This patch is a follow up from r240560 and is a step further into
mitigating the compile time performance issues in CaptureTracker.
By providing the CaptureTracker with a "cached ordered basic block"
instead of computing it every time, MemDepAnalysis can use this cache
throughout its calls to AA->callCapturesBefore, avoiding to recompute it
for every scanned instruction. In the same testcase used in r240560,
compile time is reduced from 2min to 30s.
This also fixes PR22348.
rdar://problem/19230319
Differential Revision: http://reviews.llvm.org/D11364
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Before, we were passing the pointer partitions to LAA. Now, we get all
the checks from LAA and filter out the checks within partitions in
LoopDistribution.
This effectively concludes the steps to move filtering memchecks from
LAA into its clients. There is still some cleanup left to remove the
unused interfaces in LAA that still take PtrPartition.
(Moving this functionality to LoopDistribution also requires
needsChecking on pointers to be made public.)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243613 91177308-0d34-0410-b5e6-96231b3b80d8
Bonus change to remove emacs major mode marker from SystemZMachineFunctionInfo.cpp because emacs already knows it's C++ from the extension. Also fix typo "appeary" in AMDGPUMCAsmInfo.h.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243585 91177308-0d34-0410-b5e6-96231b3b80d8
on suggestions. Currently the function is only used for inline purposes
and this is more descriptive for the use.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243578 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Make Scalar Evolution able to propagate NSW and NUW flags from instructions to SCEVs in some cases. This is based on reasoning about when poison from instructions with these flags would trigger undefined behavior. This gives a 13% speed-up on some Eigen3-based Google-internal microbenchmarks for NVPTX.
There does not seem to be clear agreement about when poison should be considered to propagate through instructions. In this analysis, poison propagates only in cases where that should be uncontroversial.
This change makes LSR able to create induction variables for expressions like &ptr[i + offset] for loops like this:
for (int i = 0; i < limit; ++i) {
sum += ptr[i + offset];
}
Here ptr is a 64 bit pointer and offset is a 32 bit integer. For NVPTX, LSR currently creates an induction variable for i + offset instead, which is not as fast. Improving this situation is what brings the 13% speed-up on some Eigen3-based Google-internal microbenchmarks for NVPTX.
There are more details in this discussion on llvmdev.
June: http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-June/thread.html#87234
July: http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-July/thread.html#87392
Patch by Bjarke Roune
Reviewers: eliben, atrick, sanjoy
Subscribers: majnemer, hfinkel, jingyue, meheff, llvm-commits
Differential Revision: http://reviews.llvm.org/D11212
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This is effectively an NFC but we can no longer print the index of the
pointer group so instead I print its address. This still lets us
cross-check the section that list the checks against the section that
list the groups (see how I modified the test).
E.g. before we printed this:
Run-time memory checks:
Check 0:
Comparing group 0:
%arrayidxC = getelementptr inbounds i16, i16* %c, i64 %store_ind
%arrayidxC1 = getelementptr inbounds i16, i16* %c, i64 %store_ind_inc
Against group 1:
%arrayidxA = getelementptr i16, i16* %a, i64 %ind
%arrayidxA1 = getelementptr i16, i16* %a, i64 %add
...
Grouped accesses:
Group 0:
(Low: %c High: (78 + %c))
Member: {%c,+,4}<%for.body>
Member: {(2 + %c),+,4}<%for.body>
Now we print this (changes are underlined):
Run-time memory checks:
Check 0:
Comparing group (0x7f9c6040c320):
~~~~~~~~~~~~~~
%arrayidxC1 = getelementptr inbounds i16, i16* %c, i64 %store_ind_inc
%arrayidxC = getelementptr inbounds i16, i16* %c, i64 %store_ind
Against group (0x7f9c6040c358):
~~~~~~~~~~~~~~
%arrayidxA1 = getelementptr i16, i16* %a, i64 %add
%arrayidxA = getelementptr i16, i16* %a, i64 %ind
...
Grouped accesses:
Group 0x7f9c6040c320:
~~~~~~~~~~~~~~
(Low: %c High: (78 + %c))
Member: {(2 + %c),+,4}<%for.body>
Member: {%c,+,4}<%for.body>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243354 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Was D9784: "Remove loop variant range check when induction variable is
strictly increasing"
This change re-implements D9784 with the two differences:
1. It does not use SCEVExpander and does not generate new
instructions. Instead, it does a quick local search for existing
`llvm::Value`s that it needs when modifying the `icmp`
instruction.
2. It is more general -- it deals with both increasing and decreasing
induction variables.
I've added all of the tests included with D9784, and two more.
As an example on what this change does (copied from D9784):
Given C code:
```
for (int i = M; i < N; i++) // i is known not to overflow
if (i < 0) break;
a[i] = 0;
}
```
This transformation produces:
```
for (int i = M; i < N; i++)
if (M < 0) break;
a[i] = 0;
}
```
Which can be unswitched into:
```
if (!(M < 0))
for (int i = M; i < N; i++)
a[i] = 0;
}
```
I went back and forth on whether the top level logic should live in
`SimplifyIndvar::eliminateIVComparison` or be put into its own
routine. Right now I've put it under `eliminateIVComparison` because
even though the `icmp` is not *eliminated*, it no longer is an IV
comparison. I'm open to putting it in its own helper routine if you
think that is better.
Reviewers: reames, nicholas, atrick
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D11278
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r243250 appeared to break clang/test/Analysis/dead-store.c on one of the build
slaves, but I couldn't reproduce this failure locally. Probably a false
positive as I saw this test was broken by r243246 or r243247 too but passed
later without people fixing anything.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243253 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch updates TargetTransformInfoImplCRTPBase::getGEPCost to consider
addressing modes. It now returns TCC_Free when the GEP can be completely folded
to an addresing mode.
I started this patch as I refactored SLSR. Function isGEPFoldable looks common
and is indeed used by some WIP of mine. So I extracted that logic to getGEPCost.
Furthermore, I noticed getGEPCost wasn't directly tested anywhere. The best
testing bed seems CostModel, but its getInstructionCost method invokes
getAddressComputationCost for GEPs which provides very coarse estimation. So
this patch also makes getInstructionCost call the updated getGEPCost for GEPs.
This change inevitably breaks some tests because the cost model changes, but
nothing looks seriously wrong -- if we believe the new cost model is the right
way to go, these tests should be updated.
This patch is not perfect yet -- the comments in some tests need to be updated.
I want to know whether this is a right approach before fixing those details.
Reviewers: chandlerc, hfinkel
Subscribers: aschwaighofer, llvm-commits, aemerson
Differential Revision: http://reviews.llvm.org/D9819
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243250 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The goal is to start moving us closer to the model where
RuntimePointerChecking will compute and store the checks. Then a client
can filter the check according to its requirements and then use the
filtered list of checks with addRuntimeCheck.
Before the patch, this is all done in addRuntimeCheck. So the patch
starts to split up addRuntimeCheck while providing the old API under
what's more or less a wrapper now.
The new underlying addRuntimeCheck takes a collection of checks now,
expands the code for the bounds then generates the code for the checks.
I am not completely happy with making expandBounds static because now it
needs so many explicit arguments but I don't want to make the type
PointerBounds part of LAI. This should get fixed when addRuntimeCheck
is moved to LoopVersioning where it really belongs, IMO.
Audited the assembly diff of the testsuite (including externals). There
is a tiny bit of assembly churn that is due to the different order the
code for the bounds is expanded now
(MultiSource/Benchmarks/Prolangs-C/bison/conflicts.s and with LoopDist
on 456.hmmer/fast_algorithms.s).
Reviewers: hfinkel
Subscribers: klimek, llvm-commits
Differential Revision: http://reviews.llvm.org/D11205
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interface prior to making more substantial and invasive changes.
No functionality changed, and should hopefully keep subsequent patches
as clean and focused as possible in addition to making the comments and
such more clear.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242964 91177308-0d34-0410-b5e6-96231b3b80d8
preparation for de-coupling the AA implementations.
In order to do this, they had to become fake-scoped using the
traditional LLVM pattern of a leading initialism. These can't be actual
scoped enumerations because they're bitfields and thus inherently we use
them as integers.
I've also renamed the behavior enums that are specific to reasoning
about the mod/ref behavior of functions when called. This makes it more
clear that they have a very narrow domain of applicability.
I think there is a significantly cleaner API for all of this, but
I don't want to try to do really substantive changes for now, I just
want to refactor the things away from analysis groups so I'm preserving
the exact original design and just cleaning up the names, style, and
lifting out of the class.
Differential Revision: http://reviews.llvm.org/D10564
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part of simplifying its interface and usage in preparation for porting
to work with the new pass manager.
Note that this will likely expose that we have dead arguments, members,
and maybe even pass requirements for AA. I'll be cleaning those up in
seperate patches. This just zaps the actual update API.
Differential Revision: http://reviews.llvm.org/D11325
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directly model in the new PM.
This also was an incredibly brittle and expensive update API that was
never fully utilized by all the passes that claimed to preserve AA, nor
could it reasonably have been extended to all of them. Any number of
places add uses of values. If we ever wanted to reliably instrument
this, we would want a callback hook much like we have with ValueHandles,
but doing this for every use addition seems *extremely* expensive in
terms of compile time.
The only user of this update mechanism is GlobalsModRef. The idea of
using this to keep it up to date doesn't really work anyways as its
analysis requires a symmetric analysis of two different memory
locations. It would be very hard to make updates be sufficiently
rigorous to *guarantee* symmetric analysis in this way, and it pretty
certainly isn't true today.
However, folks have been using GMR with this update for a long time and
seem to not be hitting the issues. The reported issue that the update
hook fixes isn't even a problem any more as other changes to
GetUnderlyingObject worked around it, and that issue stemmed from *many*
years ago. As a consequence, a prior patch provided a flag to control
the unsafe behavior of GMR, and this patch removes the update mechanism
that has questionable compile-time tradeoffs and is causing problems
with moving to the new pass manager. Note the lack of test updates --
not one test in tree actually requires this update, even for a contrived
case.
All of this was extensively discussed on the dev list, this patch will
just enact what that discussion decides on. I'm sending it for review in
part to show what I'm planning, and in part to show the *amazing* amount
of work this avoids. Every call to the AA here is something like three
to six indirect function calls, which in the non-LTO pipeline never do
any work! =[
Differential Revision: http://reviews.llvm.org/D11214
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Those new constructors make it more natural to construct an object for a function. For example, previously to build a LoopInfo for a function, we need four statements:
DominatorTree DT;
LoopInfo LI;
DT.recalculate(F);
LI.analyze(DT);
Now we only need one statement:
LoopInfo LI(DominatorTree(F));
http://reviews.llvm.org/D11274
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This is made a static public member function to allow the transition of
this logic from LAA to LoopDistribution. (Technically, it could be an
implementation-local static function but then it would not be accessible
from LoopDistribution.)
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This is useful when we want to do block frequency analysis
conditionally (e.g. only in PGO mode) but don't want to add
one more pass dependence.
Patch by congh.
Approved by dexonsmith.
Differential Revision: http://reviews.llvm.org/D11196
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I am planning to add more nested classes inside RuntimePointerCheck so
all these triple-nesting would be hard to follow.
Also rename it to RuntimePointerChecking (i.e. append 'ing').
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242218 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Before this change, personality directives were not emitted
if there was no invoke left in the function (of course until
recently this also meant that we couldn't know what
the personality actually was). This patch forces personality directives
to still be emitted, unless it is known to be a noop in the absence of
invokes, or the user explicitly specified `nounwind` (and not
`uwtable`) on the function.
Reviewers: majnemer, rnk
Subscribers: rnk, llvm-commits
Differential Revision: http://reviews.llvm.org/D10884
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This is a C++11 feature that both GCC and MSVC have supported as ane extension
long before C++11 was approved.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242042 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This at least saves compile time. I also encountered a case where
ephemeral values affect whether other variables are promoted, causing
performance issues. It may be a bug in LSR, but I didn't manage to
reduce it yet. Anyhow, I believe it's in general not worth considering
ephemeral values in LSR.
Reviewers: atrick, hfinkel
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D11115
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242011 91177308-0d34-0410-b5e6-96231b3b80d8
The following functions are moved from the LoopVectorizer to VectorUtils:
- getGEPInductionOperand
- stripGetElementPtr
- getUniqueCastUse
- getStrideFromPointer
These used to be static functions in LoopVectorize, but will also be used by
the upcoming loop versioning LICM transformation.
Patch by Ashutosh Nema!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241980 91177308-0d34-0410-b5e6-96231b3b80d8
This change adds new attribute called "argmemonly". Function marked with this attribute can only access memory through it's argument pointers. This attribute directly corresponds to the "OnlyAccessesArgumentPointees" ModRef behaviour in alias analysis.
Differential Revision: http://reviews.llvm.org/D10398
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No in-tree alias analysis used this facility, and it was not called in
any particularly rigorous way, so it seems unlikely to be correct.
Note that one of the only stateful AA implementations in-tree,
GlobalsModRef is completely broken currently (and any AA passes like it
are equally broken) because Module AA passes are not effectively
invalidated when a function pass that fails to update the AA stack runs.
Ultimately, it doesn't seem like we know how we want to build stateful
AA, and until then trying to support and maintain correctness for an
untested API is essentially impossible. To that end, I'm planning to rip
out all of the update API. It can return if and when we need it and know
how to build it on top of the new pass manager and as part of *tested*
stateful AA implementations in the tree.
Differential Revision: http://reviews.llvm.org/D10889
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DataLayout is no longer optional. It was initialized with or without
a DataLayout, and the DataLayout when supplied could have been the
one from the TargetMachine.
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.
Reviewers: echristo
Subscribers: jholewinski, llvm-commits, rafael, yaron.keren
Differential Revision: http://reviews.llvm.org/D11021
From: Mehdi Amini <mehdi.amini@apple.com>
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Summary:
Often filter-like loops will do memory accesses that are
separated by constant offsets. In these cases it is
common that we will exceed the threshold for the
allowable number of checks.
However, it should be possible to merge such checks,
sice a check of any interval againt two other intervals separated
by a constant offset (a,b), (a+c, b+c) will be equivalent with
a check againt (a, b+c), as long as (a,b) and (a+c, b+c) overlap.
Assuming the loop will be executed for a sufficient number of
iterations, this will be true. If not true, checking against
(a, b+c) is still safe (although not equivalent).
As long as there are no dependencies between two accesses,
we can merge their checks into a single one. We use this
technique to construct groups of accesses, and then check
the intervals associated with the groups instead of
checking the accesses directly.
Reviewers: anemet
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D10386
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241673 91177308-0d34-0410-b5e6-96231b3b80d8
The expressions we delinearize do not necessarily have to have a SCEVAddRecExpr
at the outermost level. At this moment, the additional flexibility is not
exploited in LLVM itself, but in Polly we will soon soonish use this
functionality. For LLVM, this change should not affect existing functionality
(which is covered by test/Analysis/Delinearization/)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240952 91177308-0d34-0410-b5e6-96231b3b80d8
CaptureTracking becomes very expensive in large basic blocks while
calling PointerMayBeCaptured. PointerMayBeCaptured scans the BB the
number of times equal to the number of uses of 'BeforeHere', which is
currently capped at 20 and bails out with Tracker->tooManyUses().
The bottleneck here is the number of calls to PointerMayBeCaptured * the
basic block scan. In a testcase with a 82k instruction BB,
PointerMayBeCaptured is called 130k times, leading to 'shouldExplore'
taking 527k runs, this currently takes ~12min.
To fix this we locally (within PointerMayBeCaptured) number the
instructions in the basic block using a DenseMap to cache instruction
positions/numbers. We build the cache incrementally every time we need
to scan an unexplored part of the BB, improving compile time to only
take ~2min.
This triggers in the flow: DeadStoreElimination -> MepDepAnalysis ->
CaptureTracking.
Side note: after multiple runs in the test-suite I've seen no
performance nor compile time regressions, but could note a couple of
compile time improvements:
Performance Improvements - Compile Time Delta Previous Current StdDev
SingleSource/Benchmarks/Misc-C++/bigfib -4.48% 0.8547 0.8164 0.0022
MultiSource/Benchmarks/TSVC/LoopRerolling-dbl/LoopRerolling-dbl -1.47% 1.3912 1.3707 0.0056
Differential Revision: http://reviews.llvm.org/D7010
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