1 //===------ FlattenSchedule.cpp --------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Try to reduce the number of scatter dimension. Useful to make isl_union_map
11 // schedules more understandable. This is only intended for debugging and
12 // unittests, not for production use.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "polly/FlattenSchedule.h"
17 #include "polly/FlattenAlgo.h"
18 #include "polly/ScopInfo.h"
19 #include "polly/ScopPass.h"
20 #include "polly/Support/ISLOStream.h"
21 #define DEBUG_TYPE "polly-flatten-schedule"
22 
23 using namespace polly;
24 using namespace llvm;
25 
26 namespace {
27 
28 /// Print a schedule to @p OS.
29 ///
30 /// Prints the schedule for each statements on a new line.
31 void printSchedule(raw_ostream &OS, const isl::union_map &Schedule,
32                    int indent) {
33   Schedule.foreach_map([&OS, indent](isl::map Map) -> isl::stat {
34     OS.indent(indent) << Map << "\n";
35     return isl::stat::ok;
36   });
37 }
38 
39 /// Flatten the schedule stored in an polly::Scop.
40 class FlattenSchedule : public ScopPass {
41 private:
42   FlattenSchedule(const FlattenSchedule &) = delete;
43   const FlattenSchedule &operator=(const FlattenSchedule &) = delete;
44 
45   std::shared_ptr<isl_ctx> IslCtx;
46   isl::union_map OldSchedule;
47 
48 public:
49   static char ID;
50   explicit FlattenSchedule() : ScopPass(ID) {}
51 
52   virtual void getAnalysisUsage(AnalysisUsage &AU) const override {
53     AU.addRequiredTransitive<ScopInfoRegionPass>();
54     AU.setPreservesAll();
55   }
56 
57   virtual bool runOnScop(Scop &S) override {
58     // Keep a reference to isl_ctx to ensure that it is not freed before we free
59     // OldSchedule.
60     IslCtx = S.getSharedIslCtx();
61 
62     DEBUG(dbgs() << "Going to flatten old schedule:\n");
63     OldSchedule = S.getSchedule();
64     DEBUG(printSchedule(dbgs(), OldSchedule, 2));
65 
66     auto Domains = S.getDomains();
67     auto RestrictedOldSchedule = OldSchedule.intersect_domain(Domains);
68     DEBUG(dbgs() << "Old schedule with domains:\n");
69     DEBUG(printSchedule(dbgs(), RestrictedOldSchedule, 2));
70 
71     auto NewSchedule = flattenSchedule(RestrictedOldSchedule);
72 
73     DEBUG(dbgs() << "Flattened new schedule:\n");
74     DEBUG(printSchedule(dbgs(), NewSchedule, 2));
75 
76     NewSchedule = NewSchedule.gist_domain(Domains);
77     DEBUG(dbgs() << "Gisted, flattened new schedule:\n");
78     DEBUG(printSchedule(dbgs(), NewSchedule, 2));
79 
80     S.setSchedule(NewSchedule);
81     return false;
82   }
83 
84   virtual void printScop(raw_ostream &OS, Scop &S) const override {
85     OS << "Schedule before flattening {\n";
86     printSchedule(OS, OldSchedule, 4);
87     OS << "}\n\n";
88 
89     OS << "Schedule after flattening {\n";
90     printSchedule(OS, S.getSchedule(), 4);
91     OS << "}\n";
92   }
93 
94   virtual void releaseMemory() override {
95     OldSchedule = nullptr;
96     IslCtx.reset();
97   }
98 };
99 
100 char FlattenSchedule::ID;
101 } // anonymous namespace
102 
103 Pass *polly::createFlattenSchedulePass() { return new FlattenSchedule(); }
104 
105 INITIALIZE_PASS_BEGIN(FlattenSchedule, "polly-flatten-schedule",
106                       "Polly - Flatten schedule", false, false)
107 INITIALIZE_PASS_END(FlattenSchedule, "polly-flatten-schedule",
108                     "Polly - Flatten schedule", false, false)
109