[IndVars] NFC Cleanup.

- Rename methods according to the LLVM Coding Style
- Merge adjacent anonymous namespace block
- Use `auto` in two places

llvm-svn: 250152

[IndVars] Use `auto`; NFC

llvm-svn: 249944

[IndVars] Don't break dominance in `eliminateIdentitySCEV`

Summary:
After r249211, `getSCEV(X) == getSCEV(Y)` does not guarantee that X and
Y are related in the dominator tree, even if X is an opera

[IndVars] Don't break dominance in `eliminateIdentitySCEV`

Summary:
After r249211, `getSCEV(X) == getSCEV(Y)` does not guarantee that X and
Y are related in the dominator tree, even if X is an operand to Y (I've
included a toy example in comments, and a real example as a test case).

This commit changes `SimplifyIndVar` to require a `DominatorTree`. I
don't think this is a problem because `ScalarEvolution` requires it
anyway.

Fixes PR25051.

Depends on D13459.

Reviewers: atrick, hfinkel

Subscribers: joker.eph, llvm-commits, sanjoy

Differential Revision: http://reviews.llvm.org/D13460

llvm-svn: 249471

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[SCEV] Introduce ScalarEvolution::getOne and getZero.

Summary:
It is fairly common to call SE->getConstant(Ty, 0) or
SE->getConstant(Ty, 1); this change makes such uses a little bit
briefer.

I've r

[SCEV] Introduce ScalarEvolution::getOne and getZero.

Summary:
It is fairly common to call SE->getConstant(Ty, 0) or
SE->getConstant(Ty, 1); this change makes such uses a little bit
briefer.

I've refactored the call sites I could find easily to use getZero /
getOne.

Reviewers: hfinkel, majnemer, reames

Subscribers: sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D12947

llvm-svn: 248362

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[IndVars] Use C++11 style field initialization; NFCI.

llvm-svn: 248131

[IndVars] Don't add a level of indentation for namespace {. NFC.

Whitespace-only change.

llvm-svn: 248130

[IndVars] Don't repeat function names in comment; NFC.

Only changes comments.

llvm-svn: 248112

[IndVars] Fix a bug in r248045.

Because -indvars widens induction variables through arithmetic,
`NeverNegative` cannot be a property of the `WidenIV` (a `WidenIV`
manages information for all transit

[IndVars] Fix a bug in r248045.

Because -indvars widens induction variables through arithmetic,
`NeverNegative` cannot be a property of the `WidenIV` (a `WidenIV`
manages information for all transitive uses of an IV being widened,
including uses of `-1 * IV`). Instead it must live on `NarrowIVDefUse`
which manages information for a specific def-use edge in the transitive
use list of an induction variable.

This change also adds a test case that demonstrates the problem with
r248045.

llvm-svn: 248107

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[IndVars] Widen more comparisons for non-negative induction vars

Summary:
If an induction variable is provably non-negative, its sign extension is
equal to its zero extension. This means narrow use

[IndVars] Widen more comparisons for non-negative induction vars

Summary:
If an induction variable is provably non-negative, its sign extension is
equal to its zero extension. This means narrow uses like

icmp slt iNarrow %indvar, %rhs

can be widened into

icmp slt iWide zext(%indvar), sext(%rhs)

Reviewers: atrick, mcrosier, hfinkel

Subscribers: hfinkel, reames, llvm-commits

Differential Revision: http://reviews.llvm.org/D12745

llvm-svn: 248045

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[IndVars] Fix PR24783.

In `IndVarSimplify::ExpandSCEVIfNeeded`,
`SCEVExpander::findExistingExpansion` may return an `llvm::Value` that
differs in type from the SCEV it was asked to find an expansion

[IndVars] Fix PR24783.

In `IndVarSimplify::ExpandSCEVIfNeeded`,
`SCEVExpander::findExistingExpansion` may return an `llvm::Value` that
differs in type from the SCEV it was asked to find an expansion for (but
computes the same value). In such cases, we fall back on
`expandCodeFor`; and rely on LLVM to CSE the two equivalent
expressions (different only by a no-op cast) into a single computation.

I tried a few other approaches to fixing PR24783, all of which turned
out to be more complex than this current version:

1. Move the `ExpandSCEVIfNeeded` logic into `expandCodeFor`. This got
problematic because currently we do not pass in the `Loop *` into
`expandCodeFor`. Changing the interface to do this is a more
invasive change, and really does not make much semantic sense unless
the SCEV being passed in is an add recurrence.

There is also the problem of `expandCodeFor` being used in places
other than `indvars` -- there may be performance / correctness
issues elsewhere if `expandCodeFor` is moved from always generating
IR from scratch to cache-like model.

2. Have `findExistingExpansion` only return expression with the correct
type. This would make `isHighCostExpansionHelper` and thus
`isHighCostExpansion` more conservative than necessary.

3. Insert casts on the value returned by `findExistingExpansion` if
needed using `InsertNoopCastOfTo`. This is complicated because
`InsertNoopCastOfTo` depends on internal state of its
`SCEVExpander` (specifically `Builder.GetInserPoint()`), and this
may not be set up when `ExpandSCEVIfNeeded` is called.

4. Manually insert casts on the value returned by
`findExistingExpansion` if needed using `InsertNoopCastOfTo` via
`CastInst::Create`. This is probably workable, but figuring out the
location where the cast instruction needs to be inserted has enough
edge cases (arguments, constants, invokes, LCSSA must be preserved)
makes me feel what I have right now is simplest solution.

llvm-svn: 247749

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[IndVars] Rename variable; NFC.

llvm-svn: 247748

Add GlobalsAA as preserved to a bunch of transforms

GlobalsAA must by definition be preserved in function passes, but the passmanager doesn't know that. Make each pass explicitly preserve GlobalsAA.

Add GlobalsAA as preserved to a bunch of transforms

GlobalsAA must by definition be preserved in function passes, but the passmanager doesn't know that. Make each pass explicitly preserve GlobalsAA.

llvm-svn: 247263

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[PM/AA] Rebuild LLVM's alias analysis infrastructure in a way compatible
with the new pass manager, and no longer relying on analysis groups.

This builds essentially a ground-up new AA infrastructur

[PM/AA] Rebuild LLVM's alias analysis infrastructure in a way compatible
with the new pass manager, and no longer relying on analysis groups.

This builds essentially a ground-up new AA infrastructure stack for
LLVM. The core ideas are the same that are used throughout the new pass
manager: type erased polymorphism and direct composition. The design is
as follows:

- FunctionAAResults is a type-erasing alias analysis results aggregation
interface to walk a single query across a range of results from
different alias analyses. Currently this is function-specific as we
always assume that aliasing queries are *within* a function.

- AAResultBase is a CRTP utility providing stub implementations of
various parts of the alias analysis result concept, notably in several
cases in terms of other more general parts of the interface. This can
be used to implement only a narrow part of the interface rather than
the entire interface. This isn't really ideal, this logic should be
hoisted into FunctionAAResults as currently it will cause
a significant amount of redundant work, but it faithfully models the
behavior of the prior infrastructure.

- All the alias analysis passes are ported to be wrapper passes for the
legacy PM and new-style analysis passes for the new PM with a shared
result object. In some cases (most notably CFL), this is an extremely
naive approach that we should revisit when we can specialize for the
new pass manager.

- BasicAA has been restructured to reflect that it is much more
fundamentally a function analysis because it uses dominator trees and
loop info that need to be constructed for each function.

All of the references to getting alias analysis results have been
updated to use the new aggregation interface. All the preservation and
other pass management code has been updated accordingly.

The way the FunctionAAResultsWrapperPass works is to detect the
available alias analyses when run, and add them to the results object.
This means that we should be able to continue to respect when various
passes are added to the pipeline, for example adding CFL or adding TBAA
passes should just cause their results to be available and to get folded
into this. The exception to this rule is BasicAA which really needs to
be a function pass due to using dominator trees and loop info. As
a consequence, the FunctionAAResultsWrapperPass directly depends on
BasicAA and always includes it in the aggregation.

This has significant implications for preserving analyses. Generally,
most passes shouldn't bother preserving FunctionAAResultsWrapperPass
because rebuilding the results just updates the set of known AA passes.
The exception to this rule are LoopPass instances which need to preserve
all the function analyses that the loop pass manager will end up
needing. This means preserving both BasicAAWrapperPass and the
aggregating FunctionAAResultsWrapperPass.

Now, when preserving an alias analysis, you do so by directly preserving
that analysis. This is only necessary for non-immutable-pass-provided
alias analyses though, and there are only three of interest: BasicAA,
GlobalsAA (formerly GlobalsModRef), and SCEVAA. Usually BasicAA is
preserved when needed because it (like DominatorTree and LoopInfo) is
marked as a CFG-only pass. I've expanded GlobalsAA into the preserved
set everywhere we previously were preserving all of AliasAnalysis, and
I've added SCEVAA in the intersection of that with where we preserve
SCEV itself.

One significant challenge to all of this is that the CGSCC passes were
actually using the alias analysis implementations by taking advantage of
a pretty amazing set of loop holes in the old pass manager's analysis
management code which allowed analysis groups to slide through in many
cases. Moving away from analysis groups makes this problem much more
obvious. To fix it, I've leveraged the flexibility the design of the new
PM components provides to just directly construct the relevant alias
analyses for the relevant functions in the IPO passes that need them.
This is a bit hacky, but should go away with the new pass manager, and
is already in many ways cleaner than the prior state.

Another significant challenge is that various facilities of the old
alias analysis infrastructure just don't fit any more. The most
significant of these is the alias analysis 'counter' pass. That pass
relied on the ability to snoop on AA queries at different points in the
analysis group chain. Instead, I'm planning to build printing
functionality directly into the aggregation layer. I've not included
that in this patch merely to keep it smaller.

Note that all of this needs a nearly complete rewrite of the AA
documentation. I'm planning to do that, but I'd like to make sure the
new design settles, and to flesh out a bit more of what it looks like in
the new pass manager first.

Differential Revision: http://reviews.llvm.org/D12080

llvm-svn: 247167

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Replace some calls to isa<LandingPadInst> with isEHPad()

No functionality change is intended.

llvm-svn: 245487

[PM] Port ScalarEvolution to the new pass manager.

This change makes ScalarEvolution a stand-alone object and just produces
one from a pass as needed. Making this work well requires making the
objec

[PM] Port ScalarEvolution to the new pass manager.

This change makes ScalarEvolution a stand-alone object and just produces
one from a pass as needed. Making this work well requires making the
object movable, using references instead of overwritten pointers in
a number of places, and other refactorings.

I've also wired it up to the new pass manager and added a RUN line to
a test to exercise it under the new pass manager. This includes basic
printing support much like with other analyses.

But there is a big and somewhat scary change here. Prior to this patch
ScalarEvolution was never *actually* invalidated!!! Re-running the pass
just re-wired up the various other analyses and didn't remove any of the
existing entries in the SCEV caches or clear out anything at all. This
might seem OK as everything in SCEV that can uses ValueHandles to track
updates to the values that serve as SCEV keys. However, this still means
that as we ran SCEV over each function in the module, we kept
accumulating more and more SCEVs into the cache. At the end, we would
have a SCEV cache with every value that we ever needed a SCEV for in the
entire module!!! Yowzers. The releaseMemory routine would dump all of
this, but that isn't realy called during normal runs of the pipeline as
far as I can see.

To make matters worse, there *is* actually a key that we don't update
with value handles -- there is a map keyed off of Loop*s. Because
LoopInfo *does* release its memory from run to run, it is entirely
possible to run SCEV over one function, then over another function, and
then lookup a Loop* from the second function but find an entry inserted
for the first function! Ouch.

To make matters still worse, there are plenty of updates that *don't*
trip a value handle. It seems incredibly unlikely that today GVN or
another pass that invalidates SCEV can update values in *just* such
a way that a subsequent run of SCEV will incorrectly find lookups in
a cache, but it is theoretically possible and would be a nightmare to
debug.

With this refactoring, I've fixed all this by actually destroying and
recreating the ScalarEvolution object from run to run. Technically, this
could increase the amount of malloc traffic we see, but then again it is
also technically correct. ;] I don't actually think we're suffering from
tons of malloc traffic from SCEV because if we were, the fact that we
never clear the memory would seem more likely to have come up as an
actual problem before now. So, I've made the simple fix here. If in fact
there are serious issues with too much allocation and deallocation,
I can work on a clever fix that preserves the allocations (while
clearing the data) between each run, but I'd prefer to do that kind of
optimization with a test case / benchmark that shows why we need such
cleverness (and that can test that we actually make it faster). It's
possible that this will make some things faster by making the SCEV
caches have higher locality (due to being significantly smaller) so
until there is a clear benchmark, I think the simple change is best.

Differential Revision: http://reviews.llvm.org/D12063

llvm-svn: 245193

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[IndVarSimplify] Make cost estimation in RewriteLoopExitValues smarter

Differential Revision: http://reviews.llvm.org/D11687

llvm-svn: 244474

[IndVars] Try to use existing values in RewriteLoopExitValues.

Summary:
In RewriteLoopExitValues, before expanding out an SCEV expression using
SCEVExpander, try to see if an existing LLVM IR expres

[IndVars] Try to use existing values in RewriteLoopExitValues.

Summary:
In RewriteLoopExitValues, before expanding out an SCEV expression using
SCEVExpander, try to see if an existing LLVM IR expression already
computes the value we're interested in. If so use that existing
expression.

Apart from reducing IndVars' reliance on the rest of the compilation
pipeline, this also prevents IndVars from concluding some expressions as
"high cost" when they're not. For instance,
`InductiveRangeCheckElimination` often emits code of the following form:

```
len = umin(len_A, len_B)

loop:
...
if (i++ < len)
goto loop

outside_loop:
use(i)
```

`SCEVExpander` refuses to rewrite the use of `i` in `outside_loop`,
since it thinks the value of `i` on loop exit, `len`, is a high cost
expansion since it contains an `umax` in it. With this change,
`IndVars` can see that it can re-use `len` instead of creating a new
expression to compute `umin(len_A, len_B)`.

I considered putting this cleverness in `SCEVExpander`, but I was
worried that it may then have a deterimental effect on other passes
that use it. So I decided it was better to just do this in the one
place where it seems like an obviously good idea, with the intent of
generalizing later if needed.

Reviewers: atrick, reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10782

llvm-svn: 241838

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Add simplify_type<const WeakVH>; simplify IndVarSimplify

r240214 fixed some UB in IndVarSimplify, and it needed a temporary
`WeakVH` to do it. Add `simplify_type<const WeakVH>` so that this
tempora

Add simplify_type<const WeakVH>; simplify IndVarSimplify

r240214 fixed some UB in IndVarSimplify, and it needed a temporary
`WeakVH` to do it. Add `simplify_type<const WeakVH>` so that this
temporary isn't necessary.

llvm-svn: 240599

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Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC)

Apparently, the style needs to be agreed upon first.

llvm-svn: 240390

IndVarSimplify: Avoid UB from binding a reference to a null pointer

Calling operator* on a WeakVH whose Value is null hits undefined
behaviour, since we bind the value to a reference. Instead, go th

IndVarSimplify: Avoid UB from binding a reference to a null pointer

Calling operator* on a WeakVH whose Value is null hits undefined
behaviour, since we bind the value to a reference. Instead, go through
`operator Value*` so that we work with the pointer itself.

Found by ubsan.

llvm-svn: 240214

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Fixed/added namespace ending comments using clang-tidy. NFC

The patch is generated using this command:

tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-c

Fixed/added namespace ending comments using clang-tidy. NFC

The patch is generated using this command:

tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
llvm/lib/


Thanks to Eugene Kosov for the original patch!

llvm-svn: 240137

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Replace push_back(Constructor(foo)) with emplace_back(foo) for non-trivial types

If the type isn't trivially moveable emplace can skip a potentially
expensive move. It also saves a couple of charact

Replace push_back(Constructor(foo)) with emplace_back(foo) for non-trivial types

If the type isn't trivially moveable emplace can skip a potentially
expensive move. It also saves a couple of characters.


Call sites were found with the ASTMatcher + some semi-automated cleanup.

memberCallExpr(
argumentCountIs(1), callee(methodDecl(hasName("push_back"))),
on(hasType(recordDecl(has(namedDecl(hasName("emplace_back")))))),
hasArgument(0, bindTemporaryExpr(
hasType(recordDecl(hasNonTrivialDestructor())),
has(constructExpr()))),
unless(isInTemplateInstantiation()))

No functional change intended.

llvm-svn: 238602

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Enable exitValue rewrite only when the cost of expansion is low.

The patch evaluates the expansion cost of exitValue in indVarSimplify pass, and only does the rewriting when the expansion cost is lo

Enable exitValue rewrite only when the cost of expansion is low.

The patch evaluates the expansion cost of exitValue in indVarSimplify pass, and only does the rewriting when the expansion cost is low or loop can be deleted with the rewriting. It provides an option "-replexitval=" to control the default aggressiveness of the exitvalue rewriting. It also fixes some missing cases in SCEVExpander::isHighCostExpansionHelper to enhance the evaluation of SCEV expansion cost.

Differential Revision: http://reviews.llvm.org/D9800

llvm-svn: 238507

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indvars cruft: don't replace phi nodes for no reason.

Don't replace a phi with an identical phi. This was done long ago to
"preserve" IVUsers analysis. The code has already called
SE->forgetValue(PN

indvars cruft: don't replace phi nodes for no reason.

Don't replace a phi with an identical phi. This was done long ago to
"preserve" IVUsers analysis. The code has already called
SE->forgetValue(PN) so I see no purpose in creating a new value for
the phi.

llvm-svn: 237587

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SimplifyIV comments and dead argument cleanup.

Remove crufty comments. IVUsers hasn't been used here for a long time.

llvm-svn: 237586