Instead of flat schedules, we now use so-called schedule trees to represent the
execution order of the statements in a SCoP. Schedule trees make it a lot easier
to analyze, understand and modify properties of a schedule, as specific nodes
in the tree can be choosen and possibly replaced.
This patch does not yet fully move our DependenceInfo pass to schedule trees,
as some additional performance analysis is needed here. (In general schedule
trees should be faster in compile-time, as the more structured representation
is generally easier to analyze and work with). We also can not yet perform the
reduction analysis on schedule trees.
For more information regarding schedule trees, please see Section 6 of
https://lirias.kuleuven.be/handle/123456789/497238
llvm-svn: 242130
Named isl sets can generally have any name if they remain within Polly, but only
certain strings can be parsed by isl. The new names we create ensure that we
can always copy-past isl strings from Polly to other isl tools, e.g. for
debugging.
llvm-svn: 241787
This is very preliminary support, but it seems to work for the most common case.
When observing more/different test cases, we can work on generalizing this.
llvm-svn: 240955
As Polly got a lot faster after the small-integer-optimization imath
patch, we now increase the compute out to optimize larger kernels. This
should also expose additional slow-downs for us to address.
In LNT this gives us a 3.4x speedup on 3mm, at a cost of a 2x increase in
compile time (now 0.77s). reg_detect, oorafft and adi also show some compile
time increases. This compile time cost is divided between more time in isl and
more time in LLVM's backends due to increased code size (versioning and tiling).
llvm-svn: 240840
In case we have modulo operations in the access function (supported since
r240518), the assumptions generated to ensure array accesses remain within
bounds can contain existentially quantified dimensions which results in more
complex and more difficult to handle integer sets. As a result LNT's linpack
benchmark started to fail due to excessive compile time.
We now just drop the existentially quantified dimensions. This should be
generally save, but may result in less precise assumptions which may
consequently make us fall back to the original (unoptimized) code more often. In
practice, these cases probably do not appear to often.
I had difficulties to extract a good test case, but fortunately our LNT bots
cover this one well.
llvm-svn: 240775
This removes old code that has been disabled since several weeks and was hidden
behind the flags -disable-polly-intra-scop-scalar-to-array=false and
-polly-model-phi-nodes=false. Earlier, Polly used to translate scalars and
PHI nodes to single element arrays, as this avoided the need for their special
handling in Polly. With Johannes' patches adding native support for such scalar
references to Polly, this code is not needed any more. After this commit both
-polly-prepare and -polly-independent are now mostly no-ops. Only a couple of
simple transformations still remain, but they are scheduled for removal too.
Thanks again to Johannes Doerfert for his nice work in making all this code
obsolete.
llvm-svn: 240766
Remainder operations with constant divisor can be modeled as quasi-affine
expression. This patch adds support for detecting and modeling them. We also
add a test that ensures they are correctly code generated.
This patch was extracted from a larger patch contributed by Johannes Doerfert
in http://reviews.llvm.org/D5293
llvm-svn: 240518
David Blaikie:
"find returns an iterator by value, so it's just added complexity/strangeness to
then use reference lifetime extension to give it the same semantics as if you'd
used a value type instead of a reference type."
llvm-svn: 238294
David Blaike suggested this as an alternative to the use of owningptr(s) for our
memory management, as value semantics allow to avoid the additional interface
complexity caused by owningptr while still providing similar memory consistency
guarantees. We could also have used a std::vector, but the use of std::vector
would yield possibly changing pointers which currently causes problems as for
example the memory accesses carry pointers to their parent statements. Such
pointers should not change.
Reviewer: jblaikie, jdoerfert
Differential Revision: http://reviews.llvm.org/D10041
llvm-svn: 238290
The feature itself has been committed by Johannes in r238070. As this is the
way forward, we now enable it to ensure we get test coverage.
Thank you Johannes for this nice work!
llvm-svn: 238088
To reduce compile time and to allow more and better quality SCoPs in
the long run we introduced scalar dependences and PHI-modeling. This
patch will now allow us to generate code if one or both of those
options are set. While the principle of demoting scalars as well as
PHIs to memory in order to communicate their value stays the same,
this allows to delay the demotion till the very end (the actual code
generation). Consequently:
- We __almost__ do not modify the code if we do not generate code
for an optimized SCoP in the end. Thus, the early exit as well as
the unprofitable option will now actually preven us from
introducing regressions in case we will probably not get better
code.
- Polly can be used as a "pure" analyzer tool as long as the code
generator is set to none.
- The original SCoP is almost not touched when the optimized version
is placed next to it. Runtime regressions if the runtime checks
chooses the original are not to be expected and later
optimizations do not need to revert the demotion for that part.
- We will generate direct accesses to the demoted values, thus there
are no "trivial GEPs" that select the first element of a scalar we
demoted and treated as an array.
Differential Revision: http://reviews.llvm.org/D7513
llvm-svn: 238070
Instead of explicitly building constraints and adding them to our maps we
now use functions like map_order_le to add the relevant information to the
maps.
llvm-svn: 237934
Being here, we extend the interface to return the element type and not a pointer
to the element type. We also provide a function to get the size (in bytes) of
the elements stored in this array.
We currently still store the element size as an innermost dimension in
ScopArrayInfo, which is somehow inconsistent and should be addressed in future
patches.
llvm-svn: 237779
This reference ID is handy for use cases where we need to identify individual
memory accesses (e.g. to modify their access functions).
This is a reworked version of a patch originally developed by Yabin Hu as part
of his summer of code project.
llvm-svn: 237431
Upcoming revisions of isl require us to include header files explicitly, which
have previously been already transitively included. Before we add them, we sort
the existing includes.
Thanks to Chandler for sort_includes.py. A simple, but very convenient script.
llvm-svn: 236930
This patch also changes the implementation of the ArrayInfoMap to a MapVector
which will ensure that iterating over the list of ArrayInfo objects gives
predictable results. The single loop that currently enumerates the ArrayInfo
objects only frees the individual objectes, hence a possibly changing
iteration order does not affect the outcome. The added robustness is for
future users of this interface.
llvm-svn: 236583
In the lnt benchmark MultiSource/Benchmarks/MallocBench/gs/gs with
scalar and PHI modeling we detected the multidimensional accesses
with sizes variant in the SCoP. This will check the sizes for validity.
llvm-svn: 236395
This change adds location information for the detected regions in Polly when the
required debug information is available.
The JSCOP output format is extended with a "location" field which contains the
information in the format "source.c:start-end"
The dot output is extended to contain the location information for each nested
region in the analyzed function.
As part of this change, the existing getDebugLocation function has been moved
into lib/Support/ScopLocation.cpp to avoid having to include
polly/ScopDetectionDiagnostics.h.
Differential Revision: http://reviews.llvm.org/D9431
Contributed-by: Roal Jordans <r.jordans@tue.nl>
llvm-svn: 236393
In Polly we used both the term 'scattering' and the term 'schedule' to describe
the execution order of a statement without actually distinguishing between them.
We now uniformly use the term 'schedule' for the execution order. This
corresponds to the terminology of isl.
History: CLooG introduced the term scattering as the generated code can be used
as a sequential execution order (schedule) or as a parallel dimension
enumerating different threads of execution (placement). In Polly and/or isl the
term placement was never used, but we uniformly refer to an execution order as a
schedule and only later introduce parallelism. When doing so we do not talk
about about specific placement dimensions.
llvm-svn: 235380
This change is a step towards using a single isl_schedule object throughout
Polly. At the moment the schedule is just constructed from the flat
isl_union_map that defines the schedule. Later we will obtain it directly
from the scop and potentially obtain a schedule with a non-trivial internal
structure that will allow faster dependence analysis.
llvm-svn: 235378
isl_union_map_compute_flow() has been replaced by
isl_union_access_info_compute_flow(). This change does not intend to
change funcitonality, yet. However, it will allow us to pass in subsequent
changes schedule trees to the dependence analysis instead of flat schedules.
This should speed up dependence analysis for important cases significantly.
llvm-svn: 235373
Otherwise, instructions in different functions that share the same pointer (due
to earlier modifications), might get assigned incorrect memory access
information (belonging to instructions in previous functions), which can result
in arbitrary memory corruption and assertion failures.
This fixes llvm.org/PR23160 and possibly also llvm.org/PR23167.
Note: InsnToMemAcc is a global variable that should never have existed in the
first place. We will clean this up in a subsequent patch.
Reported-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
Debugged-by: Johannes Doerfert <doerfert@cs.uni-saarland.de>
llvm-svn: 235254
This will allow the ScopInfo to build the polyhedral representation for
non-affine regions that contain loops. Such loops are basically not visible
in the SCoP representation. Accesses that are variant in such loops are
therefor represented as non-affine accesses.
Differential Revision: http://reviews.llvm.org/D8153
llvm-svn: 234713
This will allow the ScopDetection to detect non-affine regions that
contain loops. All loops contained will be collected and are
accessible to later passes in order to adjust the access functions.
As the loops are non-affine and will not be part of the polyhedral
representation later, all accesses that are variant in these loops
have to be over approximated as non-affine accesses. They are
therefore handled the same way as other non-affine accesses.
Additionally, we do not count non-affine loops for the profitability
heuristic, thus a region with only a non-affine loop will only be
detected if the general detection of loop free regions is enabled.
Differential Revision: http://reviews.llvm.org/D8152
llvm-svn: 234711
Tobias Grosser