Commit Graph

488 Commits

Author SHA1 Message Date
George Rimar 696a7f9ac6 [ELF] - Introduce std::vector<InputFile *> global arrays.
This patch removes lot of static Instances arrays from different input file 
classes and introduces global arrays for access instead. Similar to arrays we
have for InputSections/OutputSectionCommands.

It allows to iterate over input files in a non-templated code.

Differential revision: https://reviews.llvm.org/D35987

llvm-svn: 313619
2017-09-19 09:20:54 +00:00
Rafael Espindola 3e635f2309 Use existing helper. NFC.
llvm-svn: 313184
2017-09-13 20:07:13 +00:00
Rafael Espindola d72d97b3be If --dynamic-list is given, only those symbols are preemptible.
This allows combining --dynamic-list and version scripts too. The
version script controls which symbols are visible, and
--dynamic-list controls which of those are preemptible.

Unlike previous versions, undefined symbols are still considered
preemptible, which was the issue breaking the cfi tests.

This fixes pr34053.

llvm-svn: 312806
2017-09-08 18:16:59 +00:00
Rafael Espindola 0ff545c018 Revert "Revert "Revert r311468: If --dynamic-list is given, only those symbols are preemptible""
This reverts commit r312757.

Evgenii Stepanov reports that it broke some tests.

llvm-svn: 312771
2017-09-08 01:09:52 +00:00
Rafael Espindola b7d0be5896 Revert "Revert r311468: If --dynamic-list is given, only those symbols are preemptible"
If --dynamic-list is given, only those symbols are preemptible.

This allows combining --dynamic-list and version scripts too. The
version script controls which symbols are visible, and --dynamic-list
controls which of those are preemptible.

This fixes pr34053.

llvm-svn: 312757
2017-09-07 23:19:09 +00:00
Rui Ueyama e158f7c329 Revert r311468: If --dynamic-list is given, only those symbols are preemptible
This reverts commit r311468 because it broke some CFI bots.

llvm-svn: 311497
2017-08-22 21:54:58 +00:00
Rui Ueyama 9cbbacb910 If --dynamic-list is given, only those symbols are preemptible
Patch by Rafael Espíndola.

This is PR34053.

The implementation is a bit of a hack, given the precise location where
IsPreemtible is set, it cannot be used from
SymbolTable::handleAnonymousVersion.

I could add another method to SymbolTable if you think that would be
better.

Differential Revision: https://reviews.llvm.org/D36499

llvm-svn: 311468
2017-08-22 16:31:47 +00:00
Rui Ueyama 42479e02ca Rename {Lazy,}ObjectKind -> {Lazy,}ObjKind.
I renamed corresponding classes in r309199 but forgot to rename enums
at the moment. Rename them now to make them consistent.

llvm-svn: 311214
2017-08-19 00:13:54 +00:00
Rui Ueyama 43099e4409 Remove SymbolTable::findInCurrentDSO.
This function doesn't seem to add value to the symbol table as
it is easy to write code without it.

llvm-svn: 310925
2017-08-15 16:03:11 +00:00
Rafael Espindola 6e93d0546a Move File from SymbolBody to Symbol.
With this Symbol has the same size as before, but DefinedRegular goes
from 72 to 64 bytes.

I also find this a bit easier to read. There are fewer places
initializing File for example.

This has a small but measurable speed improvement on all tests (1%
max).

llvm-svn: 310142
2017-08-04 22:31:42 +00:00
Rui Ueyama 709fb2bb10 Rename ObjectFile -> ObjFile.
Rename it because it was too easy to conflict with llvm::object::ObjectFile
which broke buildbots several times.

llvm-svn: 309199
2017-07-26 22:13:32 +00:00
Rui Ueyama 3e96f1167c Attempt to fix buildbots.
llvm-svn: 309188
2017-07-26 21:37:11 +00:00
Rafael Espindola 244ef98161 Detemplate SymbolTable.
NFC, just makes it easier to access from non templated code.

llvm-svn: 309152
2017-07-26 18:42:48 +00:00
Rafael Espindola cb83c8c85f Simplify. NFC.
llvm-svn: 309053
2017-07-25 23:23:40 +00:00
Rafael Espindola d4fbe4fe82 Reduce templating. NFC.
llvm-svn: 309051
2017-07-25 23:15:35 +00:00
Rui Ueyama 0deaacb95a Call StringRef::contains only once for each StringRef.
llvm-svn: 308529
2017-07-19 21:49:01 +00:00
Rui Ueyama 12234f8093 Use StringRef::contains().
llvm-svn: 308526
2017-07-19 21:40:26 +00:00
Rafael Espindola 3ddf2110d5 Bring back r307364.
In addition this includes a change to prefer symbols with a default
version @@ over unversioned symbols.

Original commit message:

[ELF] - Handle symbols with default version early.

This fixes last testcase provided in PR28414.
In short issue is next: when we had X@@Version symbol in object A,
we did not resolve it to X early. Then when in another object B
we had reference to undefined X, symbol X from archive was fetched.
Since both archive and object A contains another symbol Z, duplicate
symbol definition was triggered as a result.

Correct behavior is to use X@@Version from object A instead and do not fetch
any symbols from archive.

Differential revision: https://reviews.llvm.org/D35059

llvm-svn: 308492
2017-07-19 16:45:05 +00:00
George Rimar 67c60727ce [ELF] - Apply clang-format. NFC.
llvm-svn: 308297
2017-07-18 11:55:35 +00:00
Rui Ueyama 0e0369e535 Revert r307364: [ELF] - Handle symbols with default version early.
This reverts commit r307364 because that change is likely to have
caused https://bugs.llvm.org/show_bug.cgi?id=33820.

llvm-svn: 308239
2017-07-18 00:33:14 +00:00
Rafael Espindola d3fc0c91e3 Bring back InVersionScript.
We were producing bogus warnings without it.

llvm-svn: 307820
2017-07-12 17:49:17 +00:00
George Rimar 3e8a461bdf [ELF] - Give a symbol version extracted from name a priority over version set by script.
This fixes PR33712.

Imagine following script and code:

VER1 { global: foo; local: *; };
VER2 { global: foo; };

.global bar
bar:
.symver bar, foo@VER1

.global zed
zed:
.symver zed, foo@@VER2

We add foo@@VER2 as foo to symbol table, because have to resolve references to
foo for default symbols.
Later we are trying to assign symbol versions from script. For that we are searching for 'foo'
again. Here it is placed under VER1 and VER2 at the same time, we find it twice and trying to
set version again both times, hence LLD shows a warning.
Though sample code is correct: we have 2 different versions of foo.

Patch gives a symbol version extracted from name a priority over version set by script.

Differential revision: https://reviews.llvm.org/D35207

llvm-svn: 307792
2017-07-12 13:54:42 +00:00
George Rimar d92e1286ed [ELF] - Fix handling of weak symbols from static library when using version script.
When version script was used, binding opf undefined weak symbols sometimes
was calculated as STB_LOCAL, making them non-preemtible what
broke correct relocations handling logic for them.

Fixes PR33738.

Differential revision: https://reviews.llvm.org/D35263

llvm-svn: 307767
2017-07-12 11:09:46 +00:00
Rui Ueyama 9a1898768f Remove unnecessary local variable.
llvm-svn: 307703
2017-07-11 20:33:04 +00:00
Rafael Espindola da8a47ab01 Delete redundant InVersionScript field.
Thanks to Rui for the suggestion.

llvm-svn: 307690
2017-07-11 18:59:45 +00:00
George Rimar 85e9216e8c [ELF] - Handle symbols with default version early.
This fixes last testcase provided in PR28414.
In short issue is next: when we had X@@Version symbol in object A,
we did not resolve it to X early. Then when in another object B
we had reference to undefined X, symbol X from archive was fetched.
Since both archive and object A contains another symbol Z, duplicate
symbol definition was triggered as a result.

Correct behavior is to use X@@Version from object A instead and do not fetch
any symbols from archive.

Differential revision: https://reviews.llvm.org/D35059

llvm-svn: 307364
2017-07-07 08:29:51 +00:00
George Rimar 4d2f976208 [ELF] - Resolve references properly when using .symver directive
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
2017-07-04 13:19:13 +00:00
Rui Ueyama 80cbc776cb Revert r306813: "[ELF] - Resolve references properly when using .symver directive"
This reverts commit r306813 because it broke linking of the
FreeBSD base system.

llvm-svn: 306996
2017-07-03 03:26:07 +00:00
George Rimar aad84e2ee2 [ELF] - Resolve references properly when using .symver directive
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
2017-06-30 10:19:54 +00:00
Rui Ueyama b2269ec4d3 Move copy function from Symbol to SymbolBody.
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
2017-06-28 19:43:02 +00:00
Rui Ueyama 8e11b6d94b Define Symbol::copyBody function.
This patch adds a utility function to Symbol. This function should
be useful in https://reviews.llvm.org/D33680 too.

llvm-svn: 306587
2017-06-28 19:28:49 +00:00
Rui Ueyama 4402a39981 Keep the original symbol name when renamed.
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
2017-06-22 17:30:19 +00:00
Rui Ueyama d1f8b8162b Implement the --exclude-libs option.
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
2017-06-21 15:36:24 +00:00
Dmitry Mikulin db3b87b2c0 Symbols re-defined with -wrap and -defsym need to be excluded from inter-
procedural optimizations to prevent dropping symbols and allow the linker
to process re-directs.

PR33145: --wrap doesn't work with lto.
Differential Revision: https://reviews.llvm.org/D33621

llvm-svn: 304719
2017-06-05 16:24:25 +00:00
Rafael Espindola 1c2baad6dd Revert "Simplify a variable type by using StringRef instead of CachedHashStringRef."
This reverts commit r303787.

It caused a slowdown in fast links. That is, links with no debug info
or optimizations.

llvm-svn: 303925
2017-05-25 21:53:02 +00:00
Rui Ueyama 466c82b74f Simplify a variable type by using StringRef instead of CachedHashStringRef.
A variable `ComdatGroup` is not supposed to contain a large number of
items. Even when linking clang, it ends up having only 300K strings.
It doesn't make sense to use CachedHashStringRef for this hash table.
This patch has neutral or slightly positive impact on performance while
reducing code complexity.

llvm-svn: 303787
2017-05-24 18:22:27 +00:00
Rafael Espindola 808f2d3c62 Reduce code duplication. NFC.
llvm-svn: 302155
2017-05-04 14:54:48 +00:00
Rafael Espindola 5e20c75e3a Handle mixed strong and weak undefined symbols.
We were ignoring strong undefined symbols if they followed weak ones.

Fixes pr32899.

llvm-svn: 302065
2017-05-03 18:40:27 +00:00
Rui Ueyama 330e52b018 Removes createELFFile which takes a template class as a template parameter.
This patch is to reduce amount of template uses. The new code is less
exciting and boring than before, but I think it is easier to read.

Differential Revision: https://reviews.llvm.org/D32467

llvm-svn: 301488
2017-04-26 22:51:51 +00:00
George Rimar 9703ad2221 [ELF] - Implemented --defsym option.
gnu ld description of option is:

--defsym=symbol=expression
Create a global symbol in the output file, containing the absolute address given 
by expression. You may use this option as many times as necessary to define multiple
symbols in the command line. A limited form of arithmetic is supported for the 
expression in this context: you may give a hexadecimal constant or the name of an
existing symbol, or use "+" and "-" to add or subtract hexadecimal constants or 
symbols. If you need more elaborate expressions, consider using the linker command
language from a script. Note: there should be no white space between symbol, 
the equals sign ("="), and expression.

In compare with D32082, this patch does not support math expressions and absolute
symbols. It implemented via code similar to --wrap. That covers 1 of 3 possible
--defsym cases.

Differential revision: https://reviews.llvm.org/D32171

llvm-svn: 301391
2017-04-26 10:40:02 +00:00
Rui Ueyama 321b9cd072 Export __progname even if a -dynamic-list is given.
BSD's __progname symbol is defined in crt1.o and linked against main
executables. The libc expects that main executables export __progname
symbol via .dynsym sections. In order to handle this case, we scan
undefined symbols in DSOs and exported them by setting Sym->ExportDynamic
to true.

But it turned out that setting that variable is not enough to make sure
that symbols are exported in all use cases. If a -dynamic-list option is
given, all symbols not explicitly mentioned in a version script are
hidden by default. That hides __progname symbol. This patch fixes the issue.

Fixes https://bugs.llvm.org/show_bug.cgi?id=32703

llvm-svn: 301282
2017-04-25 00:15:48 +00:00
Rafael Espindola 3460cdd440 Remove DefaultSoName.
We can just use the existing SoName member variable. It now initially
contains what was in DefaultSoName and is modified if the .so has an
actual soname.

llvm-svn: 301259
2017-04-24 21:44:20 +00:00
Rafael Espindola 8465d08392 Don't resolve hidden undef to a DSO.
The ELF spec says:

all of the non-default visibility attributes, when applied to a symbol
reference, imply that a definition to satisfy that reference must be
provided within the current executable or shared object.

But we were trying to resolve those undef references to shared
symbols. That causes odd results like creating a got entry with
a relocation pointing to 0.

llvm-svn: 299464
2017-04-04 20:03:34 +00:00
Rui Ueyama 810ce10b8c Change the error message format for duplicate symbols.
This patch is intended to improve readability of "duplicate symbol"
error messages.

Without this patch:

  /ssd/clang/bin/ld.lld: error: /ssd/llvm-project/lld/ELF/Relocations.cpp:1054: duplicate symbol 'lld:🧝:demangle(llvm::StringRef)'
  /ssd/clang/bin/ld.lld: error: /ssd/llvm-project/lld/ELF/Strings.cpp:93: previous definition was here

With this patch:

  /ssd/clang/bin/ld.lld: error: duplicate symbol: lld:🧝:demangle(llvm::StringRef)
  >>> defined at Strings.cpp:93 (/ssd/llvm-project/lld/ELF/Strings.cpp:93)
  >>>            Strings.cpp.o:(lld:🧝:demangle(llvm::StringRef)) in archive lib/liblldELF.a
  >>> defined at Relocations.cpp:1054 (/ssd/llvm-project/lld/ELF/Relocations.cpp:1054)
  >>>            Relocations.cpp.o:(.text+0x4C30) in archive lib/liblldELF.a

Discussion thread:
http://lists.llvm.org/pipermail/llvm-dev/2017-March/111459.html

Differential Revision: https://reviews.llvm.org/D31507

llvm-svn: 299280
2017-03-31 23:40:21 +00:00
Rafael Espindola 5616adf655 Remove DefinedSynthetic.
With this we have a single section hierarchy. It is a bit less code,
but the main advantage will be in a future patch being able to handle

foo = symbol_in_obj;

in a linker script. Currently that fails since we try to find the
output section of symbol_in_obj.  With this we should be able to just
return an InputSection from the expression.

llvm-svn: 297313
2017-03-08 22:36:28 +00:00
Rafael Espindola fcd208fdb3 Use uint32_t for alignment in more places, NFC.
llvm-svn: 297305
2017-03-08 19:35:29 +00:00
Rafael Espindola 9371bab55a Convert a few uses of uintX_t to uint64_t.
llvm-svn: 297282
2017-03-08 15:21:32 +00:00
Rui Ueyama 175e81cf3a Use make<> instead of new (BAlloc). NFC.
We converted them before, but there were a few remaining occurrences.

llvm-svn: 296510
2017-02-28 19:36:30 +00:00
Rui Ueyama 80474a26b9 De-template DefinedRegular.
Differential Revision: https://reviews.llvm.org/D30348

llvm-svn: 296508
2017-02-28 19:29:55 +00:00
Rui Ueyama 4076fa1e21 De-template SharedSymbol.
Differential Revision: https://reviews.llvm.org/D30351

llvm-svn: 296303
2017-02-26 23:35:34 +00:00
Rafael Espindola 24e6f363c5 Merge OutputSectionBase and OutputSection. NFC.
Now that all special sections are SyntheticSections, we only need one
OutputSection class.

llvm-svn: 296127
2017-02-24 15:07:30 +00:00
Rafael Espindola b4c9b81aad Convert InputSectionBase to a class.
Removing this template is not a big win by itself, but opens the way
for removing more templates.

llvm-svn: 295923
2017-02-23 02:28:28 +00:00
Rui Ueyama e6e206d4b4 Do not use errs() or outs() directly. Instead use message(), log() or error()
LLD is a multi-threaded program. errs() or outs() are not guaranteed
to be thread-safe (they are actually not).

LLD's message(), log() or error() are thread-safe. We should use them.

llvm-svn: 295787
2017-02-21 23:22:56 +00:00
Peter Smith 3a52eb0054 [ELF] Use SyntheticSections for Thunks
Thunks are now implemented by redirecting the relocation to the
symbol S, to a symbol TS in a Thunk. The Thunk will transfer control
to S. This has the following implications:
- All the side-effects of Thunks happen within createThunks()
- Thunks are no longer stored in InputSections and Symbols no longer
  need to hold a pointer to a Thunk
- The synthetic Thunk sections need to be merged into OutputSections
    
This implementation is almost a direct conversion of the existing
Thunks with the following exceptions:
- Mips LA25 Thunks are placed before the InputSection that defines
  the symbol that needs a Thunk.
- All ARM Thunks are placed at the end of the OutputSection of the
  first caller to the Thunk.
    
Range extension Thunks are not supported yet so it is optimistically
assumed that all Thunks can be reused.

This is a recommit of r293283 with a fixed comparison predicate as
std::merge requires a strict weak ordering.

Differential revision: https://reviews.llvm.org/D29327

llvm-svn: 293757
2017-02-01 10:26:03 +00:00
Rui Ueyama f20ee9f11a Revert "[ELF][ARM] Use SyntheticSections for Thunks"
This reverts commit r293283 because it broke MSVC build.

llvm-svn: 293352
2017-01-28 00:48:06 +00:00
Peter Smith 5191c6f945 [ELF][ARM] Use SyntheticSections for Thunks
Thunks are now implemented by redirecting the relocation to the
symbol S, to a symbol TS in a Thunk. The Thunk will transfer control
to S. This has the following implications:
- All the side-effects of Thunks happen within createThunks()
- Thunks are no longer stored in InputSections and Symbols no longer
  need to hold a pointer to a Thunk
- The synthetic Thunk sections need to be merged into OutputSections
    
This implementation is almost a direct conversion of the existing
Thunks with the following exceptions:
- Mips LA25 Thunks are placed before the InputSection that defines
  the symbol that needs a Thunk.
- All ARM Thunks are placed at the end of the OutputSection of the
  first caller to the Thunk.
    
Range extension Thunks are not supported yet so it is optimistically
assumed that all Thunks can be reused.

Differential Revision:  https://reviews.llvm.org/D29129

llvm-svn: 293283
2017-01-27 13:10:16 +00:00
Rafael Espindola b92e99cc1e Create _end symbol even if a .so defines it.
The freebsd sbrk implementation uses _end to find the initial value of
brk, so it has to be defined in the main binary.

This should fix the emacs build.

llvm-svn: 292512
2017-01-19 19:43:34 +00:00
Rafael Espindola 1d6d1b44cc Add a isInCurrentDSO helper. NFC.
llvm-svn: 292228
2017-01-17 16:08:06 +00:00
Rafael Espindola 41a93a3edf Give priority to linker scripts over preemption.
LLD exports symbols that are also present in used shared libraries to
make sure they are preempted at runtime. That is a reasonable default,
but we must allow for it to be overwritten with linker script. If we
don't, libraries that expect to be able to hide a c++ delete operator
will fail.

This should fix the firebird build.

llvm-svn: 292146
2017-01-16 17:35:23 +00:00
Rafael Espindola 8a59f5c79f Don't add DT_INIT/DT_FINI for undef and shared symbols.
The freebsd dynamic linker doesn't check if the value is null (and it
is reasonable for it to do that). That means that producing a .so with
a null DT_INIT/DT_FINI causes the base address to be called.

This should fix the libreoffice build.

llvm-svn: 291944
2017-01-13 19:18:11 +00:00
Rafael Espindola e999ddb8de Add support for anonymous local symbols.
This actually simplifies the code a bit as now all local symbols are
handled uniformly.

This should fix the build of www/webkit2-gtk3.

llvm-svn: 291569
2017-01-10 16:37:24 +00:00
Peter Smith 97c6d78f3e [ELF] Add support for thunks to undefined non-weak symbols
In a shared library an undefined symbol is implicitly imported. If the
symbol is called as a function a PLT entry is generated for it. When the
caller is a Thumb b.w a thunk to the PLT entry is needed as all PLT
entries are in ARM state.
    
This change allows undefined symbols to have thunks in the same way that
shared symbols may have thunks.

llvm-svn: 290951
2017-01-04 09:45:45 +00:00
Rui Ueyama 4c134ea3b8 Do not return null or Undefined from find{All,}ByVersion.
Vectors returned form that function contained nullptrs or Undefined symbols.
This patch filter them out. This makes use of the function a bit easier.

llvm-svn: 290334
2016-12-22 09:54:32 +00:00
Rui Ueyama 96aff3751f Define a getter function for a lazily-created object.
Previously, you had to call initDemangledSyms() before accessing DemangledSyms.
Now getDemangledSyms() initializes it and then returns it. So it is now less easy
to use it in a wrong way.

llvm-svn: 290323
2016-12-22 05:31:52 +00:00
Rui Ueyama b458841745 Simplify. NFC.
llvm-svn: 290321
2016-12-22 05:22:29 +00:00
Rui Ueyama e50e8071c2 Define a function to avoid a magic variable 0x3.
llvm-svn: 290320
2016-12-22 05:11:12 +00:00
Rui Ueyama 4f2f50dc64 De-template DefinedSynthetic.
DefinedSynthetic is not created for a real ELF object, so it doesn't
have to be a template function. It has a virtual st_value, which is
either 32 bit or 64 bit, but we can simply use 64 bit.

llvm-svn: 290241
2016-12-21 08:40:09 +00:00
Vitaly Buka 0b7de06a23 Fix build broken by changes in StringMatcher interface r290213
llvm-svn: 290231
2016-12-21 02:27:14 +00:00
Rui Ueyama 9381eb1045 Remove lld/Support/Memory.h.
I thought for a while about how to remove it, but it looks like we
can just copy the file for now. Of course I'm not happy about that,
but it's just less than 50 lines of code, and we already have
duplicate code in Error.h and some other places. I want to solve
them all at once later.

Differential Revision: https://reviews.llvm.org/D27819

llvm-svn: 290062
2016-12-18 14:06:06 +00:00
Rui Ueyama 86581e496b Rename find(SymbolVersion) to avoid overloading with find(StringRef).
llvm-svn: 289293
2016-12-10 00:34:06 +00:00
Rafael Espindola dd9dd488fc Fix a bogus warning.
We first decide that the symbol is global, than that it should have
version foo. Since it was already not the default version, we were
producing a bogus warning.

llvm-svn: 289284
2016-12-09 22:40:49 +00:00
Rafael Espindola 49cd09337c Don't crash on an extra symbol in a version script.
llvm-svn: 289217
2016-12-09 15:08:40 +00:00
Rafael Espindola 6239ce6889 Give preempting symbols precedence over linker script.
llvm-svn: 289212
2016-12-09 14:12:02 +00:00
Rui Ueyama 520d9169e6 Move Memory.{h,cpp} to lld/Support so that we can use them from COFF.
llvm-svn: 289084
2016-12-08 18:31:13 +00:00
Rafael Espindola d0ebd84c42 Change the implementation of --dynamic-list to use linker script parsing.
The feature is documented as
-----------------------------
The format of the dynamic list is the same as the version node
without scope and node name.  See *note VERSION:: for more
information.
--------------------------------

And indeed qt uses a dynamic list with an 'extern "C++"' in it. With
this patch we support that

The change to gc-sections-shared makes us match bfd. Just because we
kept bar doesn't mean it has to be in the dynamic symbol table.

The changes to invalid-dynamic-list.test and reproduce.s are because
of the new parser.

The changes to version-script.s are the only case where we change
behavior with regards to bfd, but I would like to see a mix of
--version-script and --dynamic-list used in the wild before
complicating the code.

llvm-svn: 289082
2016-12-08 17:54:26 +00:00
Rafael Espindola 191390a851 Inline function called only once.
llvm-svn: 289067
2016-12-08 16:26:20 +00:00
Rafael Espindola 361da4cef7 Handle C++ names in anon scripts.
llvm-svn: 289066
2016-12-08 16:20:29 +00:00
Rafael Espindola defdfa86c1 Inline two functions called only once. NFC.
llvm-svn: 289065
2016-12-08 16:02:48 +00:00
Rafael Espindola c65aee64ec Add two helper functions. NFC.
llvm-svn: 289064
2016-12-08 15:56:33 +00:00
Rafael Espindola 39c16dfbce Simplify. NFC.
llvm-svn: 289062
2016-12-08 15:36:58 +00:00
Simon Atanasyan 872764f6fe [ELF] Correct addAbsolute function argument name
Follow-up to r289025.

llvm-svn: 289061
2016-12-08 15:29:17 +00:00
Simon Atanasyan 6a4eb75c46 [ELF][MIPS] Make _gp, _gp_disp, __gnu_local_gp global symbols
These MIPS specific symbols should be global because in general they can
have an arbitrary value. By default this value is a fixed offset from .got
section.

This patch adds more checks to the mips-gp-local.s test case but marks
it as XFAIL because LLD does not allow redefinition of absolute symbols
value by a linker script. This should be fixed by D27276.

Differential revision: https://reviews.llvm.org/D27524

llvm-svn: 289025
2016-12-08 06:19:47 +00:00
Rui Ueyama 4c5b8cea02 Make demangle() return None instead of "" if a given string is not a mangled symbol.
llvm-svn: 288993
2016-12-07 23:17:05 +00:00
Rafael Espindola 858c092daa Allow duplicated abs symbols with the same value.
This is a fairly reasonable bfd extension since there is one obvious value.

dtrace depends on this feature as it creates multiple absolute
symbols with the same value.

llvm-svn: 288461
2016-12-02 02:58:21 +00:00
Rui Ueyama a13efc2a73 Introduce StringRefZ class to represent null-terminated strings.
StringRefZ is a class to represent a null-terminated string. String
length is computed lazily, so it's more efficient than StringRef to
represent strings in string table.

The motivation of defining this new class is to merge functions
that only differ in string types; we have many constructors that takes
`const char *` or `StringRef`. With StringRefZ, we can merge them.

Differential Revision: https://reviews.llvm.org/D27037

llvm-svn: 288172
2016-11-29 18:05:04 +00:00
Davide Italiano 3bfa081aa9 [ELF] Be compliant with LLVM and rename Lto into LTO. NFCI.
llvm-svn: 287967
2016-11-26 05:37:04 +00:00
Rui Ueyama da06bfb794 Move getLocation from Relocations.cpp to InputSection.cpp.
The function was used only within Relocations.cpp, but now we are
using it in many places, so this patch moves it to a file that fits
to the functionality.

llvm-svn: 287943
2016-11-25 18:51:53 +00:00
Rui Ueyama 26081caf48 Use toString() to report incompatible files.
llvm-svn: 287901
2016-11-24 20:59:44 +00:00
Rui Ueyama a3ac17372b Define toString(const SymbolBody &) and remove maybeDemangle instead.
Differential Revision: https://reviews.llvm.org/D27065

llvm-svn: 287899
2016-11-24 20:24:18 +00:00
Rui Ueyama f373dd76ce Remove HasError and use ErrorCount instead.
HasError was always true if ErrorCount > 0, so we can use ErrorCount instead.

llvm-svn: 287849
2016-11-24 01:43:21 +00:00
Rui Ueyama 3fc0f7e54f Define toString() as a generic function to get a string for error message.
We have different functions to stringize objects to construct
error messages. For InputFile, we have getFilename, and for
InputSection, we have getName. You had to memorize them.

I think this is the case where the function overloading comes in handy.

This patch defines toString() functions that are overloaded for all these
types, so that you just call it in error().

Differential Revision: https://reviews.llvm.org/D27030

llvm-svn: 287787
2016-11-23 18:07:33 +00:00
Rui Ueyama 0cbf749397 Remove one of SymbolTable::addRegular function that forwards other addRegular.
So that we have less number of overloaded functions.

llvm-svn: 287745
2016-11-23 06:59:47 +00:00
Rui Ueyama 768c6f0ca6 Remove a forwarding constructor that is used only once.
llvm-svn: 287742
2016-11-23 06:31:23 +00:00
Rui Ueyama 35fa6c58ad Parse symbol versions in scanVersionScript() instead of insert().
There are two ways to set symbol versions. One way is to use symbol
definition file, and the other is to embed version names to symbol
names. In the latter way, symbol name is in the form of `foo@version1`
where `foo` is a real name and `version1` is a version.

We were parsing symbol names in insert(). That seems unnecessarily
too early. We can do it later after we resolve all symbols. Doing it
lazily is a good thing because it makes code easier to read
(because now we have a separate pass to parse symbol names). Also
it could slightly improve performance because if two identical symbols
have versions, we now parse them only once.

llvm-svn: 287741
2016-11-23 05:48:40 +00:00
Rui Ueyama 8f47556796 Remove unused #include.
llvm-svn: 287467
2016-11-19 23:18:43 +00:00
Rui Ueyama 8980c92dde Use consistent variable name.
llvm-svn: 287318
2016-11-18 06:30:08 +00:00
Rui Ueyama d84124f043 Add single quotes to error messages.
llvm-svn: 287254
2016-11-17 19:57:47 +00:00
Rui Ueyama 96db27c74f Use consistent variable name.
llvm-svn: 287253
2016-11-17 19:57:45 +00:00
Rui Ueyama cd236a9577 Use llvm::reverse to get a reverse range.
llvm-svn: 287252
2016-11-17 19:57:43 +00:00
Rui Ueyama bac1c3ce85 Pass StringRefs instead of StringMatcher because it's simpler.
llvm-svn: 287234
2016-11-17 16:48:53 +00:00
Rui Ueyama da805c4800 Use uint16_t instead of size_t for symbol version ID.
Because it is uint16_t in the ELF spec. Using size_t was confusing.

llvm-svn: 287198
2016-11-17 03:39:21 +00:00
Rui Ueyama aade0e29ad Add single quotes to a warning message for consistency.
llvm-svn: 287197
2016-11-17 03:32:41 +00:00
Rui Ueyama 77d917de57 Simplify handleAnonymousVersion even more.
We used to create a vector contantaining all version definitions
with wildcards because doing that was efficient. All patterns were
compiled to a regexp and matched against symbol names. Because
a regexp can be converted to a DFA, matching against union of patterns
is as cheap as matching against one patter.

We are no longer converting them to regexp. Our own glob pattern
handler doesn't do such optimization. Therefore, creating a vector
no longer makes sense.

llvm-svn: 287196
2016-11-17 03:19:34 +00:00
Rui Ueyama 4162baa4bb Simplify. NFC.
llvm-svn: 287192
2016-11-17 02:16:06 +00:00
Rui Ueyama 94bcfae26d Split scanVersionScript. NFC.
llvm-svn: 287191
2016-11-17 02:09:42 +00:00
George Rimar 17c65af82f [ELF] - Separate locals list from versions.
This change separates all versioned locals to be a separate list in config,
that was suggested by Rafael and simplifies the logic a bit.

Differential revision: https://reviews.llvm.org/D26754

llvm-svn: 287132
2016-11-16 18:46:23 +00:00
Rafael Espindola 95eae57d78 Don't error if __tls_get_addr is defined.
Turns out some systems do define it. Not producing an error in this
case matches gold and bfd.

llvm-svn: 287125
2016-11-16 18:01:41 +00:00
George Rimar e0fc24210d [ELF] - Added support for extern "c++" local symbols in version script.
Previously we did not support them,
patch implements this functionality

Differential revision: https://reviews.llvm.org/D26604

llvm-svn: 287124
2016-11-16 17:59:10 +00:00
Eugene Leviant afaa934304 [ELF] Add Section() to expression object
This allows making symbols containing ADDR(section) synthetic,
and defining synthetic symbols outside SECTIONS block.

Differential revision: https://reviews.llvm.org/D25441

llvm-svn: 287090
2016-11-16 09:49:39 +00:00
Rui Ueyama 8249214299 Refactor symbol version assignmnt code.
The code to handle symbol versions is getting tricky and hard to
understand, so it is probably time to simplify it. This patch does
the following.

 - Add `DemangledSyms` variable to SymbolTable so that we don't
   need to pass it around to findDemangled.
 - Define `initDemangledSyms` to initialize the variable lazily.
 - hasExternCpp is removed because we no longer have to initialize
   the map eagerly.
 - scanScriptVersion is split.
 - Comments are updated.

llvm-svn: 287002
2016-11-15 18:41:52 +00:00
Rui Ueyama baf7ee3c5e Rename variables of type SymbolVersion.
In this file, `sym` was used for both SymbolBody and SymbolVersion
although the two are completely different.

llvm-svn: 286992
2016-11-15 17:51:09 +00:00
George Rimar 463984d4bf [ELF] - Better diagnostic for relative relocation to an absolute value error.
Patch adds a filename to that error message.

I faced next error when debugged one of FreeBSD port:
error: relocation R_X86_64_PLT32 cannot refer to absolute symbol __tls_get_addr

error message was poor and this patch improves it to show the locations 
of symbol declaration and using.

Differential revision: https://reviews.llvm.org/D26508

llvm-svn: 286940
2016-11-15 08:07:14 +00:00
George Rimar 92ca6f4b7d [ELF] - Fix mistype. NFC.
llvm-svn: 286801
2016-11-14 09:56:35 +00:00
George Rimar bb6c01e7c3 [ELF] - Add support for locals list in version script.
Previously we did not support anything except "local: *", patch changes that.

Actually GNU rules of proccessing wildcards are more complex than that (http://www.airs.com/blog/archives/300):
There are 2 iteration for wildcards, at first iteration "*" wildcards are ignored and handled at second iteration.

Since we previously decided not to implement such complex rules,
I suggest solution that is implemented in this patch. So for "local: *" case nothing changes,
but if we have wildcarded locals,
they are processed before wildcarded globals. 

This should fix several FreeBSD ports, one of them is jpeg-turbo-1.5.1 and
currently blocks about 5k of ports.

Differential revision: https://reviews.llvm.org/D26395

llvm-svn: 286713
2016-11-12 07:04:15 +00:00
Teresa Johnson 1e390897ba Mirror the llvm changes that split Bitcode/ReaderWriter.h
The change in D26502 splits ReaderWriter.h, which contains the APIs
into both the BitReader and BitWriter libraries, into BitcodeReader.h
and BitcodeWriter.h.

Change lld uses to the appropriate split header, removing it
completely in one case where it wasn't needed.

llvm-svn: 286568
2016-11-11 05:35:22 +00:00
Rui Ueyama 1bdaf3e30c Remove an overloaded function to simplify.
This version of addRegular is almost identical to the other except
it lacked "size" parameter.

llvm-svn: 286416
2016-11-09 23:37:40 +00:00
Rafael Espindola e08e78df6d Make OutputSectionBase a class instead of class template.
The disadvantage is that we use uint64_t instad of uint32_t for some
value in 32 bit files. The advantage is a substantially simpler code,
faster builds and less code duplication.

llvm-svn: 286414
2016-11-09 23:23:45 +00:00
Rui Ueyama edc183e437 Simplify getLocation() function.
All tests pass without the first parameter, so I guess we don't need it.

Differential Revision: https://reviews.llvm.org/D26411

llvm-svn: 286287
2016-11-08 20:30:19 +00:00
Rui Ueyama 9c5a69d2ac Rename a function to avoid function overloading. NFC.
llvm-svn: 286282
2016-11-08 20:02:23 +00:00
Eugene Leviant 825e538559 [ELF] Better error reporting for duplicate symbol
Differential revision: https://reviews.llvm.org/D26397

llvm-svn: 286244
2016-11-08 16:26:32 +00:00
Simon Atanasyan 9e0297b8bc [ELF][MIPS] N32 ABI support
In short the patch introduces support for linking object file conform
MIPS N32 ABI [1]. This ABI is similar to N64 ABI but uses 32-bit
pointer size.

The most non-trivial requirement of this ABI is one more relocation
packing format. N64 ABI puts multiple relocation type into the single
relocation record. The N32 ABI uses series of successive relocations
with the same offset for this purpose. In this patch, new function
`mergeMipsN32RelTypes` handle this case and "convert" N32 relocation to
the N64 relocation so the rest of the code keep unchanged.

For now, linker does not support series of relocations applied to sections
without SHF_ALLOC bit. Probably later I will add the support or insert
some sort of assert into the `relocateNonAlloc` routine to catch this
case.

[1] ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/MIPS-N32-ABI-Handbook.pdf

Differential revision: https://reviews.llvm.org/D26298

llvm-svn: 286052
2016-11-05 22:58:01 +00:00
Rui Ueyama f91282e1cf Add [<chars>] to the glob matcher to eliminate use of llvm::Regex.
Previously, it didn't support the character class, so we couldn't
eliminate the use fo llvm::Regex. Now that it is supported, we
can remove compileGlobPattern, which converts a glob pattern to
a regex.

This patch contains optimization for exact/prefix/suffix matches.

Differential Revision: https://reviews.llvm.org/D26284

llvm-svn: 285949
2016-11-03 17:57:38 +00:00
George Rimar bcba39ab9c [ELF] - Check that .dynsym is present in DSO if SHT_GNU_versym section is.
When we have SHT_GNU_versym section, it is should be associated with symbol table
section. Usually (and in out implementation) it is .dynsym.
In case when .dynsym is absent (due to broken object for example), 
lld crashes in parseVerdefs() when accesses null pointer:

Versym = reinterpret_cast<const Elf_Versym *>(this->ELFObj.base() +
                                              VersymSec->sh_offset) +
         this->Symtab->sh_info;

DIfferential revision: https://reviews.llvm.org/D25553

llvm-svn: 285796
2016-11-02 10:16:25 +00:00
Rui Ueyama 55518e7dd8 Consolidate BumpPtrAllocators.
Previously, we have a lot of BumpPtrAllocators, but all these
allocators virtually have the same lifetime because they are
not freed until the linker finishes its job. This patch aggregates
them into a single allocator.

Differential revision: https://reviews.llvm.org/D26042

llvm-svn: 285452
2016-10-28 20:57:25 +00:00
Rafael Espindola 093abab817 Don't create a dummy ELF to process a binary file.
Now that it is easy to create input section and symbols, this is
simple.

llvm-svn: 285322
2016-10-27 17:45:40 +00:00
Rafael Espindola 5ceeb60c6e Have on addRegular forward to another. NFC.
Another step in making it easier to create symbols without an ELf_Sym.

llvm-svn: 285241
2016-10-26 20:57:14 +00:00
Rui Ueyama 8fcc3afdd1 Move a helper function that doesn't depend on a class out of the class.
llvm-svn: 285220
2016-10-26 18:28:08 +00:00
Rui Ueyama 5ce977ccd0 Define a helper function to demangle symbols.
llvm-svn: 285219
2016-10-26 18:28:06 +00:00
Rafael Espindola 5da1d88492 Reduce the number of allocators.
We used to have one allocator per file, which reduces the advantage of
using an allocator in the first place.

This is a small speed up is most cases. The largest speedup was in
1.014X in chromium no-gc. The largest slowdown was scylla at 1.003X.

llvm-svn: 285205
2016-10-26 15:34:24 +00:00
Rafael Espindola 8b2c8536e5 Use a CachedHashString for comdats too.
We were already using it in the larger sets/maps. This provides about
1% speedup in linking xul and chromium.

llvm-svn: 284862
2016-10-21 19:49:42 +00:00
George Rimar a4c7e74d4b [ELF] - Applied clang format. NFC.
llvm-svn: 284705
2016-10-20 08:36:42 +00:00
Justin Lebar 3c11e93831 Use CachedHashStringRef instead of CachedHash<StringRef>.
Summary:
This uses one less word on 64-bit platforms, so should be a strict
improvement.  This change also lets us get rid of llvm::CachedHash.

Reviewers: rafael, timshen

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25646

llvm-svn: 284502
2016-10-18 17:50:36 +00:00
Davide Italiano bcdd6c60a0 [ThinLTO] Avoid archive member collisions.
This fixes PR30665.

Differential Revision:  https://reviews.llvm.org/D25495

llvm-svn: 284034
2016-10-12 19:35:54 +00:00
Rui Ueyama d31e13f287 Rename warning -> warn.
It's better because it's a verb.

llvm-svn: 282763
2016-09-29 21:00:23 +00:00
Davide Italiano 786d8e33db [ELF/LTO] Switch to the new resolution-based API.
Differential Revision:  https://reviews.llvm.org/D24492

llvm-svn: 282656
2016-09-29 00:40:08 +00:00
George Rimar 31c25ae90a Recommit r281318 "[ELF] - Versionscript: support mangled symbols with the same name."
Previouly bot was failing:
http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu/builds/413/steps/test-stage1-compiler/logs/stdio
Fixed possible segfault, so commit should bix the buildbot.

Initial commit message:

This is PR30312. Info from bug page:

Both of these symbols demangle to abc::abc():
_ZN3abcC1Ev
_ZN3abcC2Ev
(These would be abc's complete object constructor and base object constructor, respectively.)
however with "abc::abc()" in the version script only one of the two receives the symbol version.

Patch fixes that.
It uses testcase created by Ed Maste (D24306).

Differential revision: https://reviews.llvm.org/D24336

llvm-svn: 281605
2016-09-15 12:44:38 +00:00
Rui Ueyama 38dbd3eea9 Simplify InputFile ownership management.
Previously, all input files were owned by the symbol table.
Files were created at various places, such as the Driver, the lazy
symbols, or the bitcode compiler, and the ownership of new files
was transferred to the symbol table using std::unique_ptr.
All input files were then free'd when the symbol table is freed
which is on program exit.

I think we don't have to transfer ownership just to free all
instance at once on exit.

In this patch, all instances are automatically collected to a
vector and freed on exit. In this way, we no longer have to
use std::unique_ptr.

Differential Revision: https://reviews.llvm.org/D24493

llvm-svn: 281425
2016-09-14 00:05:51 +00:00
George Rimar 84ba4ae11d revert: [ELF] - Versionscript: support mangled symbols with the same name.
Something broked BBots:
281318 failed on step 9:
http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu/builds/413

r281317 built step 9 green:
http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu/builds/415

Initial revision commits were:
This is PR30312. Info from bug page:

Both of these symbols demangle to abc::abc():
_ZN3abcC1Ev
_ZN3abcC2Ev
(These would be abc's complete object constructor and base object constructor, respectively.)
however with "abc::abc()" in the version script only one of the two receives the symbol version.

Patch fixes that.
It uses testcase created by Ed Maste (D24306).

Differential revision: https://reviews.llvm.org/D24336

llvm-svn: 281411
2016-09-13 22:26:12 +00:00
Rui Ueyama ea26504c19 Split scanVersionScript. NFC.
llvm-svn: 281393
2016-09-13 20:51:30 +00:00
Rui Ueyama fbde710497 Add comments.
llvm-svn: 281388
2016-09-13 20:41:06 +00:00
George Rimar e2051efcbe [ELF] - Versionscript: support mangled symbols with the same name.
This is PR30312. Info from bug page:

Both of these symbols demangle to abc::abc():
_ZN3abcC1Ev
_ZN3abcC2Ev
(These would be abc's complete object constructor and base object constructor, respectively.)
however with "abc::abc()" in the version script only one of the two receives the symbol version.

Patch fixes that.
It uses testcase created by Ed Maste (D24306).

Differential revision: https://reviews.llvm.org/D24336

llvm-svn: 281318
2016-09-13 10:45:39 +00:00
Michael J. Spencer 0cb8a70adc [ELF] Fix memory leak in BinaryFile handling.
llvm-svn: 281129
2016-09-10 01:42:43 +00:00
Michael J. Spencer a9424f39c4 [ELF] Add support for -b binary
Implemented by building an ELF file in memory.

elf, default, and binary match gold behavior.

Differential Revision: https://reviews.llvm.org/D24060

llvm-svn: 281108
2016-09-09 22:08:04 +00:00
George Rimar cd574a5e46 Recommit [ELF] - Versionscript: do not treat non-wildcarded names as wildcards.
Fixed code that was not checked before on windows for me, because of testcases that are
disabled on that platform atm.

Inital commit message:
"[ELF] - Versionscript: do not treat non-wildcarded names as wildcards."
Previously we incorrectly handled cases when symbol name in extern c++ tag
was enclosed in quotes. Next case was treated as wildcard:

GLIBCXX_3.4 {                                                                   
    extern "C++" {  
    "aaa*"
   }
But it should have not. Quotes around aaa here means that we should have do exact
name matching.
That is PR30268 which has name with pointer is interpreted as wildcard by lld:

extern "C++" {                                                              
    "operator delete[](void*)";

Patch fixes the issue.

Differential revision: https://reviews.llvm.org/D24229

llvm-svn: 281049
2016-09-09 14:35:36 +00:00
George Rimar 6368525eea Revert r281045, it broke BB.
Broken BB:
http://lab.llvm.org:8011/builders/lld-x86_64-darwin13/builds/27211

llvm-svn: 281046
2016-09-09 14:16:00 +00:00
George Rimar b5e77c47fb Recommit [ELF] - Versionscript: do not treat non-wildcarded names as wildcards.
Fixed code that was not checked by testcases that are disabled on windows.

Inital commit message:
"[ELF] - Versionscript: do not treat non-wildcarded names as wildcards."
Previously we incorrectly handled cases when symbol name in extern c++ tag
was enclosed in quotes. Next case was treated as wildcard:

GLIBCXX_3.4 {                                                                   
    extern "C++" {  
    "aaa*"
   }
But it should have not. Quotes around aaa here means that we should have do exact
name matching.
That is PR30268 which has name with pointer is interpreted as wildcard by lld:

extern "C++" {                                                              
    "operator delete[](void*)";

Patch fixes the issue.

Differential revision: https://reviews.llvm.org/D24229

llvm-svn: 281045
2016-09-09 13:58:07 +00:00
George Rimar 08b1862caf [ELF] - Revert r281038 to see if that unbreaks build bot.
http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/19703

llvm-svn: 281041
2016-09-09 12:56:55 +00:00
George Rimar d220384376 [ELF] - Versionscript: do not treat non-wildcarded names as wildcards.
Previously we incorrectly handled cases when symbol name in extern c++ tag
was enclosed in quotes. Next case was treated as wildcard:

GLIBCXX_3.4 {                                                                   
    extern "C++" {  
    "aaa*"
   }
But it should have not. Quotes around aaa here means that we should have do exact
name matching.
That is PR30268 which has name with pointer is interpreted as wildcard by lld:

extern "C++" {                                                              
    "operator delete[](void*)";

Patch fixes the issue.

Differential revision: https://reviews.llvm.org/D24229

llvm-svn: 281038
2016-09-09 12:22:28 +00:00
Rafael Espindola 868fc9279e Handle globs in global symbol names.
Fixes pr28775.

llvm-svn: 280947
2016-09-08 14:50:55 +00:00
Rui Ueyama dad2b88c7d Update comments.
llvm-svn: 280548
2016-09-02 22:15:08 +00:00