Summary:
Experimentally we found that promotion to scalars carries less benefits
than sinking and hoisting in LICM. When using MemorySSA, we build an
AliasSetTracker on demand in order to reuse the current infrastructure.
We only build it if less than AccessCapForMSSAPromotion exist in the
loop, a cap that is by default set to 250. This value ensures there are
no runtime regressions, and there are small compile time gains for
pathological cases. A much lower value (20) was found to yield a single
regression in the llvm-test-suite and much higher benefits for compile
times. Conservatively we set the current cap to a high value, but we will
explore lowering it when MemorySSA is enabled by default.
Reviewers: sanjoy, chandlerc
Subscribers: nemanjai, jlebar, Prazek, george.burgess.iv, jfb, jsji, llvm-commits
Differential Revision: https://reviews.llvm.org/D56625
llvm-svn: 353339
Summary:
Pass the alias info to addPointer when available. Will save an alias()
call for must sets when adding a known Must or May alias.
[Part of a series of cleanup patches]
Reviewers: reames, mkazantsev
Subscribers: sanjoy, jlebar, llvm-commits
Differential Revision: https://reviews.llvm.org/D56613
llvm-svn: 353335
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
minted `CallBase` class instead of the `CallSite` wrapper.
This moves the largest interwoven collection of APIs that traffic in
`CallSite`s. While a handful of these could have been migrated with
a minorly more shallow migration by converting from a `CallSite` to
a `CallBase`, it hardly seemed worth it. Most of the APIs needed to
migrate together because of the complex interplay of AA APIs and the
fact that converting from a `CallBase` to a `CallSite` isn't free in its
current implementation.
Out of tree users of these APIs can fairly reliably migrate with some
combination of `.getInstruction()` on the `CallSite` instance and
casting the resulting pointer. The most generic form will look like `CS`
-> `cast_or_null<CallBase>(CS.getInstruction())` but in most cases there
is a more elegant migration. Hopefully, this migrates enough APIs for
users to fully move from `CallSite` to the base class. All of the
in-tree users were easily migrated in that fashion.
Thanks for the review from Saleem!
Differential Revision: https://reviews.llvm.org/D55641
llvm-svn: 350503
Summary:
Attempting to simplify the addPointer interface.
Currently there's code decomposing a MemoryLocation into (Ptr, Size, AAMDNodes) only to recreate the MemoryLocation inside the call.
Reviewers: reames, mkazantsev
Subscribers: sanjoy, jlebar, llvm-commits
Differential Revision: https://reviews.llvm.org/D53836
llvm-svn: 345548
Moving away from UnknownSize is part of the effort to migrate us to
LocationSizes (e.g. the cleanup promised in D44748).
This doesn't entirely remove all of the uses of UnknownSize; some uses
require tweaks to assume that UnknownSize isn't just some kind of int.
This patch is intended to just be a trivial replacement for all places
where LocationSize::unknown() will Just Work.
llvm-svn: 344186
The only point to this change is the test diffs. When I remove this code entirely (in favor of the recently added generic handling), I don't want there to be any confusion due to spurious test diffs.
As an aside, the fact out tests are AST construction order dependent is not great. I thought about fixing that, but the reasonable schemes I might want (e.g. sort by name) need the test diffs anyways.
Philip
llvm-svn: 341841
AliasSetTracker has special case handling for memset, memcpy and memmove which pre-existed argmemonly on functions and readonly and writeonly on arguments. This patch generalizes it using the AA infrastructure to any call correctly annotated.
The motivation here is to cut down on confusion, not performance per se. For most instructions, there is a direct mapping to alias set. However, this is not guaranteed by the interface and was not in fact true for these three intrinsics *and only these three intrinsics*. I kept getting myself confused about this invariant, so I figured it would be good to clearly distinguish between a instructions and alias sets. Calls happened to be an easy target.
The nice side effect is that custom implementations of memset/memcpy/memmove - including wrappers discovered by IPO - can now be optimized the same as builts by LICM.
Note: The actual removal of the memset/memtransfer specific handling will happen in a follow on NFC patch. It was originally part of this one, but separate for ease of review and rebase.
Differential Revision: https://reviews.llvm.org/D50730
llvm-svn: 341713
rL340921 has been reverted by rL340923 due to linkage dependency
from Transform/Utils to Analysis which is not allowed. In this patch
this has been fixed, a new utility function moved to Analysis.
Differential Revision: https://reviews.llvm.org/D51152
llvm-svn: 341014
Teach LICM to hoist stores out of loops when the store writes to a location otherwise unused in the loop, writes a value which is invariant, and is guaranteed to execute if the loop is entered.
Worth noting is that this transformation is partially overlapping with the existing promotion transformation. Reasons this is worthwhile anyway include:
* For multi-exit loops, this doesn't require duplication of the store.
* It kicks in for case where we can't prove we exit through a normal exit (i.e. we may throw), but can prove the store executes before that possible side exit.
Differential Revision: https://reviews.llvm.org/D50925
llvm-svn: 340974
We have multiple places in code where we try to identify whether or not
some instruction is a guard. This patch factors out this logic into a separate
utility function which works uniformly in all places.
Differential Revision: https://reviews.llvm.org/D51152
Reviewed By: fedor.sergeev
llvm-svn: 340921
Volatility is not an aliasing property. We used to model volatile as if it had extremely conservative aliasing implications, but that hasn't been true for several years now. So, it doesn't make sense to be in AliasSet.
It also turns out the code is entirely a noop. Outside of the AST code to update it, there was only one user: load store promotion in LICM. L/S promotion doesn't need the check since it walks all the users of the address anyway. It already checks each load or store via !isUnordered which causes us to bail for volatile accesses. (Look at the lines immediately following the two remove asserts.)
There is the possibility of some small compile time impact here, but the only case which will get noticeably slower is a loop with a large number of loads and stores to the same address where only the last one we inspect is volatile. This is sufficiently rare it's not worth optimizing for..
llvm-svn: 340312
These intrinsics are modelled as writing for control flow purposes, but they don't actually write to any location. Marking these - as we did for guards - allows LICM to hoist loads out of loops containing invariant.starts.
Differential Revision: https://reviews.llvm.org/D50861
llvm-svn: 340245
Main value is just simplifying code. I'll further simply the argument handling case in a bit, but that involved a slightly orthogonal change so I went with the mildy ugly intermediate for this patch.
Note that the isSized check in the old LICM code was not carried across. It turns out that check was dead. a) no test exercised it, and b) langref and verifier had been updated to disallow unsized types used in loads.
llvm-svn: 339930
The `experimental_guard` intrinsic has memory write semantics to model the thread-exiting
logic, but does not do any actual writes to memory. Currently, `AliasSetTracker` treats it as a
normal memory write. As result, a loop-invariant load cannot be hoisted out of loop because
the guard may possibly alias with it.
This patch makes `AliasSetTracker` so that it doesn't treat guards as memory writes.
Differential Revision: https://reviews.llvm.org/D50497
Reviewed By: reames
llvm-svn: 339753
Summary:
AliasSet::print uses `I->printAsOperand` to print UnknownInstructions. The problem is that not all UnknownInstructions have names (e.g. call instructions). When such instructions are printed, they appear as `<badref>` in AliasSets, which is very confusing, as the values are perfectly valid.
This patch fixes that by printing UnknownInstructions without a name using `print` instead of `printAsOperand`.
Reviewers: asbirlea, chandlerc, sanjoy, grosser
Reviewed By: asbirlea
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D48609
llvm-svn: 335751
Summary:
The atomic variants of the memcpy/memmove/memset intrinsics can be treated
the same was as the regular forms, with respect to aliasing. Update the
AliasSetTracker to treat the atomic forms the same was as the regular forms.
llvm-svn: 333551
The uint64_ts that we pass around AA to represent MemoryLocation sizes
are logically an Optional<uint64_t>. In D44748, we want to add an extra
'imprecise' bit to this Optional<uint64_t> to represent whether a given
MemoryLocation size is an upper-bound or an exact size. For more context
on why, please see D44748.
That patch is quite large, but reviewers seem to be OK with the
approach. In D45581 (my first attempt to split 'noise' out of D44748),
reames asked that I land a precursor that is solely replacing uint64_t
with LocationSize, which starts out as `using LocationSize = uint64_t;`.
He also gave me the OK to submit this rename without further review.
llvm-svn: 333314
See r331124 for how I made a list of files missing the include.
I then ran this Python script:
for f in open('filelist.txt'):
f = f.strip()
fl = open(f).readlines()
found = False
for i in xrange(len(fl)):
p = '#include "llvm/'
if not fl[i].startswith(p):
continue
if fl[i][len(p):] > 'Config':
fl.insert(i, '#include "llvm/Config/llvm-config.h"\n')
found = True
break
if not found:
print 'not found', f
else:
open(f, 'w').write(''.join(fl))
and then looked through everything with `svn diff | diffstat -l | xargs -n 1000 gvim -p`
and tried to fix include ordering and whatnot.
No intended behavior change.
llvm-svn: 331184
Summary:
The aim is to make ModRefInfo checks and changes more intuitive
and less error prone using inline methods that abstract the bit operations.
Ideally ModRefInfo would become an enum class, but that change will require
a wider set of changes into FunctionModRefBehavior.
Reviewers: sanjoy, george.burgess.iv, dberlin, hfinkel
Subscribers: nlopes, llvm-commits
Differential Revision: https://reviews.llvm.org/D40749
llvm-svn: 319821
This patch implements Chandler's idea [0] for supporting languages that
require support for infinite loops with side effects, such as Rust, providing
part of a solution to bug 965 [1].
Specifically, it adds an `llvm.sideeffect()` intrinsic, which has no actual
effect, but which appears to optimization passes to have obscure side effects,
such that they don't optimize away loops containing it. It also teaches
several optimization passes to ignore this intrinsic, so that it doesn't
significantly impact optimization in most cases.
As discussed on llvm-dev [2], this patch is the first of two major parts.
The second part, to change LLVM's semantics to have defined behavior
on infinite loops by default, with a function attribute for opting into
potential-undefined-behavior, will be implemented and posted for review in
a separate patch.
[0] http://lists.llvm.org/pipermail/llvm-dev/2015-July/088103.html
[1] https://bugs.llvm.org/show_bug.cgi?id=965
[2] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118632.html
Differential Revision: https://reviews.llvm.org/D38336
llvm-svn: 317729
Summary:
Add LLVM_FORCE_ENABLE_DUMP cmake option, and use it along with
LLVM_ENABLE_ASSERTIONS to set LLVM_ENABLE_DUMP.
Remove NDEBUG and only use LLVM_ENABLE_DUMP to enable dump methods.
Move definition of LLVM_ENABLE_DUMP from config.h to llvm-config.h so
it'll be picked up by public headers.
Differential Revision: https://reviews.llvm.org/D38406
llvm-svn: 315590
Summary:
Make sure we are comparing the unknown instructions in the alias set and the instruction interested in.
I believe this is clearly a bug (missed opportunity). I can also add some test cases if desired.
Reviewers: hfinkel, davide, dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34597
llvm-svn: 306241
I did this a long time ago with a janky python script, but now
clang-format has built-in support for this. I fed clang-format every
line with a #include and let it re-sort things according to the precise
LLVM rules for include ordering baked into clang-format these days.
I've reverted a number of files where the results of sorting includes
isn't healthy. Either places where we have legacy code relying on
particular include ordering (where possible, I'll fix these separately)
or where we have particular formatting around #include lines that
I didn't want to disturb in this patch.
This patch is *entirely* mechanical. If you get merge conflicts or
anything, just ignore the changes in this patch and run clang-format
over your #include lines in the files.
Sorry for any noise here, but it is important to keep these things
stable. I was seeing an increasing number of patches with irrelevant
re-ordering of #include lines because clang-format was used. This patch
at least isolates that churn, makes it easy to skip when resolving
conflicts, and gets us to a clean baseline (again).
llvm-svn: 304787
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
This reverts commit r285191.
LICM appears to rely on the Alias Set Tracker hitting lifetime markers to prevent
code from being moved outside of the original scope.
llvm-svn: 285227
Repeated inserts into AliasSetTracker have quadratic behavior - inserting a
pointer into AST is linear, since it requires walking over all "may" alias
sets and running an alias check vs. every pointer in the set.
We can avoid this by tracking the total number of pointers in "may" sets,
and when that number exceeds a threshold, declare the tracker "saturated".
This lumps all pointers into a single "may" set that aliases every other
pointer.
(This is a stop-gap solution until we migrate to MemorySSA)
This fixes PR28832.
Differential Revision: https://reviews.llvm.org/D23432
llvm-svn: 279274
