Commit Graph

281 Commits

Author SHA1 Message Date
Chandler Carruth 6bda14b313 Sort the remaining #include lines in include/... and lib/....
I did this a long time ago with a janky python script, but now
clang-format has built-in support for this. I fed clang-format every
line with a #include and let it re-sort things according to the precise
LLVM rules for include ordering baked into clang-format these days.

I've reverted a number of files where the results of sorting includes
isn't healthy. Either places where we have legacy code relying on
particular include ordering (where possible, I'll fix these separately)
or where we have particular formatting around #include lines that
I didn't want to disturb in this patch.

This patch is *entirely* mechanical. If you get merge conflicts or
anything, just ignore the changes in this patch and run clang-format
over your #include lines in the files.

Sorry for any noise here, but it is important to keep these things
stable. I was seeing an increasing number of patches with irrelevant
re-ordering of #include lines because clang-format was used. This patch
at least isolates that churn, makes it easy to skip when resolving
conflicts, and gets us to a clean baseline (again).

llvm-svn: 304787
2017-06-06 11:49:48 +00:00
Eugene Zelenko 7ea692373c [CodeGen] Fix some Clang-tidy modernize-use-using and Include What You Use warnings; other minor fixes (NFC).
llvm-svn: 304495
2017-06-01 23:25:02 +00:00
Matthias Braun 868bbd4022 ScheduleDAGInstrs: Fix fixupKills()
Rewrite fixupKills() to use the LivePhysRegs class. Simplifies the code
and fixes a bug where the CSR registers in return blocks where missed
leading to invalid kill flags. Also remove the unnecessary rule that we
wouldn't set kill flags on tied operands.

No tests as I have an upcoming commit improving MachineVerifier checks
to catch these cases in multiple existing lit tests.

llvm-svn: 304055
2017-05-27 02:50:50 +00:00
Eli Friedman 93f47e5ffb Refactor alias check from MISched into common helper. NFC.
Differential Revision: https://reviews.llvm.org/D30598

llvm-svn: 297421
2017-03-09 23:33:36 +00:00
Eli Friedman 49f0220086 [MISched] Remove unused arguments. NFC.
llvm-svn: 296934
2017-03-04 00:42:55 +00:00
Matthias Braun 8c209aa877 Cleanup dump() functions.
We had various variants of defining dump() functions in LLVM. Normalize
them (this should just consistently implement the things discussed in
http://lists.llvm.org/pipermail/cfe-dev/2014-January/034323.html

For reference:
- Public headers should just declare the dump() method but not use
  LLVM_DUMP_METHOD or #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
- The definition of a dump method should look like this:
  #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  LLVM_DUMP_METHOD void MyClass::dump() {
    // print stuff to dbgs()...
  }
  #endif

llvm-svn: 293359
2017-01-28 02:02:38 +00:00
Matthias Braun c91e28af4b ScheduleDAGInstrs: Do not try to toggle kill flags on debug uses
Preparation for upcoming changes. No testcase as none of the public
targets bundles early enough and has a post machine scheduler enabled at
the same time. The error is also easily catched by asserts.

llvm-svn: 293324
2017-01-27 18:53:07 +00:00
Matthias Braun 26e8c350f9 ScheduleDAGInstrs: Cleanup toggleKillFlag(); NFC
llvm-svn: 293323
2017-01-27 18:53:05 +00:00
Matthias Braun bd7d91838e ScheduleDAGInstrs: Cleanup; NFC
Comment, doxygen and a bit of whitespace cleanup.

llvm-svn: 293322
2017-01-27 18:53:00 +00:00
Krzysztof Parzyszek ea9f8ce03c Implement LaneBitmask::any(), use it to replace !none(), NFCI
llvm-svn: 289974
2016-12-16 19:11:56 +00:00
Krzysztof Parzyszek 91b5cf8412 Extract LaneBitmask into a separate type
Specifically avoid implicit conversions from/to integral types to
avoid potential errors when changing the underlying type. For example,
a typical initialization of a "full" mask was "LaneMask = ~0u", which
would result in a value of 0x00000000FFFFFFFF if the type was extended
to uint64_t.

Differential Revision: https://reviews.llvm.org/D27454

llvm-svn: 289820
2016-12-15 14:36:06 +00:00
Matthias Braun 40639885f5 ScheduleDAGInstrs: Move VRegUses to ScheduleDAGMILive; NFCI
Push VRegUses/collectVRegUses() down the class hierarchy towards its
only user ScheduleDAGMILive.

NFCI: The initialization of the map happens at a later point but that
should not matter.

This is in preparation to allow DAG mutators to merge nodes, which
relies on this map getting computed later.

llvm-svn: 286654
2016-11-11 22:37:31 +00:00
Matthias Braun 325cd2c98a ScheduleDAGInstrs: Add condjump deps to addSchedBarrierDeps()
addSchedBarrierDeps() is supposed to add use operands to the ExitSU
node. The current implementation adds uses for calls/barrier instruction
and the MBB live-outs in all other cases. The use
operands of conditional jump instructions were missed.

Also added code to macrofusion to set the latencies between nodes to
zero to avoid problems with the fusing nodes lingering around in the
pending list now.

Differential Revision: https://reviews.llvm.org/D25140

llvm-svn: 286544
2016-11-11 01:34:21 +00:00
Matthias Braun f29b12dca8 ScheduleDAGInstrs: Ignore dependencies of constant physregs
There is no need to track dependencies for constant physregs, as they
don't change their value no matter in what order you read/write to them.

Differential Revision: https://reviews.llvm.org/D26221

llvm-svn: 286526
2016-11-10 23:46:44 +00:00
Matthias Braun 111603f933 ScheduleDAGInstrs: Slightly simplify code; NFC
llvm-svn: 286510
2016-11-10 22:11:00 +00:00
Matthias Braun c8440dddb2 MachineInstrBundle: Pass iterators to getBundle(Start|End); NFC
This is a function to go backwards in a block to find the first
instruction in a bundle, so iterator is a more natural choice for
parameter/return rather than a reference to a MachineInstruction.

llvm-svn: 285051
2016-10-25 02:55:17 +00:00
Krzysztof Parzyszek e7c72cdbb0 Fix machine operand traversal in ScheduleDAGInstrs::fixupKills
llvm-svn: 283315
2016-10-05 13:15:06 +00:00
Matthias Braun 298e007e99 ScheduleDAGInstrs: Cleanup, use range based for; NFC
llvm-svn: 282979
2016-09-30 23:08:07 +00:00
Justin Lebar d98cf00c95 [CodeGen] Rename MachineInstr::isInvariantLoad to isDereferenceableInvariantLoad. NFC
Summary:
I want to separate out the notions of invariance and dereferenceability
at the MI level, so that they correspond to the equivalent concepts at
the IR level.  (Currently an MI load is MI-invariant iff it's
IR-invariant and IR-dereferenceable.)

First step is renaming this function.

Reviewers: chandlerc

Subscribers: MatzeB, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D23370

llvm-svn: 281125
2016-09-10 01:03:20 +00:00
Matthias Braun 941a705b7b MachineFunction: Return reference for getFrameInfo(); NFC
getFrameInfo() never returns nullptr so we should use a reference
instead of a pointer.

llvm-svn: 277017
2016-07-28 18:40:00 +00:00
NAKAMURA Takumi d6ddc7e0a8 Untabify.
llvm-svn: 276597
2016-07-25 00:59:51 +00:00
Duncan P. N. Exon Smith b77911be02 CodeGen: Use MachineInstr& in ScheduleDAGIntrs, NFC
Use MachineInstr& to avoid implicit conversions from
MachineBasicBlock::iterator to MachineInstr*.  In one case, this could
use a range-based for loop, but the other loops iterated in reverse
order.

One of the reverse-loops checked the MachineInstr* for nullptr, a
condition that is provably unreachable.  (And even if my proof has a
flaw, UBSan would catch the bug.)

llvm-svn: 274360
2016-07-01 16:21:48 +00:00
Duncan P. N. Exon Smith 9cfc75c214 CodeGen: Use MachineInstr& in TargetInstrInfo, NFC
This is mostly a mechanical change to make TargetInstrInfo API take
MachineInstr& (instead of MachineInstr* or MachineBasicBlock::iterator)
when the argument is expected to be a valid MachineInstr.  This is a
general API improvement.

Although it would be possible to do this one function at a time, that
would demand a quadratic amount of churn since many of these functions
call each other.  Instead I've done everything as a block and just
updated what was necessary.

This is mostly mechanical fixes: adding and removing `*` and `&`
operators.  The only non-mechanical change is to split
ARMBaseInstrInfo::getOperandLatencyImpl out from
ARMBaseInstrInfo::getOperandLatency.  Previously, the latter took a
`MachineInstr*` which it updated to the instruction bundle leader; now,
the latter calls the former either with the same `MachineInstr&` or the
bundle leader.

As a side effect, this removes a bunch of MachineInstr* to
MachineBasicBlock::iterator implicit conversions, a necessary step
toward fixing PR26753.

Note: I updated WebAssembly, Lanai, and AVR (despite being
off-by-default) since it turned out to be easy.  I couldn't run tests
for AVR since llc doesn't link with it turned on.

llvm-svn: 274189
2016-06-30 00:01:54 +00:00
Matthias Braun 4c994ee42b ScheduleDAGInstrs: Fix memory corruption
We have to modify V2SU before inserting new elements into the
CurrentVRegDefs set because that may move V2SU in memory invalidating
the reference.

llvm-svn: 270644
2016-05-25 01:18:00 +00:00
Matthias Braun 8a5b46737a ScheduleDAGInstrs: Comment on why subreg defs are not seen as uses; NFC
Usually subregister definitions are consider uses of the remaining
lanes that did not get defined. Add a comment why the code in
ScheduleDAGInstrs does not add use dependencies regardless.

llvm-svn: 269107
2016-05-10 20:11:58 +00:00
Mandeep Singh Grang e5a2f116d6 Fix PR26655: Bail out if all regs of an inst BUNDLE have the correct kill flag
Summary:
While setting kill flags on instructions inside a BUNDLE, we bail out as soon
as we set kill flag on a register.  But we are missing a check when all the
registers already have the correct kill flag set. We need to bail out in that
case as well.

This patch refactors the old code and simply makes use of the addRegisterKilled
function in MachineInstr.cpp in order to determine whether to set/remove kill
on an instruction.

Reviewers: apazos, t.p.northover, pete, MatzeB

Subscribers: MatzeB, davide, llvm-commits

Differential Revision: http://reviews.llvm.org/D17356

llvm-svn: 269092
2016-05-10 17:57:27 +00:00
Krzysztof Parzyszek a356bb7fa4 [ScheduleDAG] Make sure to process all def operands before any use operands
An example from Hexagon where things went wrong:
  %R0<def> = L2_loadrigp <ga:@fp04>      ; load function address
  J2_callr %R0<kill>, ..., %R0<imp-def>  ; call *R0, return value in R0

ScheduleDAGInstrs::buildSchedGraph would visit all instructions going
backwards, and in each instruction it would visit all operands in their
order on the operand list. In the case of this call, it visited the use
of R0 first, then removed it from the set Uses after it visited the def.
This caused the DAG to be missing the data dependence edge on R0 between
the load and the call.

Differential Revision: http://reviews.llvm.org/D20102

llvm-svn: 269076
2016-05-10 16:50:30 +00:00
NAKAMURA Takumi bc46f624cd ScheduleDAGInstrs.cpp: Don't peel the iterator when it points the end. This will fix the crash in r268143.
llvm-svn: 268257
2016-05-02 17:29:55 +00:00
Mehdi Amini b550cb1750 [NFC] Header cleanup
Removed some unused headers, replaced some headers with forward class declarations.

Found using simple scripts like this one:
clear && ack --cpp -l '#include "llvm/ADT/IndexedMap.h"' | xargs grep -L 'IndexedMap[<]' | xargs grep -n --color=auto 'IndexedMap'

Patch by Eugene Kosov <claprix@yandex.ru>

Differential Revision: http://reviews.llvm.org/D19219

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266595
2016-04-18 09:17:29 +00:00
Mehdi Amini 59ae854503 Do not modify a cl::opt programmatically, global mutable state is evil.
Found by TSAN on ThinLTO.

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266514
2016-04-16 04:58:30 +00:00
Geoff Berry 6381713b37 [ScheduleDAGInstrs] Re-factor for based on review feedback. NFC.
Summary:
Re-factor some code to improve clarity and style based on review
comments from http://reviews.llvm.org/D18093.

Reviewers: MatzeB, mcrosier

Subscribers: MatzeB, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D19128

llvm-svn: 266372
2016-04-14 21:31:07 +00:00
Geoff Berry c0739d8305 [ScheduleDAGInstrs] Handle instructions with multiple MMOs
Summary:
In getUnderlyingObjectsForInstr(): Don't give up on instructions with
multiple MMOs, instead look through all the MMOs and if they all meet
the conservative criteria previously used for single MMO instructions,
then return all of the underlying objects derived from the MMOs.

The change to ScheduleDAGInstrs::buildSchedGraph() is needed to avoid
the case where multiple underlying objects are present and are related
in such a way that successive iterations of the loop end up adding a
dependency from an instruction to itself.

Reviewers: atrick, hfinkel

Subscribers: MatzeB, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D18093

llvm-svn: 266084
2016-04-12 15:50:19 +00:00
Chandler Carruth b472856a73 Fix PR26940 where compiles times regressed massively.
Patch by Jonas Paulsson. Original description:
Bugfix in buildSchedGraph() to make -dag-maps-huge-region work properly

I found that the reduction of the maps did in fact never happen in this
test case. This was because *all* the stores / loads were made with
addresses from arguments and they thus became "unknown" stores / loads.
Fixed by removing continue statements and making sure that the test for
reduction always takes place.

Differential Revision: http://reviews.llvm.org/D18673

llvm-svn: 265063
2016-03-31 21:55:58 +00:00
Duncan P. N. Exon Smith f9ab416d70 WIP: CodeGen: Use MachineInstr& in MachineInstrBundle.h, NFC
Update APIs in MachineInstrBundle.h to take and return MachineInstr&
instead of MachineInstr* when the instruction cannot be null.  Besides
being a nice cleanup, this is tacking toward a fix for PR26753.

llvm-svn: 262141
2016-02-27 17:05:33 +00:00
Duncan P. N. Exon Smith 3ac9cc6156 CodeGen: Take MachineInstr& in SlotIndexes and LiveIntervals, NFC
Take MachineInstr by reference instead of by pointer in SlotIndexes and
the SlotIndex wrappers in LiveIntervals.  The MachineInstrs here are
never null, so this cleans up the API a bit.  It also incidentally
removes a few implicit conversions from MachineInstrBundleIterator to
MachineInstr* (see PR26753).

At a couple of call sites it was convenient to convert to a range-based
for loop over MachineBasicBlock::instr_begin/instr_end, so I added
MachineBasicBlock::instrs.

llvm-svn: 262115
2016-02-27 06:40:41 +00:00
Duncan P. N. Exon Smith c5b668deb8 Revert "CodeGen: MachineInstr::getIterator() => getInstrIterator(), NFC"
This reverts commit r261504, since it's not obvious the new name is
better:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160222/334298.html

I'll recommit if we get consensus that it's the right direction.

llvm-svn: 261567
2016-02-22 20:49:58 +00:00
Duncan P. N. Exon Smith dc0848c029 CodeGen: MachineInstr::getIterator() => getInstrIterator(), NFC
Delete MachineInstr::getIterator(), since the term "iterator" is
overloaded when talking about MachineInstr.

- Downcast to ilist_node in iplist::getNextNode() and getPrevNode() so
  that ilist_node::getIterator() is still available.
- Add it back as MachineInstr::getInstrIterator().  This matches the
  naming in MachineBasicBlock.
- Add MachineInstr::getBundleIterator().  This is explicitly called
  "bundle" (not matching MachineBasicBlock) to disintinguish it clearly
  from ilist_node::getIterator().
- Update all calls.  Some of these I switched to `auto` to remove
  boiler-plate, since the new name is clear about the type.

There was one call I updated that looked fishy, but it wasn't clear what
the right answer was.  This was in X86FrameLowering::inlineStackProbe(),
added in r252578 in lib/Target/X86/X86FrameLowering.cpp.  I opted to
leave the behaviour unchanged, but I'll reply to the original commit on
the list in a moment.

llvm-svn: 261504
2016-02-21 22:58:35 +00:00
Jonas Paulsson 98963fec41 [ScheduleDAGInstrs] isUnsafeMemoryObject() removed
This function was basically useless, since volatile memacesses or MIs with
unmodelled sideffects become global memory objects, and the other little
checks are also done elsewhere.

Reviewed by Andy Trick
http://reviews.llvm.org/D16881

llvm-svn: 260899
2016-02-15 16:43:15 +00:00
Jonas Paulsson 2293685731 [ScheduleDagInstrs] Improved comments
llvm-svn: 259783
2016-02-04 13:08:48 +00:00
Jonas Paulsson ac29f01788 [ScheduleDAGInstrs::buildSchedGraph()] Handling of memory dependecies rewritten.
Recommited, after some fixing with test cases.

Updated test cases:
test/CodeGen/AArch64/arm64-misched-memdep-bug.ll
test/CodeGen/AArch64/tailcall_misched_graph.ll

Temporarily disabled test cases:
test/CodeGen/AMDGPU/split-vector-memoperand-offsets.ll
test/CodeGen/PowerPC/ppc64-fastcc.ll (partially updated)
test/CodeGen/PowerPC/vsx-fma-m.ll
test/CodeGen/PowerPC/vsx-fma-sp.ll

http://reviews.llvm.org/D8705
Reviewers: Hal Finkel, Andy Trick.

llvm-svn: 259673
2016-02-03 17:52:29 +00:00
Jonas Paulsson 8c738635b1 Temporarily revert "[ScheduleDAGInstrs::buildSchedGraph()] Handling of memory dependecies rewritten."
Some buildbot failures needs to be debugged.

llvm-svn: 259213
2016-01-29 17:22:43 +00:00
Jonas Paulsson 23f12e5c02 [ScheduleDAGInstrs::buildSchedGraph()] Handling of memory dependecies rewritten.
The buildSchedGraph() was in need of reworking as the AA features had been
added on top of earlier code. It was very difficult to understand, and buggy.
There had been found cases where scheduling dependencies had actually been
missed (see r228686).

AliasChain, RejectMemNodes, adjustChainDeps() and iterateChainSucc() have
been removed. There are instead now just the four maps from Value to SUs, which
have been renamed to Stores, Loads, NonAliasStores and NonAliasLoads.

An unknown store used to become the AliasChain, but now becomes a store mapped
to 'unknownValue' (in Stores). What used to be PendingLoads is instead the
list of SUs mapped to 'unknownValue' in Loads.

RejectMemNodes and adjustChainDeps() used to be a safety-net for everything.
The SU maps were sometimes cleared and SUs were put in RejectMemNodes, where
adjustChainDeps() would look. Instead of this, a more straight forward approach
is used in maintaining the SU maps without clearing them and simply letting
them grow over time. Instead of the cutt-off in adjustChainDeps() search, a
reduction of maps will be done if needed (see below).

Each SUnit either becomes the BarrierChain, or is put into one of the maps. For
each SUnit encountered, all the information about previous ones are still
available until a new BarrierChain is set, at which point the maps are cleared.

For huge regions, the algorithm becomes slow, therefore the maps will get
reduced at a threshold (current default is 1000 nodes), by a fraction (default 1/2).
These values can be tuned by use of CL options in case some test case shows that
they need to be changed (-dag-maps-huge-region and -dag-maps-reduction-size).

There has not been any considerable change observed in output quality or compile
time. There may now be more DAG edges inserted than before (i.e. if A->B->C,
then A->C is not needed). However, in a comparison run there were fewer total
calls to AA, and a somewhat improved compile time, which means this seems to
be not a problem.

http://reviews.llvm.org/D8705
Reviewers: Hal Finkel, Andy Trick.

llvm-svn: 259201
2016-01-29 16:11:18 +00:00
Chad Rosier b46d0f9a71 [ScheduleDAGInstrs] Simplify logic to improve readability. NFC.
The call to isInvariantLoad() already returns false for non-load instructions.

llvm-svn: 258841
2016-01-26 19:33:57 +00:00
Matthias Braun d4f6409dff MachineScheduler: Allow independent scheduling of sub register defs
Note that this is disabled by default and still requires a patch to
handleMove() which is not upstreamed yet.

If the TrackLaneMasks policy/strategy is enabled the MachineScheduler
will build a schedule graph where definitions of independent
subregisters are no longer serialised.

Implementation comments:
- Without lane mask tracking a sub register def also counts as a use
  (except for the first one with the read-undef flag set), with lane
  mask tracking enabled this is no longer the case.
- Pressure Diffs where previously maintained per definition of a
  vreg with the help of the SSA information contained in the
  LiveIntervals.  With lanemask tracking enabled we cannot do this
  anymore and instead change the pressure diffs for all uses of the vreg
  as it becomes live/dead.  For this changed style to work correctly we
  ignore uses of instructions that define the same register again: They
  won't affect register pressure.
- With lanemask tracking we remove all read-undef flags from
  sub register defs when building the graph and re-add them later when
  all vreg lanes have become dead.

Differential Revision: http://reviews.llvm.org/D14969

llvm-svn: 258259
2016-01-20 00:23:32 +00:00
Matthias Braun 5d458617aa RegisterPressure: Make liveness tracking subregister aware
Differential Revision: http://reviews.llvm.org/D14968

llvm-svn: 258258
2016-01-20 00:23:26 +00:00
Matthias Braun b505c76c9a RegisterPressure: Expose RegisterOperands API
Previously the RegisterOperands have only been used internally in
RegisterPressure.cpp. However this datastructure can be useful for other
tasks as well and allows refactoring of PDiff initialisation out of
RPTracker::recede().

This patch:
- Exposes RegisterOperands as public API
- Splits RPTracker::recede() into a part that skips DebugValues and
  maintains the region borders, and the core that changes register
  pressure when given a set of RegisterOperands.
- This allows to move the PDiff initialisation out recede() into a
  method of the PressureDiffs class.
- The upcoming subregister scheduling code will also use
  RegisterOperands to avoid pushing more unrelated functionality into
  recede()/advance().

Differential Revision: http://reviews.llvm.org/D15473

llvm-svn: 257535
2016-01-12 22:57:35 +00:00
Geoff Berry 12fe2279f3 ScheduleDAGInstrs: Bug fix for missed memory dependency.
Summary:
In buildSchedGraph(), when adding memory dependencies for loads, move
the call to adjustChainDeps() after the call to
addChainDependency(AliasChain) to handle the case where
addChainDependency(AliasChain) ends up not adding a dependency and
instead putting the SU on the RejectMemNodes list.  The call to
adjustChainDeps() must be done after the call to addChainDependency() in
order to process the SU added to the RejectMemNodes list to create
memory dependencies for it.

Reviewers: hfinkel, atrick, jonpa, resistor

Subscribers: mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D15927

llvm-svn: 256950
2016-01-06 18:14:26 +00:00
Matthias Braun b17e8b1c1d ScheduleDAGInstrs: Move LiveIntervals field to ScheduleDAGMI
Now that ScheduleDAGInstrs doesn't need it anymore we can move the field
down the class hierarcy to ScheduleDAGMI.

llvm-svn: 254759
2015-12-04 19:54:24 +00:00
Matthias Braun 97d0ffbe06 ScheduleDAGInstrs: Rework schedule graph builder.
Re-comitting with a change that avoids undefined uses getting put into
the VRegUses list.

The new algorithm remembers the uses encountered while walking backwards
until a matching def is found. Contrary to the previous version this:
- Works without LiveIntervals being available
- Allows to increase the precision to subregisters/lanemasks
  (not used for now)

The changes in the AMDGPU tests are necessary because the R600 scheduler
is not stable with respect to the order of nodes in the ready queues.

Differential Revision: http://reviews.llvm.org/D9068

llvm-svn: 254683
2015-12-04 01:51:19 +00:00
Matthias Braun 2fd672a221 Revert "ScheduleDAGInstrs: Rework schedule graph builder."
This works mostly fine but breaks some stage 1 builders when compiling
compiler-rt on i386. Revert for further investigation as I can't see an
obvious cause/fix.

This reverts commit r254577.

llvm-svn: 254586
2015-12-03 03:01:10 +00:00