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 #define DEBUG_TYPE "polly-flatten-schedule"
21 
22 using namespace polly;
23 using namespace llvm;
24 
25 namespace {
26 
27 /// Print a schedule to @p OS.
28 ///
29 /// Prints the schedule for each statements on a new line.
30 void printSchedule(raw_ostream &OS, NonowningIslPtr<isl_union_map> Schedule,
31                    int indent) {
32   foreachElt(Schedule, [&OS, indent](IslPtr<isl_map> Map) {
33     OS.indent(indent) << Map << "\n";
34   });
35 }
36 
37 /// Flatten the schedule stored in an polly::Scop.
38 class FlattenSchedule : public ScopPass {
39 private:
40   FlattenSchedule(const FlattenSchedule &) = delete;
41   const FlattenSchedule &operator=(const FlattenSchedule &) = delete;
42 
43   std::shared_ptr<isl_ctx> IslCtx;
44   IslPtr<isl_union_map> OldSchedule;
45 
46 public:
47   static char ID;
48   explicit FlattenSchedule() : ScopPass(ID) {}
49 
50   virtual void getAnalysisUsage(AnalysisUsage &AU) const override {
51     AU.addRequiredTransitive<ScopInfoRegionPass>();
52     AU.setPreservesAll();
53   }
54 
55   virtual bool runOnScop(Scop &S) override {
56     // Keep a reference to isl_ctx to ensure that it is not freed before we free
57     // OldSchedule.
58     IslCtx = S.getSharedIslCtx();
59 
60     DEBUG(dbgs() << "Going to flatten old schedule:\n");
61     OldSchedule = give(S.getSchedule());
62     DEBUG(printSchedule(dbgs(), OldSchedule, 2));
63 
64     auto Domains = give(S.getDomains());
65     auto RestrictedOldSchedule = give(
66         isl_union_map_intersect_domain(OldSchedule.copy(), Domains.copy()));
67     DEBUG(dbgs() << "Old schedule with domains:\n");
68     DEBUG(printSchedule(dbgs(), RestrictedOldSchedule, 2));
69 
70     auto NewSchedule = flattenSchedule(RestrictedOldSchedule);
71 
72     DEBUG(dbgs() << "Flattened new schedule:\n");
73     DEBUG(printSchedule(dbgs(), NewSchedule, 2));
74 
75     NewSchedule =
76         give(isl_union_map_gist_domain(NewSchedule.take(), Domains.take()));
77     DEBUG(dbgs() << "Gisted, flattened new schedule:\n");
78     DEBUG(printSchedule(dbgs(), NewSchedule, 2));
79 
80     S.setSchedule(NewSchedule.take());
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, give(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