Commit Graph

8618 Commits

Author SHA1 Message Date
Fangrui Song b251cc0d91 Delete dead stores
llvm-svn: 365903
2019-07-12 14:58:15 +00:00
Vitaly Buka 52096ee9a9 Return Undef from isBytewiseValue for empty arrays or structs
Reviewers: pcc, eugenis

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64052

llvm-svn: 365864
2019-07-12 02:23:07 +00:00
Vitaly Buka c559e63798 Handle IntToPtr in isBytewiseValue
Summary:
This helps with more efficient use of memset for pattern initialization

From @pcc prototype for -ftrivial-auto-var-init=pattern optimizations

Binary size change on CTMark, (with -fuse-ld=lld -Wl,--icf=all, similar results with default linker options)
```
                   master           patch      diff
Os           8.238864e+05    8.238864e+05       0.0
O3           1.054797e+06    1.054797e+06       0.0
Os zero      8.292384e+05    8.292384e+05       0.0
O3 zero      1.062626e+06    1.062626e+06       0.0
Os pattern   8.579712e+05    8.338048e+05 -0.030299
O3 pattern   1.090502e+06    1.067574e+06 -0.020481
```

Zero vs Pattern on master
```
               zero       pattern      diff
Os     8.292384e+05  8.579712e+05  0.036578
O3     1.062626e+06  1.090502e+06  0.025124
```

Zero vs Pattern with the patch
```
               zero       pattern      diff
Os     8.292384e+05  8.338048e+05  0.003333
O3     1.062626e+06  1.067574e+06  0.003193
```

Reviewers: pcc, eugenis

Subscribers: hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D63967

llvm-svn: 365858
2019-07-12 01:42:03 +00:00
Tim Northover 67828edbbd OpaquePtr: switch to GlobalValue::getValueType in a few places. NFC.
llvm-svn: 365770
2019-07-11 13:13:02 +00:00
Tim Northover 030bb3d363 InstructionSimplify: Simplify InstructionSimplify. NFC.
The interface predates CallBase, so both it and implementation were
significantly more complicated than they needed to be. There was even
some redundancy that could be eliminated.

Should also help with OpaquePointers by not trying to derive a
function's type from it's PointerType.

llvm-svn: 365767
2019-07-11 13:11:44 +00:00
Chen Zheng 627095ec5b [SCEV] teach SCEV symbolical execution about overflow intrinsics folding.
Differential Revision: https://reviews.llvm.org/D64422

llvm-svn: 365726
2019-07-11 02:18:22 +00:00
Johannes Doerfert 3ed286a388 Replace three "strip & accumulate" implementations with a single one
This patch replaces the three almost identical "strip & accumulate"
implementations for constant pointer offsets with a single one,
combining the respective functionalities. The old interfaces are kept
for now.

Differential Revision: https://reviews.llvm.org/D64468

llvm-svn: 365723
2019-07-11 01:14:48 +00:00
Vitaly Buka d03bd1db59 NFC: Pass DataLayout into isBytewiseValue
Summary:
We will need to handle IntToPtr which I will submit in a separate patch as it's
not going to be NFC.

Reviewers: eugenis, pcc

Reviewed By: eugenis

Subscribers: hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D63940

llvm-svn: 365709
2019-07-10 22:53:52 +00:00
Jinsong Ji 06fef0b359 Revert "[HardwareLoops] NFC - move hardware loop checking code to isHardwareLoopProfitable()"
This reverts commit d955573065.

llvm-svn: 365520
2019-07-09 17:53:09 +00:00
Chen Zheng d955573065 [HardwareLoops] NFC - move hardware loop checking code to isHardwareLoopProfitable()
Differential Revision: https://reviews.llvm.org/D64197

llvm-svn: 365497
2019-07-09 14:56:17 +00:00
Tim Northover 60afa49abe OpaquePtr: add Type parameter to Loads analysis API.
This makes the functions in Loads.h require a type to be specified
independently of the pointer Value so that when pointers have no structure
other than address-space, it can still do its job.

Most callers had an obvious memory operation handy to provide this type, but a
SROA and ArgumentPromotion were doing more complicated analysis. They get
updated to merge the properties of the various instructions they were
considering.

llvm-svn: 365468
2019-07-09 11:35:35 +00:00
Denis Bakhvalov 74be349bcf [SCEV] Fix for PR42397. SCEVExpander wrongly adds nsw to shl instruction.
Change-Id: I76c9f628c092ae3e6e78ebdaf55cec726e25d692
llvm-svn: 365363
2019-07-08 18:03:43 +00:00
Brian Homerding b4b21d807e Add, and infer, a nofree function attribute
This patch adds a function attribute, nofree, to indicate that a function does
not, directly or indirectly, call a memory-deallocation function (e.g., free,
C++'s operator delete).

Reviewers: jdoerfert

Differential Revision: https://reviews.llvm.org/D49165

llvm-svn: 365336
2019-07-08 15:57:56 +00:00
Eugene Leviant 3aef35288b [ThinLTO] Attempt to recommit r365188 after alignment fix
llvm-svn: 365215
2019-07-05 15:25:05 +00:00
Eugene Leviant e91f86f0ac Reverted r365188 due to alignment problems on i686-android
llvm-svn: 365206
2019-07-05 13:26:05 +00:00
Eugene Leviant 820cc01d1e [ThinLTO] Attempt to recommit r365040 after caching fix
It's possible that some function can load and store the same
variable using the same constant expression:

store %Derived* @foo, %Derived** bitcast (%Base** @bar to %Derived**)
%42 = load %Derived*, %Derived** bitcast (%Base** @bar to %Derived**)

The bitcast expression was mistakenly cached while processing loads,
and never examined later when processing store. This caused @bar to
be mistakenly treated as read-only variable. See load-store-caching.ll.

llvm-svn: 365188
2019-07-05 12:00:10 +00:00
Reid Kleckner f7e52fbdb5 Revert [ThinLTO] Optimize writeonly globals out
This reverts r365040 (git commit 5cacb91475)

Speculatively reverting, since this appears to have broken check-lld on
Linux. Partial analysis in https://crbug.com/981168.

llvm-svn: 365097
2019-07-04 00:03:30 +00:00
Evgeniy Stepanov 50dc28b556 Teach ValueTracking that aarch64.irg result aliases its input.
Reviewers: javed.absar, olista01

Subscribers: kristof.beyls, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64103

llvm-svn: 365079
2019-07-03 20:19:14 +00:00
Philip Reames 39e7a97ad7 [SCEV] Preserve flags on add/muls in getSCEVATScope
We haven't changed the set of users, just specialized an operand for those users.  Given that, the previous wrap flags must still be correct.

Sorry for the lack of test case.  Noticed this while working on something else, and haven't figured out to exercise this standalone.

llvm-svn: 365053
2019-07-03 16:34:08 +00:00
Eugene Leviant 5cacb91475 [ThinLTO] Optimize writeonly globals out
Differential revision: https://reviews.llvm.org/D63444

llvm-svn: 365040
2019-07-03 14:14:52 +00:00
Eugene Leviant ac407a7b4a [SCEV][LSR] Prevent using undefined value in binops
On some occasions ReuseOrCreateCast may convert previously
expanded value to undefined. That value may be passed by
SCEVExpander as an argument to InsertBinop making IV chain
undefined.

Differential revision: https://reviews.llvm.org/D63928 

llvm-svn: 365009
2019-07-03 09:36:32 +00:00
Jordan Rupprecht 02647f73d4 Revert [InlineCost] cleanup calculations of Cost and Threshold
This reverts r364422 (git commit 1a3dc76186)

The inlining cost calculation is incorrect, leading to stack overflow due to large stack frames from heavy inlining.

llvm-svn: 365000
2019-07-03 04:01:51 +00:00
Chen Zheng dfdccbb26b [PowerPC] exclude ICmpZero in LSR if icmp can be replaced in later hardware loop.
Differential Revision: https://reviews.llvm.org/D63477

llvm-svn: 364993
2019-07-03 01:49:03 +00:00
Teresa Johnson a700436323 [ThinLTO] Add summary entries for index-based WPD
Summary:
If LTOUnit splitting is disabled, the module summary analysis computes
the summary information necessary to perform single implementation
devirtualization during the thin link with the index and no IR. The
information collected from the regular LTO IR in the current hybrid WPD
algorithm is summarized, including:
1) For vtable definitions, record the function pointers and their offset
within the vtable initializer (subsumes the information collected from
IR by tryFindVirtualCallTargets).
2) A record for each type metadata summarizing the vtable definitions
decorated with that metadata (subsumes the TypeIdentiferMap collected
from IR).

Also added are the necessary bitcode records, and the corresponding
assembly support.

The follow-on index-based WPD patch is D55153.

Depends on D53890.

Reviewers: pcc

Subscribers: mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits

Differential Revision: https://reviews.llvm.org/D54815

llvm-svn: 364960
2019-07-02 19:38:02 +00:00
Kristof Umann 9353421ecd [IDF] Generalize IDFCalculator to be used with Clang's CFG
I'm currently working on a GSoC project that aims to improve the the bug reports
of the analyzer. The main heuristic I plan to use is to explain values that are
a control dependency of the bug location better.

01 bool b = messyComputation();
02 int i = 0;
03 if (b) // control dependency of the bug site, let's explain why we assume val
04        // to be true
05   10 / i; // warn: division by zero

Because of this, I'd like to generalize IDFCalculator so that I could use it for
Clang's CFG: D62883.

In detail:

* Rename IDFCalculator to IDFCalculatorBase, make it take a general CFG node
  type as a template argument rather then strictly BasicBlock (but preserve
  ForwardIDFCalculator and ReverseIDFCalculator)
* Move IDFCalculatorBase from llvm/include/llvm/Analysis to
  llvm/include/llvm/Support (but leave the BasicBlock variants in
  llvm/include/llvm/Analysis)
* clang-format the file since this patch messes up git blame anyways
* Change typedef to using
* Add the new type ChildrenGetterTy, and store an instance of it in
  IDFCalculatorBase. This is important because I'll have to specialize it for
  Clang's CFG to filter out nullpointer successors, similarly to D62507.

Differential Revision: https://reviews.llvm.org/D63389

llvm-svn: 364911
2019-07-02 11:30:12 +00:00
Fangrui Song 78ee2fbf98 Cleanup: llvm::bsearch -> llvm::partition_point after r364719
llvm-svn: 364720
2019-06-30 11:19:56 +00:00
Johannes Doerfert 6ed459fd41 Use "willreturn" in isGuaranteedToTransferExecutionToSuccessor
The `willreturn` function attribute guarantees that a function call will
come back to the call site if the call is also known not to throw.
Therefore, this attribute can be used in
`isGuaranteedToTransferExecutionToSuccessor`.

Patch by Hideto Ueno (@uenoku)

Reviewers: jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63372

llvm-svn: 364580
2019-06-27 19:29:48 +00:00
Philip Reames 1cf9e72cbc Update -analyze -scalar-evolution output for multiple exit loops w/computable exit values
The previous output was next to useless if *any* exit was not computable.  If we have more than one exit, show the exit count for each so that it's easier to see what's going from with SCEV analysis when debugging.

llvm-svn: 364579
2019-06-27 19:22:43 +00:00
Fedor Sergeev 1a3dc76186 [InlineCost] cleanup calculations of Cost and Threshold
Summary:
Doing better separation of Cost and Threshold.
Cost counts the abstract complexity of live instructions, while Threshold is an upper bound of complexity that inlining is comfortable to pay.
There are two parts:
     - huge 15K last-call-to-static bonus is no longer subtracted from Cost
       but rather is now added to Threshold.

       That makes much more sense, as the cost of inlining (Cost) is not changed by the fact
       that internal function is called once. It only changes the likelyhood of this inlining
       being profitable (Threshold).

     - bonus for calls proved-to-be-inlinable into callee is no longer subtracted from Cost
       but added to Threshold instead.

While calculations are somewhat different,  overall InlineResult should stay the same since Cost >= Threshold compares the same.

Reviewers: eraman, greened, chandlerc, yrouban, apilipenko
Reviewed By: apilipenko
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60740

llvm-svn: 364422
2019-06-26 13:24:24 +00:00
Chen Zheng aa99952896 [HardwareLoops] NFC - move loop with irreducible control flow checking logic to HarewareLoopInfo.
llvm-svn: 364415
2019-06-26 12:02:43 +00:00
Chen Zheng 46ce9e4fff [HardwareLoops] NFC - move loop with irreducible control flow checking logic to isHardwareLoopProfitable()
llvm-svn: 364397
2019-06-26 09:12:52 +00:00
Clement Courbet 3bc5ad551a [ExpandMemCmp] Move all options to TargetTransformInfo.
Split off from D60318.

llvm-svn: 364281
2019-06-25 08:04:13 +00:00
Bjorn Pettersson 485a421876 [ConstantFolding] Use hasVectorInstrinsicScalarOpd. NFC
Summary:
Use the hasVectorInstrinsicScalarOpd helper function
in ConstantFoldVectorCall.

Reviewers: rengolin, RKSimon, dblaikie

Reviewed By: rengolin, RKSimon

Subscribers: tschuett, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63705

llvm-svn: 364178
2019-06-24 12:07:17 +00:00
Bjorn Pettersson 512b118779 [Scalarizer] Add scalarizer support for smul.fix.sat
Summary:
Handle smul.fix.sat in the scalarizer. This is done by
adding smul.fix.sat to the set of "isTriviallyVectorizable"
intrinsics.

The addition of smul.fix.sat in isTriviallyVectorizable and
hasVectorInstrinsicScalarOpd can also be seen as a preparation
to be able to use hasVectorInstrinsicScalarOpd in ConstantFolding.

Reviewers: rengolin, RKSimon, dblaikie

Reviewed By: rengolin

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63704

llvm-svn: 364177
2019-06-24 12:07:11 +00:00
Fangrui Song dc8de6037c Simplify std::lower_bound with llvm::{bsearch,lower_bound}. NFC
llvm-svn: 364006
2019-06-21 05:40:31 +00:00
Sanjay Patel b342f026a4 [InstSimplify] simplify power-of-2 (single bit set) sequences
As discussed in PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314

Improving the canonicalization for these patterns:
rL363956
...means we should adjust/enhance the related simplification.

https://rise4fun.com/Alive/w1cp

  Name: isPow2 or zero
  %x = and i32 %xx, 2048
  %a = add i32 %x, -1
  %r = and i32 %a, %x
  =>
  %r = i32 0

llvm-svn: 363997
2019-06-20 22:55:28 +00:00
Alina Sbirlea 109d2ea153 [MemorySSA] Cleanup trivial phis.
Summary:
This is unfortunately needed for correctness, if we are to extend the tolerance of the update API to the way simple loop unswitch is doing cloning.

In simple loop unswitch (as opposed to loop unswitch), not all blocks are cloned. This can create unreachable cloned blocks (no predecessor), which are later cleaned up.

In MemorySSA, the  APIs for supporting these kind of updates (clone + update exit blocks), make certain assumption on the integrity of the CFG. When cloning, if something was not cloned, it's values in MemorySSA default to LiveOnEntry. When updating exit blocks, it is safe to assume that we can first insert phis in the blocks merging two clones, then add additional phis in the IDF of the blocks that received phis. This no longer holds true if one of the clones being merged comes from an unreachable block. We'd conservatively need to add all phis before filling in their incoming definitions. In practice this restriction can be relaxed if we clean up trivial phis after the first round of insertion.

Reviewers: george.burgess.iv

Subscribers: jlebar, Prazek, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63354

llvm-svn: 363880
2019-06-19 21:33:09 +00:00
Alina Sbirlea 238b8e62b6 [MemorySSA] Use GraphDiff info when computing IDF.
Summary:
When computing IDF for insert updates, ensure we use the snapshot CFG offered by GraphDiff.
Caught by D63389.

Reviewers: kuhar, george.burgess.iv

Subscribers: jlebar, Prazek, llvm-commits, Szelethus

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63443

llvm-svn: 363879
2019-06-19 21:17:31 +00:00
Bjorn Pettersson 16ff5fea87 [ConstantFolding] Add constant folding for smul.fix and smul.fix.sat
Summary:
This patch teaches ConstantFolding to constant fold
both scalar and vector variants of llvm.smul.fix and
llvm.smul.fix.sat.

As described in the LangRef rounding is unspecified for
these instrinsics. If the result cannot be represented
exactly the default behavior in ConstantFolding is to
round down towards negative infinity. If a target has a
preferred rounding that is different some kind of target
hook would be needed (same strategy as used by the
SelectionDAG legalizer).

Reviewers: nikic, leonardchan, RKSimon

Reviewed By: leonardchan

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63385

llvm-svn: 363811
2019-06-19 14:28:03 +00:00
Bjorn Pettersson b81b9a4e7b [ConstantFolding] Refactor ConstantFoldScalarCall. NFC
This patch splits ConstantFoldScalarCall into several
functions.

Benefits:
- Reduces indentation levels and avoids long if-statements.
- Makes it easier to add support for > 3 operands.

llvm-svn: 363810
2019-06-19 14:27:51 +00:00
Jay Foad 45d19fb470 [ConstantFolding] Fix assertion failure on non-power-of-two vector load.
Summary:
The test case does an (out of bounds) load from a global constant with
type <3 x float>. InstSimplify tried to turn this into an integer load
of the whole alloc size of the vector, which is 128 bits due to
alignment padding, and then bitcast this to <3 x vector> which failed
an assertion due to the type size mismatch.

The fix is to do an integer load of the normal size of the vector, with
no alignment padding.

Reviewers: tpr, arsenm, majnemer, dstuttard

Reviewed By: arsenm

Subscribers: hfinkel, wdng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63375

llvm-svn: 363784
2019-06-19 10:28:48 +00:00
Chen Zheng c5b918de58 [NFC] move some hardware loop checking code to a common place for other using.
Differential Revision: https://reviews.llvm.org/D63478

llvm-svn: 363758
2019-06-19 01:26:31 +00:00
Amara Emerson 146882242f [GlobalISel][Localizer] Rewrite localizer to run in 2 phases, inter & intra block.
Inter-block localization is the same as what currently happens, except now it
only runs on the entry block because that's where the problematic constants with
long live ranges come from.

The second phase is a new intra-block localization phase which attempts to
re-sink the already localized instructions further right before one of the
multiple uses.

One additional change is to also localize G_GLOBAL_VALUE as they're constants
too. However, on some targets like arm64 it takes multiple instructions to
materialize the value, so some additional heuristics with a TTI hook have been
introduced attempt to prevent code size regressions when localizing these.

Overall, these changes improve CTMark code size on arm64 by 1.2%.

Full code size results:

Program                                         baseline       new       diff
------------------------------------------------------------------------------
 test-suite...-typeset/consumer-typeset.test    1249984      1217216     -2.6%
 test-suite...:: CTMark/ClamAV/clamscan.test    1264928      1232152     -2.6%
 test-suite :: CTMark/SPASS/SPASS.test          1394092      1361316     -2.4%
 test-suite...Mark/mafft/pairlocalalign.test    731320       714928      -2.2%
 test-suite :: CTMark/lencod/lencod.test        1340592      1324200     -1.2%
 test-suite :: CTMark/kimwitu++/kc.test         3853512      3820420     -0.9%
 test-suite :: CTMark/Bullet/bullet.test        3406036      3389652     -0.5%
 test-suite...ark/tramp3d-v4/tramp3d-v4.test    8017000      8016992     -0.0%
 test-suite...TMark/7zip/7zip-benchmark.test    2856588      2856588      0.0%
 test-suite...:: CTMark/sqlite3/sqlite3.test    765704       765704       0.0%
 Geomean difference                                                      -1.2%

Differential Revision: https://reviews.llvm.org/D63303

llvm-svn: 363632
2019-06-17 23:20:29 +00:00
Philip Reames 44475363e8 Teach getSCEVAtScope how to handle loop phis w/invariant operands in loops w/taken backedges
This patch really contains two pieces:
    Teach SCEV how to fold a phi in the header of a loop to the value on the backedge when a) the backedge is known to execute at least once, and b) the value is safe to use globally within the scope dominated by the original phi.
    Teach IndVarSimplify's rewriteLoopExitValues to allow loop invariant expressions which already exist (and thus don't need new computation inserted) even in loops where we can't optimize away other uses.

Differential Revision: https://reviews.llvm.org/D63224

llvm-svn: 363619
2019-06-17 21:06:17 +00:00
Alina Sbirlea 7a0098aa6e [MemorySSA] Don't use template when the clone is a simplified instruction.
Summary:
LoopRotate doesn't create a faithful clone of an instruction, it may
simplify it beforehand. Hence the clone of an instruction that has a
MemoryDef associated may not be a definition, but a use or not a memory
alternig instruction.
Don't rely on the template when the clone may be simplified.

Reviewers: george.burgess.iv

Subscribers: jlebar, Prazek, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63355

llvm-svn: 363597
2019-06-17 18:58:40 +00:00
Alina Sbirlea 05f77803f4 [MemorySSA] Add all MemoryPhis before filling their values.
Summary:
Add all MemoryPhis in IDF before filling in their incomign values.
Otherwise, a new Phi can be added that needs to become the incoming
value of another Phi.
Test fails the verification in verifyPrevDefInPhis.

Reviewers: george.burgess.iv

Subscribers: jlebar, Prazek, zzheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63353

llvm-svn: 363590
2019-06-17 18:16:53 +00:00
Warren Ristow 6452bdd29b [LV] Suppress vectorization in some nontemporal cases
When considering a loop containing nontemporal stores or loads for
vectorization, suppress the vectorization if the corresponding
vectorized store or load with the aligment of the original scaler
memory op is not supported with the nontemporal hint on the target.

This adds two new functions:
  bool isLegalNTStore(Type *DataType, unsigned Alignment) const;
  bool isLegalNTLoad(Type *DataType, unsigned Alignment) const;

to TTI, leaving the target independent default implementation as
returning true, but with overriding implementations for X86 that
check the legality based on available Subtarget features.

This fixes https://llvm.org/PR40759

Differential Revision: https://reviews.llvm.org/D61764

llvm-svn: 363581
2019-06-17 17:20:08 +00:00
Sam Parker 60d6fb2a63 [SCEV] Use NoWrapFlags when expanding a simple mul
Second functional change following on from rL362687. Pass the
NoWrapFlags from the MulExpr to InsertBinop when we're generating a
shl or mul.

Differential Revision: https://reviews.llvm.org/D61934

llvm-svn: 363540
2019-06-17 10:05:18 +00:00
Roman Lebedev 5a663bd77a [InstSimplify] Fix addo/subo undef folds (PR42209)
Fix folds of addo and subo with an undef operand to be:

`@llvm.{u,s}{add,sub}.with.overflow` all fold to `{ undef, false }`,
 as per LLVM undef rules.
Same for commuted variants.

Based on the original version of the patch by @nikic.

Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=42209 | PR42209 ]]

Differential Revision: https://reviews.llvm.org/D63065

llvm-svn: 363522
2019-06-16 20:39:45 +00:00
Nikita Popov 8550fb386a [SCEV] Use unsigned/signed intersection type in SCEV
Based on D59959, this switches SCEV to use unsigned/signed range
intersection based on the sign hint. This will prefer non-wrapping
ranges in the relevant domain. I've left the one intersection in
getRangeForAffineAR() to use the smallest intersection heuristic,
as there doesn't seem to be any obvious preference there.

Differential Revision: https://reviews.llvm.org/D60035

llvm-svn: 363490
2019-06-15 09:15:52 +00:00