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.)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242376 91177308-0d34-0410-b5e6-96231b3b80d8
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:
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 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!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240137 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
We need to add a runtime memcheck for pair of accesses (x,y) where at least one of x and y
are writes.
Assuming we have w writes and r reads, currently this number is estimated as being
w* (w+r-1). This estimation will count (write,write) pairs twice and will overestimate
the number of checks required.
This change adds a getNumberOfChecks method to RuntimePointerCheck, which
will count the number of runtime checks needed (similar in implementation to
needsAnyChecking) and uses it to produce the correct number of runtime checks.
Test Plan:
llvm test suite
spec2k
spec2k6
Performance results: no changes observed (not surprising since the formula for 1 writer is basically the same, which would covers most cases - at least with the current check limit).
Reviewers: anemet
Reviewed By: anemet
Subscribers: mzolotukhin, llvm-commits
Differential Revision: http://reviews.llvm.org/D10217
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239295 91177308-0d34-0410-b5e6-96231b3b80d8
Interleaved memory accesses are grouped and vectorized into vector load/store and shufflevector.
E.g. for (i = 0; i < N; i+=2) {
a = A[i]; // load of even element
b = A[i+1]; // load of odd element
... // operations on a, b, c, d
A[i] = c; // store of even element
A[i+1] = d; // store of odd element
}
The loads of even and odd elements are identified as an interleave load group, which will be transfered into vectorized IRs like:
%wide.vec = load <8 x i32>, <8 x i32>* %ptr
%vec.even = shufflevector <8 x i32> %wide.vec, <8 x i32> undef, <4 x i32> <i32 0, i32 2, i32 4, i32 6>
%vec.odd = shufflevector <8 x i32> %wide.vec, <8 x i32> undef, <4 x i32> <i32 1, i32 3, i32 5, i32 7>
The stores of even and odd elements are identified as an interleave store group, which will be transfered into vectorized IRs like:
%interleaved.vec = shufflevector <4 x i32> %vec.even, %vec.odd, <8 x i32> <i32 0, i32 4, i32 1, i32 5, i32 2, i32 6, i32 3, i32 7>
store <8 x i32> %interleaved.vec, <8 x i32>* %ptr
This optimization is currently disabled by defaut. To try it by adding '-enable-interleaved-mem-accesses=true'.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239291 91177308-0d34-0410-b5e6-96231b3b80d8
When dependence analysis encounters a non-constant distance between
memory accesses it aborts the analysis and falls back to run-time checks
only. In this case we weren't resetting the array of dependences.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237574 91177308-0d34-0410-b5e6-96231b3b80d8
Specifically, if a pointer accesses different underlying objects in each
iteration, don't look through the phi node defining the pointer.
The motivating case is the underlyling-objects-2.ll testcase. Consider
the loop nest:
int **A;
for (i)
for (j)
A[i][j] = A[i-1][j] * B[j]
This loop is transformed by Load-PRE to stash away A[i] for the next
iteration of the outer loop:
Curr = A[0]; // Prev_0
for (i: 1..N) {
Prev = Curr; // Prev = PHI (Prev_0, Curr)
Curr = A[i];
for (j: 0..N)
Curr[j] = Prev[j] * B[j]
}
Since A[i] and A[i-1] are likely to be independent pointers,
getUnderlyingObjects should not assume that Curr and Prev share the same
underlying object in the inner loop.
If it did we would try to dependence-analyze Curr and Prev and the
analysis of the corresponding SCEVs would fail with non-constant
distance.
To fix this, the getUnderlyingObjects API is extended with an optional
LoopInfo parameter. This is effectively what controls whether we want
the above behavior or the original. Currently, I only changed to use
this approach for LoopAccessAnalysis.
The other testcase is to guard the opposite case where we do want to
look through the loop PHI. If we step through an array by incrementing
a pointer, the underlying object is the incoming value of the phi as the
loop is entered.
Fixes rdar://problem/19566729
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235634 91177308-0d34-0410-b5e6-96231b3b80d8
(Re-apply r234361 with a fix and a testcase for PR23157)
Both run-time pointer checking and the dependence analysis are capable
of dealing with uniform addresses. I.e. it's really just an orthogonal
property of the loop that the analysis computes.
Run-time pointer checking will only try to reason about SCEVAddRec
pointers or else gives up. If the uniform pointer turns out the be a
SCEVAddRec in an outer loop, the run-time checks generated will be
correct (start and end bounds would be equal).
In case of the dependence analysis, we work again with SCEVs. When
compared against a loop-dependent address of the same underlying object,
the difference of the two SCEVs won't be constant. This will result in
returning an Unknown dependence for the pair.
When compared against another uniform access, the difference would be
constant and we should return the right type of dependence
(forward/backward/etc).
The changes also adds support to query this property of the loop and
modify the vectorizer to use this.
Patch by Ashutosh Nema!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234424 91177308-0d34-0410-b5e6-96231b3b80d8
Both run-time pointer checking and the dependence analysis are capable
of dealing with uniform addresses. I.e. it's really just an orthogonal
property of the loop that the analysis computes.
Run-time pointer checking will only try to reason about SCEVAddRec
pointers or else gives up. If the uniform pointer turns out the be a
SCEVAddRec in an outer loop, the run-time checks generated will be
correct (start and end bounds would be equal).
In case of the dependence analysis, we work again with SCEVs. When
compared against a loop-dependent address of the same underlying object,
the difference of the two SCEVs won't be constant. This will result in
returning an Unknown dependence for the pair.
When compared against another uniform access, the difference would be
constant and we should return the right type of dependence
(forward/backward/etc).
The changes also adds support to query this property of the loop and
modify the vectorizer to use this.
Patch by Ashutosh Nema!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234361 91177308-0d34-0410-b5e6-96231b3b80d8
This is the final patch that actually introduces the new parameter of
partition mapping to RuntimePointerCheck::needsChecking.
Another API (LAI::getInstructionsForAccess) is also exposed that helps
to map pointers to instructions because ultimately we partition
instructions.
The WIP version of the Loop Distribution pass in D6930 has been adapted
to use all this. See for example, how
InstrPartitionContainer::computePartitionSetForPointers sets up the
partitions using the above API and then calls to LAI::addRuntimeCheck
with the pointer partitions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231818 91177308-0d34-0410-b5e6-96231b3b80d8
Now the analysis won't "fail" if the memchecks exceed the threshold. It
is the transform pass' responsibility to perform the check.
This allows the transform pass to further analyze/eliminate the
memchecks. E.g. in Loop distribution we only need to check pointers
that end up in different partitions.
Note that there is a slight change of functionality here. The logic in
analyzeLoop is that if dependence checking fails due to non-constant
distance between the pointers, another attempt is made to prove safety
of the dependences purely using run-time checks.
Before this patch we could fail the loop due to exceeding the memcheck
threshold after the first step, now we only check the threshold in the
client after the full analysis. There is no measurable compile-time
effect but I wanted to record this here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231817 91177308-0d34-0410-b5e6-96231b3b80d8
The dependences are now expose through the new getInterestingDependences
API so we can use that with -analyze too and fix the FIXME.
This lets us remove the test that relied on -debug to check the
dependences.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231807 91177308-0d34-0410-b5e6-96231b3b80d8
Gather an array of interesting dependences rather than just failing
after the first unsafe one and regarding the loop unsafe. Loop
Distribution needs to be able to collect all dependences in order to
isolate the dependence cycles into their own partition.
Since the dependence checking algorithm is quadratic in terms of
accesses sharing the same underlying pointer, I am applying a cut-off
threshold (MaxInterestingDependence). Exceeding that, the logic reverts
back to the original approach deeming the loop unsafe upon encountering
the first unsafe dependence.
The main idea of the patch is to split isDepedent from directly
answering the question whether the dep is safe for vectorization to
return a dependence type which then gets mapped to old boolean result
using Dependence::isSafeForVectorization.
Tested that this was compile-time neutral on SpecINT2006 LTO bitcode
inputs. No assembly change on the testsuite including external.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231806 91177308-0d34-0410-b5e6-96231b3b80d8
LoopDistribution needs to query various results of the dependence
analysis. This series will expose some more APIs and state of the
dependence checker.
This patch is a simple one to just expose the DepChecker instance. The
set is compile-time neutral measured with LTO bitcode files of
SpecINT2006. Also there is no assembly change on the testsuite.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231805 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Now that the DataLayout is a mandatory part of the module, let's start
cleaning the codebase. This patch is a first attempt at doing that.
This patch is not exactly NFC as for instance some places were passing
a nullptr instead of the DataLayout, possibly just because there was a
default value on the DataLayout argument to many functions in the API.
Even though it is not purely NFC, there is no change in the
validation.
I turned as many pointer to DataLayout to references, this helped
figuring out all the places where a nullptr could come up.
I had initially a local version of this patch broken into over 30
independant, commits but some later commit were cleaning the API and
touching part of the code modified in the previous commits, so it
seemed cleaner without the intermediate state.
Test Plan:
Reviewers: echristo
Subscribers: llvm-commits
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231740 91177308-0d34-0410-b5e6-96231b3b80d8
Also remove the somewhat misleading initializers from
VectorizationFactor and VectorizationInterleave. They will get
initialized with the default ctor since no cl::init is provided.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230608 91177308-0d34-0410-b5e6-96231b3b80d8
The LoopInfo in combination with depth_first is used to enumerate the
loops.
Right now -analyze is not yet complete. It only prints the result of
the analysis, the report and the run-time checks. Printing the unsafe
depedences will require a bit more reshuffling which I'd like to do in a
follow-on to this patchset. Unsafe dependences are currently checked
via -debug-only=loop-accesses in the new test.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229898 91177308-0d34-0410-b5e6-96231b3b80d8
The only difference between these two is that VectorizerReport adds a
vectorizer-specific prefix to its messages. When LAA is used in the
vectorizer context the prefix is added when we promote the
LoopAccessReport into a VectorizerReport via one of the constructors.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229897 91177308-0d34-0410-b5e6-96231b3b80d8
When I split out LoopAccessReport from this, I need to create some temps
so constness becomes necessary.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229896 91177308-0d34-0410-b5e6-96231b3b80d8
This allows the analysis to be attempted with any loop. This feature
will be used with -analysis. (LV only requests the analysis on loops
that have already satisfied these tests.)
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229895 91177308-0d34-0410-b5e6-96231b3b80d8
Also add pass name as an argument to VectorizationReport::emitAnalysis.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229894 91177308-0d34-0410-b5e6-96231b3b80d8
This is a function pass that runs the analysis on demand. The analysis
can be initiated by querying the loop access info via LAA::getInfo. It
either returns the cached info or runs the analysis.
Symbolic stride information continues to reside outside of this analysis
pass. We may move it inside later but it's not a priority for me right
now. The idea is that Loop Distribution won't support run-time stride
checking at least initially.
This means that when querying the analysis, symbolic stride information
can be provided optionally. Whether stride information is used can
invalidate the cache entry and rerun the analysis. Note that if the
loop does not have any symbolic stride, the entry should be preserved
across Loop Distribution and LV.
Since currently the only user of the pass is LV, I just check that the
symbolic stride information didn't change when using a cached result.
On the LV side, LoopVectorizationLegality requests the info object
corresponding to the loop from the analysis pass. A large chunk of the
diff is due to LAI becoming a pointer from a reference.
A test will be added as part of the -analyze patch.
Also tested that with AVX, we generate identical assembly output for the
testsuite (including the external testsuite) before and after.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229893 91177308-0d34-0410-b5e6-96231b3b80d8
LAA will be an on-demand analysis pass, so we need to cache the result
of the analysis. canVectorizeMemory is renamed to analyzeLoop which
computes the result. canVectorizeMemory becomes the query function for
the cached result.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229892 91177308-0d34-0410-b5e6-96231b3b80d8
The transformation passes will query this and then emit them as part of
their own report. The currently only user LV is modified to do just
that.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229891 91177308-0d34-0410-b5e6-96231b3b80d8
As LAA is becoming a pass, we can no longer pass the params to its
constructor. This changes the command line flags to have external
storage. These can now be accessed both from LV and LAA.
VectorizerParams is moved out of LoopAccessInfo in order to shorten the
code to access it.
This commits also has the fix (D7731) to the break dependence cycle
between the analysis and vector libraries.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229890 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r229651.
I'd like to ultimately revert r229650 but this reformat stands in the
way. I'll reformat the affected files once the the loop-access pass is
fully committed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229889 91177308-0d34-0410-b5e6-96231b3b80d8
r229622: "[LoopAccesses] Make VectorizerParams global"
r229623: "[LoopAccesses] Stash the report from the analysis rather than emitting it"
r229624: "[LoopAccesses] Cache the result of canVectorizeMemory"
r229626: "[LoopAccesses] Create the analysis pass"
r229628: "[LoopAccesses] Change debug messages from LV to LAA"
r229630: "[LoopAccesses] Add canAnalyzeLoop"
r229631: "[LoopAccesses] Add missing const to APIs in VectorizationReport"
r229632: "[LoopAccesses] Split out LoopAccessReport from VectorizerReport"
r229633: "[LoopAccesses] Add -analyze support"
r229634: "[LoopAccesses] Change LAA:getInfo to return a constant reference"
r229638: "Analysis: fix buildbots"
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229650 91177308-0d34-0410-b5e6-96231b3b80d8
The LoopInfo in combination with depth_first is used to enumerate the
loops.
Right now -analyze is not yet complete. It only prints the result of
the analysis, the report and the run-time checks. Printing the unsafe
depedences will require a bit more reshuffling which I'd like to do in a
follow-on to this patchset. Unsafe dependences are currently checked
via -debug-only=loop-accesses in the new test.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229633 91177308-0d34-0410-b5e6-96231b3b80d8
The only difference between these two is that VectorizerReport adds a
vectorizer-specific prefix to its messages. When LAA is used in the
vectorizer context the prefix is added when we promote the
LoopAccessReport into a VectorizerReport via one of the constructors.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229632 91177308-0d34-0410-b5e6-96231b3b80d8
When I split out LoopAccessReport from this, I need to create some temps
so constness becomes necessary.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229631 91177308-0d34-0410-b5e6-96231b3b80d8
This allows the analysis to be attempted with any loop. This feature
will be used with -analysis. (LV only requests the analysis on loops
that have already satisfied these tests.)
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229630 91177308-0d34-0410-b5e6-96231b3b80d8
Will be used by the new RuntimePointerCheck::print.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229629 91177308-0d34-0410-b5e6-96231b3b80d8
Also add pass name as an argument to VectorizationReport::emitAnalysis.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229628 91177308-0d34-0410-b5e6-96231b3b80d8
This is a function pass that runs the analysis on demand. The analysis
can be initiated by querying the loop access info via LAA::getInfo. It
either returns the cached info or runs the analysis.
Symbolic stride information continues to reside outside of this analysis
pass. We may move it inside later but it's not a priority for me right
now. The idea is that Loop Distribution won't support run-time stride
checking at least initially.
This means that when querying the analysis, symbolic stride information
can be provided optionally. Whether stride information is used can
invalidate the cache entry and rerun the analysis. Note that if the
loop does not have any symbolic stride, the entry should be preserved
across Loop Distribution and LV.
Since currently the only user of the pass is LV, I just check that the
symbolic stride information didn't change when using a cached result.
On the LV side, LoopVectorizationLegality requests the info object
corresponding to the loop from the analysis pass. A large chunk of the
diff is due to LAI becoming a pointer from a reference.
A test will be added as part of the -analyze patch.
Also tested that with AVX, we generate identical assembly output for the
testsuite (including the external testsuite) before and after.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229626 91177308-0d34-0410-b5e6-96231b3b80d8
blockNeedsPredication is in LoopAccess in order to share it with the
vectorizer. It's a utility needed by LoopAccess not strictly provided
by it but it's a good place to share it. This makes the function static
so that it no longer required to create an LoopAccessInfo instance in
order to access it from LV.
This was actually causing problems because it would have required
creating LAI much earlier that LV::canVectorizeMemory().
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229625 91177308-0d34-0410-b5e6-96231b3b80d8
LAA will be an on-demand analysis pass, so we need to cache the result
of the analysis. canVectorizeMemory is renamed to analyzeLoop which
computes the result. canVectorizeMemory becomes the query function for
the cached result.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229624 91177308-0d34-0410-b5e6-96231b3b80d8
The transformation passes will query this and then emit them as part of
their own report. The currently only user LV is modified to do just
that.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229623 91177308-0d34-0410-b5e6-96231b3b80d8
As LAA is becoming a pass, we can no longer pass the params to its
constructor. This changes the command line flags to have external
storage. These can now be accessed both from LV and LAA.
VectorizerParams is moved out of LoopAccessInfo in order to shorten the
code to access it.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229622 91177308-0d34-0410-b5e6-96231b3b80d8
LoopAccessAnalysis will be used as the name of the pass.
This is part of the patchset that converts LoopAccessAnalysis into an
actual analysis pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229621 91177308-0d34-0410-b5e6-96231b3b80d8
