Commit Graph

403 Commits

Author SHA1 Message Date
Tyker c95ffadb24 [AssumeBundles] Use operand bundles to encode alignment assumptions
Summary:
NOTE: There is a mailing list discussion on this: http://lists.llvm.org/pipermail/llvm-dev/2019-December/137632.html

Complemantary to the assumption outliner prototype in D71692, this patch
shows how we could simplify the code emitted for an alignemnt
assumption. The generated code is smaller, less fragile, and it makes it
easier to recognize the additional use as a "assumption use".

As mentioned in D71692 and on the mailing list, we could adopt this
scheme, and similar schemes for other patterns, without adopting the
assumption outlining.

Reviewers: hfinkel, xbolva00, lebedev.ri, nikic, rjmccall, spatel, jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: yamauchi, kuter, fhahn, merge_guards_bot, hiraditya, bollu, rkruppe, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D71739
2020-06-25 12:59:44 +02:00
Simon Pilgrim 5adf6a24e1 ProfileSummaryInfoTest.cpp - fix implicit CommandLine.h dependency. NFC.
ProfileSummaryInfoTest references cl::opt but don't include CommandLine.h.
2020-06-23 13:07:18 +01:00
Simon Pilgrim a5f1f9c9b8 ScalarEvolution.h - reduce LoopInfo.h include to forward declarations. NFC.
Move ScalarEvolution::forgetLoopDispositions implementation to ScalarEvolution.cpp to remove the dependency.

Add implicit header dependency to source files where necessary.
2020-06-17 15:48:23 +01:00
Christopher Tetreault eb81c85afd [SVE] Deprecate default false variant of VectorType::get
Reviewers: efriedma, fpetrogalli, kmclaughlin, huntergr

Reviewed By: fpetrogalli

Subscribers: cfe-commits, tschuett, rkruppe, psnobl, llvm-commits

Tags: #llvm, #clang

Differential Revision: https://reviews.llvm.org/D80342
2020-06-16 15:16:11 -07:00
Hiroshi Yamauchi 6bc2b042f4 [TLI] Add four C++17 delete variants.
Summary:
delete(void*, unsigned int, align_val_t)
delete(void*, unsigned long, align_val_t)
delete[](void*, unsigned int, align_val_t)
delete[](void*, unsigned long, align_val_t)

Differential Revision: https://reviews.llvm.org/D81853
2020-06-16 11:12:02 -07:00
Mircea Trofin e2cc854015 [llvm][NFC] Move content of ML subdirectory into Analysis
The initial intent was to organize ML stuff in its own directory, but
it turns out that conflicts with llvm component layering policies: it
is not a component, because subsequent changes want to rely on other
analyses, which would create a cycle; and we don't have a reliable,
cross-platform mechanism to compile files in a subdirectory, and fit in
the existing LLVM build structure.

This change moves the files into Analysis, and subsequent changes will
leverage conditional compilation for those that have optional
dependencies.
2020-06-15 14:35:33 -07:00
Mircea Trofin 29e5722949 Revert "[llvm] Added support for stand-alone cmake object libraries."
This reverts commit 695c7d6313.

Breaks windows (e.g.
http://lab.llvm.org:8011/builders/clang-x64-windows-msvc/builds/16497)

Likely to cause problems with XCode.
2020-06-15 12:15:39 -07:00
Mircea Trofin 695c7d6313 [llvm] Added support for stand-alone cmake object libraries.
Summary:
Currently, add_llvm_library would create an OBJECT library alongside
of a STATIC / SHARED library, but losing the link interface (its
elements would become dependencies instead). To support scenarios
where linking an object library also brings in its usage
requirements, this patch adds support for 'stand-alone' OBJECT
libraries - i.e. without an accompanying SHARED/STATIC library, and
maintaining the link interface defined by the user.

The support is via a new option, OBJECT_ONLY, to avoid breaking changes
- since just specifying "OBJECT" would currently imply also STATIC or
SHARED, depending on BUILD_SHARED_LIBS.

This is useful for cases where, for example, we want to build a part
of a component separately. Using a STATIC target would incur the risk
that symbols not referenced in the consumer would be dropped (which may
be undesirable).

The current application is the ML part of Analysis. It should be part
of the Analysis component, so it may reference other analyses; and (in
upcoming changes) it has dependencies on optional libraries.

Reviewers: karies, davidxl

Subscribers: mgorny, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81447
2020-06-15 12:01:43 -07:00
Wenlei He b559535a3a [NewPM] Avoid redundant CGSCC run for updated SCC
Summary:
When an SCC got split due to inlining, we have two mechanisms for reprocessing the updated SCC, first is UR.UpdatedC
that repeatedly rerun the new, current SCC; second is a worklist for all newly split SCCs. We can avoid rerun of
the same SCC when the SCC is set to be processed by both mechanisms *back to back*. In pathological cases, such redundant
rerun could cause exponential size growth due to inlining along cycles, even when there's no SCC mutation and hence
convergence is not a problem.

Note that it's ok to have SCC updated and rerun immediately, and also in the work list if we have actually moved an SCC
to be topologically "below" the current one due to merging. In that case, we will need to revisit the current SCC after
those moved SCCs. For that reason, the redundant avoidance here only targets back to back rerun of the same SCC - the
case described by the now removed FIXME comment.

Reviewers: chandlerc, wmi

Subscribers: llvm-commits, hoy

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80589
2020-06-14 19:54:52 -07:00
Simon Pilgrim 5006e551d3 LoopAnalysisManager.h - reduce includes to forward declarations. NFC.
Move implicit include dependencies down to header/source files.
2020-06-06 14:06:46 +01:00
Simon Pilgrim 06fd973c85 TargetLibraryInfo.h - reduce Triple.h include to forward declaration. NFC.
Move implicit include dependencies down to source files.
2020-06-05 14:35:30 +01:00
Hiroshi Yamauchi 6c27c61d32 [PGO] Improve the working set size heuristics under the partial sample PGO.
Summary:
The working set size heuristics (ProfileSummaryInfo::hasHugeWorkingSetSize)
under the partial sample PGO may not be accurate because the profile is partial
and the number of hot profile counters in the ProfileSummary may not reflect the
actual working set size of the program being compiled.

To improve this, the (approximated) ratio of the the number of profile counters
of the program being compiled to the number of profile counters in the partial
sample profile is computed (which is called the partial profile ratio) and the
working set size of the profile is scaled by this ratio to reflect the working
set size of the program being compiled and used for the working set size
heuristics.

The partial profile ratio is approximated based on the number of the basic
blocks in the program and the NumCounts field in the ProfileSummary and computed
through the thin LTO indexing. This means that there is the limitation that the
scaled working set size is available to the thin LTO post link passes only.

Reviewers: davidxl

Subscribers: mgorny, eraman, hiraditya, steven_wu, dexonsmith, arphaman, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79831
2020-06-01 10:29:23 -07:00
Mircea Trofin 98ef93eabd [llvm] Add function feature extraction analysis
Summary:
This patch introduces an analysis pass to extract function features,
which will be needed by the ML InlineAdvisor.

RFC: http://lists.llvm.org/pipermail/llvm-dev/2020-April/140763.html

Reviewers: davidxl, dblaikie, jdoerfert

Subscribers: mgorny, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80579
2020-05-27 13:38:50 -07:00
Bardia Mahjour 0d20ed664f [DDG] Data Dependence Graph - Add query function for memory dependencies between two nodes
Summary:
When working with the DDG it's useful to be able to query details of the
memory dependencies between two nodes connected by a memory edge. The DDG
does not hold a copy of the dependencies, but it contains a reference to a
DependenceInfo object through which dependence information can be queried.
This patch adds a query function to the DDG to obtain all the Dependence
objects that exist between instructions of two nodes.

Authored By: bmahjour

Reviewers: Meinersbur, Whitney, etiotto

Reviewed By: Whitney

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80529
2020-05-27 12:40:14 -04:00
Paul Walker 495f18292b [VFABI] Fix parsing of uniform parameters that shouldn't expect step or positional data.
Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80575
2020-05-27 16:07:45 +00:00
Serge Pavlov 4d20e31f73 [FPEnv] Intrinsic llvm.roundeven
This intrinsic implements IEEE-754 operation roundToIntegralTiesToEven,
and performs rounding to the nearest integer value, rounding halfway
cases to even. The intrinsic represents the missed case of IEEE-754
rounding operations and now llvm provides full support of the rounding
operations defined by the standard.

Differential Revision: https://reviews.llvm.org/D75670
2020-05-26 19:24:58 +07:00
Florian Hahn 8d04181198 [ValueTracking] Use assumptions in computeConstantRange.
This patch updates computeConstantRange to optionally take an assumption
cache as argument and use the available assumptions to limit the range
of the result.

Currently this is limited to assumptions that are comparisons.

Reviewers: reames, nikic, spatel, jdoerfert, lebedev.ri

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D76193
2020-05-23 20:07:52 +01:00
Florian Hahn bcbd26bfe6 [SCEV] Move ScalarEvolutionExpander.cpp to Transforms/Utils (NFC).
SCEVExpander modifies the underlying function so it is more suitable in
Transforms/Utils, rather than Analysis. This allows using other
transform utils in SCEVExpander.

This patch was originally committed as b8a3c34eee, but broke the
modules build, as LoopAccessAnalysis was using the Expander.

The code-gen part of LAA was moved to lib/Transforms recently, so this
patch can be landed again.

Reviewers: sanjoy.google, efriedma, reames

Reviewed By: sanjoy.google

Differential Revision: https://reviews.llvm.org/D71537
2020-05-20 10:53:40 +01:00
Nikita Popov d86fff6ae7 [ValueTracking] Fix computeKnownBits() with bitwidth-changing ptrtoint
computeKnownBitsFromAssume() currently asserts if m_V matches a
ptrtoint that changes the bitwidth. Because InstCombine
canonicalizes ptrtoint instructions to use explicit zext/trunc,
we never ran into the issue in practice. I'm adding unit tests,
as I don't know if this can be triggered via IR anywhere.

Fix this by calling anyextOrTrunc(BitWidth) on the computed
KnownBits. Note that we are going from the KnownBits of the
ptrtoint result to the KnownBits of the ptrtoint operand,
so we need to truncate if the ptrtoint zexted and anyext if
the ptrtoint truncated.

Differential Revision: https://reviews.llvm.org/D79234
2020-05-16 14:17:11 +02:00
Anna Thomas 7cc3769adb [VectorUtils] Expose vector-function-abi-variant mangling as a utility.
Summary:
This change exposes the vector name mangling with LLVM ISA (used as part
of vector-function-abi-variant) as a utility.
This can then be used by front-ends that add this attribute.
Note that all parameters passed in to the function will be mangled with
the "v" token to identify that they are of of vector type. So, it is the
responsibility of the caller to confirm that all parameters in the
vectorized variant is of vector type.

Added unit test to show vector name mangling.

Reviewed-By: fpetrogalli, simoll

Differential Revision: https://reviews.llvm.org/D79867
2020-05-15 11:42:20 -04:00
Alina Sbirlea bd541b217f [NewPassManager] Add assertions when getting statefull cached analysis.
Summary:
Analyses that are statefull should not be retrieved through a proxy from
an outer IR unit, as these analyses are only invalidated at the end of
the inner IR unit manager.
This patch disallows getting the outer manager and provides an API to
get a cached analysis through the proxy. If the analysis is not
stateless, the call to getCachedResult will assert.

Reviewers: chandlerc

Subscribers: mehdi_amini, eraman, hiraditya, zzheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72893
2020-05-13 12:38:38 -07:00
Juneyoung Lee e5f602d82c [ValueTracking] Let propagatesPoison support binops/unaryops/cast/etc.
Summary:
This patch makes propagatesPoison be more accurate by returning true on
more bin ops/unary ops/casts/etc.

The changed test in ScalarEvolution/nsw.ll was introduced by
a19edc4d15 .
IIUC, the goal of the tests is to show that iv.inc's SCEV expression still has
no-overflow flags even if the loop isn't in the wanted form.
It becomes more accurate with this patch, so think this is okay.

Reviewers: spatel, lebedev.ri, jdoerfert, reames, nikic, sanjoy

Reviewed By: spatel, nikic

Subscribers: regehr, nlopes, efriedma, fhahn, javed.absar, llvm-commits, hiraditya

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78615
2020-05-13 02:51:42 +09:00
Nikita Popov 7cf0f8568c [ValueTracking] Convert test to unit test (NFC)
Test this directly, rather than going through InstSimplify.
2020-05-03 12:23:57 +02:00
Anh Tuyen Tran c7878ad231 [VFDatabase] Scalar functions are vector functions with VF =1
Summary:
Return scalar function when VF==1. The new trivial mapping scalar --> scalar when VF==1 to prevent false positive for "isVectorizable" query.

Author: masoud.ataei (Masoud Ataei)

Reviewers: Whitney (Whitney Tsang), fhahn (Florian Hahn), pjeeva01 (Jeeva P.), fpetrogalli (Francesco Petrogalli), rengolin (Renato Golin)

Reviewed By: fpetrogalli (Francesco Petrogalli)

Subscribers: hiraditya (Aditya Kumar), llvm-commits, LLVM

Tag: LLVM

Differential Revision: https://reviews.llvm.org/D78054
2020-04-29 17:20:37 +00:00
Tyker e5f8a77c19 [AssumeBundles] Refactor asssume builder
Summary:
refactor assume bulider for the next patch.
the assume builder now generate only one assume per attribute kind and per value they are on. to do this it takes the highest. this is desirable because currently, for all attributes the higest value is the most valuable.

Reviewers: jdoerfert

Reviewed By: jdoerfert

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78013
2020-04-25 13:43:52 +02:00
Craig Topper be04aba6fc [CallSite removal][ValueTracking] Use CallBase instead of ImmutableCallSite for getIntrinsicForCallSite. NFC
Differential Revision: https://reviews.llvm.org/D78613
2020-04-22 12:06:58 -07:00
Craig Topper 05a11974ae [CallSite removal] Remove unneeded includes of CallSite.h. NFC 2020-04-22 00:07:13 -07:00
Craig Topper e13c0b650a [CallSite removal][Analysis] Use CallBase instead of CallSite in SparsePropagation unit test. NFC 2020-04-19 22:39:24 -07:00
Mircea Trofin 1586d0d382 [llvm][NFC] Dereferencing before cast-ing in ProfileSummaryInfoTest
Incorporated feedback from https://reviews.llvm.org/D78414
2020-04-18 17:47:37 -07:00
Mircea Trofin ec73ae11a3 [llvm][NFC][CallSite] Remove CallSite from ProfileSummary
Summary: Depends on D78395.

Reviewers: craig.topper, dblaikie, wmi, davidxl

Subscribers: eraman, hiraditya, haicheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78414
2020-04-18 12:03:14 -07:00
Craig Topper 8e1408695c [CallSite removal][TargetLibraryInfo] Replace ImmutableCallSite with CallBase in one of the getLibFunc signatures. NFC
Differential Revision: https://reviews.llvm.org/D78083
2020-04-15 22:43:41 -07:00
Juneyoung Lee 994543abc9 [ValueTracking] Implement canCreatePoison
Summary:
This PR adds `canCreatePoison(Instruction *I)` which returns true if `I` can generate poison from non-poison
operands.

Reviewers: spatel, nikic, lebedev.ri

Reviewed By: spatel

Subscribers: hiraditya, llvm-commits, regehr, nlopes

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77890
2020-04-15 05:58:06 +09:00
Aaron Puchert e833e58300 [ValueLattice] Remove unused DataLayout parameter of mergeIn, NFC
Reviewed By: fhahn, echristo

Differential Revision: https://reviews.llvm.org/D78061
2020-04-14 13:32:53 +02:00
Tyker 813f438baa [AssumeBundles] adapt Assumption cache to assume bundles
Summary: change assumption cache to store an assume along with an index to the operand bundle containing the knowledge.

Reviewers: jdoerfert, hfinkel

Reviewed By: jdoerfert

Subscribers: hiraditya, mgrang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77402
2020-04-13 12:04:51 +02:00
Sanjay Patel c23cbefd9d [VectorUtils] add IR-level analysis for widening of shuffle mask
This is similar to the recent move/addition of "scaleShuffleMask" (D76508),
but there are a couple of differences:

1. The existing x86 helper (canWidenShuffleElements) always tries to
   divide-by-2, so it gets called iteratively and wouldn't handle the
   general case of non-pow-2 length.
2. The existing x86 code handles "SM_SentinelZero" - we don't have
   that in IR, but this code should be safe to use with that or other
   special (negative) values.

The motivation is to enable shuffle folds in instcombine/vector-combine
that are similar to D76844 and D76727, but in the reverse-bitcast direction.
Those patterns are visible in the tests for D40633.

Differential Revision: https://reviews.llvm.org/D77881
2020-04-12 10:14:19 -04:00
Sanjay Patel 1318ddbc14 [VectorUtils] rename scaleShuffleMask to narrowShuffleMaskElts; NFC
As proposed in D77881, we'll have the related widening operation,
so this name becomes too vague.

While here, change the function signature to take an 'int' rather
than 'size_t' for the scaling factor, add an assert for overflow of
32-bits, and improve the documentation comments.
2020-04-11 10:05:49 -04:00
Johannes Doerfert cb0ecc5c33 [CallGraphUpdater] Remove dead constants before replacing a function
Dead constants might be left when a function is replaced, we can
gracefully handle this case and avoid complexity for the users who would
see an assertion otherwise.
2020-04-08 22:52:46 -05:00
Sanjay Patel fbb1b43f13 [ValueTracking] enhance matching of umin/umax with 'not' operands
The cmyk test is based on the known regression that resulted from:
rGf2fbdf76d8d0

This improves on the equivalent signed min/max change:
rG867f0c3c4d8c

The underlying icmp equivalence is:
  ~X pred ~Y --> Y pred X

For an icmp with constant, canonicalization results in a swapped pred:
  ~X < C -->  X > ~C
2020-04-06 11:51:59 -04:00
Sanjay Patel 463143f0d6 [ValueTracking] add/adjust tests for min/max; NFC 2020-04-06 11:14:05 -04:00
Sanjay Patel 867f0c3c4d [ValueTracking] enhance matching of smin/smax with 'not' operands
The cmyk tests are based on the known regression that resulted from:
rGf2fbdf76d8d0

So this improvement in analysis might be enough to restore that commit.
2020-04-05 08:54:12 -04:00
Sanjay Patel 6d34374043 [ValueTracking] add tests for smin/smax; NFC 2020-04-04 13:44:06 -04:00
Tyker c00cb76274 [NFC] Split Knowledge retention and place it more appropriatly
Summary:
Splitting Knowledge retention into Queries in Analysis and Builder into Transform/Utils
allows Queries and Transform/Utils to use Analysis.

Reviewers: jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: mgorny, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77171
2020-04-02 15:01:41 +02:00
Craig Topper f92563f907 [VectorUtils][X86] De-templatize scaleShuffleMask and 2 X86 shuffle mask helpers and move their implementation to cpp files
Summary: These were templated due to SelectionDAG using int masks for shuffles and IR using unsigned masks for shuffles. But now that D72467 has landed we have an int mask version of IRBuilder::CreateShuffleVector. So just use int instead of a template

Reviewers: spatel, efriedma, RKSimon

Reviewed By: efriedma

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D77183
2020-04-01 00:46:48 -07:00
Uday Bondhugula c0955edfd6 Introduce support for lib function aligned_alloc in TLI / memory builtins
Aligned_alloc is a standard lib function and has been in glibc since
2.16 and in the C11 standard. It has semantics similar to malloc/calloc
for several analyses/transforms. This patch introduces aligned_alloc
in target library info and memory builtins. Subsequent ones will
make other passes aware and fix https://bugs.llvm.org/show_bug.cgi?id=44062

This change will also be useful to LLVM generators that need to allocate
buffers of vector elements larger than 16 bytes (for eg. 256-bit ones),
element boundary alignment for which is not typically provided by glibc malloc.

Signed-off-by: Uday Bondhugula <uday@polymagelabs.com>

Differential Revision: https://reviews.llvm.org/D76970
2020-03-29 23:36:24 +05:30
Sanjay Patel ebf83c36e2 [Analysis] simplify code for scaleShuffleMask
This is NFC-ish. The results should be identical, but perf is hopefully
better with the fast-path for no scaling. Added a unit test for that.

The code is adapted from what used to be the DAGCombiner equivalent
function before D76508 (rG0eeee83d7513).
2020-03-23 11:47:14 -04:00
Sanjay Patel 0eeee83d75 [VectorUtils] move x86's scaleShuffleMask to generic VectorUtils
We have some long-standing missing shuffle optimizations that could
use this transform via VectorCombine now:
https://bugs.llvm.org/show_bug.cgi?id=35454
(and we still don't get that case in the backend either)

This function is apparently templated because there's existing code
in IR that treats mask values as unsigned and backend code that
treats masks values as signed.

The mask values are not endian-dependent (as shown by the existing
bitcast transform from DAGCombiner).

Differential Revision: https://reviews.llvm.org/D76508
2020-03-23 09:58:55 -04:00
Hiroshi Yamauchi 4b4e5d41ec [PSI] Add tests for is(Hot|Cold)FunctionInCallGraphNthPercentile.
Summary:
Follow up on D75283.

Also remove the test code that was moved to another test and was to be removed.

Reviewers: davidxl

Subscribers: eraman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75630
2020-03-10 08:21:10 -07:00
Whitney Tsang c84532a70a [LoopNest]: Analysis to discover properties of a loop nest.
Summary: This patch adds an analysis pass to collect loop nests and
summarize properties of the nest (e.g the nest depth, whether the nest
is perfect, what's the innermost loop, etc...).

The motivation for this patch was discussed at the latest meeting of the
LLVM loop group (https://ibm.box.com/v/llvm-loop-nest-analysis) where we
discussed
the unimodular loop transformation framework ( “A Loop Transformation
Theory and an Algorithm to Maximize Parallelism”, Michael E. Wolf and
Monica S. Lam, IEEE TPDS, October 1991). The unimodular framework
provides a convenient way to unify legality checking and code generation
for several loop nest transformations (e.g. loop reversal, loop
interchange, loop skewing) and their compositions. Given that the
unimodular framework is applicable to perfect loop nests this is one
property of interest we expose in this analysis. Several other utility
functions are also provided. In the future other properties of interest
can be added in a centralized place.
Authored By: etiotto
Reviewer: Meinersbur, bmahjour, kbarton, Whitney, dmgreen, fhahn,
reames, hfinkel, jdoerfert, ppc-slack
Reviewed By: Meinersbur
Subscribers: bryanpkc, ppc-slack, mgorny, hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D68789
2020-03-03 18:25:19 +00:00
Whitney Tsang 613f791131 Revert "[LoopNest]: Analysis to discover properties of a loop nest."
This reverts commit 3a063d68e3.

Broke the build with modules enabled:
http://green.lab.llvm.org/green/job/lldb-cmake/10655/console .
2020-03-03 14:07:49 +00:00
Whitney Tsang 3a063d68e3 [LoopNest]: Analysis to discover properties of a loop nest.
Summary: This patch adds an analysis pass to collect loop nests and
summarize properties of the nest (e.g the nest depth, whether the nest
is perfect, what's the innermost loop, etc...).

The motivation for this patch was discussed at the latest meeting of the
LLVM loop group (https://ibm.box.com/v/llvm-loop-nest-analysis) where we
discussed
the unimodular loop transformation framework ( “A Loop Transformation
Theory and an Algorithm to Maximize Parallelism”, Michael E. Wolf and
Monica S. Lam, IEEE TPDS, October 1991). The unimodular framework
provides a convenient way to unify legality checking and code generation
for several loop nest transformations (e.g. loop reversal, loop
interchange, loop skewing) and their compositions. Given that the
unimodular framework is applicable to perfect loop nests this is one
property of interest we expose in this analysis. Several other utility
functions are also provided. In the future other properties of interest
can be added in a centralized place.
Authored By: etiotto
Reviewer: Meinersbur, bmahjour, kbarton, Whitney, dmgreen, fhahn,
reames, hfinkel, jdoerfert, ppc-slack
Reviewed By: Meinersbur
Subscribers: bryanpkc, ppc-slack, mgorny, hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D68789
2020-03-03 13:25:28 +00:00