Commit Graph

113 Commits

Author SHA1 Message Date
Krzysztof Parzyszek a0dd08a806 [Hexagon] Check for potential bank conflicts in post-RA scheduling
Insert artificial edges between loads that could cause a cache bank
conflict.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311901 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-28 18:36:21 +00:00
Krzysztof Parzyszek 30898f12ad [Hexagon] Break up DAG mutations into separate classes, move to subtarget
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311895 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-28 16:24:22 +00:00
Krzysztof Parzyszek 33287d8a69 [Hexagon] Fix check for HMOTF_ConstExtend operand flag
This fixes https://llvm.org/PR33718.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307566 91177308-0d34-0410-b5e6-96231b3b80d8
2017-07-10 18:38:52 +00:00
Chandler Carruth e3e43d9d57 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).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304787 91177308-0d34-0410-b5e6-96231b3b80d8
2017-06-06 11:49:48 +00:00
Krzysztof Parzyszek 7dc680c89a [Hexagon] Fix dependence check in the packetizer
An incorrect check in the packetizer lead to an attempt to convert
an unconditional branch to a .new (conditional) form.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304442 91177308-0d34-0410-b5e6-96231b3b80d8
2017-06-01 18:02:40 +00:00
Krzysztof Parzyszek 4338f39804 [Hexagon] Fix comment in HexagonPacketizer::runOnMachineFunction
Patch by Wei-Ren Chen.

Differential Revision: https://reviews.llvm.org/D33439


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303745 91177308-0d34-0410-b5e6-96231b3b80d8
2017-05-24 13:43:42 +00:00
Krzysztof Parzyszek c272a4dc8d [Hexagon] Use automatically-generated scheduling information for HVX
Patch by Jyotsna Verma.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302073 91177308-0d34-0410-b5e6-96231b3b80d8
2017-05-03 20:10:36 +00:00
Krzysztof Parzyszek 7cff8063d1 [Hexagon] Implement undoing .cur instructions in packetizer
The packetizer needs to convert .cur instruction to its regular form if
the use is not in the same packet as the .cur. The code in the packetizer
handles one type of .cur, which is the vector load case. This patch
updates the packetizer so that it can undo all the .cur instructions.
In the test case, the .cur is the 128B version, but there are also the
post-increment versions.

Patch by Brendon Cahoon.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302032 91177308-0d34-0410-b5e6-96231b3b80d8
2017-05-03 15:28:56 +00:00
Krzysztof Parzyszek 32526ea5c1 [Hexagon] Don't ignore mult-cycle latency information
The compiler was generating code that ends up ignoring a multiple
latency dependence between two instructions by scheduling the
intructions in back-to-back packets. 

The packetizer needs to end a packet if the latency of the current
current insruction and the source in the previous packet is
greater than 1 cycle. This case occurs when there is still room in
the current packet, but scheduling the instruction causes a stall.
Instead, the packetizer should start a new packet. Also, if the
current packet already contains a stall, then it is okay to add
another instruction to the packet that also causes a stall. This
occurs when there are no instructions that can be scheduled in
between the producer and consumer instructions.

This patch changes the latency for loads to 2 cycles from 3 cycles.
This change refects that a load only needs to be separated by
one extra packet to eliminate the stall.

Patch by Ikhlas Ajbar.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301954 91177308-0d34-0410-b5e6-96231b3b80d8
2017-05-02 18:12:19 +00:00
Krzysztof Parzyszek f47f1166e4 [Hexagon] Pick a dot-old instruction that matches the architecture
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297031 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-06 17:03:16 +00:00
Krzysztof Parzyszek eee70a1f65 [Hexagon] Start using regmasks on calls
Reapply r295371 with a fix for the Windows bot failures.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295504 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-17 22:14:51 +00:00
Rafael Espindola 675c18fef3 Revert "[Hexagon] Start using regmasks on calls"
This reverts commit r295371.

It broke windows bots:

http://bb.pgr.jp/builders/ninja-clang-i686-msc19-R/builds/11402/steps/test-llvm/logs/stdio

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295402 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-17 02:08:58 +00:00
Krzysztof Parzyszek 075abc4ae8 [Hexagon] Start using regmasks on calls
All the cool targets are doing it...


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295371 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-16 20:25:23 +00:00
Krzysztof Parzyszek 051dda606b [Hexagon] Update instruction types
Remove TypeXTYPE, TypeALU32, TypeSYSTEM, TypeJR, and instead use their
architecture counterparts.

Patch by Colin LeMahieu.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294321 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-07 17:47:37 +00:00
Mehdi Amini 67f335d992 Use StringRef in Pass/PassManager APIs (NFC)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283004 91177308-0d34-0410-b5e6-96231b3b80d8
2016-10-01 02:56:57 +00:00
Matthias Braun 690a3cbc95 MachineFunctionProperties/MIRParser: Rename AllVRegsAllocated->NoVRegs, compute it
Rename AllVRegsAllocated to NoVRegs. This avoids the connotation of
running after register and simply describes that no vregs are used in
a machine function. With that we can simply compute the property and do
not need to dump/parse it in .mir files.

Differential Revision: http://reviews.llvm.org/D23850

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279698 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-25 01:27:13 +00:00
Matthias Braun fa5c5c7db3 CodeGen: Remove MachineFunctionAnalysis => Enable (Machine)ModulePasses
Re-apply this patch, hopefully I will get away without any warnings
in the constructor now.

This patch removes the MachineFunctionAnalysis. Instead we keep a
map from IR Function to MachineFunction in the MachineModuleInfo.

This allows the insertion of ModulePasses into the codegen pipeline
without breaking it because the MachineFunctionAnalysis gets dropped
before a module pass.

Peak memory should stay unchanged without a ModulePass in the codegen
pipeline: Previously the MachineFunction was freed at the end of a codegen
function pipeline because the MachineFunctionAnalysis was dropped; With
this patch the MachineFunction is freed after the AsmPrinter has
finished.

Differential Revision: http://reviews.llvm.org/D23736

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279602 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-24 01:52:46 +00:00
Richard Smith 5a65f77485 Revert r279564. It introduces undefined behavior (binding a reference to a
dereferenced null pointer) in MachineModuleInfo::MachineModuleInfo that causes
-Werror builds (including several buildbots) to fail.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279580 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-23 22:08:27 +00:00
Matthias Braun 1bb228f703 CodeGen: Remove MachineFunctionAnalysis => Enable (Machine)ModulePasses
Re-apply this commit with the deletion of a MachineFunction delegated to
a separate pass to avoid use after free when doing this directly in
AsmPrinter.

This patch removes the MachineFunctionAnalysis. Instead we keep a
map from IR Function to MachineFunction in the MachineModuleInfo.

This allows the insertion of ModulePasses into the codegen pipeline
without breaking it because the MachineFunctionAnalysis gets dropped
before a module pass.

Peak memory should stay unchanged without a ModulePass in the codegen
pipeline: Previously the MachineFunction was freed at the end of a codegen
function pipeline because the MachineFunctionAnalysis was dropped; With
this patch the MachineFunction is freed after the AsmPrinter has
finished.

Differential Revision: http://reviews.llvm.org/D23736

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279564 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-23 20:58:29 +00:00
Krzysztof Parzyszek 7fd3acfecb [Hexagon] Packetize return value setup with the return instruction
Commit r279241 unintentionally reverted that ability.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279526 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-23 16:01:01 +00:00
Matthias Braun eb3b7392bb Revert "(HEAD -> master, origin/master, origin/HEAD) CodeGen: Remove MachineFunctionAnalysis => Enable (Machine)ModulePasses"
Reverting while tracking down a use after free.

This reverts commit r279502.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279503 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-23 05:17:11 +00:00
Matthias Braun ded269b907 CodeGen: Remove MachineFunctionAnalysis => Enable (Machine)ModulePasses
This patch removes the MachineFunctionAnalysis. Instead we keep a
map from IR Function to MachineFunction in the MachineModuleInfo.

This allows the insertion of ModulePasses into the codegen pipeline
without breaking it because the MachineFunctionAnalysis gets dropped
before a module pass.

Peak memory should stay unchanged without a ModulePass in the codegen
pipeline: Previously the MachineFunction was freed at the end of a codegen
function pipeline because the MachineFunctionAnalysis was dropped; With
this patch the MachineFunction is freed after the AsmPrinter has
finished.

Differential Revision: http://reviews.llvm.org/D23736

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279502 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-23 03:20:09 +00:00
Krzysztof Parzyszek 48a33fd8e5 [Hexagon] Avoid register dependencies on indirect branches in packetizer
Do not packetize the instruction setting the branch address with the
indirect branch itself.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279324 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-19 21:07:35 +00:00
Krzysztof Parzyszek 1ea0947ff4 [Hexagon] Enforce LLSC packetization rules
Ensure that load locked and store conditional instructions are only
packetized with ALU32 instructions.

Patch by Ben Craig.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279272 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-19 16:57:05 +00:00
Krzysztof Parzyszek 8fa77e005c [Hexagon] Mark PS_jumpret as pseudo-instruction, expand it into J2_jumpr
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279241 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-19 14:04:45 +00:00
David Majnemer 975248e4fb Use the range variant of find instead of unpacking begin/end
If the result of the find is only used to compare against end(), just
use is_contained instead.

No functionality change is intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278433 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-11 22:21:41 +00:00
Krzysztof Parzyszek c54b1ec0f8 Replace MachineInstr* with MachineInstr& in TargetInstrInfo, NFC
There were a few cases introduced with the modulo scheduler.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277358 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-01 17:55:48 +00:00
Krzysztof Parzyszek 33bf01e7cc [Hexagon] Referencify MachineInstr in HexagonInstrInfo, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277220 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-29 21:49:42 +00:00
Matthias Braun f79c57a412 MachineFunction: Return reference for getFrameInfo(); NFC
getFrameInfo() never returns nullptr so we should use a reference
instead of a pointer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277017 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-28 18:40:00 +00:00
Krzysztof Parzyszek 43492b2a7a [Hexagon] Post-increment loads/stores enhancements
- Generate vector post-increment stores more aggressively.
- Predicate post-increment and vector stores in early if-conversion.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276800 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-26 20:30:30 +00:00
Krzysztof Parzyszek c4320ab2d8 [Hexagon] Update store offset when not packetizing it with allocframe
When the packetizer wants to put a store to a stack slot in the same
packet with an allocframe, it updates the store offset to reflect the
value of SP before it is updated by allocframe. If the store cannot
be packetized with the allocframe after all, the offset needs to be
updated back to the previous value.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276749 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-26 14:24:46 +00:00
Krzysztof Parzyszek 5e3461ebc2 [Hexagon] Add a scheduling DAG mutation
- Remove output dependencies on USR_OVF register.
- Update chain edge latencies between v60 vector loads/stores.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275586 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-15 17:48:09 +00:00
Krzysztof Parzyszek 1a360b3be9 [Hexagon] Packetize function call arguments with tail call instructions
On Hexagon is it legal to packetize the instructions setting up call
arguments with the call instruction itself. This was already done,
except for tail calls. Make sure tail calls are handled as well.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275458 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-14 19:30:55 +00:00
Duncan P. N. Exon Smith 8c13ec21d3 Hexagon: Avoid implicit iterator conversions, NFC
Avoid implicit iterator conversions from MachineInstrBundleIterator to
MachineInstr* in the Hexagon backend, mostly by preferring MachineInstr&
over MachineInstr* and switching to range-based for loops.

There's a long tail of API cleanup here, but I'm planning to leave the
rest to the Hexagon maintainers.  HexagonInstrInfo defines many of its
own predicates, and most of them still take MachineInstr*.  Some of
those actually check for nullptr, so I didn't feel comfortable changing
them to MachineInstr& en masse.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275142 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-12 01:55:32 +00:00
Duncan P. N. Exon Smith 567409db69 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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274189 91177308-0d34-0410-b5e6-96231b3b80d8
2016-06-30 00:01:54 +00:00
Krzysztof Parzyszek 687c1919cc [Hexagon] Be careful about anti-dependencies with a call in packetizer
In a case like
  J2_callr <ga:@foo>, %R0<imp-use>, ...
  R0<def> = ...
the anti-dependency on R0 cannot be ignored and the two instructions
cannot be packetized together, since if they were, the assignment to
R0 would take place before the call.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268776 91177308-0d34-0410-b5e6-96231b3b80d8
2016-05-06 19:13:38 +00:00
Andrew Kaylor 650fa7d863 Add optimization bisect opt-in calls for Hexagon passes
Differential Revision: http://reviews.llvm.org/D19509



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267593 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-26 19:46:28 +00:00
Mehdi Amini f6071e14c5 [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>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266595 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-18 09:17:29 +00:00
Derek Schuff 9b3da26fa8 Add MachineFunctionProperty checks for AllVRegsAllocated for target passes
Summary:
This adds the same checks that were added in r264593 to all
target-specific passes that run after register allocation.

Reviewers: qcolombet

Subscribers: jyknight, dsanders, llvm-commits

Differential Revision: http://reviews.llvm.org/D18525

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265313 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-04 17:09:25 +00:00
Duncan P. N. Exon Smith 0ce039da16 CodeGen: Update DFAPacketizer API to take MachineInstr&, NFC
In all but one case, change the DFAPacketizer API to take MachineInstr&
instead of MachineInstr*.  In DFAPacketizer::endPacket(), take
MachineBasicBlock::iterator.  Besides cleaning up the API, this is in
search of PR26753.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@262142 91177308-0d34-0410-b5e6-96231b3b80d8
2016-02-27 19:09:00 +00:00
Duncan P. N. Exon Smith 5b9b80ea30 CodeGen: TII: Take MachineInstr& in predicate API, NFC
Change TargetInstrInfo API to take `MachineInstr&` instead of
`MachineInstr*` in the functions related to predicated instructions
(I'll try to come back later and get some of the rest).  All of these
functions require non-null parameters already, so references are more
clear.  As a bonus, this happens to factor away a host of implicit
iterator => pointer conversions.

No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261605 91177308-0d34-0410-b5e6-96231b3b80d8
2016-02-23 02:46:52 +00:00
Duncan P. N. Exon Smith 110284e56c CodeGen: Bring back MachineBasicBlock::iterator::getInstrIterator()...
This is a little embarrassing.

When I reverted r261504 (getIterator() => getInstrIterator()) in
r261567, I did a `git grep` to see if there were new calls to
`getInstrIterator()` that I needed to migrate.  There were 10-20 hits,
and I blindly did a `sed ...` before calling `ninja check`.

However, these were `MachineInstrBundleIterator::getInstrIterator()`,
which predated r261567.  Perhaps coincidentally, these had an identical
name and return type.

This commit undoes my careless sed and restores
`MachineBasicBlock::iterator::getInstrIterator()`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261577 91177308-0d34-0410-b5e6-96231b3b80d8
2016-02-22 21:30:15 +00:00
Duncan P. N. Exon Smith 20a62528ef 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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261567 91177308-0d34-0410-b5e6-96231b3b80d8
2016-02-22 20:49:58 +00:00
Krzysztof Parzyszek 1895c55f4f [Hexagon] Misc fixes to r255807
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255811 91177308-0d34-0410-b5e6-96231b3b80d8
2015-12-16 20:07:04 +00:00
Krzysztof Parzyszek dcf9d4a0cb [Hexagon] Update the Hexagon packetizer
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255807 91177308-0d34-0410-b5e6-96231b3b80d8
2015-12-16 19:36:12 +00:00
Krzysztof Parzyszek e0d5233e36 [Packetizer] Add AliasAnalysis as a parameter to the packetizer
This will make the depedence graph more accurate if an alias analysis
is provided. If nullptr is specified in its place, the behavior will
remain as it is currently.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255540 91177308-0d34-0410-b5e6-96231b3b80d8
2015-12-14 20:35:13 +00:00
Krzysztof Parzyszek fe9f74ec61 Add "const" to function arguments in DFAPacketizer
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255526 91177308-0d34-0410-b5e6-96231b3b80d8
2015-12-14 18:54:44 +00:00
Krzysztof Parzyszek 8e716832ef [Hexagon] Bring HexagonInstrInfo up to date
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253986 91177308-0d34-0410-b5e6-96231b3b80d8
2015-11-24 14:55:26 +00:00
Matthias Braun e5065bdcd7 Fix build problme introduced in r251883
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251888 91177308-0d34-0410-b5e6-96231b3b80d8
2015-11-03 02:19:07 +00:00
Oleg Ranevskyy cd69ab5ddf Test commit: fix typo in comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251122 91177308-0d34-0410-b5e6-96231b3b80d8
2015-10-23 17:10:44 +00:00