Commit Graph

42 Commits

Author SHA1 Message Date
Raphael Isemann 808142876c [lldb][NFC] Fix all formatting errors in .cpp file headers
Summary:
A *.cpp file header in LLDB (and in LLDB) should like this:
```
//===-- TestUtilities.cpp -------------------------------------------------===//
```
However in LLDB most of our source files have arbitrary changes to this format and
these changes are spreading through LLDB as folks usually just use the existing
source files as templates for their new files (most notably the unnecessary
editor language indicator `-*- C++ -*-` is spreading and in every review
someone is pointing out that this is wrong, resulting in people pointing out that this
is done in the same way in other files).

This patch removes most of these inconsistencies including the editor language indicators,
all the different missing/additional '-' characters, files that center the file name, missing
trailing `===//` (mostly caused by clang-format breaking the line).

Reviewers: aprantl, espindola, jfb, shafik, JDevlieghere

Reviewed By: JDevlieghere

Subscribers: dexonsmith, wuzish, emaste, sdardis, nemanjai, kbarton, MaskRay, atanasyan, arphaman, jfb, abidh, jsji, JDevlieghere, usaxena95, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D73258
2020-01-24 08:52:55 +01:00
Jason Molenda 7dd7a36075 Add arm64_32 support to lldb, an ILP32 codegen
that runs on arm64 ISA targets, specifically 
Apple watches.


Differential Revision: https://reviews.llvm.org/D68858

llvm-svn: 375032
2019-10-16 19:14:49 +00:00
Jonas Devlieghere 63e5fb76ec [Logging] Replace Log::Printf with LLDB_LOG macro (NFC)
This patch replaces explicit calls to log::Printf with the new LLDB_LOGF
macro. The macro is similar to LLDB_LOG but supports printf-style format
strings, instead of formatv-style format strings.

So instead of writing:

  if (log)
    log->Printf("%s\n", str);

You'd write:

  LLDB_LOG(log, "%s\n", str);

This change was done mechanically with the command below. I replaced the
spurious if-checks with vim, since I know how to do multi-line
replacements with it.

  find . -type f -name '*.cpp' -exec \
  sed -i '' -E 's/log->Printf\(/LLDB_LOGF\(log, /g' "{}" +

Differential revision: https://reviews.llvm.org/D65128

llvm-svn: 366936
2019-07-24 17:56:10 +00:00
Joseph Tremoulet 3fd917d886 Support Linux signal return trampolines in frame initialization
Summary:
Add __kernel_rt_sigreturn to the list of trap handlers for Linux (it's
used as such on aarch64 at least), and __restore_rt as well (used on
x86_64).

Skip decrement-and-recompute for trap handlers in
InitializeNonZerothFrame, as signal dispatch may point the child frame's
return address to the start of the return trampoline.

Parse the 'S' flag for signal handlers from eh_frame augmentation, and
propagate it to the unwind plan.

Reviewers: labath, jankratochvil, compnerd, jfb, jasonmolenda

Reviewed By: jasonmolenda

Subscribers: clayborg, MaskRay, wuzish, nemanjai, kbarton, jrtc27, atanasyan, jsji, javed.absar, kristof.beyls, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D63667

llvm-svn: 366580
2019-07-19 14:05:55 +00:00
Konrad Kleine 248a13057a [lldb] NFC modernize codebase with modernize-use-nullptr
Summary:
NFC = [[ https://llvm.org/docs/Lexicon.html#nfc | Non functional change ]]

This commit is the result of modernizing the LLDB codebase by using
`nullptr` instread of `0` or `NULL`. See
https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-nullptr.html
for more information.

This is the command I ran and I to fix and format the code base:

```
run-clang-tidy.py \
	-header-filter='.*' \
	-checks='-*,modernize-use-nullptr' \
	-fix ~/dev/llvm-project/lldb/.* \
	-format \
	-style LLVM \
	-p ~/llvm-builds/debug-ninja-gcc
```

NOTE: There were also changes to `llvm/utils/unittest` but I did not
include them because I felt that maybe this library shall be updated in
isolation somehow.

NOTE: I know this is a rather large commit but it is a nobrainer in most
parts.

Reviewers: martong, espindola, shafik, #lldb, JDevlieghere

Reviewed By: JDevlieghere

Subscribers: arsenm, jvesely, nhaehnle, hiraditya, JDevlieghere, teemperor, rnkovacs, emaste, kubamracek, nemanjai, ki.stfu, javed.absar, arichardson, kbarton, jrtc27, MaskRay, atanasyan, dexonsmith, arphaman, jfb, jsji, jdoerfert, lldb-commits, llvm-commits

Tags: #lldb, #llvm

Differential Revision: https://reviews.llvm.org/D61847

llvm-svn: 361484
2019-05-23 11:14:47 +00:00
Jonas Devlieghere 8b3af63b89 [NFC] Remove ASCII lines from comments
A lot of comments in LLDB are surrounded by an ASCII line to delimit the
begging and end of the comment.

Its use is not really consistent across the code base, sometimes the
lines are longer, sometimes they are shorter and sometimes they are
omitted. Furthermore, it looks kind of weird with the 80 column limit,
where the comment actually extends past the line, but not by much.
Furthermore, when /// is used for Doxygen comments, it looks
particularly odd. And when // is used, it incorrectly gives the
impression that it's actually a Doxygen comment.

I assume these lines were added to improve distinguishing between
comments and code. However, given that todays editors and IDEs do a
great job at highlighting comments, I think it's worth to drop this for
the sake of consistency. The alternative is fixing all the
inconsistencies, which would create a lot more churn.

Differential revision: https://reviews.llvm.org/D60508

llvm-svn: 358135
2019-04-10 20:48:55 +00:00
Jonas Devlieghere 796ac80b86 Use std::make_shared in LLDB (NFC)
Unlike std::make_unique, which is only available since C++14,
std::make_shared is available since C++11. Not only is std::make_shared
a lot more readable compared to ::reset(new), it also performs a single
heap allocation for the object and control block.

Differential revision: https://reviews.llvm.org/D57990

llvm-svn: 353764
2019-02-11 23:13:08 +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
Pavel Labath f760f5aef4 Simplify ObjectFile::GetArchitecture
Summary:
instead of returning the architecture through by-ref argument and a
boolean value indicating success, we can just return the ArchSpec
directly. Since the ArchSpec already has an invalid state, it can be
used to denote the failure without the additional bool.

Reviewers: clayborg, zturner, espindola

Subscribers: emaste, arichardson, JDevlieghere, lldb-commits

Differential Revision: https://reviews.llvm.org/D56129

llvm-svn: 350291
2019-01-03 10:37:19 +00:00
Jonas Devlieghere a6682a413d Simplify Boolean expressions
This patch simplifies boolean expressions acorss LLDB. It was generated
using clang-tidy with the following command:

run-clang-tidy.py -checks='-*,readability-simplify-boolean-expr' -format -fix $PWD

Differential revision: https://reviews.llvm.org/D55584

llvm-svn: 349215
2018-12-15 00:15:33 +00:00
Pavel Labath d1e3fe2190 Rename ObjectFile::GetHeaderAddress to GetBaseAddress
Summary:
This function was named such because in the case of MachO files, the
mach header is located at this address. However all (most?) usages of
this function were not interested in that fact, but the fact that this
address is used as the base address for expressing various relative
addresses in the object file.

For other object file formats, this name is not appropriate (and it's
probably the reason why this function was not implemented in these
classes). In the ELF case the ELF header will usually end up at this
address, but this is a result of the linker optimizing the file layout
and not a requirement of the spec. For COFF files, I believe the is no
header located at this address either.

Reviewers: clayborg, jasonmolenda, amccarth, lemo, stella.stamenova

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D55422

llvm-svn: 348849
2018-12-11 15:21:15 +00:00
Adrian Prantl 05097246f3 Reflow paragraphs in comments.
This is intended as a clean up after the big clang-format commit
(r280751), which unfortunately resulted in many of the comment
paragraphs in LLDB being very hard to read.

FYI, the script I used was:

import textwrap
import commands
import os
import sys
import re
tmp = "%s.tmp"%sys.argv[1]
out = open(tmp, "w+")
with open(sys.argv[1], "r") as f:
  header = ""
  text = ""
  comment = re.compile(r'^( *//) ([^ ].*)$')
  special = re.compile(r'^((([A-Z]+[: ])|([0-9]+ )).*)|(.*;)$')
  for line in f:
      match = comment.match(line)
      if match and not special.match(match.group(2)):
          # skip intentionally short comments.
          if not text and len(match.group(2)) < 40:
              out.write(line)
              continue

          if text:
              text += " " + match.group(2)
          else:
              header = match.group(1)
              text = match.group(2)

          continue

      if text:
          filled = textwrap.wrap(text, width=(78-len(header)),
                                 break_long_words=False)
          for l in filled:
              out.write(header+" "+l+'\n')
              text = ""

      out.write(line)

os.rename(tmp, sys.argv[1])

Differential Revision: https://reviews.llvm.org/D46144

llvm-svn: 331197
2018-04-30 16:49:04 +00:00
Pavel Labath 5f19b90783 Move ArchSpec to the Utility module
The rationale here is that ArchSpec is used throughout the codebase,
including in places which should not depend on the rest of the code in
the Core module.

This commit touches many files, but most of it is just renaming of
 #include lines. In a couple of cases, I removed the #include ArchSpec
line altogether, as the file was not using it. In one or two places,
this necessitated adding other #includes like lldb-private-defines.h.

llvm-svn: 318048
2017-11-13 16:16:33 +00:00
Zachary Turner 97206d5727 Rename Error -> Status.
This renames the LLDB error class to Status, as discussed
on the lldb-dev mailing list.

A change of this magnitude cannot easily be done without
find and replace, but that has potential to catch unwanted
occurrences of common strings such as "Error".  Every effort
was made to find all the obvious things such as the word "Error"
appearing in a string, etc, but it's possible there are still
some lingering occurences left around.  Hopefully nothing too
serious.

llvm-svn: 302872
2017-05-12 04:51:55 +00:00
Zachary Turner 666cc0b291 Move DataBuffer / DataExtractor and friends from Core -> Utility.
llvm-svn: 296943
2017-03-04 01:30:05 +00:00
Zachary Turner 6f9e690199 Move Log from Core -> Utility.
All references to Host and Core have been removed, so this
class can now safely be lowered into Utility.

Differential Revision: https://reviews.llvm.org/D30559

llvm-svn: 296909
2017-03-03 20:56:28 +00:00
Zachary Turner bf9a77305f Move classes from Core -> Utility.
This moves the following classes from Core -> Utility.

ConstString
Error
RegularExpression
Stream
StreamString

The goal here is to get lldbUtility into a state where it has
no dependendencies except on itself and LLVM, so it can be the
starting point at which to start untangling LLDB's dependencies.
These are all low level and very widely used classes, and
previously lldbUtility had dependencies up to lldbCore in order
to use these classes.  So moving then down to lldbUtility makes
sense from both the short term and long term perspective in
solving this problem.

Differential Revision: https://reviews.llvm.org/D29427

llvm-svn: 293941
2017-02-02 21:39:50 +00:00
Kate Stone b9c1b51e45 *** This commit represents a complete reformatting of the LLDB source code
*** to conform to clang-format’s LLVM style.  This kind of mass change has
*** two obvious implications:

Firstly, merging this particular commit into a downstream fork may be a huge
effort.  Alternatively, it may be worth merging all changes up to this commit,
performing the same reformatting operation locally, and then discarding the
merge for this particular commit.  The commands used to accomplish this
reformatting were as follows (with current working directory as the root of
the repository):

    find . \( -iname "*.c" -or -iname "*.cpp" -or -iname "*.h" -or -iname "*.mm" \) -exec clang-format -i {} +
    find . -iname "*.py" -exec autopep8 --in-place --aggressive --aggressive {} + ;

The version of clang-format used was 3.9.0, and autopep8 was 1.2.4.

Secondly, “blame” style tools will generally point to this commit instead of
a meaningful prior commit.  There are alternatives available that will attempt
to look through this change and find the appropriate prior commit.  YMMV.

llvm-svn: 280751
2016-09-06 20:57:50 +00:00
Jason Molenda c7afda5a09 Add support for using armv7 compact unwind information
as an asynchronous unwind plan source.

Two small fixes to the compact unwind dumper tool for
armv7 encodings.

A change to DWARFCallFrameInfo to strip the 0th bit on
addresses in eh_frame sections when armv7.  In the 
clang generated examples I have, the 0th bit is set for
thumb functions and that's causing the unwinder to pick
the wrong function for eh_frame info.

llvm-svn: 271970
2016-06-07 02:19:54 +00:00
Jason Molenda b667c20222 Add support for arm64 compact unwind tables, used on darwin arm64
systems (ios, tvos, watchos).  It's a simple format to use now that
I have i386/x86_64 supported already.

The unwind instructions are only valid at call sites -- that is,
when lldb is unwinding a frame in the middle of the stack.  It
cannot be used for the currently executing frame; it has no information
about prologues/epilogues/etc.

<rdar://problem/12062336> 

llvm-svn: 270658
2016-05-25 04:20:28 +00:00
Saleem Abdulrasool bb19a13c0b second pass over removal of Mutex and Condition
llvm-svn: 270024
2016-05-19 05:13:57 +00:00
Jason Molenda 63bd0db071 Clean up register naming conventions inside lldb.
"gcc" register numbers are now correctly referred to as "ehframe"
register numbers.  In almost all cases, ehframe and dwarf register
numbers are identical (the one exception is i386 darwin where ehframe
regnums were incorrect).

The old "gdb" register numbers, which I incorrectly thought were
stabs register numbers, are now referred to as "Process Plugin"
register numbers.  This is the register numbering scheme that the
remote process controller stub (lldb-server, gdbserver, core file
support, kdp server, remote jtag devices, etc) uses to refer to the
registers.  The process plugin register numbers may not be contiguous
- there are remote jtag devices that have gaps in their register
numbering schemes.

I removed all of the enums for "gdb" register numbers that we had
in lldb - these were meaningless - and I put LLDB_INVALID_REGNUM
in all of the register tables for the Process Plugin regnum slot.

This change is almost entirely mechnical; the one actual change in
here is to ProcessGDBRemote.cpp's ParseRegisters() which parses the
qXfer:features:read:target.xml response.  As it parses register
definitions from the xml, it will assign sequential numbers as the
eRegisterKindLLDB numbers (the lldb register numberings must be
sequential, without any gaps) and if the xml file specifies register
numbers, those will be used as the eRegisterKindProcessPlugin
register numbers (and those may have gaps).  A J-Link jtag device's
target.xml does contain a gap in register numbers, and it only 
specifies the register numbers for the registers after that gap.
The device supports many different ARM boards and probably selects
different part of its register file as appropriate.

http://reviews.llvm.org/D12791
<rdar://problem/22623262> 

llvm-svn: 247741
2015-09-15 23:20:34 +00:00
Jason Molenda a18f7071c2 A messy bit of cleanup: Move towards more descriptive names
for eh_frame and stabs register numberings.  This is not
complete but it's a step in the right direction.  It's almost
entirely mechanical.

lldb informally uses "gcc register numbering" to mean eh_frame.
Why?  Probably because there's a notorious bug with gcc on i386
darwin where the register numbers in eh_frame were incorrect.
In all other cases, eh_frame register numbering is identical to
dwarf.

lldb informally uses "gdb register numbering" to mean stabs.
There are no official definitions of stabs register numbers
for different architectures, so the implementations of gdb
and gcc are the de facto reference source.

There were some incorrect uses of these register number types
in lldb already.  I fixed the ones that I saw as I made
this change.

This commit changes all references to "gcc" and "gdb" register
numbers in lldb to "eh_frame" and "stabs" to make it clear 
what is actually being represented.

lldb cannot parse the stabs debug format, and given that no
one is using stabs any more, it is unlikely that it ever will.
A more comprehensive cleanup would remove the stabs register
numbers altogether - it's unnecessary cruft / complication to
all of our register structures.

In ProcessGDBRemote, when we get register definitions from
the gdb-remote stub, we expect to see "gcc:" (qRegisterInfo)
or "gcc_regnum" (qXfer:features:read: packet to get xml payload).
This patch changes ProcessGDBRemote to also accept "ehframe:"
and "ehframe_regnum" from these remotes.

I did not change GDBRemoteCommunicationServerLLGS or debugserver
to send these new packets.  I don't know what kind of interoperability
constraints we might be working under.  At some point in the future
we should transition to using the more descriptive names.

Throughout lldb we're still using enum names like "gcc_r0" and "gdb_r0",
for eh_frame and stabs register numberings.  These should be cleaned
up eventually too.

The sources link cleanly on macosx native with xcode build.  I
don't think we'll see problems on other platforms but please let
me know if I broke anyone.

llvm-svn: 245141
2015-08-15 01:21:01 +00:00
Bruce Mitchener e171da5cb7 Fix typos.
Summary: Fix a bunch of typos.

Reviewers: clayborg

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D11386

llvm-svn: 242856
2015-07-22 00:16:02 +00:00
Jason Molenda d99bb0a7ad Update comment about the UNWIND_X86_64_MODE_STACK_IND encoding
bug in old clang's.

llvm-svn: 240070
2015-06-18 22:16:10 +00:00
Jason Molenda 114fb91217 Correct the end-of-vector check in GetCompactUnwindInfoForFunction().
Problem noticed by Todd Fiala.

llvm-svn: 240060
2015-06-18 21:15:58 +00:00
Vince Harron d7e6a4f2f0 Fixed a ton of gcc compile warnings
Removed some unused variables, added some consts, changed some casts
to const_cast. I don't think any of these changes are very
controversial.

Differential Revision: http://reviews.llvm.org/D9674

llvm-svn: 237218
2015-05-13 00:25:54 +00:00
Jason Molenda 9060e987a0 Fix an uninitialized memory use error when interpreting
compact unwind encodings for x86_64 / i386 omit-frame-pointer
code.  It was possible for lldb to get the location of saved
registers incorrect for some of these functions.
<rdar://problem/20753264> 

llvm-svn: 236478
2015-05-05 02:05:53 +00:00
Zachary Turner 48b475cbaa Fix warnings generated by clang-cl.
There were a couple of real bugs here regarding error checking and
signed/unsigned comparisons, but mostly these were just noise.

There was one class of bugs fixed here which is particularly
annoying, dealing with MSVC's non-standard behavior regarding
the underlying type of enums.  See the comment in
lldb-enumerations.h for details.  In short, from now on please use
FLAGS_ENUM and FLAGS_ANONYMOUS_ENUM when defining enums which
contain values larger than can fit into a signed integer.

llvm-svn: 233943
2015-04-02 20:57:38 +00:00
Jason Molenda c48ef341e1 Add a tiny bit of hardening to the eh_frame and compact unwind parsing.
When we're seeing offsets that exceed the size of our section, don't 
try to use that unwind info.
<rdar://problem/20113673> 

llvm-svn: 233886
2015-04-02 04:35:32 +00:00
Zachary Turner af0f45f1c9 Don't #include ClangPersistentVariables.h from Process.h
Nothing from this header file was even being referenced in
Process.h anyway, so it was a completely unnecessary include.

llvm-svn: 231131
2015-03-03 21:05:17 +00:00
Pavel Labath ab970f5e08 UnwindPlan::Row refactor -- add support for CFA set by a DWARF expression
Summary:
This change refactors UnwindPlan::Row to be able to store the fact that the CFA is value is set
by evaluating a dwarf expression (DW_CFA_def_cfa_expression). This is achieved by creating a new
class CFAValue and moving all CFA setting/getting code there. Note that code using the new
CFAValue::isDWARFExpression is not yet present and will be added in a follow-up patch. Therefore,
this patch should not change the functionality in any way.

Test Plan: Ran tests on Mac and Linux. No regressions detected.

Reviewers: jasonmolenda, clayborg

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D7755

llvm-svn: 230210
2015-02-23 10:19:16 +00:00
Benjamin Kramer 2ea1961629 Update after LLVM API change.
llvm-svn: 228933
2015-02-12 16:16:56 +00:00
Jason Molenda f16dbb8b07 debug printfs that got left in. I blame greg.
llvm-svn: 226892
2015-01-23 01:34:19 +00:00
Jason Molenda 8122bb0e19 Two fixes for compact unwind decoding for frameless large-stack-size
i386/x86_64 functions.  The stack size was being multiplied by the
pointer size incorrectly.  The register permutation placeholders
(UNWIND_X86_REG_NONE) were decrementing the stack offset of the
saved registers when it should not have been.

<rdar://problem/19570035> 

llvm-svn: 226889
2015-01-23 01:02:32 +00:00
Andy Gibbs 3acfe1a3d9 Fix trivial signed/unsigned comparison warnings
llvm-svn: 224932
2014-12-29 13:03:19 +00:00
Jason Molenda 19ba9fbf27 Add support for frameless function compact unwind encodings on x86_64/i386.
This completes the compact unwind support for x86 targets.  

I'm still skipping the UNWIND_X86_64_MODE_STACK_IND encodings for
x86_64 right now because clang was emitting bad data for this form
until it was fixed in r217020 circa Sep 2014.

arm64 parsing still needs to be added.

llvm-svn: 224698
2014-12-22 11:02:02 +00:00
Jason Molenda 5c45c541a2 Various unwinder work.
Most of the changes are to the FuncUnwinders class -- as we've added
more types of unwind information, the way this class was written was
making it a mess to maintain.  Instead of trying to keep one
"non-call site" unwind plan and one "call site" unwind plan, track
all the different types of unwind plans we can possibly retrieve for
each function and have the call-site/non-call-site accessor methods
retrieve those.

Add a real "fast unwind plan" for x86_64 / i386 -- when doing an
unwind through a function, this only has to read the first 4 bytes 
to tell if the function has a standard prologue sequence.  If so, 
we can use the architecture default unwind plan to backtrace 
through this function.  If we try to retrieve the save location for
other registers later on, a real unwind plan will be used.  This
one is just for doing fast backtraces.

Change the compact unwind plan importer to fill in the valid address
range it is valid for. 

Compact unwind, in theory, may have multiple entries for a single
function.  The FuncUnwinders rewrite includes the start of supporting
this correctly.  In practice compact unwind encodings are used for
the entire range of the function today -- in fact, sometimes the same
encoding is used for multiple functions that have the same unwind
rules.  But I want to handle a single function that has multiple
different compact unwind UnwindPlans eventually.

llvm-svn: 224689
2014-12-21 10:44:54 +00:00
Jason Molenda b12a136cdd Re-enable compact unwind use on Mac platforms.
When lldb has a binary with protected section contents,
don't use the on-disk representation of that compact 
uwnind -- read it only out of live memory where it has
been decrypted.

llvm-svn: 224670
2014-12-20 03:12:51 +00:00
Jason Molenda 0f479da711 Temporarily disable CompactUnwindInfo::GetCompactUnwindInfoForFunction.
The compact unwind importer is getting the wrong unwind info for one
case that I found.  I haven't been able to fix the problem tonight 
and I don't want to leave TOT behaving incorrectly, so just ignore
compact unwind until I can get to the bottom of this.

llvm-svn: 224321
2014-12-16 06:20:30 +00:00
Zachary Turner 818a3676aa Remove use of GCC-style intrinsics, as they are non-portable.
Differential Revision: http://reviews.llvm.org/D6567

llvm-svn: 223687
2014-12-08 20:00:33 +00:00
Jason Molenda e589e7e336 The lldb unwinder can now use the unwind information from the compact-unwind
section for x86_64 and i386 targets on Darwin systems.  Currently only the
compact unwind encoding for normal frame-using functions is supported but it
will be easy handle frameless functions when I have a bit more free time to
test it.  The LSDA and personality routines for functions are also retrieved
correctly for functions from the compact unwind section.

This new code is very fresh -- it passes the lldb testsuite and I've done
by-hand inspection of many functions and am getting correct behavior for all
of them.  There may need to be some bug fixing over the next couple weeks as
I exercise and test it further.  But I think it's fine right now so I'm
committing it.

<rdar://problem/13220837> 

llvm-svn: 223625
2014-12-08 03:09:00 +00:00