
.global bar
.symver _start, bar@@SOME_VERSION
_start:
  jmp bar
```

Manual has next description:
//
.symver name, name2@@nodename
In this case, the symbol name must exist and be defined within the file being assembled. It is similar to name2@nodename. 
**The difference is name2@@nodename will also be used to resolve references to name2 by the linker**
https://sourceware.org/binutils/docs/as/Symver.html
//

Patch implements that. If we have name@@ver symbol and name is undefined, 
name@@ver is used to resolve references to name.

Differential revision: https://reviews.llvm.org/D33680

llvm-svn: 306813

Differential Revision: https://reviews.llvm.org/D34852

llvm-svn: 306772

llvm-svn: 306700

Now that _GLOBAL_OFFSET_TABLE_ is defined, we can just use R_PC for it
if needed.

llvm-svn: 306614

llvm-svn: 306609

We could have add this function either Symbol or SymbolBody. I added it
to Symbol at first. But I noticed that if I've added it to SymbolBody,
we could've removed SymbolBody::setName(). So I'll do that in this patch.

llvm-svn: 306590

This patch adds a utility function to Symbol. This function should
be useful in https://reviews.llvm.org/D33680 too.

llvm-svn: 306587

Add support for the most common SPARC relocations.
Make DT_PLTGOT point to the PLT on SPARC.
Mark the PLT as executable on SPARC.

This adds a basic test that creates a SPARV9 executable
that invokes the exit system call on OpenBSD.

Patch by Mark Kettenis.

Differential Revision: https://reviews.llvm.org/D34618

llvm-svn: 306565

This is PR33596. Previously LLD would crash
because BYTE command synthesized output section,
but it was not assigned to Sec member of OutputSectionCommand.

Behaviour of -script and -r combination is not well defined,
but it seems after this change LLD naturally inherits behavior of
GNU linkers - creates output section requested in script and does not
crash anymore.

Differential revision: https://reviews.llvm.org/D34676

llvm-svn: 306527

This fixes PR33598.

Size field for undefined symbols is not significant.
Setting it to fixed value, like zero, may be useful though.

For example when we have 2 DSO's, like in this PR, if lower level DSO may
change slightly (in part of some symbol's st_size)  and higher-level DSO is
rebuilt, then tools that monitoring checksum of high level DSO file can notice
it and trigger cascade of some other unnecessary actions. 
If we set st_size to zero, that can be avoided.

Differential revision: https://reviews.llvm.org/D34673

llvm-svn: 306526

When -ffunction-sections and ARM C++ exceptions are used each .text.suffix
section will have at least one .ARM.exidx.suffix section and may have an
additional .ARM.extab.suffix section if the unwinding instructions are too
large to inline into the .ARM.exidx table entry. For a large program without
a linker script this can lead to a large number of section header table
entries that can increase the size of the ELF file.

This change introduces a default rule for .ARM.extab.* to be placed in
a single output section called .ARM.extab . This follows the behavior of
ld.gold and ld.bfd.

fixes pr33407

Differential Revision: https://reviews.llvm.org/D34678

llvm-svn: 306522

This patch fills holes in executable sections with 0xd4 (ARM) or
0xef (MIPS). These trap instructions were suggested by Theo de Raadt.

llvm-svn: 306322

llvm-svn: 306308

`addInputSec` returns void. Even though it is syntactically correct,
the use of `return` here is just confusing.

llvm-svn: 306307

Most "reserved" symbols are in ElfSym and it looks like there's no
reason to not do the same thing for _GLOBAL_OFFSET_TABLE_. This should
help https://reviews.llvm.org/D34618 too.

llvm-svn: 306292

On many architectures gcc and clang will recognize _GLOBAL_OFFSET_TABLE_ - .
and produce a relocation that can be processed without needing to know the
value of _GLOBAL_OFFSET_TABLE_. This is not always the case; for example ARM
gcc produces R_ARM_BASE_PREL but clang produces the more general
R_ARM_REL32 to _GLOBAL_OFFSET_TABLE_. To evaluate this relocation
correctly _GLOBAL_OFFSET_TABLE_ must be defined to be the either the base of
the GOT or end of the GOT dependent on architecture..

If/when llvm-mc is changed to recognize _GLOBAL_OFFSET_TABLE_ - . this
change will not be necessary for new objects. However there may still be
old objects and versions of clang.

Differential Revision: https://reviews.llvm.org/D34355

llvm-svn: 306282

Previously, when symbol A is renamed B, both A and B end up having
the same name. This is because name is a symbol's attribute, and
we memcpy symbols for symbol renaming.

This pathc saves the original symbol name and restore it after memcpy
to keep the original name.

This patch shouldn't change program's meaning, but names in symbol
tables make more sense than before.

llvm-svn: 306036

Differential Revision: https://reviews.llvm.org/D34442

llvm-svn: 305983

This is unnecessary because --gc-sections runs before ICF.

Differential Revision: https://reviews.llvm.org/D34465

llvm-svn: 305954

The --exclude-libs option is not a popular option, but at least some
programs in Android depend on it, so it's worth to support it.

Differential Revision: https://reviews.llvm.org/D34422

llvm-svn: 305920

llvm-svn: 305877