Commit Graph

7231 Commits

Author SHA1 Message Date
Zhaoshi Zheng f47c27513b revert test commit r298629
llvm-svn: 298630
2017-03-23 17:52:20 +00:00
Zhaoshi Zheng 49ae35580e test commit
llvm-svn: 298629
2017-03-23 17:38:47 +00:00
Craig Topper 93683b6aff [ValueTracking] Use APInt::isNegative instead of using operator[BitWidth-1]. NFCI
llvm-svn: 298584
2017-03-23 07:06:42 +00:00
Craig Topper d73c6b4ef8 [ValueTracking] Use setAllBits/setSignBit/setLowBits/setHighBits. NFCI
llvm-svn: 298583
2017-03-23 07:06:39 +00:00
Anna Thomas e27b39a976 [LVI] Add an LVI printer pass to capture test LVI cache after transformations
Summary:
Adding a printer pass for printing the LVI cache values after transformations
that use LVI.
This will help us in identifying cases where LVI
invariants are violated, or transforms that leave LVI in an incorrect state.
Right now, I have added two test cases to show that the printer pass is working.
I will be adding more test cases in a later change, once this change is
checked in upstream.

Reviewers: reames, dberlin, sanjoy, apilipenko

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D30790

llvm-svn: 298542
2017-03-22 19:27:12 +00:00
Max Kazantsev c6effaa495 Revert "[ScalarEvolution] Predicate implication from operations"
This reverts commit rL298481

Fails clang-with-lto-ubuntu build.

llvm-svn: 298489
2017-03-22 07:50:33 +00:00
Craig Topper ad5c2d04f7 [ValueTracking] Make sure we keep range metadata information when calculating known bits for calls to bitreverse intrinsic.
llvm-svn: 298488
2017-03-22 07:22:49 +00:00
Craig Topper 57d8ca72d1 [ValueTracking] use setLowBits/setHighBits/setBitsFrom to replace |= getHighBits/getLowBits. NFCI
llvm-svn: 298486
2017-03-22 06:19:37 +00:00
Max Kazantsev 15e76aa0f8 [ScalarEvolution] Predicate implication from operations
This patch allows SCEV predicate analysis to prove implication of some expression predicates
from context predicates related to arguments of those expressions.
It introduces three new rules:

For addition:
  (A >X && B >= 0) || (B >= 0 && A > X) ===> (A + B) > X.

For division:
  (A > X) && (0 < B <= X + 1) ===> (A / B > 0).
  (A > X) && (-B <= X < 0) ===> (A / B >= 0).

Using these rules, SCEV is able to prove facts like "if X > 1 then X / 2 > 0".
They can also be combined with the same context, to prove more complex expressions like
"if X > 1 then X/2 + 1 > 1".

Diffirential Revision: https://reviews.llvm.org/D30887

Reviewed by: sanjoy

llvm-svn: 298481
2017-03-22 04:48:46 +00:00
George Burgess IV 56c7e88c2c Let llvm.objectsize be conservative with null pointers
This adds a parameter to @llvm.objectsize that makes it return
conservative values if it's given null.

This fixes PR23277.

Differential Revision: https://reviews.llvm.org/D28494

llvm-svn: 298430
2017-03-21 20:08:59 +00:00
Dehao Chen 9907e9d860 Do not inline hot callsites for samplepgo in thinlto compile phase.
Summary: Because SamplePGO passes will be invoked twice in ThinLTO build: once at compile phase, the other at backend. We want to make sure the IR at the 2nd phase matches the hot part in profile, thus we do not want to inline hot callsites in the first phase.

Reviewers: tejohnson, eraman

Reviewed By: tejohnson

Subscribers: mehdi_amini, llvm-commits, Prazek

Differential Revision: https://reviews.llvm.org/D31201

llvm-svn: 298428
2017-03-21 19:55:36 +00:00
Dehao Chen 190f17cae7 Use ProfileSummary:getProfileCount to get ScaledCount for ModuleSummary
Summary: ModuleSummary should use the standard interface of ProfileSummary::getProfileCount.

Reviewers: eraman, tejohnson

Reviewed By: tejohnson

Subscribers: tejohnson, mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D31154

llvm-svn: 298404
2017-03-21 17:22:35 +00:00
Reid Kleckner b518054b87 Rename AttributeSet to AttributeList
Summary:
This class is a list of AttributeSetNodes corresponding the function
prototype of a call or function declaration. This class used to be
called ParamAttrListPtr, then AttrListPtr, then AttributeSet. It is
typically accessed by parameter and return value index, so
"AttributeList" seems like a more intuitive name.

Rename AttributeSetImpl to AttributeListImpl to follow suit.

It's useful to rename this class so that we can rename AttributeSetNode
to AttributeSet later. AttributeSet is the set of attributes that apply
to a single function, argument, or return value.

Reviewers: sanjoy, javed.absar, chandlerc, pete

Reviewed By: pete

Subscribers: pete, jholewinski, arsenm, dschuff, mehdi_amini, jfb, nhaehnle, sbc100, void, llvm-commits

Differential Revision: https://reviews.llvm.org/D31102

llvm-svn: 298393
2017-03-21 16:57:19 +00:00
David Green da21170c49 [ConstantFolding] Fix to prevent constant folding having to repeatedly scan operands. NFCI
After the loop unroll threshold was increased in r295538, very
large constant expressions can be created. This prevents them
from having to be recursively scanned, leading to a compile
time blow-up.

Differential Revision: https://reviews.llvm.org/D30689

llvm-svn: 298356
2017-03-21 10:17:39 +00:00
Eli Friedman b1578d3612 [SCEV] Fix trip multiple calculation
If loop bound containing calculations like min(a,b), the Scalar
Evolution API getSmallConstantTripMultiple returns 4294967295 "-1"
as the trip multiple. The problem is that, SCEV use -1 * umax to
represent umin. The multiple constant -1 was returned, and the logic
of guarding against huge trip counts was skipped. Because -1 has 32
active bits.

The fix attempt to factor more general cases. First try to get the
greatest power of two divisor of trip count expression. In case
overflow happens, the trip count expression is still divisible by the
greatest power of two divisor returned. Returns 1 if not divisible by 2.

Patch by Huihui Zhang <huihuiz@codeaurora.org>

Differential Revision: https://reviews.llvm.org/D30840

llvm-svn: 298301
2017-03-20 20:25:46 +00:00
Simon Pilgrim 00b34996b4 Use MutableArrayRef for APFloat::convertToInteger
As discussed on D31074, use MutableArrayRef for destination integer buffers to help assert before stack overflows happen.

llvm-svn: 298253
2017-03-20 14:40:12 +00:00
Xin Tong aef0fcb191 Extract FindAvailablePtrLoadStore out of FindAvailableLoadedValue. NFCI
Summary:
Extract FindAvailablePtrLoadStore out of FindAvailableLoadedValue.
Prepare for upcoming change which will do phi-translation for load on
phi pointer in jump threading SimplifyPartiallyRedundantLoad.

This is in preparation for https://reviews.llvm.org/D30543

Reviewers: efriedma, sanjoy, davide, dberlin

Reviewed By: davide

Subscribers: junbuml, davide, llvm-commits

Differential Revision: https://reviews.llvm.org/D30524

llvm-svn: 298216
2017-03-19 15:27:52 +00:00
Brian Gesiak 1640e68728 [Analysis] bitreverse(undef) returns undef
Summary:
The reverse of an artbitrary bitpattern is also an arbitrary
bitpattern.

Reviewers: trentxintong, arsenm, majnemer

Reviewed By: majnemer

Subscribers: majnemer, wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D31118

llvm-svn: 298201
2017-03-19 04:40:42 +00:00
Craig Topper 7cfd4a9d7a [ValueTracking] Remove deadish code from computeKnownBitsAddSub.
The code assigned to KnownZero, but later code unconditionally assigned over it. I'm pretty sure the later code can handle the same cases and more equally well.

llvm-svn: 298190
2017-03-18 18:21:46 +00:00
Craig Topper 3eb0d80de0 [ValueTracking] Add APInt::setSignBit and use it to replace ORing with getSignBit which will malloc if the bit width is larger than 64.
llvm-svn: 298180
2017-03-18 04:01:29 +00:00
Eli Friedman f7b060bd3e [SCEV] Use const Loop *L instead of Loop *L. NFC
Use const pointer in the trip count and trip multiple calculations.

Patch by Huihui Zhang <huihuiz@codeaurora.org>

llvm-svn: 298161
2017-03-17 22:19:52 +00:00
Michael Zolotukhin 99de88d1f3 [SCEV] Compute affine range in another way to avoid bitwidth extending.
Summary:
This approach has two major advantages over the existing one:
1. We don't need to extend bitwidth in our computations. Extending
bitwidth is a big issue for compile time as we often end up working with
APInts wider than 64bit, which is a slow case for APInt.
2. When we zero extend a wrapped range, we lose some information (we
replace the range with [0, 1 << src bit width)). Thus, avoiding such
extensions better preserves information.

Correctness testing:
I ran 'ninja check' with assertions that the new implementation of
getRangeForAffineAR gives the same results as the old one (this
functionality is not present in this patch). There were several failures
- I inspected them manually and found out that they all are caused by
the fact that we're returning more accurate results now (see bullet (2)
above).
Without such assertions 'ninja check' works just fine, as well as
SPEC2006.

Compile time testing:
CTMark/Os:
 - mafft/pairlocalalign	-16.98%
 - tramp3d-v4/tramp3d-v4	-12.72%
 - lencod/lencod	-11.51%
 - Bullet/bullet	-4.36%
 - ClamAV/clamscan	-3.66%
 - 7zip/7zip-benchmark	-3.19%
 - sqlite3/sqlite3	-2.95%
 - SPASS/SPASS	-2.74%
 - Average	-5.81%

Performance testing:
The changes are expected to be neutral for runtime performance.

Reviewers: sanjoy, atrick, pete

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D30477

llvm-svn: 297992
2017-03-16 21:07:38 +00:00
Oliver Stannard 062041113f [ValueTracking] Out of range shifts might be undef
If it is possible for the RHS of a shift operation to be greater than or equal
to the bit-width, then the result might be undef, and we can't report any known
bits.

In some cases, this was allowing a transformation in instcombine which widened
an undef value from i1 to i32, increasing the range of values that a function
could return.

Differential revision: https://reviews.llvm.org/D30781

llvm-svn: 297724
2017-03-14 10:13:17 +00:00
Jonas Paulsson a48ea231c0 [TargetTransformInfo] getIntrinsicInstrCost() scalarization estimation improved
getIntrinsicInstrCost() used to only compute scalarization cost based on types.
This patch improves this so that the actual arguments are checked when they are
available, in order to handle only unique non-constant operands.

Tests updates:

Analysis/CostModel/X86/arith-fp.ll
Transforms/LoopVectorize/AArch64/interleaved_cost.ll
Transforms/LoopVectorize/ARM/interleaved_cost.ll

The improvement in getOperandsScalarizationOverhead() to differentiate on
constants made it necessary to update the interleaved_cost.ll tests even
though they do not relate to intrinsics.

Review: Hal Finkel
https://reviews.llvm.org/D29540

llvm-svn: 297705
2017-03-14 06:35:36 +00:00
Anna Thomas a10e3e4c34 [LVI] Add Datalayout to the class LazyValueInfo since all its Impls require it. NFC
llvm-svn: 297583
2017-03-12 14:06:41 +00:00
Sanjoy Das 3f1e8e0102 Use a WeakVH for UnknownInstructions in AliasSetTracker
Summary:
This change solves the same problem as D30726, except that this only
throws out the bathwater.

AST was not correctly tracking and deleting UnknownInstructions via
handles.  The existing code only tracks "pointers" in its
`ASTCallbackVH`, so an UnknownInstruction (that isn't also def'ing a
pointer used by another memory instruction) never gets a
`ASTCallbackVH`.

There are two other ways to solve this problem:

 - Use the `PointerRec` scheme for both known and unknown instructions.
 - Use a `CallbackVH` that erases the offending Instruction from the
   UnknownInstruction list.

Both of the above changes seemed to be significantly (and unnecessarily
IMO) more complex than this.

Reviewers: chandlerc, dberlin, hfinkel, reames

Subscribers: mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D30849

llvm-svn: 297539
2017-03-11 01:15:48 +00:00
Davide Italiano 574e59786e [ProfileSummaryInfo] Remove unneeded braces. NFCI.
llvm-svn: 297506
2017-03-10 20:50:51 +00:00
Dehao Chen c2048155a0 Refactor the PSI to extract getCallSiteCount and remove checks for profile type.
Summary: There is no need to check profile count as only CallInst will have metadata attached.

Reviewers: eraman

Reviewed By: eraman

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D30799

llvm-svn: 297500
2017-03-10 19:45:16 +00:00
Michael Kuperstein 5fb39a7966 [SLP] Revert everything that has to do with memory access sorting.
This reverts r293386, r294027, r294029 and r296411.

Turns out the SLP tree isn't actually a "tree" and we don't handle
accessing the same packet of loads in several different orders well,
causing miscompiles.

Revert until we can fix this properly.

llvm-svn: 297493
2017-03-10 18:59:07 +00:00
Yaron Keren 1de4792c55 Implement getPassName() for IR printing passes.
llvm-svn: 297442
2017-03-10 07:09:20 +00:00
Dehao Chen 22645eea7a Do not use branch metadata to check if a basic block is hot.
Summary: We should not use that to check basic block hotness as optimization may mess it up.

Reviewers: eraman

Reviewed By: eraman

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D30800

llvm-svn: 297437
2017-03-10 01:44:37 +00:00
Sanjay Patel 962a8431ea [InstSimplify] allow folds for bool vector div/rem
llvm-svn: 297411
2017-03-09 21:56:03 +00:00
Sanjay Patel 2b1f6f4b92 [InstSimplify] vector div/rem with any zero element in divisor is undef
This was suggested as a DAG simplification in the review for rL297026 :
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170306/435253.html
...but let's start with IR since we have actual docs for IR (LangRef).

Differential Revision:
https://reviews.llvm.org/D30665

llvm-svn: 297390
2017-03-09 16:20:52 +00:00
Teresa Johnson d820447212 Perform symbol binding for .symver versioned symbols
Summary:
In a .symver assembler directive like:
.symver name, name2@@nodename
"name2@@nodename" should get the same symbol binding as "name".

While the ELF object writer is updating the symbol binding for .symver
aliases before emitting the object file, not doing so when the module
inline assembly is handled by the RecordStreamer is causing the wrong
behavior in *LTO mode.

E.g. when "name" is global, "name2@@nodename" must also be marked as
global. Otherwise, the symbol is skipped when iterating over the LTO
InputFile symbols (InputFile::Symbol::shouldSkip). So, for example,
when performing any *LTO via the gold-plugin, the versioned symbol
definition is not recorded by the plugin and passed back to the
linker. If the object was in an archive, and there were no other symbols
needed from that object, the object would not be included in the final
link and references to the versioned symbol are undefined.

The llvm-lto2 tests added will give an error about an unused symbol
resolution without the fix.

Reviewers: rafael, pcc

Reviewed By: pcc

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D30485

llvm-svn: 297332
2017-03-09 00:19:49 +00:00
Amjad Aboud 5448e989a5 [SLP] Fixed non-deterministic behavior in Loop Vectorizer.
Differential Revision: https://reviews.llvm.org/D30638

llvm-svn: 297257
2017-03-08 05:09:10 +00:00
Sebastian Pop 4a4d245b19 Handle UnreachableInst in isGuaranteedToTransferExecutionToSuccessor
A block with an UnreachableInst does not transfer execution to a successor.
The problem was exposed by GVN-hoist. This patch fixes bug 32153.

Patch by Aditya Kumar.

Differential Revision: https://reviews.llvm.org/D30667

llvm-svn: 297254
2017-03-08 01:54:50 +00:00
Michael Kuperstein 768d013a03 [SLP] Revert r296863 due to miscompiles.
Details and reproducer are on the email thread for r296863.

llvm-svn: 297103
2017-03-06 23:54:51 +00:00
Sanjay Patel 0cb2ee9287 [InstSimplify] refactor related div/rem folds; NFCI
llvm-svn: 297052
2017-03-06 19:08:35 +00:00
Sanjay Patel 79a9ecbe80 [InstSimplify] remove misleading comments; NFC
Div/rem-of-0 does not cause faults/undef (not the same as div/rem-by-0).

llvm-svn: 297029
2017-03-06 16:49:35 +00:00
Sanjoy Das 1bd479dd5c [SCEV] Decrease the recursion threshold for CompareValueComplexity
Fixes PR32142.

r287232 accidentally increased the recursion threshold for
CompareValueComplexity from 2 to 32.  This change reverses that change
by introducing a separate flag for CompareValueComplexity's threshold.

llvm-svn: 296992
2017-03-05 23:49:17 +00:00
Mohammad Shahid bdac9f30c0 [SLP] Fixes the bug due to absence of in order uses of scalars which needs to be available
for VectorizeTree() API.This API uses it for proper mask computation to be used in shufflevector IR.
The fix is to compute the mask for out of order memory accesses while building the vectorizable tree
instead of actual vectorization of vectorizable tree.It also needs to recompute the proper Lane for
external use of vectorizable scalars based on shuffle mask.

Reviewers: mkuper

Differential Revision: https://reviews.llvm.org/D30159

Change-Id: Ide8773ce0ad3562f3cf4d1a0ad0f487e2f60ce5d
llvm-svn: 296863
2017-03-03 10:02:47 +00:00
Hans Wennborg cc4ff78c9d Revert r296575 "[SLP] Fixes the bug due to absence of in order uses of scalars which needs to be available"
It caused miscompiles, e.g. in Chromium (PR32109).

llvm-svn: 296654
2017-03-01 18:57:16 +00:00
Igor Laevsky 37cba43604 [BasicAA] Take attributes into account when requesting modref info for a call site
Differential Revision: https://reviews.llvm.org/D29989

llvm-svn: 296617
2017-03-01 13:19:51 +00:00
Mohammad Shahid 175ffa8c35 [SLP] Fixes the bug due to absence of in order uses of scalars which needs to be available
for VectorizeTree() API.This API uses it for proper mask computation to be used in shufflevector IR.
The fix is to compute the mask for out of order memory accesses while building the vectorizable tree
instead of actual vectorization of vectorizable tree.

Reviewers: mkuper

Differential Revision: https://reviews.llvm.org/D30159

Change-Id: Id1e287f073fa4959713ba545fa4254db5da8b40d
llvm-svn: 296575
2017-03-01 03:51:54 +00:00
Francis Visoiu Mistrih 262ad16a3a [LCG] Fix EXPENSIVE_CHECKS typo. NFC
Differential Revision: https://reviews.llvm.org/D30434

llvm-svn: 296500
2017-02-28 18:34:55 +00:00
Dehao Chen a60cdd3881 Add function importing info from samplepgo profile to the module summary.
Summary: For SamplePGO, the profile may contain cross-module inline stacks. As we need to make sure the profile annotation happens when all the hot inline stacks are expanded, we need to pass this info to the module importer so that it can import proper functions if necessary. This patch implemented this feature by emitting cross-module targets as part of function entry metadata. In the module-summary phase, the metadata is used to build call edges that points to functions need to be imported.

Reviewers: mehdi_amini, tejohnson

Reviewed By: tejohnson

Subscribers: davidxl, llvm-commits

Differential Revision: https://reviews.llvm.org/D30053

llvm-svn: 296498
2017-02-28 18:09:44 +00:00
Michael Kuperstein c07cca85fb [SLP] Load sorting should not try to sort things that aren't loads.
We may get a VL where the first element is a load, but the others
aren't. Trying to sort such VLs can only lead to sorrow.

llvm-svn: 296411
2017-02-27 23:18:11 +00:00
Sanjoy Das 39a684d117 [ValueTracking] Don't do an unchecked shift in ComputeNumSignBits
Summary:
Previously we used to return a bogus result, 0, for IR like `ashr %val,
-1`.

I've also added an assert checking that `ComputeNumSignBits` at least
returns 1.  That assert found an already checked in test case where we
were returning a bad result for `ashr %val, -1`.

Fixes PR32045.

Reviewers: spatel, majnemer

Reviewed By: spatel, majnemer

Subscribers: efriedma, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D30311

llvm-svn: 296273
2017-02-25 20:30:45 +00:00
Easwaran Raman a8b9cdc9e2 [InlineCost] Move the code in isGEPOffsetConstant to a lambda.
Differential revision: https://reviews.llvm.org/D30112

llvm-svn: 296208
2017-02-25 00:10:22 +00:00
Xin Tong 68ea9aa23a Fix Indentation. NFCI
llvm-svn: 296169
2017-02-24 20:59:26 +00:00
Adam Nemet 2531df3d49 [ORE] Remove ORE.emit{{.+}} functions
Last use was killed in my previous patch. The preferred way is now to
construct the remark, pipe things to it and pass it to ORE.emit.

llvm-svn: 296019
2017-02-23 21:32:53 +00:00
Adam Nemet 41b019a39c [LAA] Remove unused LoopAccessReport
The need for this removed when I converted everything to use the opt-remark
classes directly with the streaming interface.

llvm-svn: 296017
2017-02-23 21:17:36 +00:00
Davide Italiano e122d6885a [ModuleSummaryAnalysis] Don't crash when referencing unnamed globals.
Instead, just be conservative as these are unfrequent enough. Thanks
to Peter Collingbourne for the discussion about this on IRC.

llvm-svn: 295861
2017-02-22 18:53:38 +00:00
Justin Bogner 8281c81413 OptDiag: Add const to some interfaces that don't modify anything. NFC
This needed a const_cast for the dominator tree recalculation in
OptimizationRemarkEmitter, but we do that all over the place already
and it's safe.

llvm-svn: 295812
2017-02-22 07:38:17 +00:00
Sanjoy Das 5cd6c5cacf [ValueTracking] Make poison propagation more aggressive
Summary:
Motivation: fix PR31181 without regression (the actual fix is still in
progress).  However, the actual content of PR31181 is not relevant
here.

This change makes poison propagation more aggressive in the following
cases:

 1. poision * Val == poison, for any Val.  In particular, this changes
    existing intentional and documented behavior in these two cases:
     a. Val is 0
     b. Val is 2^k * N
 2. poison << Val == poison, for any Val
 3. getelementptr is poison if any input is poison

I think all of these are justified (and are axiomatically true in the
new poison / undef model):

1a: we need poison * 0 to be poison to allow transforms like these:

  A * (B + C) ==> A * B + A * C

If poison * 0 were 0 then the above transform could not be allowed
since e.g. we could have A = poison, B = 1, C = -1, making the LHS

  poison * (1 + -1) = poison * 0 = 0

and the RHS

  poison * 1 + poison * -1 = poison + poison = poison

1b: we need e.g. poison * 4 to be poison since we want to allow

  A * 4 ==> A + A + A + A

If poison * 4 were a value with all of their bits poison except the
last four; then we'd not be able to do this transform since then if A
were poison the LHS would only be "partially" poison while the RHS
would be "full" poison.

2: Same reasoning as (1b), we'd like have the following kinds
transforms be legal:

  A << 1 ==> A + A

Reviewers: majnemer, efriedma

Subscribers: mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D30185

llvm-svn: 295809
2017-02-22 06:52:32 +00:00
Sanjoy Das 7b0b408973 [ValueTracking] clang-format a section I'm about to touch; NFC
(Whitespace only change)

llvm-svn: 295690
2017-02-21 02:42:42 +00:00
Sanjay Patel fe67255961 [InstSimplify] add nsw/nuw (xor X, signbit), signbit --> X
The change to InstCombine in:
https://reviews.llvm.org/D29729
...exposes this missing fold in InstSimplify, so adding this
first to avoid a regression.

llvm-svn: 295573
2017-02-18 21:59:09 +00:00
Easwaran Raman 617f63640b Refactor instruction simplification code in visitors. NFC.
Several visitors check if operands to the instruction are constants,
either as it is or after looking up SimplifiedValues, check if the
result is a constant and update the SimplifiedValues map. This
refactoring splits it into a common function that does the checking of
whether the operands are constants and updating of the SimplifiedValues
table, and an instruction specific part that is implemented by each
instruction visitor as a lambda and passed to the common function.

Differential revision: https://reviews.llvm.org/D30104

llvm-svn: 295552
2017-02-18 17:22:52 +00:00
Justin Bogner d890f95bf6 OptDiag: Decouple backend diagnostics from debug info metadata
This creates and uses a DiagnosticLocation type rather than using
DebugLoc for this purpose in the backend diagnostics. This is NFC for
now, but will allow us to create locations for diagnostics without
having to create new metadata nodes when we don't have a DILocation.

llvm-svn: 295519
2017-02-18 00:42:23 +00:00
Matthew Simpson a899f86054 [LAA] Remove unused code (NFC)
llvm-svn: 295493
2017-02-17 20:46:52 +00:00
Peter Collingbourne 9421c2dc54 AssumptionCache: Disable the verifier by default, move it behind a hidden cl::opt and verify from releaseMemory().
This is a short term solution to the problem that many passes currently fail
to update the assumption cache. In the long term the verifier should not
be controllable with a flag. We should either fix all passes to correctly
update the assumption cache and enable the verifier unconditionally or
somehow arrange for the assumption list to be updated automatically by passes.

Differential Revision: https://reviews.llvm.org/D30003

llvm-svn: 295236
2017-02-15 21:10:09 +00:00
Adam Nemet 4c98023724 [LazyBFI] Fix typos
llvm-svn: 295073
2017-02-14 17:21:12 +00:00
Igor Laevsky c11c1ed909 [SCEV] Cache results during GetMinTrailingZeros query
Differential Revision: https://reviews.llvm.org/D29759

llvm-svn: 295060
2017-02-14 15:53:12 +00:00
Sanjay Patel 97e4b98749 [ValueTracking] use nonnull argument attribute to eliminate null checks
Enhancing value tracking's analysis of null-ness was suggested in D27855, so here's a first attempt at that.

This is part of solving:
https://llvm.org/bugs/show_bug.cgi?id=28430

Differential Revision: https://reviews.llvm.org/D28204

llvm-svn: 294897
2017-02-12 15:35:34 +00:00
Dorit Nuzman eac89d736c [LV/LoopAccess] Check statically if an unknown dependence distance can be
proven larger than the loop-count

This fixes PR31098: Try to resolve statically data-dependences whose
compile-time-unknown distance can be proven larger than the loop-count, 
instead of resorting to runtime dependence checking (which are not always 
possible).

For vectorization it is sufficient to prove that the dependence distance 
is >= VF; But in some cases we can prune unknown dependence distances early,
and even before selecting the VF, and without a runtime test, by comparing 
the distance against the loop iteration count. Since the vectorized code 
will be executed only if LoopCount >= VF, proving distance >= LoopCount 
also guarantees that distance >= VF. This check is also equivalent to the 
Strong SIV Test.

Reviewers: mkuper, anemet, sanjoy

Differential Revision: https://reviews.llvm.org/D28044

llvm-svn: 294892
2017-02-12 09:32:53 +00:00
Peter Collingbourne be9ffaacfa IR: Function summary extensions for whole-program devirtualization pass.
The summary information includes all uses of llvm.type.test and
llvm.type.checked.load intrinsics that can be used to devirtualize calls,
including any constant arguments for virtual constant propagation.

Differential Revision: https://reviews.llvm.org/D29734

llvm-svn: 294795
2017-02-10 22:29:38 +00:00
Chandler Carruth 1f8fcfeac5 [PM/LCG] Teach LCG to support spurious reference edges.
Somewhat amazingly, this only requires teaching it to clean them up when
deleting a dead function from the graph. And we already have exactly the
necessary data structures to do that in the parent RefSCCs.

This allows ArgPromote to work in a much simpler way be merely letting
reference edges linger in the graph after the causing IR is deleted. We
will clean up these edges when we run any function pass over the IR, but
don't remove them eagerly.

This avoids all of the quadratic update issues both in the current pass
manager and in my previous attempt with the new pass manager.

Differential Revision: https://reviews.llvm.org/D29579

llvm-svn: 294663
2017-02-09 23:30:14 +00:00
Chandler Carruth aaad9f84be [PM/LCG] Teach the LazyCallGraph how to replace a function without
disturbing the graph or having to update edges.

This is motivated by porting argument promotion to the new pass manager.
Because of how LLVM IR Function objects work, in order to change their
signature a new object needs to be created. This is efficient and
straight forward in the IR but previously was very hard to implement in
LCG. We could easily replace the function a node in the graph
represents. The challenging part is how to handle updating the edges in
the graph.

LCG previously used an edge to a raw function to represent a node that
had not yet been scanned for calls and references. This was the core
of its laziness. However, that model causes this kind of update to be
very hard:
1) The keys to lookup an edge need to be `Function*`s that would all
   need to be updated when we update the node.
2) There will be some unknown number of edges that haven't transitioned
   from `Function*` edges to `Node*` edges.

All of this complexity isn't necessary. Instead, we can always build
a node around any function, always pointing edges at it and always using
it as the key to lookup an edge. To maintain the laziness, we need to
sink the *edges* of a node into a secondary object and explicitly model
transitioning a node from empty to populated by scanning the function.
This design seems much cleaner in a number of ways, but importantly
there is now exactly *one* place where the `Function*` has to be
updated!

Some other cleanups that fall out of this include having something to
model the *entry* edges more accurately. Rather than hand rolling parts
of the node in the graph itself, we have an explicit `EdgeSequence`
object that gives us exactly the functionality needed. We also have
a consistent place to define the edge iterators and can use them for
both the entry edges and the internal edges of the graph.

The API used to model the separation between a node and its edges is
intentionally very thin as most clients are expected to deal with nodes
that have populated edges. We model this exactly as an optional does
with an additional method to populate the edges when that is
a reasonable thing for a client to do. This is based on API design
suggestions from Richard Smith and David Blaikie, credit goes to them
for helping pick how to model this without it being either too explicit
or too implicit.

The patch is somewhat noisy due to shifting around iterator types and
new syntax for walking the edges of a node, but most of the
functionality change is in the `Edge`, `EdgeSequence`, and `Node` types.

Differential Revision: https://reviews.llvm.org/D29577

llvm-svn: 294653
2017-02-09 23:24:13 +00:00
Daniel Berlin 73ad5cb9b1 Drop graph_ prefix
llvm-svn: 294621
2017-02-09 20:37:46 +00:00
Daniel Berlin 58a6e57394 GraphTraits: Add range versions of graph traits functions (graph_nodes, graph_children, inverse_graph_nodes, inverse_graph_children).
Summary:
Convert all obvious node_begin/node_end and child_begin/child_end
pairs to range based for.

Sending for review in case someone has a good idea how to make
graph_children able to be inferred. It looks like it would require
changing GraphTraits to be two argument or something. I presume
inference does not happen because it would have to check every
GraphTraits in the world to see if the noderef types matched.

Note: This change was 3-staged with clang as well, which uses
Dominators/etc from LLVM.

Reviewers: chandlerc, tstellarAMD, dblaikie, rsmith

Subscribers: arsenm, llvm-commits, nhaehnle

Differential Revision: https://reviews.llvm.org/D29767

llvm-svn: 294620
2017-02-09 20:37:24 +00:00
Vitaly Buka 9987d98370 LVI: Fix use-of-uninitialized-value after r294463
BlockValueStack can be reallocated making reference e invalid.

llvm-svn: 294572
2017-02-09 09:28:05 +00:00
Daniel Berlin 9c92a469b4 LVI: Add a per-value worklist limit to LazyValueInfo.
Summary:
LVI is now depth first, which is optimal for iteration strategy in
terms of work per call.  However, the way the results get cached means
it can still go very badly N^2 or worse right now.  The overdefined
cache is per-block, because LVI wants to try to get different results
for the same name in different blocks (IE solve the problem
PredicateInfo solves).  This means even if we discover a value is
overdefined after going very deep, it doesn't cache this information,
causing it to end up trying to rediscover it again and again.  The
same is true for values along the way.  In practice, overdefined
anywhere should mean overdefined everywhere (this is how, for example,
SCCP works).

Until we get around to reworking the overdefined cache, we need to
limit the worklist size we process.  Note that permanently reverting
the DFS strategy exploration seems the wrong strategy (temporarily
seems fine if we really want).  BFS is clearly the wrong approach, it
just gets luckier on some testcases.  It's also very hard to design
an effective throttle for BFS. For DFS, the throttle is directly related
to the depth of the CFG.  So really deep CFGs will get cutoff, smaller
ones will not. As the CFG simplifies, you get better results.
In BFS, the limit is it's related to the fan-out times average block size,
which is harder to reason about or make good choices for.

Bug being filed about the overdefined cache, but it will require major
surgery to fix it (plumbing predicateinfo through CVP or LVI).

Note: I did not make this number configurable because i'm not sure
anyone really needs to tweak this knob.  We run CVP 3 times. On the
testcases i have the slow ones happen in the middle, where CVP is
doing cleanup work other things are effective at.  Over the course of
3 runs, we don't see to have any real loss of performance.

I haven't gotten a minimized testcase yet, but just imagine in your
head a testcase where, going *up* the CFG, you have branches, one of
which leads 50000 blocks deep, and the other, to something where the
answer is overdefined immediately.  BFS would discover the overdefined
faster than DFS, but do more work to do so.  In practice, the right
answer is "once DFS discovers overdefined for a value, stop trying to
get more info about that value" (and so, DFS would normally cache the
overdefined results for every value it passed through in those 50k
blocks, and never do that work again. But it don't, because of the
naming problem)

Reviewers: chandlerc, djasper

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29715

llvm-svn: 294463
2017-02-08 15:22:52 +00:00
Chandler Carruth 346542b769 Revert r293017 and fix the actual underlying issue.
The patch committed in r293017, as discussed on the list, doesn't really
make sense but was causing an actual issue to go away.

The issue turns out to be that in one place the extra template arguments
were dropped from the OuterAnalysisManagerProxy. This in turn caused the
types used in one set of places to access the key to be completely
different from the types used in another set of places for both Loop and
CGSCC cases where there are extra arguments.

I have literally no idea how anything seemed to work with this bug in
place. It blows my mind. But it did except for mingw64 in a DLL build.

I've added a really handy static assert that helps ensure we don't break
this in the future. It immediately diagnoses the issue with a compile
failure and a very clear error message. Much better that staring at
backtraces on a build bot. =]

llvm-svn: 294267
2017-02-07 01:50:48 +00:00
Philip Reames c80bd0486d [LVI] Switch from BFS to DFS exploration order
This patch changes the order in which LVI explores previously unexplored paths.

Previously, the code used an BFS strategy where each unexplored input was added to the search queue before any of them were explored. This has the effect of causing all inputs to be explored before returning to re-evaluate the merge point (non-local or phi node). This has the unfortunate property of doing redundant work if one of the inputs to the merge is found to be overdefined (i.e. unanalysable). If any input is overdefined, the result of the merge will be too; regardless of the values of other inputs.

The new code uses a DFS strategy where we re-evaluate the merge after evaluating each input. If we discover an overdefined input, we immediately return without exploring other inputs.

We have reports of large (4-10x) improvements of compile time with this patch and some reports of more precise analysis results as well.  See the review discussion for details.  The original motivating case was pr10584.

Differential Revision: https://reviews.llvm.org/D28190

llvm-svn: 294264
2017-02-07 00:25:24 +00:00
Chandler Carruth a80cfb3063 [PM/LCG] Fix the no-asserts build after r294227. Sorry for the noise.
llvm-svn: 294235
2017-02-06 20:59:07 +00:00
Chandler Carruth 2e0fe3e65b [PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during
iteration.

The lazy formation of RefSCCs isn't really the most important part of
the laziness here -- that has to do with walking the functions
themselves -- and isn't essential to maintain. Originally, there were
incremental update algorithms that relied on updates happening
predominantly near the most recent RefSCC formed, but those have been
replaced with ones that have much tighter general case bounds at this
point. We do still perform asserts that only scale well due to this
incrementality, but those are easy to place behind EXPENSIVE_CHECKS.

Removing this simplifies the entire analysis by having a single up-front
step that builds all of the RefSCCs in a direct Tarjan walk. We can even
easily replace this with other or better algorithms at will and with
much less confusion now that there is no iterator-based incremental
logic involved. This removes a lot of complexity from LCG.

Another advantage of moving in this direction is that it simplifies
testing the system substantially as we no longer have to worry about
observing and mutating the graph half-way through the RefSCC formation.

We still need a somewhat special iterator for RefSCCs because we want
the iterator to remain stable in the face of graph updates. However,
this now merely involves relative indexing to the current RefSCC's
position in the sequence which isn't too hard.

Differential Revision: https://reviews.llvm.org/D29381

llvm-svn: 294227
2017-02-06 19:38:06 +00:00
Sanjay Patel 54656ca7db [ValueTracking] emit a remark when we detect a conflicting assumption (PR31809)
This is a follow-up to D29395 where we try to be good citizens and let the user know that
we've probably gone off the rails.

This should allow us to resolve:
https://llvm.org/bugs/show_bug.cgi?id=31809

Differential Revision: https://reviews.llvm.org/D29404

llvm-svn: 294208
2017-02-06 18:26:06 +00:00
Daniil Fukalov 6378bdb2dd [SCEV] limit recursion depth and operands number in getAddExpr
for a quite big function with source like

%add = add nsw i32 %mul, %conv
%mul1 = mul nsw i32 %add, %conv
%add2 = add nsw i32 %mul1, %add
%mul3 = mul nsw i32 %add2, %add
; repeat couple of thousands times
that can be produced by loop unroll, getAddExpr() tries to recursively construct SCEV and runs almost infinite time.

Added recursion depth restriction (with new parameter to set it)

Reviewers: sanjoy

Subscribers: hfinkel, llvm-commits, mzolotukhin

Differential Revision: https://reviews.llvm.org/D28158

llvm-svn: 294181
2017-02-06 12:38:06 +00:00
Michael Kuperstein 2a735b71b6 [SLP] Make sortMemAccesses explicitly return an error. NFC.
llvm-svn: 294029
2017-02-03 19:32:50 +00:00
Michael Kuperstein 723999d4aa [SLP] Use SCEV to sort memory accesses.
This generalizes memory access sorting to use differences between SCEVs,
instead of relying on constant offsets. That allows us to properly do
SLP vectorization of non-sequentially ordered loads within loops bodies.

Differential Revision: https://reviews.llvm.org/D29425

llvm-svn: 294027
2017-02-03 19:09:45 +00:00
Mehdi Amini 1380edf4ef Revert "[ThinLTO] Add an auto-hide feature"
This reverts commit r293970.

After more discussion, this belongs to the linker side and
there is no added value to do it at this level.

llvm-svn: 293993
2017-02-03 07:41:43 +00:00
Mehdi Amini b0a8ff71e5 [ThinLTO] Add an auto-hide feature
When a symbol is not exported outside of the
DSO, it is can be hidden. Usually we try to internalize
as much as possible, but it is not always possible, for
instance a symbol can be referenced outside of the LTO
unit, or there can be cross-module reference in ThinLTO.

This is a recommit of r293912 after fixing build failures,
and a recommit of r293918 after fixing LLD tests.

Differential Revision: https://reviews.llvm.org/D28978

llvm-svn: 293970
2017-02-03 00:32:38 +00:00
Mehdi Amini 21c89dc920 Revert "[ThinLTO] Add an auto-hide feature"
This reverts commit r293918, one lld test does not pass.

llvm-svn: 293961
2017-02-02 23:20:36 +00:00
Xinliang David Li 58fcc9bdce [PGO] internal option cleanups
1. Added comments for options
2. Added missing option cl::desc field
3. Uniified function filter option for graph viewing.
   Now PGO count/raw-counts share the same
   filter option: -view-bfi-func-name=.

llvm-svn: 293938
2017-02-02 21:29:17 +00:00
Xinliang David Li 1eb4ec6a2e [PGO] make graph view internal options available for all builds
Differential Revision: https://reviews.llvm.org/D29259

llvm-svn: 293921
2017-02-02 19:18:56 +00:00
Mehdi Amini 97624fb1ec [ThinLTO] Add an auto-hide feature
When a symbol is not exported outside of the
DSO, it is can be hidden. Usually we try to internalize
as much as possible, but it is not always possible, for
instance a symbol can be referenced outside of the LTO
unit, or there can be cross-module reference in ThinLTO.

This is a recommit of r293912 after fixing build failures.

Differential Revision: https://reviews.llvm.org/D28978

llvm-svn: 293918
2017-02-02 18:31:35 +00:00
Mehdi Amini 827600deaf Revert "[ThinLTO] Add an auto-hide feature"
This reverts r293912, bots are broken.

llvm-svn: 293914
2017-02-02 18:24:37 +00:00
Mehdi Amini dc5a7444f0 [ThinLTO] Add an auto-hide feature
When a symbol is not exported outside of the
DSO, it is can be hidden. Usually we try to internalize
as much as possible, but it is not always possible, for
instance a symbol can be referenced outside of the LTO
unit, or there can be cross-module reference in ThinLTO.

Differential Revision: https://reviews.llvm.org/D28978

llvm-svn: 293912
2017-02-02 18:13:46 +00:00
Jun Bum Lim 180bc5a021 [JumpThread] Enhance finding partial redundant loads by continuing scanning single predecessor
Summary: While scanning predecessors to find an available loaded value, if the predecessor has a single predecessor, we can continue scanning through the single predecessor.

Reviewers: mcrosier, rengolin, reames, davidxl, haicheng

Reviewed By: rengolin

Subscribers: zzheng, llvm-commits

Differential Revision: https://reviews.llvm.org/D29200

llvm-svn: 293896
2017-02-02 15:12:34 +00:00
Adam Nemet 0bf1b863b9 [LV] Also port failure remarks to new OptimizationRemarkEmitter API
llvm-svn: 293866
2017-02-02 05:41:51 +00:00
Sanjay Patel 52e4e6594e [ValueTracking] remove a FIXME for something we don't want to do; NFC
The comment was added with:
https://reviews.llvm.org/rL293773
...but there would be a cost to implement this and possibly no payoff.

llvm-svn: 293823
2017-02-01 22:27:34 +00:00
Matthew Simpson ba5cf9dfee [LV] Move interleaved access helper functions to VectorUtils (NFC)
This patch moves some helper functions related to interleaved access
vectorization out of LoopVectorize.cpp and into VectorUtils.cpp. We would like
to use these functions in a follow-on patch that improves interleaved load and
store lowering in (ARM/AArch64)ISelLowering.cpp. One of the functions was
already duplicated there and has been removed.

Differential Revision: https://reviews.llvm.org/D29398

llvm-svn: 293788
2017-02-01 17:45:46 +00:00
Sanjay Patel 25f6d710d9 [ValueTracking] avoid crashing from bad assumptions (PR31809)
A program may contain llvm.assume info that disagrees with other analysis. 
This may be caused by UB in the program, so we must not crash because of that.

As noted in the code comments:
https://llvm.org/bugs/show_bug.cgi?id=31809
...we can do better, but this at least avoids the assert/crash in the bug report.

Differential Revision: https://reviews.llvm.org/D29395

llvm-svn: 293773
2017-02-01 15:41:32 +00:00
Eli Friedman 10d1ff64fe [SCEV] Simplify/generalize howFarToZero solving.
Make SolveLinEquationWithOverflow take the start as a SCEV, so we can
solve more cases. With that implemented, get rid of the special case
for powers of two.

The additional functionality probably isn't particularly useful,
but it might help a little for certain cases involving pointer
arithmetic.

Differential Revision: https://reviews.llvm.org/D28884

llvm-svn: 293576
2017-01-31 00:42:42 +00:00
Matt Arsenault 42b6478344 NVPTX: Refactor NVPTXInferAddressSpaces to check TTI
Add a new TTI hook for getting the generic address space value.

llvm-svn: 293563
2017-01-30 23:02:12 +00:00
Sanjay Patel 14a4b8185f [ValueTracking] clean up lookThroughCast; NFCI
1. Use auto with dyn_cast.
2. Don't use else after return.
3. Convert chain of 'else if' to switch.
4. Improve variable names.

llvm-svn: 293432
2017-01-29 16:34:57 +00:00
Mohammad Shahid 3121334d32 [SLP] Vectorize loads of consecutive memory accesses, accessed in non-consecutive (jumbled) way.
The jumbled scalar loads will be sorted while building the tree and these accesses will be marked to generate shufflevector after the vectorized load with proper mask.

Reviewers: hfinkel, mssimpso, mkuper

Differential Revision: https://reviews.llvm.org/D26905

Change-Id: I9c0c8e6f91a00076a7ee1465440a3f6ae092f7ad
llvm-svn: 293386
2017-01-28 17:59:44 +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
Peter Collingbourne 5ad775f2e8 Analysis: Add appropriate const qualification to functions in TypeMetadataUtils.cpp. NFC.
llvm-svn: 293341
2017-01-27 22:55:30 +00:00
Mehdi Amini 1726fc698c Fix BasicAA incorrect assumption on GEP
This is fixing pr31761: BasicAA is deducing NoAlias
on the result of the GEP if the base pointer is itself NoAlias.

This is possible only if the NoAlias on the base pointer is
deduced with a non-sized query: this should guarantee that
the pointers are belonging to different memory allocation
and that the GEP can't legally jump from one to another.

Differential Revision: https://reviews.llvm.org/D29216

llvm-svn: 293293
2017-01-27 16:12:22 +00:00
Justin Lebar 322c127bee [ValueTracking] Add comment that CannotBeOrderedLessThanZero does the wrong thing for powi.
Summary:
CannotBeOrderedLessThanZero(powi(x, exp)) returns true if
CannotBeOrderedLessThanZero(x).  But powi(-0, exp) is negative if exp is
odd, so we actually want to return SignBitMustBeZero(x).

Except that also isn't right, because we want to return true if x is
NaN, even if x has a negative sign bit.

What we really need in order to fix this is a consistent approach in
this function to handling the sign bit of NaNs.  Without this it's very
difficult to say what the correct behavior here is.

Reviewers: hfinkel, efriedma, sanjoy

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28927

llvm-svn: 293243
2017-01-27 00:58:34 +00:00
Daniil Fukalov b09dac59fc [SCEV] Introduce add operation inlining limit
Inlining in getAddExpr() can cause abnormal computational time in some cases.
New parameter -scev-addops-inline-threshold is intruduced with default value 500.

Reviewers: sanjoy

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D28812

llvm-svn: 293176
2017-01-26 13:33:17 +00:00
Chandler Carruth 41421df02b [PM] Use PoisoningVH correctly when merely deleting entries in a map
with it.

This code was dereferencing the PoisoningVH which isn't allowed once it
is poisoned. But the code itself really doesn't need to access the
pointer, it is just doing the safe stuff of clearing out data structures
keyed on the pointer value.

Change the code to use iterators to erase directly from a DenseMap. This
is also substantially more efficient as it avoids lots of hashing and
lookups to do the erasure. DenseMap supports iterating behind the
iteration which is fairly easy to implement.

Sadly, I don't have a test case here. I'm not even close and I don't
know that I ever will be. The issue is that several of the tricky
aspects of fixing this only show up when you cause the stack's
SmallVector to be in *EXACTLY* the right location. I only ever got
a reproduction for those with Clang, and only with *exactly* the right
command line flags. Any adjustment, even to seemingly unrelated flags,
would make partial and half-way solutions magically start to "work". In
good news, all of this was caught with the LLVM test suite. Also, there
is no *specific* code here that is untested, just that the old pattern
of code won't immediately fail on any test case I've managed to
contrive.

llvm-svn: 293160
2017-01-26 08:31:54 +00:00
Jonas Paulsson 8e2f948ef0 [TargetTransformInfo] Refactor and improve getScalarizationOverhead()
Refactoring to remove duplications of this method.

New method getOperandsScalarizationOverhead() that looks at the present unique
operands and add extract costs for them. Old behaviour was to just add extract
costs for one operand of the type always, which still happens in
getArithmeticInstrCost() if no operands are provided by the caller.

This is a good start of improving on this, but there are more places
that can be improved by using getOperandsScalarizationOverhead().

Review: Hal Finkel
https://reviews.llvm.org/D29017

llvm-svn: 293155
2017-01-26 07:03:25 +00:00
Adam Nemet 916923e689 [llc] Add -pass-remarks-output
This is the opt/llc counterpart of -fsave-optimization-record to output
optimization remarks in a YAML file.

llvm-svn: 293121
2017-01-26 00:39:51 +00:00
Justin Lebar 7e3184c412 [ValueTracking] Implement SignBitMustBeZero correctly for sqrt.
Summary:
Previously we assumed that the result of sqrt(x) always had 0 as its
sign bit.  But sqrt(-0) == -0.

Reviewers: hfinkel, efriedma, sanjoy

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28928

llvm-svn: 293115
2017-01-26 00:10:26 +00:00
Adam Nemet a964066705 New OptimizationRemarkEmitter pass for MIR
This allows MIR passes to emit optimization remarks with the same level
of functionality that is available to IR passes.

It also hooks up the greedy register allocator to report spills.  This
allows for interesting use cases like increasing interleaving on a loop
until spilling of registers is observed.

I still need to experiment whether reporting every spill scales but this
demonstrates for now that the functionality works from llc
using -pass-remarks*=<pass>.

Differential Revision: https://reviews.llvm.org/D29004

llvm-svn: 293110
2017-01-25 23:20:33 +00:00
Adam Nemet 484f93db30 [OptDiag] Split code region out of DiagnosticInfoOptimizationBase
Code region is the only part of this class that is IR-specific.  Code
region is moved down in the inheritance tree to a new derived class,
called DiagnosticInfoIROptimization.

All the existing remarks are derived from this new class now.

This allows the new MIR pass-remark classes to be derived from
DiagnosticInfoOptimizationBase.

Also because we keep the name DiagnosticInfoOptimizationBase, the clang
parts don't need any adjustment.

Differential Revision: https://reviews.llvm.org/D29003

llvm-svn: 293109
2017-01-25 23:20:25 +00:00
whitequark 16f1e5f1ca Mark @llvm.powi.* as safe to speculatively execute.
Floating point intrinsics in LLVM are generally not speculatively
executed, since most of them are defined to behave the same as libm
functions, which set errno.

However, the @llvm.powi.* intrinsics do not correspond to any libm
function, and lacks any defined error handling semantics in LangRef.
It most certainly does not alter errno.

llvm-svn: 293041
2017-01-25 09:32:30 +00:00
NAKAMURA Takumi 28dc4d5122 Rewind instantiations of OuterAnalysisManagerProxy in r289317, r291651, and r291662.
I found root class should be instantiated for variadic tempate to instantiate static member explicitly.

This will fix failures in mingw DLL build.

llvm-svn: 293017
2017-01-25 04:26:29 +00:00
Sanjay Patel 562272536a [InstSimplify] try to eliminate icmp Pred (add nsw X, C1), C2
I was surprised to see that we're missing icmp folds based on 'add nsw' in InstCombine, 
but we should handle the InstSimplify cases first because that could make the InstCombine
code simpler.

Here are Alive-based proofs for the logic:

Name: add_neg_constant
Pre: C1 < 0 && (C2 > ((1<<(width(C1)-1)) + C1))
%a = add nsw i7 %x, C1
%b = icmp sgt %a, C2
  =>
%b = false

Name: add_pos_constant
Pre: C1 > 0 && (C2 < ((1<<(width(C1)-1)) + C1 - 1))
%a = add nsw i6 %x, C1
%b = icmp slt %a, C2
  =>
%b = false

Name: nuw
Pre: C1 u>= C2
%a = add nuw i11 %x, C1
%b = icmp ult %a, C2
  =>
%b = false

Differential Revision: https://reviews.llvm.org/D29053

llvm-svn: 292952
2017-01-24 17:03:24 +00:00
Chandler Carruth 6acdca78a0 [PH] Replace uses of AssertingVH from members of analysis results with
a lazy-asserting PoisoningVH.

AssertVH is fundamentally incompatible with cache-invalidation of
analysis results. The invaliadtion happens after the AssertingVH has
already fired. Instead, use a PoisoningVH that will assert if the
dangling handle is ever used rather than merely be assigned or
destroyed.

This patch also removes all of the (numerous) doomed attempts to work
around this fundamental incompatibility. It is a pretty significant
simplification IMO.

The most interesting change is in the Inliner where we still do some
clearing because we don't want to rely on the coarse grained
invalidation strategy of the containing pass manager. However, I prefer
the approach that contains this logic to the cleanup phase of the
Inliner, and I think we could enhance the CGSCC analysis management
layer to make this even better in the future if desired.

The rest is straight cleanup.

I've also added a test for one of the harder cases to work around: when
a *module analysis* contains many AssertingVHes pointing at functions.

Differential Revision: https://reviews.llvm.org/D29006

llvm-svn: 292928
2017-01-24 12:55:57 +00:00
Serge Pavlov 69b3ff9d93 Make VerifyDomInfo and VerifyLoopInfo global variables
Verifications of dominator tree and loop info are expensive operations
so they are disabled by default. They can be enabled by command line
options -verify-dom-info and -verify-loop-info. These options however
enable checks only in files Dominators.cpp and LoopInfo.cpp. If some
transformation changes dominaror tree and/or loop info, it would be
convenient to place similar checks to the files implementing the
transformation.

This change makes corresponding flags global, so they can be used in
any file to optionally turn verification on.

llvm-svn: 292889
2017-01-24 05:52:07 +00:00
David L. Jones d21529fa0d [Analysis] Add LibFunc_ prefix to enums in TargetLibraryInfo. (NFC)
Summary:
The LibFunc::Func enum holds enumerators named for libc functions.
Unfortunately, there are real situations, including libc implementations, where
function names are actually macros (musl uses "#define fopen64 fopen", for
example; any other transitively visible macro would have similar effects).

Strictly speaking, a conforming C++ Standard Library should provide any such
macros as functions instead (via <cstdio>). However, there are some "library"
functions which are not part of the standard, and thus not subject to this
rule (fopen64, for example). So, in order to be both portable and consistent,
the enum should not use the bare function names.

The old enum naming used a namespace LibFunc and an enum Func, with bare
enumerators. This patch changes LibFunc to be an enum with enumerators prefixed
with "LibFFunc_". (Unfortunately, a scoped enum is not sufficient to override
macros.)

There are additional changes required in clang.

Reviewers: rsmith

Subscribers: mehdi_amini, mzolotukhin, nemanjai, llvm-commits

Differential Revision: https://reviews.llvm.org/D28476

llvm-svn: 292848
2017-01-23 23:16:46 +00:00
Xinliang David Li cb253ce90b [PGO] add debug option to view annotated cfg after prof use annotation
Differential Revision: http://reviews.llvm.org/D28967 

llvm-svn: 292815
2017-01-23 18:58:24 +00:00
Sanjay Patel be332137fd [InstSimplify] refactor finding limits for icmp with binop; NFCI
llvm-svn: 292812
2017-01-23 18:22:26 +00:00
Chandler Carruth a504f2b8e8 [PM] Teach LVI to correctly invalidate itself when its dependencies
become unavailable.

The AssumptionCache is now immutable but it still needs to respond to
DomTree invalidation if it ended up caching one.

This lets us remove one of the explicit invalidates of LVI but the
other one continues to avoid hitting a latent bug.

llvm-svn: 292769
2017-01-23 06:35:12 +00:00
Sanjay Patel 24c6f88e4c [ValueTracking] tighten up matchMinMax(); NFCI
This is similar to what the caller (matchSelectPattern()) does. In all
cases where we succeed in matching a min/max pattern, the values in
that pattern will be the values of the 'select', so hoist that and
remove a bunch of duplicated code.

llvm-svn: 292725
2017-01-21 17:51:25 +00:00
Mehdi Amini 8902948fff Add missing dependency to "Module Summary Analysis" pass
This is fixing a clang crash when running `clang -flto=thin -save-temps`

llvm-svn: 292711
2017-01-21 06:01:22 +00:00
Justin Lebar 8b18a347b6 [ConstantFolding] Constant-fold llvm.sqrt(x) like other intrinsics.
Summary:
Currently we return undef, but we're in the process of changing the
LangRef so that llvm.sqrt behaves like the other math intrinsics,
matching the return value of the standard libcall but not setting errno.

This change is legal even without the LangRef change because currently
calling llvm.sqrt(x) where x is negative is spec'ed to be UB.  But in
practice it's also safe because we're simply constant-folding fewer
inputs: Inputs >= -0 get constant-folded as before, but inputs < -0 now
aren't constant-folded, because ConstantFoldFP aborts if the host math
function raises an fp exception.

Reviewers: hfinkel, efriedma, sanjoy

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28929

llvm-svn: 292692
2017-01-21 00:59:57 +00:00
Easwaran Raman 12585b0148 Improve PGO support for the new inliner
This adds the following to the new PM based inliner in PGO mode:

* Use block frequency analysis to derive callsite's profile count and use
that to adjust thresholds of hot and cold callsites.

* Incrementally update the BFI of the caller after a callee gets inlined
into it. This incremental update is only within an invocation of the run
method - BFI is not preserved across calls to run.
Update the function entry count of the callee after inlining it into a
caller.

* I've tuned the thresholds for the hot and cold callsites using a hacked
up version of the old inliner that explicitly computes BFI on a set of
internal benchmarks and spec. Once the new PM based pipeline stabilizes
(IIRC Chandler mentioned there are known issues) I'll benchmark this
again and adjust the thresholds if required.
Inliner PGO support.

Differential revision: https://reviews.llvm.org/D28331

llvm-svn: 292666
2017-01-20 22:44:04 +00:00
Sanjay Patel 0c1c70aef4 [ValueTracking] recognize variations of 'clamp' to improve codegen (PR31693)
By enhancing value tracking, we allow an existing min/max canonicalization to
kick in and improve codegen for several targets that have min/max instructions.

Unfortunately, recognizing min/max in value tracking may cause us to hit
a hack in InstCombiner::visitICmpInst() more often:
http://lists.llvm.org/pipermail/llvm-dev/2017-January/109340.html
...but I'm hoping we can remove that soon.

Correctness proofs based on Alive:

Name: smaxmin
Pre: C1 < C2
%cmp2 = icmp slt i8 %x, C2
%min = select i1 %cmp2, i8 %x, i8 C2
%cmp3 = icmp slt i8 %x, C1
%r = select i1 %cmp3, i8 C1, i8 %min
=>
%cmp2 = icmp slt i8 %x, C2
%min = select i1 %cmp2, i8 %x, i8 C2
%cmp1 = icmp sgt i8 %min, C1
%r = select i1 %cmp1, i8 %min, i8 C1

Name: sminmax
Pre: C1 > C2
%cmp2 = icmp sgt i8 %x, C2
%max = select i1 %cmp2, i8 %x, i8 C2
%cmp3 = icmp sgt i8 %x, C1
%r = select i1 %cmp3, i8 C1, i8 %max
=>
%cmp2 = icmp sgt i8 %x, C2
%max = select i1 %cmp2, i8 %x, i8 C2
%cmp1 = icmp slt i8 %max, C1
%r = select i1 %cmp1, i8 %max, i8 C1

---------------------------------------- 
Optimization: smaxmin 
Done: 1 
Optimization is correct! 
---------------------------------------- 
Optimization: sminmax 
Done: 1 
Optimization is correct!



Name: umaxmin
Pre: C1 u< C2
%cmp2 = icmp ult i8 %x, C2
%min = select i1 %cmp2, i8 %x, i8 C2
%cmp3 = icmp ult i8 %x, C1
%r = select i1 %cmp3, i8 C1, i8 %min
=>
%cmp2 = icmp ult i8 %x, C2
%min = select i1 %cmp2, i8 %x, i8 C2
%cmp1 = icmp ugt i8 %min, C1
%r = select i1 %cmp1, i8 %min, i8 C1

Name: uminmax
Pre: C1 u> C2
%cmp2 = icmp ugt i8 %x, C2
%max = select i1 %cmp2, i8 %x, i8 C2
%cmp3 = icmp ugt i8 %x, C1
%r = select i1 %cmp3, i8 C1, i8 %max
=>
%cmp2 = icmp ugt i8 %x, C2
%max = select i1 %cmp2, i8 %x, i8 C2
%cmp1 = icmp ult i8 %max, C1
%r = select i1 %cmp1, i8 %max, i8 C1

---------------------------------------- 
Optimization: umaxmin 
Done: 1 
Optimization is correct! 
---------------------------------------- 
Optimization: uminmax 
Done: 1 
Optimization is correct! 
 

llvm-svn: 292660
2017-01-20 22:18:47 +00:00
Haicheng Wu 201b191b82 Recommit "[InlineCost] Use TTI to check if GEP is free." #3
This is the third attemp to recommit r292526.

The original summary:

Currently, a GEP is considered free only if its indices are all constant.
TTI::getGEPCost() can give target-specific more accurate analysis. TTI is
already used for the cost of many other instructions.

llvm-svn: 292633
2017-01-20 18:51:22 +00:00
Haicheng Wu 71ef5bc0ff Revert "Recommit "[InlineCost] Use TTI to check if GEP is free." #2"
This reverts commit r292616 because the test case still has problem.

llvm-svn: 292618
2017-01-20 16:52:22 +00:00
Haicheng Wu 8f34ae2aae Recommit "[InlineCost] Use TTI to check if GEP is free." #2
This is the second attemp to recommit r292526.

The original summary:

Currently, a GEP is considered free only if its indices are all constant.
TTI::getGEPCost() can give target-specific more accurate analysis. TTI is
already used for the cost of many other instructions.

llvm-svn: 292616
2017-01-20 16:36:34 +00:00
Haicheng Wu 8f2aca388b Revert "Recommit "[InlineCost] Use TTI to check if GEP is free.""
This reverts commit r292570.  The test still has problem.

llvm-svn: 292572
2017-01-20 03:40:41 +00:00
Haicheng Wu 1af1f071ea Recommit "[InlineCost] Use TTI to check if GEP is free."
This recommits r292526 which is reverted in r292529 after fixing the test case.

The original summary:

Currently, a GEP is considered free only if its indices are all constant.
TTI::getGEPCost() can give target-specific more accurate analysis. TTI is
already used for the cost of many other instructions.

llvm-svn: 292570
2017-01-20 03:09:11 +00:00
Chandler Carruth f002264d49 [LoopInfo] Add helper methods to compute two useful orderings of the
loops in a function.

These are relatively confusing to talk about and compute correctly so it
seems really good to write down their implementation in one place. I've
replaced one place we needed this in the loop PM infrastructure and
I have another place in a pending patch that wants it.

We can't quite use this for the core loop PM walk because there we're
sometimes working on a sub-forest.

I'll add the expected unittests before committing this but wanted to
make sure folks were happy with these names / comments.

Credit goes to Richard Smith for the idea for naming the order where siblings
are in reverse program order but the tree traversal remains preorder.

Differential Revision: https://reviews.llvm.org/D28932

llvm-svn: 292569
2017-01-20 02:41:20 +00:00
Anna Thomas 698f0deea9 [AliasAnalysis] Fences do not modify constant memory location
Summary:
Fence instructions are currently marked as `ModRef` for all memory locations.

We can improve this for constant memory locations (such as constant globals),
since fence instructions cannot modify these locations.

This helps us to forward constant loads across fences (added test case in GVN).
There were no changes in behaviour for similar test cases in early-cse and licm.

Reviewers: dberlin, sanjoy, reames

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28914

llvm-svn: 292546
2017-01-20 00:21:33 +00:00
Haicheng Wu e036df4723 Revert "[InlineCost] Use TTI to check if GEP is free."
This reverts commit r292526.  The test case has problem.

llvm-svn: 292529
2017-01-19 22:51:03 +00:00
Haicheng Wu da556345dc [InlineCost] Use TTI to check if GEP is free.
Currently, a GEP is considered free only if its indices are all constant.
TTI::getGEPCost() can give target-specific more accurate analysis. TTI is
already used for the cost of many other instructions.

Differential Revision: https://reviews.llvm.org/D28693

llvm-svn: 292526
2017-01-19 22:28:34 +00:00
Easwaran Raman 6c8f511f82 Add an interface to scale the frequencies of a set of blocks.
The scaling is done with reference to the the new frequency of a reference block.

Differential Revision: https://reviews.llvm.org/D28535

llvm-svn: 292507
2017-01-19 18:53:16 +00:00
Eli Friedman f1f49c8265 [SCEV] Make getUDivExactExpr handle non-nuw multiplies correctly.
To avoid regressions, make ScalarEvolution::createSCEV a bit more
clever.

Also get rid of some useless code in ScalarEvolution::howFarToZero
which was hiding this bug.

No new testcase because it's impossible to actually expose this bug:
we don't have any in-tree users of getUDivExactExpr besides the two
functions I just mentioned, and they both dodged the problem. I'll
try to add some interesting users in a followup.

Differential Revision: https://reviews.llvm.org/D28587

llvm-svn: 292449
2017-01-18 23:56:42 +00:00
Mehdi Amini 062b3fed4c Improve the `-filter-print-funcs` option to skip the banner for CGSCC pass when nothing is to be printed
Before, it would print a sequence of:

  *** IR Dump After Function Integration/Inlining ******
  *** IR Dump After Function Integration/Inlining ******
  *** IR Dump After Function Integration/Inlining ******
  ...

for every single function in the module.

llvm-svn: 292442
2017-01-18 21:37:11 +00:00
Ahmed Bougacha 86b680a372 [TLI] Appease spurious MSVC warning using llvm_unreachable. NFC.
r292188 confused MSVC because of the combined lack of a default
case and return statement.

Move the unreachable outside of the NumLibFuncs case, to make it
obvious that all cases should be handled.

llvm_unreachable is __declspec(noreturn), so I'm assuming this
does appease MSVC.

llvm-svn: 292246
2017-01-17 19:54:18 +00:00
Sanjay Patel 9666996563 [ValueTracking] recognize a 'not' of an assumed condition as false
Also, add the corresponding match to the AssumptionCache's 'Affected Values' list.

Differential Revision: https://reviews.llvm.org/D28485

llvm-svn: 292239
2017-01-17 18:15:49 +00:00
Chad Rosier 8520429bdd [ValueTracking] Extend known bits to understand @llvm.bitreverse.
Differential Revision: https://reviews.llvm.org/D28780

llvm-svn: 292233
2017-01-17 17:23:51 +00:00
Ahmed Bougacha 6b9be1dbe1 [TLI] Add prototype checking for all remaining LibFuncs.
This is another step towards unifying all LibFunc prototype checks.
This work started in r267758 (D19469);  add the remaining checks.

Also add a unittest that checks each libfunc declared with a known-valid
and known-invalid prototype.  New libfuncs added in the future are
required to have prototype checking in place; the known-valid test will
fail otherwise.

Differential Revision: https://reviews.llvm.org/D28030

llvm-svn: 292188
2017-01-17 03:10:02 +00:00
Ahmed Bougacha a65de7e241 [TLI] Alphabetize some of the prototype check switch. NFC.
llvm-svn: 292187
2017-01-17 03:10:00 +00:00
Hal Finkel c29d5f1674 Fix use-after-free bug in AffectedValueCallbackVH::allUsesReplacedWith
When transferring affected values in the cache from an old value, identified by
the value of the current callback, to the specified new value we might need to
insert a new entry into the DenseMap which constitutes the cache. Doing so
might delete the current callback object. Move the copying logic into a new
function, a member of the assumption cache itself, so that we don't run into UB
should the callback handle itself be removed mid-copy.

Differential Revision: https://reviews.llvm.org/D28749

llvm-svn: 292133
2017-01-16 15:22:01 +00:00
Xin Tong ca02360f46 Use getLoopLatch in place of isLoopSimplifyForm
Summary:
Use getLoopLatch in place of isLoopSimplifyForm. we do not need
to know whether the loop has a preheader nor dedicated exits.

Reviewers: hfinkel, sanjoy, atrick, mkuper

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D28724

llvm-svn: 292078
2017-01-15 21:17:52 +00:00
Serge Pavlov ed5eb93384 Reverted: Track validity of pass results
Commits r291882 and related r291887.

llvm-svn: 292062
2017-01-15 10:23:18 +00:00
Chandler Carruth 1ae34c35ba [PM] Teach the optimization remarks emitter to handle invalidation
events.

This pass sometimes has a pointer to BlockFrequencyInfo so it needs
custom invalidation logic. It is also otherwise immutable so we can
reduce the number of invalidations that happen substantially.

llvm-svn: 292058
2017-01-15 08:20:50 +00:00
Chandler Carruth ca68a3ec47 [PM] Introduce an analysis set used to preserve all analyses over
a function's CFG when that CFG is unchanged.

This allows transformation passes to simply claim they preserve the CFG
and analysis passes to check for the CFG being preserved to remove the
fanout of all analyses being listed in all passes.

I've gone through and removed or cleaned up as many of the comments
reminding us to do this as I could.

Differential Revision: https://reviews.llvm.org/D28627

llvm-svn: 292054
2017-01-15 06:32:49 +00:00
Chandler Carruth 2f19a324cb [PM] The assumption cache is fundamentally designed to be self-updating,
mark it as never invalidated in the new PM.

The old PM already required this to work, and after a discussion with
Hal this seems to really be the only sensible answer. The cache
gracefully degrades as the IR is mutated, and most things which do this
should already be incrementally updating the cache.

This gets rid of a bunch of logic preserving and testing the
invalidation of this analysis.

llvm-svn: 292039
2017-01-15 00:26:18 +00:00
Marcello Maggioni 0616b5ff5c Removing potentially error-prone fallthrough. NFC
This fallthrough if other cases are added between fabs and default
could cause fabs to fall to the next case resulting in a bug.
Better getting rid of it immediately just to be sure.

llvm-svn: 292003
2017-01-14 07:28:47 +00:00
Easwaran Raman a7bdb8a513 Compute summary before calling extractProfTotalWeight
extractProfTotalWeight checks if the profile type is sample profile, but
before that we have to ensure that summary is available. Also expanded
the unittest to test the case where there is no summar

Differential Revision: https://reviews.llvm.org/D28708

llvm-svn: 291982
2017-01-14 00:32:37 +00:00
Michael Liao 468fb745e8 [SCEV] Limit recursion depth of constant evolving.
- For a loop body with VERY complicated exit condition evaluation, constant
  evolving may run out of stack on platforms such as Windows. Need to limit the
  recursion depth.

Differential Revision: https://reviews.llvm.org/D28629

llvm-svn: 291927
2017-01-13 18:28:30 +00:00
Malcolm Parsons 17d266bc96 Remove unused lambda captures. NFC
llvm-svn: 291916
2017-01-13 17:12:16 +00:00
Benjamin Kramer 061f4a5fe6 Apply clang-tidy's performance-unnecessary-value-param to LLVM.
With some minor manual fixes for using function_ref instead of
std::function. No functional change intended.

llvm-svn: 291904
2017-01-13 14:39:03 +00:00
Tobias Grosser 190d4e5fa2 RegionPass: Set isExecuted flag correctly
This was forgotten in r291882. Without this fix, the Polly build bots are
broken.

llvm-svn: 291887
2017-01-13 09:00:17 +00:00
Serge Pavlov d409411ef1 Track validity of pass results
Running tests with expensive checks enabled exhibits some problems with
verification of pass results.

First, the pass verification may require results of analysis that are not
available. For instance, verification of loop info requires results of dominator
tree analysis. A pass may be marked as conserving loop info but does not need to
be dependent on DominatorTreePass. When a pass manager tries to verify that loop
info is valid, it needs dominator tree, but corresponding analysis may be
already destroyed as no user of it remained.

Another case is a pass that is skipped. For instance, entities with linkage
available_externally do not need code generation and such passes are skipped for
them. In this case result verification must also be skipped.

To solve these problems this change introduces a special flag to the Pass
structure to mark passes that have valid results. If this flag is reset,
verifications dependent on the pass result are skipped.

Differential Revision: https://reviews.llvm.org/D27190

llvm-svn: 291882
2017-01-13 06:09:54 +00:00
Easwaran Raman b035f914e4 ProfileSummaryInfo improvements.
* Add is{Hot|Cold}CallSite methods
* Fix a bug in isHotBB where it was looking for MD_prof on a return instruction
* Use MD_prof data only if sample profiling was used to collect profiles.
* Add an unit test to ProfileSummaryInfo

Differential Revision: https://reviews.llvm.org/D28584

llvm-svn: 291878
2017-01-13 01:34:00 +00:00
Eli Friedman b5c3a0d1c3 [SCEV] Simplify SolveLinEquationWithOverflow a bit.
Cleanup in preparation for generalizing it.

llvm-svn: 291808
2017-01-12 20:21:00 +00:00
Piotr Padlewski 9530883e8c [Devirtualization] MemDep returns non-local !invariant.group dependencies
Summary:
Memory Dependence Analysis was limited to return only local dependencies
for invariant.group handling. Now it returns NonLocal when it finds it
and then by asking getNonLocalPointerDependency we get found dep.

Thanks to this we are able to devirtualize loops!

    void indirect(A &a, int n) {
      for (int i = 0 ; i < n; i++)
        a.foo();

    }
    void test(int n) {
      A a;
      indirect(a);
    }

After inlining a.foo() will be changed to direct call, even if foo and A::A()
is external (but only if vtable definition is be available).

Reviewers: nlewycky, dberlin, chandlerc, rsmith

Subscribers: mehdi_amini, davide, llvm-commits

Differential Revision: https://reviews.llvm.org/D28137

llvm-svn: 291762
2017-01-12 11:33:58 +00:00
Eli Friedman bd6dedaa7f [SCEV] Make howFarToZero max backedge-taken count check for precondition.
Refines max backedge-taken count if a loop like
"for (int i = 0; i != n; ++i) { /* body */ }" is rotated.

Differential Revision: https://reviews.llvm.org/D28536

llvm-svn: 291704
2017-01-11 21:07:15 +00:00
Eli Friedman 8396265655 [SCEV] Make howFarToZero use a simpler formula for max backedge-taken count.
This is both easier to understand, and produces a tighter bound in certain
cases.

Differential Revision: https://reviews.llvm.org/D28393

llvm-svn: 291701
2017-01-11 20:55:48 +00:00
Piotr Padlewski e41beed403 [MemDep] NFC variable name change
llvm-svn: 291679
2017-01-11 16:23:54 +00:00
Hal Finkel 8a9a783f2c Make processing @llvm.assume more efficient - Add affected values to the assumption cache
Here's my second try at making @llvm.assume processing more efficient. My
previous attempt, which leveraged operand bundles, r289755, didn't end up
working: it did make assume processing more efficient but eliminating the
assumption cache made ephemeral value computation too expensive. This is a
more-targeted change. We'll keep the assumption cache, but extend it to keep a
map of affected values (i.e. values about which an assumption might provide
some information) to the corresponding assumption intrinsics. This allows
ValueTracking and LVI to find assumptions relevant to the value being queried
without scanning all assumptions in the function. The fact that ValueTracking
started doing O(number of assumptions in the function) work, for every
known-bits query, has become prohibitively expensive in some cases.

As discussed during the review, this is a pragmatic fix that, longer term, will
likely be replaced by a more-principled solution (perhaps based on an extended
SSA form).

Differential Revision: https://reviews.llvm.org/D28459

llvm-svn: 291671
2017-01-11 13:24:24 +00:00
Chandler Carruth 3bab7e1a79 [PM] Separate the LoopAnalysisManager from the LoopPassManager and move
the latter to the Transforms library.

While the loop PM uses an analysis to form the IR units, the current
plan is to have the PM itself establish and enforce both loop simplified
form and LCSSA. This would be a layering violation in the analysis
library.

Fundamentally, the idea behind the loop PM is to *transform* loops in
addition to running passes over them, so it really seemed like the most
natural place to sink this was into the transforms library.

We can't just move *everything* because we also have loop analyses that
rely on a subset of the invariants. So this patch splits the the loop
infrastructure into the analysis management that has to be part of the
analysis library, and the transform-aware pass manager.

This also required splitting the loop analyses' printer passes out to
the transforms library, which makes sense to me as running these will
transform the code into LCSSA in theory.

I haven't split the unittest though because testing one component
without the other seems nearly intractable.

Differential Revision: https://reviews.llvm.org/D28452

llvm-svn: 291662
2017-01-11 09:43:56 +00:00
Mohammed Agabaria 2c96c43388 [X86] updating TTI costs for arithmetic instructions on X86\SLM arch.
updated instructions:
pmulld, pmullw, pmulhw, mulsd, mulps, mulpd, divss, divps, divsd, divpd, addpd and subpd.

special optimization case which replaces pmulld with pmullw\pmulhw\pshuf seq. 
In case if the real operands bitwidth <= 16.

Differential Revision: https://reviews.llvm.org/D28104 

llvm-svn: 291657
2017-01-11 08:23:37 +00:00
Chandler Carruth 410eaeb064 [PM] Rewrite the loop pass manager to use a worklist and augmented run
arguments much like the CGSCC pass manager.

This is a major redesign following the pattern establish for the CGSCC layer to
support updates to the set of loops during the traversal of the loop nest and
to support invalidation of analyses.

An additional significant burden in the loop PM is that so many passes require
access to a large number of function analyses. Manually ensuring these are
cached, available, and preserved has been a long-standing burden in LLVM even
with the help of the automatic scheduling in the old pass manager. And it made
the new pass manager extremely unweildy. With this design, we can package the
common analyses up while in a function pass and make them immediately available
to all the loop passes. While in some cases this is unnecessary, I think the
simplicity afforded is worth it.

This does not (yet) address loop simplified form or LCSSA form, but those are
the next things on my radar and I have a clear plan for them.

While the patch is very large, most of it is either mechanically updating loop
passes to the new API or the new testing for the loop PM. The code for it is
reasonably compact.

I have not yet updated all of the loop passes to correctly leverage the update
mechanisms demonstrated in the unittests. I'll do that in follow-up patches
along with improved FileCheck tests for those passes that ensure things work in
more realistic scenarios. In many cases, there isn't much we can do with these
until the loop simplified form and LCSSA form are in place.

Differential Revision: https://reviews.llvm.org/D28292

llvm-svn: 291651
2017-01-11 06:23:21 +00:00
Matt Arsenault 8260666d11 InstSimplify: Refactor function to use more switches
llvm-svn: 291634
2017-01-11 00:57:54 +00:00
Matt Arsenault 1e0edbf03c InstSimplify: Eliminate fabs on known positive
llvm-svn: 291624
2017-01-11 00:33:24 +00:00
Easwaran Raman e08b139d7d Refactor inline threshold update code.
Functional change: Previously, if a callee is cold, we used ColdThreshold if it minimizes the existing threshold. This was irrespective of whether we were optimizing for minsize (-Oz) or not. But -Oz uses very low threshold to begin with and the inlining with -Oz is expected to be tuned for lowering code size, so there is no good reason to set an even lower threshold for cold callees. We now lower the threshold for cold callees only when -Oz is not used. For default values of -inlinethreshold and -inlinecold-threshold, this change has no effect and this simplifies the code.

NFC changes: Group all threshold updates that are guarded by !Caller->optForMinSize() and within that group threshold updates that require profile summary info.

Differential revision: https://reviews.llvm.org/D28369

llvm-svn: 291487
2017-01-09 21:56:26 +00:00
Xin Tong c13a8e84d1 Intrinsic::Bitreverse is safe to speculate
Summary: Intrinsic::Bitreverse is safe to speculate

Reviewers: hfinkel, mkuper, arsenm, jmolloy

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28471

llvm-svn: 291456
2017-01-09 17:57:08 +00:00
Chandler Carruth 082c183f06 [PM] Teach SCEV to invalidate itself when its dependencies become
invalid.

This fixes use-after-free bugs that will arise with any interesting use
of SCEV.

I've added a dedicated test that works diligently to trigger these kinds
of bugs in the new pass manager and also checks for them explicitly as
well as triggering ASan failures when things go squirly.

llvm-svn: 291426
2017-01-09 07:44:34 +00:00
Piotr Padlewski 09ad678bc4 [MemDep] NFC walk invariant.group graph only down
Summary:
By using stripPointerCasts we can get to the root
value and then walk down the bitcast graph

Reviewers: reames

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28181

llvm-svn: 291405
2017-01-08 22:26:06 +00:00
Davide Italiano 362cc7b0fd [LCSSA] Fix some typos. NFCI.
llvm-svn: 291404
2017-01-08 22:22:09 +00:00
David Majnemer 63da0c238b [InstSimplify] Optimize away udivs in the presence of range metadata
We know that udiv %V, C can be optimized away to 0 if %V is ult C.

llvm-svn: 291296
2017-01-06 22:58:02 +00:00
David Majnemer 8c0e62f507 [InstSimplify] Optimize away urems in the presence of range metadata
We know that urem %V, C can be optimized away to %V if %V is ult C.

llvm-svn: 291282
2017-01-06 21:23:51 +00:00
Teresa Johnson 6c475a7595 ThinLTO: add early "dead-stripping" on the Index
Summary:
Using the linker-supplied list of "preserved" symbols, we can compute
the list of "dead" symbols, i.e. the one that are not reachable from
a "preserved" symbol transitively on the reference graph.
Right now we are using this information to mark these functions as
non-eligible for import.

The impact is two folds:
- Reduction of compile time: we don't import these functions anywhere
  or import the function these symbols are calling.
- The limited number of import/export leads to better internalization.

Patch originally by Mehdi Amini.

Reviewers: mehdi_amini, pcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D23488

llvm-svn: 291177
2017-01-05 21:34:18 +00:00
Teresa Johnson e27b058de3 [ThinLTO] Use DenseSet instead of SmallPtrSet for holding GUIDs
Should fix some more bot failures from r291108.
This should have been a DenseSet, since GUID is not a pointer type.
It caused some bots to fail, but for some reason I wasnt't getting a
build failure.

llvm-svn: 291115
2017-01-05 14:59:56 +00:00
Teresa Johnson 519465b993 [ThinLTO] Subsume all importing checks into a single flag
Summary:
This adds a new summary flag NotEligibleToImport that subsumes
several existing flags (NoRename, HasInlineAsmMaybeReferencingInternal
and IsNotViableToInline). It also subsumes the checking of references
on the summary that was being done during the thin link by
eligibleForImport() for each candidate. It is much more efficient to
do that checking once during the per-module summary build and record
it in the summary.

Reviewers: mehdi_amini

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28169

llvm-svn: 291108
2017-01-05 14:32:16 +00:00
Mohammed Agabaria 23599ba794 Currently isLikelyComplexAddressComputation tries to figure out if the given stride seems to be 'complex' and need some extra cost for address computation handling.
This code seems to be target dependent which may not be the same for all targets.
Passed the decision whether the given stride is complex or not to the target by sending stride information via SCEV to getAddressComputationCost instead of 'IsComplex'.

Specifically at X86 targets we dont see any significant address computation cost in case of the strided access in general.

Differential Revision: https://reviews.llvm.org/D27518

llvm-svn: 291106
2017-01-05 14:03:41 +00:00
Sanjay Patel 4382997a13 [ValueTracking] remove stale comments; NFC
The checks were improved with:
https://reviews.llvm.org/rL290194

llvm-svn: 290826
2017-01-02 19:04:07 +00:00
Elena Demikhovsky 21706cbd24 AVX-512 Loop Vectorizer: Cost calculation for interleave load/store patterns.
X86 target does not provide any target specific cost calculation for interleave patterns.It uses the common target-independent calculation, which gives very high numbers. As a result, the scalar version is chosen in many cases. The situation on AVX-512 is even worse, since we have 3-src shuffles that significantly reduce the cost.

In this patch I calculate the cost on AVX-512. It will allow to compare interleave pattern with gather/scatter and choose a better solution (PR31426).

* Shiffle-broadcast cost will be changed in Simon's upcoming patch.

Differential Revision: https://reviews.llvm.org/D28118

llvm-svn: 290810
2017-01-02 10:37:52 +00:00
Sanjoy Das 3bb2dbd665 Fix an issue with isGuaranteedToTransferExecutionToSuccessor
I'm not sure if this was intentional, but today
isGuaranteedToTransferExecutionToSuccessor returns true for readonly and
argmemonly calls that may throw.  This commit changes the function to
not implicitly infer nounwind this way.

Even if we eventually specify readonly calls as not throwing,
isGuaranteedToTransferExecutionToSuccessor is not the best place to
infer that.  We should instead teach FunctionAttrs or some other such
pass to tag readonly functions / calls as nounwind instead.

llvm-svn: 290794
2016-12-31 22:12:34 +00:00
Sanjoy Das 0945530d4d Avoid const_cast; NFC
llvm-svn: 290793
2016-12-31 22:12:31 +00:00
Sanjay Patel 7fd779f09f [ValueTracking] make dominator tree requirement explicit for isKnownNonNullFromDominatingCondition(); NFCI
I don't think this hole is currently exposed, but I crashed regression tests for
jump-threading and loop-vectorize after I added calls to isKnownNonNullAt() in
InstSimplify as part of trying to solve PR28430:
https://llvm.org/bugs/show_bug.cgi?id=28430

That's because they call into value tracking with a context instruction, but no
other parts of the query structure filled in.

For more background, see the discussion in:
https://reviews.llvm.org/D27855

llvm-svn: 290786
2016-12-31 17:37:01 +00:00
Philip Reames fdbb05b469 [LVI] Remove count/erase idiom in favor of checking result value of erase
Minor compile time win.  Avoids an additional O(N) scan in the case where we are removing an element and costs nothing when we aren't.

llvm-svn: 290768
2016-12-30 22:09:10 +00:00
Piotr Padlewski da36215017 [MemDep] Handle gep with zeros for invariant.group
Summary:
gep 0, 0 is equivalent to bitcast. LLVM canonicalizes it
to getelementptr because it make SROA can then handle it.

Simple case like

    void g(A &a) {
        z(a);
        if (glob)
            a.foo();
    }
    void testG() {
        A a;
        g(a);
    }

was not devirtualized with -fstrict-vtable-pointers because luck of
handling for gep 0 in Memory Dependence Analysis

Reviewers: dberlin, nlewycky, chandlerc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28126

llvm-svn: 290763
2016-12-30 18:45:07 +00:00
Philip Reames 1e48efcfc5 [LVI] Manually hoist computation from loop
Minor compile time win.  Not known to be a hot spot, just something I noticed while reading.

llvm-svn: 290759
2016-12-30 17:56:47 +00:00
Chandler Carruth 443e57e01d [PM] Teach the CGSCC's CG update utility to more carefully invalidate
analyses when we're about to break apart an SCC.

We can't wait until after breaking apart the SCC to invalidate things:
1) Which SCC do we then invalidate? All of them?
2) Even if we invalidate all of them, a newly created SCC may not have
   a proxy that will convey the invalidation to functions!

Previously we only invalidated one of the SCCs and too late. This led to
stale analyses remaining in the cache. And because the caching strategy
actually works, they would get used and chaos would ensue.

Doing invalidation early is somewhat pessimizing though if we *know*
that the SCC structure won't change. So it turns out that the design to
make the mutation API force the caller to know the *kind* of mutation in
advance was indeed 100% correct and we didn't do enough of it. So this
change also splits two cases of switching a call edge to a ref edge into
two separate APIs so that callers can clearly test for this and take the
easy path without invalidating when appropriate. This is particularly
important in this case as we expect most inlines to be between functions
in separate SCCs and so the common case is that we don't have to so
aggressively invalidate analyses.

The LCG API change in turn needed some basic cleanups and better testing
in its unittest. No interesting functionality changed there other than
more coverage of the returned sequence of SCCs.

While this seems like an obvious improvement over the current state, I'd
like to revisit the core concept of invalidating within the CG-update
layer at all. I'm wondering if we would be better served forcing the
callers to handle the invalidation beforehand in the cases that they
can handle it. An interesting example is when we want to teach the
inliner to *update and preserve* analyses. But we can cross that bridge
when we get there.

With this patch, the new pass manager an build all of the LLVM test
suite at -O3 and everything passes. =D I haven't bootstrapped yet and
I'm sure there are still plenty of bugs, but this gives a nice baseline
so I'm going to increasingly focus on fleshing out the missing
functionality, especially the bits that are just turned off right now in
order to let us establish this baseline.

llvm-svn: 290664
2016-12-28 10:34:50 +00:00
Chandler Carruth c6334579e9 [LCG] Teach the ref edge removal to handle a ref edge that is trivial
due to a call cycle.

This actually crashed the ref removal before.

I've added a unittest that covers this kind of interesting graph
structure and mutation.

llvm-svn: 290645
2016-12-28 02:24:58 +00:00
Chandler Carruth e14524ca30 [PM] Teach MemDep to invalidate its result object when its cached
analysis handles become invalid.

Add a test case for its invalidation logic.

llvm-svn: 290620
2016-12-27 19:33:04 +00:00
Chandler Carruth 56fe48b7e4 [PM] Remove a pointless optimization.
There is no need to do this within an analysis. That method shouldn't
even be reached if this predicate holds as the actual useful
optimization is in the analysis manager itself.

llvm-svn: 290614
2016-12-27 18:04:11 +00:00
Teresa Johnson e0ee5cf7c8 [ThinLTO] Fix "||" vs "|" mixup.
The effect of the bug was that we would incorrectly create summaries
for global and weak values defined in module asm (since we were
essentially testing for bit 1 which is SF_Undefined, and the
RecordStreamer ignores local undefined references). This would have
resulted in conservatively disabling importing of anything referencing
globals and weaks defined in module asm. Added these cases to the test
which now fails without this bug fix.

Fixes PR31459.

llvm-svn: 290610
2016-12-27 17:45:09 +00:00
Piotr Padlewski 2202aa9765 [MemDep] Operand visited twice bugfix
Because operand was not marked as seen it was visited twice.
It doesn't change behavior of optimization, it just saves redudant
visit, so no test changes.

llvm-svn: 290607
2016-12-27 15:06:07 +00:00
Chandler Carruth aa35167578 [PM] Teach BasicAA how to invalidate its result object.
This requires custom handling because BasicAA caches handles to other
analyses and so it needs to trigger indirect invalidation.

This fixes one of the common crashes when using the new PM in real
pipelines. I've also tweaked a regression test to check that we are at
least handling the most immediate case.

I'm going to work at re-structuring this test some to both scale better
(rather than all being in one file) and check more invalidation paths in
a follow-up commit, but I wanted to get the basic bug fix in place.

llvm-svn: 290603
2016-12-27 10:30:45 +00:00
Chandler Carruth 17c630a09c [PM] Teach the AAManager and AAResults layer (the worst offender for
inter-analysis dependencies) to use the new invalidation infrastructure.

This teaches it to invalidate itself when any of the peer function
AA results that it uses become invalid. We do this by just tracking the
originating IDs. I've kept it in a somewhat clunky API since some users
of AAResults are outside the new PM right now. We can clean this API up
if/when those users go away.

Secondly, it uses the registration on the outer analysis manager proxy
to trigger deferred invalidation when a module analysis result becomes
invalid.

I've included test cases that specifically try to trigger use-after-free
in both of these cases and they would crash or hang pretty horribly for
me even without ASan. Now they work nicely.

The `InvalidateAnalysis` utility pass required some tweaking to be
useful in this context and it still is pretty garbage. I'd like to
switch it back to the previous implementation and teach the explicit
invalidate method on the AnalysisManager to take care of correctly
triggering indirect invalidation, but I wanted to go ahead and send this
out so folks could see how all of this stuff works together in practice.
And, you know, that it does actually work. =]

Differential Revision: https://reviews.llvm.org/D27205

llvm-svn: 290595
2016-12-27 08:44:39 +00:00
Chandler Carruth ba90ae969c [PM] Introduce the facilities for registering cross-IR-unit dependencies
that require deferred invalidation.

This handles the other real-world invalidation scenario that we have
cases of: a function analysis which caches references to a module
analysis. We currently do this in the AA aggregation layer and might
well do this in other places as well.

Since this is relative rare, the technique is somewhat more cumbersome.
Analyses need to register themselves when accessing the outer analysis
manager's proxy. This proxy is already necessarily present to allow
access to the outer IR unit's analyses. By registering here we can track
and trigger invalidation when that outer analysis goes away.

To make this work we need to enhance the PreservedAnalyses
infrastructure to support a (slightly) more explicit model for "sets" of
analyses, and allow abandoning a single specific analyses even when
a set covering that analysis is preserved. That allows us to describe
the scenario of preserving all Function analyses *except* for the one
where deferred invalidation has triggered.

We also need to teach the invalidator API to support direct ID calls
instead of always going through a template to dispatch so that we can
just record the ID mapping.

I've introduced testing of all of this both for simple module<->function
cases as well as for more complex cases involving a CGSCC layer.

Much like the previous patch I've not tried to fully update the loop
pass management layer because that layer is due to be heavily reworked
to use similar techniques to the CGSCC to handle updates. As that
happens, we'll have a better testing basis for adding support like this.

Many thanks to both Justin and Sean for the extensive reviews on this to
help bring the API design and documentation into a better state.

Differential Revision: https://reviews.llvm.org/D27198

llvm-svn: 290594
2016-12-27 08:40:39 +00:00
George Burgess IV ed16024a9b [Analysis] Ignore `nobuiltin` on `allocsize` function calls.
We currently ignore the `allocsize` attribute on functions calls with
the `nobuiltin` attribute when trying to lower `@llvm.objectsize`. We
shouldn't care about `nobuiltin` here: `allocsize` is explicitly added
by the user, not inferred based on a function's symbol.

llvm-svn: 290588
2016-12-27 06:32:14 +00:00
George Burgess IV ce04489515 [Analysis] Refactor as promised in r290397.
This also makes us no longer check for `allocsize` on intrinsic calls.
This shouldn't matter, since intrinsics should provide the information
we get from `allocsize` on their own.

llvm-svn: 290585
2016-12-27 06:10:50 +00:00
Bryant Wong b5e03b61e2 [InstCombiner] Simplify lib calls to `round{,f}`
Differential Revision: https://reviews.llvm.org/D28110

llvm-svn: 290542
2016-12-26 14:29:29 +00:00
Bryant Wong a07d9b1460 [AliasAnalysis] Teach BasicAA about memcpy.
Differential Revision: https://reviews.llvm.org/D27034

llvm-svn: 290526
2016-12-25 22:42:27 +00:00
Piotr Padlewski 383edba1fd [MemDep] NFC changes
llvm-svn: 290428
2016-12-23 13:13:32 +00:00
George Burgess IV ccae43a247 Don't consider allocsize functions to be allocation functions.
This patch fixes some ASAN unittest failures on FreeBSD. See the
cfe-commits email thread for r290169 for more on those.

According to the LangRef, the allocsize attribute only tells us about
the number of bytes that exist at the memory location pointed to by the
return value of a function. It does not necessarily mean that the
function will only ever allocate. So, we need to be very careful about
treating functions with allocsize as general allocation functions. This
patch makes us fully conservative in this regard, though I suspect that
we have room to be a bit more aggressive if we want.

This has a FIXME that can be fixed by a relatively straightforward
refactor; I just wanted to keep this patch minimal. If this sticks, I'll
come back and fix it in a few days.

llvm-svn: 290397
2016-12-23 01:18:09 +00:00
Chandler Carruth 9c36c922d9 [PM] Remove now-dead extern template and explicit instantiation
declarations.

We're using a custom class here instead of the helper template, these
bits just didn't get deleted when the other bits did get deleted. This
was found by a really nice MSVC warning about explicitly instantiating
a template where some member functions aren't defined and thus can't be
instantiatied.

llvm-svn: 290327
2016-12-22 07:14:33 +00:00
Chandler Carruth e3f5064b72 [PM] Introduce a reasonable port of the main per-module pass pipeline
from the old pass manager in the new one.

I'm not trying to support (initially) the numerous options that are
currently available to customize the pass pipeline. If we end up really
wanting them, we can add them later, but I suspect many are no longer
interesting. The simplicity of omitting them will help a lot as we sort
out what the pipeline should look like in the new PM.

I've also documented to the best of my ability *why* each pass or group
of passes is used so that reading the pipeline is more helpful. In many
cases I think we have some questionable choices of ordering and I've
left FIXME comments in place so we know what to come back and revisit
going forward. But for now, I've left it as similar to the current
pipeline as I could.

Lastly, I've had to comment out several places where passes are not
ported to the new pass manager or where the loop pass infrastructure is
not yet ready. I did at least fix a few bugs in the loop pass
infrastructure uncovered by running the full pipeline, but I didn't want
to go too far in this patch -- I'll come back and re-enable these as the
infrastructure comes online. But I'd like to keep the comments in place
because I don't want to lose track of which passes need to be enabled
and where they go.

One thing that seemed like a significant API improvement was to require
that we don't build pipelines for O0. It seems to have no real benefit.

I've also switched back to returning pass managers by value as at this
API layer it feels much more natural to me for composition. But if
others disagree, I'm happy to go back to an output parameter.

I'm not 100% happy with the testing strategy currently, but it seems at
least OK. I may come back and try to refactor or otherwise improve this
in subsequent patches but I wanted to at least get a good starting point
in place.

Differential Revision: https://reviews.llvm.org/D28042

llvm-svn: 290325
2016-12-22 06:59:15 +00:00