llvm-project/polly/lib/Transform/FlattenSchedule.cpp
Tobias Grosser 75aa1a9a49 Use isl C++ foreach implementation
This commit switches Polly over to the isl::obj::foreach_* implementation, which
is part of the new isl bindings and follows the foreach pattern established in
Polly by Michael Kruse.

The original isl C function:

  isl_stat isl_union_set_foreach_set(__isl_keep isl_union_set *uset,
      isl_stat (*fn)(__isl_take isl_set *set, void *user), void *user);

which required the user to define a static callback function to which all
interesting parameters are passed via a 'void *' user-pointer, is on the
C++ side available as a function that takes a std::function<>, which can
carry any additional arguments without the need for a user pointer:

  stat UnionSet::foreach_set(const std::function<stat(set)> &fn) const;

The following code illustrates the use of the new C++ interface:

  auto Lambda = [=, &Result](isl::set Set) -> isl::stat {
    auto Shifted = shiftDimension(Set, Pos, Amount);
    Result = Result.add(Shifted);
    return isl::stat::ok;
  }

  UnionSet.foreach_set(Lambda);

Polly had some specialized foreach functions which did not require the lambdas
to return a status flag. We remove these functions in this commit to move Polly
completely over to the new isl interface. We may in the future discuss if
functors without return values can be supported easily.

Another extension proposed by Michael Kruse is the use of C++ iterators to allow
the use of normal for loops to iterate over these sets. Such an extension would
allow us to further simplify the code.

Reviewed-by: Michael Kruse <llvm@meinersbur.de>

Differential Revision: https://reviews.llvm.org/D30620

llvm-svn: 300323
2017-04-14 13:39:40 +00:00

108 lines
3.3 KiB
C++

//===------ FlattenSchedule.cpp --------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Try to reduce the number of scatter dimension. Useful to make isl_union_map
// schedules more understandable. This is only intended for debugging and
// unittests, not for production use.
//
//===----------------------------------------------------------------------===//
#include "polly/FlattenSchedule.h"
#include "polly/FlattenAlgo.h"
#include "polly/ScopInfo.h"
#include "polly/ScopPass.h"
#define DEBUG_TYPE "polly-flatten-schedule"
using namespace polly;
using namespace llvm;
namespace {
/// Print a schedule to @p OS.
///
/// Prints the schedule for each statements on a new line.
void printSchedule(raw_ostream &OS, const isl::union_map &Schedule,
int indent) {
Schedule.foreach_map([&OS, indent](isl::map Map) -> isl::stat {
OS.indent(indent) << Map << "\n";
return isl::stat::ok;
});
}
/// Flatten the schedule stored in an polly::Scop.
class FlattenSchedule : public ScopPass {
private:
FlattenSchedule(const FlattenSchedule &) = delete;
const FlattenSchedule &operator=(const FlattenSchedule &) = delete;
std::shared_ptr<isl_ctx> IslCtx;
isl::union_map OldSchedule;
public:
static char ID;
explicit FlattenSchedule() : ScopPass(ID) {}
virtual void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequiredTransitive<ScopInfoRegionPass>();
AU.setPreservesAll();
}
virtual bool runOnScop(Scop &S) override {
// Keep a reference to isl_ctx to ensure that it is not freed before we free
// OldSchedule.
IslCtx = S.getSharedIslCtx();
DEBUG(dbgs() << "Going to flatten old schedule:\n");
OldSchedule = give(S.getSchedule());
DEBUG(printSchedule(dbgs(), OldSchedule, 2));
auto Domains = give(S.getDomains());
auto RestrictedOldSchedule = OldSchedule.intersect_domain(Domains);
DEBUG(dbgs() << "Old schedule with domains:\n");
DEBUG(printSchedule(dbgs(), RestrictedOldSchedule, 2));
auto NewSchedule = flattenSchedule(RestrictedOldSchedule);
DEBUG(dbgs() << "Flattened new schedule:\n");
DEBUG(printSchedule(dbgs(), NewSchedule, 2));
NewSchedule = NewSchedule.gist_domain(Domains);
DEBUG(dbgs() << "Gisted, flattened new schedule:\n");
DEBUG(printSchedule(dbgs(), NewSchedule, 2));
S.setSchedule(NewSchedule.take());
return false;
}
virtual void printScop(raw_ostream &OS, Scop &S) const override {
OS << "Schedule before flattening {\n";
printSchedule(OS, OldSchedule, 4);
OS << "}\n\n";
OS << "Schedule after flattening {\n";
printSchedule(OS, give(S.getSchedule()), 4);
OS << "}\n";
}
virtual void releaseMemory() override {
OldSchedule = nullptr;
IslCtx.reset();
}
};
char FlattenSchedule::ID;
} // anonymous namespace
Pass *polly::createFlattenSchedulePass() { return new FlattenSchedule(); }
INITIALIZE_PASS_BEGIN(FlattenSchedule, "polly-flatten-schedule",
"Polly - Flatten schedule", false, false)
INITIALIZE_PASS_END(FlattenSchedule, "polly-flatten-schedule",
"Polly - Flatten schedule", false, false)