Enable the use for partial writes for PHI write accesses with a switch.
This simply skips the test for whether a PHI write would be partial.
The analog test for partial value writes also protects for partial reads
which we do not support (yet). It is possible to test for partial reads
separately such that we could skip the partial write check as well. In
case this shows up to be useful, I can implement it as well.
Differential Revision: https://reviews.llvm.org/D33487
llvm-svn: 303762
Instead of relying on these functions to be part of the isl C++ bindings, we
just define this functionality independently. This allows us to use isl C++
bindings that do not contain LLVM specific functionality.
llvm-svn: 303503
As with the scalar operand of the initial StoreInst, also use input
accesses when searching for new opportunities after mapping a
PHI write.
The same rational applies here: After LICM has been applied, the
promoted value will either be an instruction in the same statement
(in which case we fall back to try every scalar access of the
statement), or in another statement such that there will be such
an input access. In the latter case other scalars cannot have
originated from the same register promotion, at least not by LICM.
This mostly helps to decrease compilation time and makes debugging
easier by not pursuing unpromising routes. In some circumstances,
it may change the compiler's output.
llvm-svn: 302839
Previous to this patch, we used VirtualUse to determine the input
access of an llvm::Value in a statement. The input access is the
READ MemoryAccess that makes a value available in that statement,
which can either be a READ of a MemoryKind::Value or the
MemoryKind::PHI for a PHINode in the statement. DeLICM uses the input
access to heuristically find a candidate to map without searching all
possible values.
This might modify the behaviour in that previously PHI accesses were
not considered input accesses before. This was unintentially lost when
"VirtualUse" was extracted from the "Known Knowledge" patch.
llvm-svn: 302838
Some isl functions can simplify their __isl_keep arguments. The
argument object after the call uses different contraints to represent
the same set. Different contraints can result in different outputs
when printed to a string.
In assert builds additional isl functions are called (in assert() or
mentioned, these can change the internal representation of its read-only
arguments such that printed strings are different in debug and non-debug
builds.
What happened here is that a call to isl_set_is_equal inside an assert
in getScatterFor normalizes one of its arguments such that one redundant
constraint is removed. The redundant constraint therefore does not appear
in the string representing the domain, which FileCheck notices as a
regression test failure compared to a build with assertions disabled.
This fix removes the redundant contraints the domain from the start such
that the redundant contraint is removed in assert and non-assert builds.
Isl adds a flag to such sets such that the removal of redundancies is
not done multiple times (here: by isl_set_is_equal).
Thanks to Tobias Grosser for reporting and hinting to the cause.
llvm-svn: 302711
Extend the Knowledge class to store information about the contents
of array elements and which values are written. Two knowledges do
not conflict the known content is the same. The content information
if computed from writes to and loads from the array elements, and
represented by "ValInst": isl spaces that compare equal if the value
represented is the same.
Differential Revision: https://reviews.llvm.org/D31247
llvm-svn: 302339
Do not conflict if a write writes the same value as already known.
This change only affects unit tests, but no functional changes are
expected on LLVM-IR, as no Known information is yet extracted and
consequently this functionality is only triggered through unit tests.
Differential Revision: https://reviews.llvm.org/D32026
llvm-svn: 301460
Do not conflict if the value of Existing and Proposed are the same.
This change only affects unit tests, but no functional changes are
expected on LLVM-IR, as no Known information is yet extracted and
consequently this functionality is only triggered through unit tests.
Differential Revision: https://reviews.llvm.org/D32025
llvm-svn: 301301
This change only affects unit tests, but no functional changes are
expected on LLVM-IR, as no Known information is yet extracted and
consequently this functionality is only triggered through unit tests.
Differential Revision: https://reviews.llvm.org/D32027
llvm-svn: 300874
After the isl C++ binding generator is now close to being upstreamed to isl, we
synchronize the latest changes to Polly. These are mostly formatting changes
plus a small interface change for the foreach callback function and some naming
changes in isl::boolean.
llvm-svn: 300398
The isl C++ bindings now has implicit conversions from isl::set to
isl::union_set. Therefore the additional overload accepting isl::set
is not required anymore.
llvm-svn: 298529
Over the last couple of months several authors of independent isl C++ bindings
worked together to jointly design an official set of isl C++ bindings which
combines their experience in developing isl C++ bindings. The new bindings have
been designed around a value pointer style interface and remove the need for
explicit pointer managenent and instead use C++ language features to manage isl
objects.
This commit introduces the smart-pointer part of the isl C++ bindings and
replaces the current IslPtr<T> classes, which served the very same purpose, but
had to be manually maintained. Instead, we now rely on automatically generated
classes for each isl object, which provide value_ptr semantics.
An isl object has the following smart pointer interface:
inline set manage(__isl_take isl_set *ptr);
class set {
friend inline set manage(__isl_take isl_set *ptr);
isl_set *ptr = nullptr;
inline explicit set(__isl_take isl_set *ptr);
public:
inline set();
inline set(const set &obj);
inline set &operator=(set obj);
inline ~set();
inline __isl_give isl_set *copy() const &;
inline __isl_give isl_set *copy() && = delete;
inline __isl_keep isl_set *get() const;
inline __isl_give isl_set *release();
inline bool is_null() const;
}
The interface and behavior of the new value pointer style classes is inspired
by http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3339.pdf, which
proposes a std::value_ptr, a smart pointer that applies value semantics to its
pointee.
We currently only provide a limited set of public constructors and instead
require provide a global overloaded type constructor method "isl::obj
isl::manage(isl_obj *)", which allows to convert an isl_set* to an isl::set by
calling 'S = isl::manage(s)'. This pattern models the make_unique() constructor
for unique pointers.
The next two functions isl::obj::get() and isl::obj::release() are taken
directly from the std::value_ptr proposal:
S.get() extracts the raw pointer of the object managed by S.
S.release() extracts the raw pointer of the object managed by S and sets the
object in S to null.
We additionally add std::obj::copy(). S.copy() returns a raw pointer refering
to a copy of S, which is a shortcut for "isl::obj(oldobj).release()", a
functionality commonly needed when interacting directly with the isl C
interface where all methods marked with __isl_take require consumable raw
pointers.
S.is_null() checks if S manages a pointer or if the managed object is currently
null. We add this function to provide a more explicit way to check if the
pointer is empty compared to a direct conversion to bool.
This commit also introduces a couple of polly-specific extensions that cover
features currently not handled by the official isl C++ bindings draft, but
which have been provided by IslPtr<T> and are consequently added to avoid code
churn. These extensions include:
- operator bool() : Conversion from objects to bool
- construction from nullptr_t
- get_ctx() method
- take/keep/give methods, which match the currently used naming
convention of IslPtr<T> in Polly. They just forward to
(release/get/manage).
- raw_ostream printers
We expect that these extensions are over time either removed or upstreamed to
the official isl bindings.
We also export a couple of classes that have not yet been exported in isl (e.g.,
isl::space)
As part of the code review, the following two questions were asked:
- Why do we not use a standard smart pointer?
std::value_ptr was a proposal that has not been accepted. It is consequently
not available in the standard library. Even if it would be available, we want
to expand this interface with a complete method interface that is conveniently
available from each managed pointer. The most direct way to achieve this is to
generate a specialiced value style pointer class for each isl object type and
add any additional methods to this class. The relevant changes follow in
subsequent commits.
- Why do we not use templates or macros to avoid code duplication?
It is certainly possible to use templates or macros, but as this code is
auto-generated there is no need to make writing this code more efficient. Also,
most of these classes will be specialized with individual member functions in
subsequent commits, such that there will be little code reuse to exploit. Hence,
we decided to do so at the moment.
These bindings are not yet officially part of isl, but the draft is already very
stable. The smart pointer interface itself did not change since serveral months.
Adding this code to Polly is against our normal policy of only importing
official isl code. In this case however, we make an exception to showcase a
non-trivial use case of these bindings which should increase confidence in these
bindings and will help upstreaming them to isl.
Tags: #polly
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D30325
llvm-svn: 297452
One of the current limitations of DeLICM is that it only creates
PHI WRITEs that it knows are read by some PHI. Such writes may not span
all instances of a statement. Polly's code generator currently does not
support MemoryAccesses that are not executed in all instances
('partial accesses') and so has to give up on a possible mapping.
This workaround has once been suggested by Tobias Grosser: Try to
interpolate an arbitrary expansion to all instances. It will be checked
for possible conflicts with the existing Knowledge and can be applied if
the conflict checking result is that no semantics are changed.
Expansion is done by simplifying the mapping by coalescing with the hope
that coalescing will find a polyhedral 'rule' of the relevant map. It is
then 'gist'-ed using the domain of the relevant instances such that the
rule is expanded to the universe and finally intersected with the domain
of all statement instances.
The expansion makes conflicts become more likely, the found rule may
still not encompass all statement instances and the found rule exposes
internals of isl's implementation of coalesce and gist. The latter means
that the result depends on how much effort the implementation invests
into finding a rule which may change between versions of isl. Trivial
implementations of gist and coalesce just return the input arguments.
A patch that makes codegen support partial accesses is in preparation
as well.
Differential Revision: https://reviews.llvm.org/D30763
llvm-svn: 297373
Control flow would flow-through after the check whether the operations
quota exceeded, with the intention that it would later be caught by
Knowledge::isUsable(). However, the Knowledge constructor has its own
assertions to check consistency which would fail if its fields have only
been initialized partially because some sets have been computed correctly
before the operations quota takes effect.
Fix by erroring-out early instead of falling-throught into the code that
might expect that everything has been computed correctly. For robustness,
also bail-out if any of the fields contain nullptr values instead of
relying on isl always setting exactly this error code if something went
wrong.
This should fix the
perf-x86_64-penryn-O3-polly-before-vectorizer-unprofitable
(-polly-process-unprofitable -polly-position=before-vectorizer
-polly-enable-delicm) buildbot.
llvm-svn: 296022
These tests were not included in the main DeLICM commit. These check the
cases where zone analysis cannot be successful because of assumption
violations.
We use the LLVM optimization remark infrastructure as it seems to be the
best fit for this kind of messages. I tried to make use if the
OptimizationRemarkEmitter. However, it would insert additional function
passes into the pass manager to get the hotness information. The pass
manager would insert them between the flatten pass and delicm, causing
the ScopInfo with the flattened schedule being thrown away.
Differential Revision: https://reviews.llvm.org/D30253
llvm-svn: 295846
There is no template specialization for cl::parser<unsigned long> such
that parsing an cl::opt<unsigned long> command line argument will fail.
Use opt<int> instead which has an associated parser.
llvm-svn: 295832
Implement the -polly-delicm pass. The pass intends to undo the
effects of LoopInvariantCodeMotion (LICM) which adds additional scalar
dependencies into SCoPs. DeLICM will try to map those scalars back to
the array elements they were promoted from, as long as the array
element is unused.
The is the main patch from the DeLICM/DePRE patch series. It does not
yet undo GVN PRE for which additional information about known values
is needed and does not handle PHI write accesses that have have no
target. As such its usefulness is limited. Patches for these issues
including regression tests for error situatons will follow.
Reviewers: grosser
Differential Revision: https://reviews.llvm.org/D24716
llvm-svn: 295713
The Knowledge class remembers the state of data at any timepoint of a SCoP's
execution. Currently, it tracks whether an array element is unused or is
occupied by some value, and the writes to it. A future addition will be to also
remember which value it contains.
Objects are used to determine whether two Knowledge contain conflicting
information, i.e. two states cannot be true a the same time.
This commit was extracted from the DeLICM algorithm at
https://reviews.llvm.org/D24716.
llvm-svn: 295197
Add an empty DeLICM pass, without any functional parts.
Extracting the boilerplate from the the functional part reduces the size of the
code to review (https://reviews.llvm.org/D24716)
Suggested-by: Tobias Grosser <tobias@grosser.es>
llvm-svn: 288160
Michael Kruse