The most important part required to make clang
devirtualization works ( ͡°͜ʖ ͡°).
The code is able to find non local dependencies, but unfortunatelly
because the caller can only handle local dependencies, I had to add
some restrictions to look for dependencies only in the same BB.
http://reviews.llvm.org/D12992
llvm-svn: 249196
Summary:
The instructions SeenExprs records may be deleted during rewriting.
FindClosestMatchingDominator should ignore these deleted instructions.
Fixes PR24301.
Reviewers: grosser
Subscribers: grosser, llvm-commits
Differential Revision: http://reviews.llvm.org/D13315
llvm-svn: 248983
Same strategy as simplifyInstructionsInBlock. ~1/3 less time
on my test suite. This pass doesn't have many in-tree users,
but getting rid of an O(N^2) worst case and making it cleaner
should at least make it a viable alternative to ADCE, since
it's now consistently somewhat faster.
llvm-svn: 248927
Summary: This patch adds block frequency analysis to LoopUnswitch pass to recognize hot/cold regions. For cold regions the pass only performs trivial unswitches since they do not increase code size, and for hot regions everything works as before. This helps to minimize code growth in cold regions and be more aggressive in hot regions. Currently the default cold regions are blocks with frequencies below 20% of function entry frequency, and it can be adjusted via -loop-unswitch-cold-block-frequency flag. The entire feature is controlled via -loop-unswitch-with-block-frequency flag and it is off by default.
Reviewers: broune, silvas, dnovillo, reames
Subscribers: davidxl, llvm-commits
Differential Revision: http://reviews.llvm.org/D11605
llvm-svn: 248777
Originally, debug intrinsics and annotation intrinsics may prevent
the loop to be rerolled, now they are ignored.
Differential Revision: http://reviews.llvm.org/D13150
llvm-svn: 248718
This patch changes the order of GEPs generated by Splitting GEPs
pass, specially when one of the GEPs has constant and the base is
loop invariant, then we will generate the GEP with constant first
when beneficial, to expose more cases for LICM.
If originally Splitting GEP generate the following:
do.body.i:
%idxprom.i = sext i32 %shr.i to i64
%2 = bitcast %typeD* %s to i8*
%3 = shl i64 %idxprom.i, 2
%uglygep = getelementptr i8, i8* %2, i64 %3
%uglygep7 = getelementptr i8, i8* %uglygep, i64 1032
...
Now it genereates:
do.body.i:
%idxprom.i = sext i32 %shr.i to i64
%2 = bitcast %typeD* %s to i8*
%3 = shl i64 %idxprom.i, 2
%uglygep = getelementptr i8, i8* %2, i64 1032
%uglygep7 = getelementptr i8, i8* %uglygep, i64 %3
...
For no-loop cases, the original way of generating GEPs seems to
expose more CSE cases, so we don't change the logic for no-loop
cases, and only limit our change to the specific case we are
interested in.
llvm-svn: 248420
This change allows dead store elimination to remove zero and null stores into memory freshly allocated with calloc-like function.
Differential Revision: http://reviews.llvm.org/D13021
llvm-svn: 248374
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
Apart from checking that GlobalVariable is a constant, we should check
that it's not a weak constant, in which case we can't propagate its
value.
llvm-svn: 248327
Summary:
We should either require the DT info to be available, or check if it's
available in every place we use DT (and we already miss such check in
one place, which causes failures in some cases). As other loop passes
preserve DT and it's usually available, it makes sense to just require
it here.
There is no regression test, because the bug only shows up if pass
manager decides to clean DT info right before LoopUnswitch. If
loop-unswitch is run separately, DT is available, so bug isn't exposed.
Reviewers: chandlerc, hfinkel
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D13036
llvm-svn: 248230
We know that an argmemonly function can only access memory pointed to by it's pointer arguments. Rather than needing to consider all possible stores as aliasing (as we do for a readonly function), we can only consider the aliasing of the pointer arguments.
Note that this change only addresses hoisting. I'm thinking about how to address speculation safety as well, but that will be a different change.
FYI, argmemonly disallows accessing memory through non-pointer typed arguments.
Differential Revision: http://reviews.llvm.org/D12771
llvm-svn: 248220
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
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
We only checked that a global is initialized with constants, which is
incorrect. We should be checking that GlobalVariable *is* a constant,
not just initialized with it.
llvm-svn: 247769
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
LazuValueInfo can prove that value is nonnull based on the context information.
Make use of this ability to infer nonnull attributes for the call arguments.
Differential Revision: http://reviews.llvm.org/D12836
llvm-svn: 247707
Summary:
This change lets a `PlaceSafepoints` client change how wide the trip
count of a loop has to be for the loop to be considerd "counted", via
`CountedLoopTripWidth`. It also removes the boolean `SkipCounted` flag
and the `upperTripBound` constant -- we can get the old behavior of
`SkipCounted` == `false` by setting `CountedLoopTripWidth` to `13` (2 ^
13 == 8192).
Reviewers: reames
Subscribers: llvm-commits, sanjoy
Differential Revision: http://reviews.llvm.org/D12789
llvm-svn: 247656
In some ways this is a very boring port to the new pass manager as there
are no interesting analyses or dependencies or other oddities.
However, this does introduce the first good example of a transformation
pass with non-trivial state porting to the new pass manager. I've tried
to carve out patterns here to replicate elsewhere, and would appreciate
comments on whether folks like these patterns:
- A common need in the new pass manager is to effectively lift the pass
class and some of its state into a public header file. Prior to this,
LLVM used anonymous namespaces to provide "module private" types and
utilities, but that doesn't scale to cases where a public header file
is needed and the new pass manager will exacerbate that. The pattern
I've adopted here is to use the namespace-cased-name of the core pass
(what would be a module if we had them) as a module-private namespace.
Then utility and other code can be declared and defined in this
namespace. At some point in the future, we could even have
(conditionally compiled) code that used modules features when
available to do the same basic thing.
- I've split the actual pass run method in two in order to expose
a private method usable by the old pass manager to wrap the new class
with a minimum of duplicated code. I actually looked at a bunch of
ways to automate or generate these, but they are all quite terrible
IMO. The fundamental need is to extract the set of analyses which need
to cross this interface boundary, and that will end up being too
unpredictable to effectively encapsulate IMO. This is also
a relatively small amount of boiler plate that will live a relatively
short time, so I'm not too worried about the fact that it is boiler
plate.
The rest of the patch is totally boring but results in a massive diff
(sorry). It just moves code around and removes or adds qualifiers to
reflect the new name and nesting structure.
Differential Revision: http://reviews.llvm.org/D12773
llvm-svn: 247501
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
The assertion was weaker than it should be and gave the impression we're growing the number of base defining values being considered during the fixed point interation. That's not true. The tighter form of the assert is useful documentation.
llvm-svn: 247221
This change is simply enhancing the existing inference algorithm to handle insertelement instructions by conservatively inserting a new instruction to propagate the vector of associated base pointers. In the process, I'm ripping out the peephole optimizations which mostly helped cover the fact this hadn't been done.
Note that most of the newly inserted nodes will be nearly immediately removed by the post insertion optimization pass introduced in 246718. Arguably, we should be trying harder to avoid the malloc traffic here, but I'd rather get the code correct, then worry about compile time.
Unlike previous extensions of the algorithm to handle more case, I discovered the existing code was causing miscompiles in some cases. In particular, we had an implicit assumption that the peephole covered *all* insert element instructions, so if we had a value directly based on a insert element the peephole didn't cover, we proceeded as if it were a base anyways. Not good. I believe we had the same issue with shufflevector which is why I adjusted the predicate for them as well.
Differential Revision: http://reviews.llvm.org/D12583
llvm-svn: 247210
Previously, the base pointer algorithm wasn't deterministic. The core fixed point was (of course), but we were inserting new nodes and optimizing them in an order which was unspecified and variable. We'd somewhat hacked around this for testing by sorting by value name, but that doesn't solve the general determinism problem.
Instead, we can use the order of traversal over the def/use graph to give us a single consistent ordering. Today, this is a DFS order, but the exact order doesn't mater provided it's deterministic for a given input.
(Q: It is safe to rely on a deterministic order of operands right?)
Note that this only fixes the determinism within a single inference step. The inference step is currently invoked many times in a non-deterministic order. That's a future change in the sequence. :)
Differential Revision: http://reviews.llvm.org/D12640
llvm-svn: 247208
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
As a first step towards a new implementation of the base pointer inference algorithm, introduce an abstraction for BDVs, strengthen the assertions around them, and rewrite the BDV relation code in terms of the abstraction which includes an explicit notion of whether the BDV is also a base. The later is motivated by the fact we had a bug where insertelement was always assumed to be a base pointer even though the BDV code knew it wasn't. The strengthened assertions in this patch would have caught that bug.
The next step will be to separate the DefiningValueMap into a BDV use list cache (entirely within findBasePointers) and a base pointer cache. Having the former will allow me to use a deterministic visit order when visiting BDVs in the inference algorithm and remove a bunch of ordering related hacks. Before actually doing the last step, I'm likely going to extend the lattice with a 'BaseN' (seen only base inputs) state so that I can kill the post process optimization step.
Phabricator Revision: http://reviews.llvm.org/D12608
llvm-svn: 246809
Piotr Padlewski