Commit Graph

170 Commits

Author SHA1 Message Date
Rui Ueyama cac8df1ab9 Re-submit r367649: Improve raw_ostream so that you can "write" colors using operator<<
The original patch broke buildbots, perhaps because it changed the
default setting whether colors are enabled or not.

llvm-svn: 368131
2019-08-07 08:08:17 +00:00
Fangrui Song d9b948b6eb Rename F_{None,Text,Append} to OF_{None,Text,Append}. NFC
F_{None,Text,Append} are kept for compatibility since r334221.

llvm-svn: 367800
2019-08-05 05:43:48 +00:00
Rui Ueyama 4d41c332ef Revert r367649: Improve raw_ostream so that you can "write" colors using operator<<
This reverts commit r367649 in an attempt to unbreak Windows bots.

llvm-svn: 367658
2019-08-02 07:22:34 +00:00
Rui Ueyama a52f982f1c Improve raw_ostream so that you can "write" colors using operator<<
1. raw_ostream supports ANSI colors so that you can write messages to
the termina with colors. Previously, in order to change and reset
color, you had to call `changeColor` and `resetColor` functions,
respectively.

So, if you print out "error: " in red, for example, you had to do
something like this:

  OS.changeColor(raw_ostream::RED);
  OS << "error: ";
  OS.resetColor();

With this patch, you can write the same code as follows:

  OS << raw_ostream::RED << "error: " << raw_ostream::RESET;

2. Add a boolean flag to raw_ostream so that you can disable colored
output. If you disable colors, changeColor, operator<<(Color),
resetColor and other color-related functions have no effect.

Most LLVM tools automatically prints out messages using colors, and
you can disable it by passing a flag such as `--disable-colors`.
This new flag makes it easy to write code that works that way.

Differential Revision: https://reviews.llvm.org/D65564

llvm-svn: 367649
2019-08-02 04:48:30 +00:00
Fangrui Song 2e2038b647 [COFF] Rename variale references in comments after VariableName -> variableName change
llvm-svn: 366193
2019-07-16 08:26:38 +00:00
Rui Ueyama 49a3ad21d6 Fix parameter name comments using clang-tidy. NFC.
This patch applies clang-tidy's bugprone-argument-comment tool
to LLVM, clang and lld source trees. Here is how I created this
patch:

$ git clone https://github.com/llvm/llvm-project.git
$ cd llvm-project
$ mkdir build
$ cd build
$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug \
    -DLLVM_ENABLE_PROJECTS='clang;lld;clang-tools-extra' \
    -DCMAKE_EXPORT_COMPILE_COMMANDS=On -DLLVM_ENABLE_LLD=On \
    -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ../llvm
$ ninja
$ parallel clang-tidy -checks='-*,bugprone-argument-comment' \
    -config='{CheckOptions: [{key: StrictMode, value: 1}]}' -fix \
    ::: ../llvm/lib/**/*.{cpp,h} ../clang/lib/**/*.{cpp,h} ../lld/**/*.{cpp,h}

llvm-svn: 366177
2019-07-16 04:46:31 +00:00
Rui Ueyama 136d27ab4d [Coding style change][lld] Rename variables for non-ELF ports
This patch does the same thing as r365595 to other subdirectories,
which completes the naming style change for the entire lld directory.

With this, the naming style conversion is complete for lld.

Differential Revision: https://reviews.llvm.org/D64473

llvm-svn: 365730
2019-07-11 05:40:30 +00:00
Nico Weber a780276301 lld, llvm-dlltool, llvm-lib: Use getAsString() instead of getSpelling() for printing unknown args
Since OPT_UNKNOWN args never have any values and consist only of
spelling (and are never aliased), this doesn't make any difference in
practice, but it's more consistent with Arg's guidance to use
getAsString() for diagnostics, and it matches what clang does.

Also tweak two tests to use an unknown option that contains '=' for
additional coverage while here. (The new tests pass fine with the old
code too though.)

llvm-svn: 365200
2019-07-05 12:31:32 +00:00
Martin Storsjo b20fefc89b [COFF] Allow setting subsystem versions while inferring the subsystem type implicitly
Differential Revision: https://reviews.llvm.org/D63248

llvm-svn: 363431
2019-06-14 17:50:29 +00:00
Nico Weber af6bc65ddf lld-link: Reject more than one resource .obj file
Users are exepcted to pass all .res files to the linker, which then
merges all the resource in all .res files into a tree structure and then
converts the final tree structure to a .obj file with .rsrc$01 and
.rsrc$02 sections and then links that.

If the user instead passes several .obj files containing such resources,
the correct thing to do would be to have custom code to merge the trees
in the resource sections instead of doing normal section merging -- but
link.exe rejects if multiple resource obj files are passed in with
LNK4078, so let lld-link do that too instead of silently writing broken
.rsrc sections in that case.

The only real way to run into this is if users manually convert .res
files to .obj files by running cvtres and then handing the resulting
.obj files to lld-link instead, which in practice likely never happens.

(lld-link is slightly stricter than link.exe now: If link.exe is passed
one .obj file created by cvtres, and a .res file, for some reason it
just emits a warning instead of an error and outputs strange looking
data. lld-link now errors out on mixed input like this.)

One way users could accidentally run into this is the following
scenario: If a .res file is passed to lib.exe, then lib.exe calls
cvtres.exe on the .res file before putting it in the output .lib.
(llvm-lib currently doesn't do this.)
link.exe's /wholearchive seems to only add obj files referenced from the
static library index, but lld-link current really adds all files in the
archive. So if lld-link /wholearchive is used with .lib files produced
by lib.exe and .res files were among the files handed to lib.exe, we
previously silently produced invalid output, but now we error out.

link.exe's /wholearchive semantics on the other hand mean that it
wouldn't load the resource object files from the .lib file at all.
Since this scenario is probably still an unlikely corner case,
the difference in behavior here seems fine -- and lld-link might have to
change to use link.exe's /wholearchive semantics in the future anyways.

Vaguely related to PR42180.

Differential Revision: https://reviews.llvm.org/D63109

llvm-svn: 363078
2019-06-11 15:22:28 +00:00
Nico Weber dd6019526d Let writeWindowsResourceCOFF() take a TimeStamp parameter
For lld, pass in Config->Timestamp (which is set based on lld's
/timestamp: and /Brepro flags). Since the writeWindowsResourceCOFF()
data is only used in-memory by LLD and the obj's timestamp isn't used
for anything in the output, this doesn't change behavior.

For llvm-cvtres, add an optional /timestamp: parameter, and use the
current behavior of calling time() if the parameter is not passed in.

This doesn't really change observable behavior (unless someone passes
/timestamp: to llvm-cvtres, which wasn't possible before), but it
removes the last unqualified call to time() from llvm/lib, which seems
like a good thing.

Differential Revision: https://reviews.llvm.org/D63116

llvm-svn: 363050
2019-06-11 11:26:50 +00:00
Nico Weber b941fa8821 llvm-lib: Implement /machine: argument
And share some code with lld-link.

While here, also add a FIXME about PR42180 and merge r360150 to llvm-lib.

Differential Revision: https://reviews.llvm.org/D63021

llvm-svn: 363016
2019-06-11 01:13:41 +00:00
Reid Kleckner 53cd7406bb [COFF] Fix /export:foo=bar when bar is a weak alias
Summary:
When handling exports from the command line or from .def files, the
linker does a "fuzzy" string lookup to allow finding mangled symbols.
However, when the symbol is re-exported under a new name, the linker has
to transfer the decorations from the exported symbol over to the new
name. This is implemented by taking the mangled symbol that was found in
the object and replacing the original symbol name with the export name.

Before this patch, LLD implemented the fuzzy search by adding an
undefined symbol with the unmangled name, and then during symbol
resolution, checking if similar mangled symbols had been added after the
last round of symbol resolution. If so, LLD makes the original symbol a
weak alias of the mangled symbol. Later, to get the original symbol
name, LLD would look through the weak alias and forward it on to the
import library writer, which copies the symbol decorations. This
approach doesn't work when bar is itself a weak alias, as is the case in
asan. It's especially bad when the aliasee of bar contains the string
"bar", consider "bar_default". In this case, we would end up exporting
the symbol "foo_default" when we should've exported just "foo".

To fix this, don't look through weak aliases to find the mangled name.
Save the mangled name earlier during fuzzy symbol lookup.

Fixes PR42074

Reviewers: mstorsjo, ruiu

Subscribers: thakis, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62984

llvm-svn: 362849
2019-06-07 22:05:12 +00:00
Nico Weber 9b2830b46e lld-link, clang: Treat non-existent input files as possible spellos for option flags
OptTable treats arguments starting with / that aren't a known option
as filenames. This means lld-link's and clang-cl's typo correction for
unknown flags didn't do spell checking for misspelled options that start
with /.

I first tried changing OptTable, but that got pretty messy, see PR41787
comments 2 and 3.

Instead, let lld-link's and clang's (including clang-cl's) "file not
found" diagnostic check if a non-existent file looks like it could be a
mis-spelled option, and if so add a "did you mean" suggestion to the
"file not found" diagnostic.

While here, make formatting of a few diagnostics a bit more
self-consistent.

Fixes PR41787.

Differential Revision: https://reviews.llvm.org/D62276

llvm-svn: 361518
2019-05-23 17:58:33 +00:00
Nico Weber 54743d5767 Add typo correction for command-line flags to ELF and COFF lld drivers
For lld-link, unknown '/'-style flags are treated as filenames on POSIX
systems, so only '-'-style flags get typo correction for now. This
matches clang-cl.

PR37006.

Differential Revision: https://reviews.llvm.org/D61443

llvm-svn: 360145
2019-05-07 13:48:30 +00:00
Nico Weber 81862f82ee lld-link: Add /force:multipleres extension to make dupe resource diag non-fatal
As a side benefit, lld-link now reports more than one duplicate resource
entry before exiting with an error even if the new flag is not passed.

llvm-svn: 359829
2019-05-02 21:21:55 +00:00
Nico Weber 413517ecfe lld-link: Make "duplicate resource" error message a bit more concise
Reduces the error message from:
    lld-link: error: failed to parse .res file: duplicate resource: type STRINGTABLE (ID 6)/name ID 3/language 1033, in test1.res and in test2.res

To:
    lld-link: error: duplicate resource: type STRINGTABLE (ID 6)/name ID 3/language 1033, in test1.res and in test2.res

Make sure every error message emitted by cvtres contains the name of at
least one ".res" file, so that removing the "failed to parse .res file"
string doesn't lose information.

Differential Revision: https://reviews.llvm.org/D61388

llvm-svn: 359749
2019-05-02 01:52:24 +00:00
Nico Weber c0838af754 lld-link: Implement /swaprun: flag
r191276 added this to old LLD, but it never made it to new LLD -- except
that the flag was in Options.td, so it was silently ignored. I figured
it should be easy to implement, so I did that instead of removing the
flags from Options.td.

I then discovered that link.exe also supports comma-separated lists of
'cd' and 'net', which made the parsing code a bit annoying.

The Alias technique in Options.td is to get nice help output.

Differential Revision: https://reviews.llvm.org/D61067

llvm-svn: 359192
2019-04-25 14:02:26 +00:00
Alexandre Ganea 347a45ccd5 [LLD][COFF] Improve checkFailIfMismatch()
As suggested by ruiu here (https://reviews.llvm.org/D58910#1425484), defer a call to toString(File) until it's really needed (if there's an error)

Differential Revision: https://reviews.llvm.org/D59411

llvm-svn: 357305
2019-03-29 19:58:58 +00:00
Alexandre Ganea d8ec81059e [LLD][COFF] More detailed information for /failifmismatch
When mismatched #pragma detect_mismatch declarations occur, now print the conflicting OBJs.

  lld-link: error: /failifmismatch: mismatch detected for 'TEST':
  >>> test.obj has value 1
  >>> test2.obj has value 2

Fixes PR38579

Differential Revision: https://reviews.llvm.org/D58910

llvm-svn: 355543
2019-03-06 20:18:38 +00:00
Alexandre Ganea d307c4c47f [LLD][COFF] Add support for /FUNCTIONPADMIN command-line option
Initial patch by Stefan Reinalter.

Fixes PR36775

Differential Revision: https://reviews.llvm.org/D49366

llvm-svn: 354716
2019-02-23 01:46:18 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Fangrui Song a535e0543f Eliminate dependency to formatv(). NFC.
llvm-svn: 344212
2018-10-11 00:58:00 +00:00
Fangrui Song 2043a58abe Adapt OptTable::PrintHelp change in D51009
Summary: Before, OptTable::PrintHelp append "[options] <inputs>" to its parameter `Help`. It is more flexible to change its semantic to `Usage` and let user customize the usage line.

Reviewers: rupprecht, ruiu, espindola

Reviewed By: rupprecht

Subscribers: emaste, sbc100, arichardson, aheejin, llvm-commits

Differential Revision: https://reviews.llvm.org/D53054

llvm-svn: 344099
2018-10-10 00:15:36 +00:00
Nico Weber 11f14904d3 lld-link: Remove /msvclto option
This was useful for LTO bringup in lld-link while lld couldn't write PDBs. Now
that it can, this should no longer be needed. Hopefully the flag is obscure
enough and recent enough, that nobody uses it – but if somebody should use it,
they should be able to just stop passing it and things should continue to work.

https://reviews.llvm.org/D50139

llvm-svn: 338615
2018-08-01 19:00:49 +00:00
Reid Kleckner 276d7167d0 [PDB] Write the command line after response file expansion
Summary: Fixes PR38085

Reviewers: ruiu, zturner

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49566

llvm-svn: 337628
2018-07-20 22:34:20 +00:00
Nico Weber c421fe5ef4 lld-link: Add /lib to Options.td so that it appears in lld-link's help output.
https://reviews.llvm.org/D49319

llvm-svn: 337086
2018-07-14 04:07:51 +00:00
Zachary Turner 08426e1f9f Refactor ExecuteAndWait to take StringRefs.
This simplifies some code which had StringRefs to begin with, and
makes other code more complicated which had const char* to begin
with.

In the end, I think this makes for a more idiomatic and platform
agnostic API.  Not all platforms launch process with null terminated
c-string arrays for the environment pointer and argv, but the api
was designed that way because it allowed easy pass-through for
posix-based platforms.  There's a little additional overhead now
since on posix based platforms we'll be takign StringRefs which
were constructed from null terminated strings and then copying
them to null terminate them again, but from a readability and
usability standpoint of the API user, I think this API signature
is strictly better.

llvm-svn: 334518
2018-06-12 17:43:52 +00:00
Nico Weber cac2b3349e lld-link: Add --color-diagnostics(={always,never,auto})?, --no-color-diagnostics flags.
This is most useful when using lld-link on a non-Win host (but it might become
useful on Windows too if lld also grows a fansi-escape-codes flag).

Also make the help for --color-diagnostic mention the valid values in ELF and
wasm, and print the flag name with two dashes in diags, since the one-dash form
is seen as a list of many one-letter flags in some contexts.

https://reviews.llvm.org/D46693

llvm-svn: 332012
2018-05-10 18:19:02 +00:00
Peter Collingbourne 4902508934 COFF: Process /merge flag as we create output sections.
With this we can merge builtin sections.

Differential Revision: https://reviews.llvm.org/D45350

llvm-svn: 329471
2018-04-07 00:46:55 +00:00
Martin Storsjo 5351891b55 [COFF] Add support for the GNU ld flag --kill-at
GNU ld has got a number of different flags for adjusting how to
behave around stdcall functions. The --kill-at flag strips the
trailing sdcall suffix from exported functions (which otherwise
is included by default in MinGW setups).

This also strips it from the corresponding import library though.
That makes it hard to link to such an import library from code
that calls the functions - but this matches what GNU ld does with
this flag. Therefore, this flag is probably not sensibly used
together with import libraries, but probably mostly when creating
some sort of plugin, or if creating the import library separately
with dlltool.

Differential Revision: https://reviews.llvm.org/D44292

llvm-svn: 327561
2018-03-14 20:17:16 +00:00
Nico Weber f06ae4f3b4 Make lld-link shout at me less.
This makes the output of some flag names in warning messages consistent with
the output of /? and the output of flags in most other diagnostics.

https://reviews.llvm.org/D44307

llvm-svn: 327261
2018-03-12 12:45:40 +00:00
Reid Kleckner fd52096259 [LLD] Implement /guard:[no]longjmp
Summary:
This protects calls to longjmp from transferring control to arbitrary
program points. Instead, longjmp calls are limited to the set of
registered setjmp return addresses.

This also implements /guard:nolongjmp to allow users to link in object
files that call setjmp that weren't compiled with /guard:cf. In this
case, the linker will approximate the set of address taken functions,
but it will leave longjmp unprotected.

I used the following program to test, compiling it with different -guard
flags:
  $ cl -c t.c -guard:cf
  $ lld-link t.obj -guard:cf

  #include <setjmp.h>
  #include <stdio.h>
  jmp_buf buf;
  void g() {
    printf("before longjmp\n");
    fflush(stdout);
    longjmp(buf, 1);
  }
  void f() {
    if (setjmp(buf)) {
      printf("setjmp returned non-zero\n");
      return;
    }
    g();
  }
  int main() {
    f();
    printf("hello world\n");
  }

In particular, the program aborts when the code is compiled *without*
-guard:cf and linked with -guard:cf. That indicates that longjmps are
protected.

Reviewers: ruiu, inglorion, amccarth

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D43217

llvm-svn: 325047
2018-02-13 20:32:53 +00:00
Reid Kleckner af2f7da74c [COFF] Add minimal support for /guard:cf
Summary:
This patch adds some initial support for Windows control flow guard. At
the end of the day, the linker needs to synthesize a table of RVAs very
similar to the structured exception handler table (/safeseh).

Both /safeseh and /guard:cf take sections of symbol table indices
(.sxdata and .gfids$y) and turn them into RVA tables referenced by the
load config struct in the CRT through special symbols.

Reviewers: ruiu, amccarth

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D42592

llvm-svn: 324306
2018-02-06 01:58:26 +00:00
Martin Storsjo 3b611fa93f [COFF] Keep the underscore on exported decorated stdcall functions in MSVC mode
This fixes PR35733.

Differential Revision: https://reviews.llvm.org/D41632

llvm-svn: 323036
2018-01-20 11:44:42 +00:00
Pavel Labath a006baa620 Attempt to fix FreeBSD build broken by the previous commit
The compiler could not find the conversion from
unique_ptr<WritableMemoryBuffer> to unique_ptr<MemoryBuffer>. This will
hopefully help it along.

llvm-svn: 322365
2018-01-12 10:09:10 +00:00
Pavel Labath 1c1e24ad96 [lld/COFF] Use WritableMemoryBuffer for creating the manifest
This avoids the need for const_casting the memory buffer contents in
order to write to it.

NFCI.

llvm-svn: 322363
2018-01-12 09:48:41 +00:00
Rui Ueyama 5fa0d6e4a2 [COFF] Process /EXPORT option in fastpath
Patch by Takuto Ikuta.

This patch reduces lld link time of chromium's blink_core.dll in
component build.

Total size of input argument in .directives become nearly 300MB in the
build and almost all its content are /EXPORT.

To reduce time of parsing too many /EXPORT option in the build, I
introduce fastpath for /EXPORT in ArgParser::parseDirectives.

On my desktop machine, 4 times stats of the link time are like below.
Improved around 20%.

This patch
TotalSeconds : 8.6217627
TotalSeconds : 8.5402175
TotalSeconds : 8.6855853
TotalSeconds : 8.3624441
Ave : 8.5525024

master
TotalSeconds : 10.9975031
TotalSeconds : 11.3409428
TotalSeconds : 10.6332897
TotalSeconds : 10.7650687
Ave : 10.934201075

llvm-svn: 322117
2018-01-09 20:36:42 +00:00
Rui Ueyama 130eb04689 [COFF] Do not parse args twice if no rsp files exists
Patch by Takuto Ikuta.

This patch reduces link time of chromium's blink_core.dll in component
build. Total size of input argument in .directives become nearly 300MB
in the build and no rsp file is used. Speedup link by skipping duplicate
parsing.

On my desktop machine, 4 times stats are like below. Improved around 15%.

This patch
TotalSeconds : 18.408538
TotalSeconds : 17.2996744
TotalSeconds : 17.1053862
TotalSeconds : 17.809777
avg: 17.6558439

master
TotalSeconds : 20.9290504
TotalSeconds : 19.9158213
TotalSeconds : 21.0643515
TotalSeconds : 20.8775831
avg: 20.696701575

Differential Revision: https://reviews.llvm.org/D41581

llvm-svn: 321470
2017-12-27 06:08:10 +00:00
Rui Ueyama 6074e6b094 Remove redundant local variables.
llvm-svn: 320436
2017-12-11 23:19:11 +00:00
Sam Clegg 0fb6faa0be Prefer `ArrayRef` over `const std::vector&`
Differential Revision: https://reviews.llvm.org/D40993

llvm-svn: 320125
2017-12-08 01:09:21 +00:00
Rui Ueyama bdc5150984 Always evaluate the second argument for CHECK() lazily.
This patch is to rename check CHECK and make it a C macro, so that
we can evaluate the second argument lazily.

Differential Revision: https://reviews.llvm.org/D40915

llvm-svn: 319974
2017-12-06 22:08:17 +00:00
Rui Ueyama 2017d52b54 Move Memory.{h,cpp} to Common.
Differential Revision: https://reviews.llvm.org/D40571

llvm-svn: 319221
2017-11-28 20:39:17 +00:00
Reid Kleckner 8320a1753f Use DenseMap instead of std::map in fixupExports
Some DLLs have many exports, and this data structure shows up in the
profile of linking content.dll.

llvm-svn: 317910
2017-11-10 19:12:01 +00:00
Rui Ueyama f52496e1e0 Rename SymbolBody -> Symbol
Now that we have only SymbolBody as the symbol class. So, "SymbolBody"
is a bit strange name now. This is a mechanical change generated by

  perl -i -pe s/SymbolBody/Symbol/g $(git grep -l SymbolBody lld/ELF lld/COFF)

nd clang-format-diff.

Differential Revision: https://reviews.llvm.org/D39459

llvm-svn: 317370
2017-11-03 21:21:47 +00:00
Bob Haarman b8a59c8aa5 [lld] unified COFF and ELF error handling on new Common/ErrorHandler
Summary:
The COFF linker and the ELF linker have long had similar but separate
Error.h and Error.cpp files to implement error handling. This change
introduces new error handling code in Common/ErrorHandler.h, changes the
COFF and ELF linkers to use it, and removes the old, separate
implementations.

Reviewers: ruiu

Reviewed By: ruiu

Subscribers: smeenai, jyknight, emaste, sdardis, nemanjai, nhaehnle, mgorny, javed.absar, kbarton, fedor.sergeev, llvm-commits

Differential Revision: https://reviews.llvm.org/D39259

llvm-svn: 316624
2017-10-25 22:28:38 +00:00
Shoaib Meenai b57e640f3a [COFF] Add support for /WX
link.exe supports this option to convert warnings into errors, and it's
useful to support in LLD as well.

Differential Revision: https://reviews.llvm.org/D39148

llvm-svn: 316502
2017-10-24 21:19:22 +00:00
Peter Collingbourne 9362ac60bc COFF: Add resource files to linkrepro instead of the cvtres object file.
Now that we have our own implementation of cvtres, we can add resource
files directly to the linkrepro.

Differential Revision: https://reviews.llvm.org/D38974

llvm-svn: 315954
2017-10-16 23:15:04 +00:00
Peter Collingbourne ccd43758ad COFF: Give manifest resource file a name.
Without this, /linkrepro would create an invalid tar file.

No tests because this requires Windows and the linkrepro tests
require not-Windows.

Differential Revision: https://reviews.llvm.org/D38973

llvm-svn: 315948
2017-10-16 22:37:56 +00:00
Eric Beckmann 0aa4b7d4c5 Fix crbug 759265 by suppressing llvm mt warnings.
Summary:
Previous would throw warning whenever libxml2 is not installed.  Now
only give this warning if merging manifest fails.

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D37240

llvm-svn: 312604
2017-09-06 01:50:36 +00:00