1 //===--------- PolyhedralInfo.cpp - Create Scops from LLVM IR-------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // An interface to the Polyhedral analysis engine(Polly) of LLVM.
10 //
11 // This pass provides an interface to the polyhedral analysis performed by
12 // Polly.
13 //
14 // This interface provides basic interface like isParallel, isVectorizable
15 // that can be used in LLVM transformation passes.
16 //
17 // Work in progress, this file is subject to change.
18 //
19 //===----------------------------------------------------------------------===//
20
21 #include "polly/PolyhedralInfo.h"
22 #include "polly/DependenceInfo.h"
23 #include "polly/LinkAllPasses.h"
24 #include "polly/Options.h"
25 #include "polly/ScopInfo.h"
26 #include "polly/Support/GICHelper.h"
27 #include "llvm/Analysis/LoopInfo.h"
28 #include "llvm/InitializePasses.h"
29 #include "llvm/Support/Debug.h"
30 #include "isl/union_map.h"
31
32 using namespace llvm;
33 using namespace polly;
34
35 #include "polly/Support/PollyDebug.h"
36 #define DEBUG_TYPE "polyhedral-info"
37
38 static cl::opt<bool> CheckParallel("polly-check-parallel",
39 cl::desc("Check for parallel loops"),
40 cl::Hidden, cl::cat(PollyCategory));
41
42 static cl::opt<bool> CheckVectorizable("polly-check-vectorizable",
43 cl::desc("Check for vectorizable loops"),
44 cl::Hidden, cl::cat(PollyCategory));
45
getAnalysisUsage(AnalysisUsage & AU) const46 void PolyhedralInfo::getAnalysisUsage(AnalysisUsage &AU) const {
47 AU.addRequiredTransitive<DependenceInfoWrapperPass>();
48 AU.addRequired<LoopInfoWrapperPass>();
49 AU.addRequiredTransitive<ScopInfoWrapperPass>();
50 AU.setPreservesAll();
51 }
52
runOnFunction(Function & F)53 bool PolyhedralInfo::runOnFunction(Function &F) {
54 DI = &getAnalysis<DependenceInfoWrapperPass>();
55 SI = getAnalysis<ScopInfoWrapperPass>().getSI();
56 return false;
57 }
58
print(raw_ostream & OS,const Module *) const59 void PolyhedralInfo::print(raw_ostream &OS, const Module *) const {
60 auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
61 for (auto *TopLevelLoop : LI) {
62 for (auto *L : depth_first(TopLevelLoop)) {
63 OS.indent(2) << L->getHeader()->getName() << ":\t";
64 if (CheckParallel && isParallel(L))
65 OS << "Loop is parallel.\n";
66 else if (CheckParallel)
67 OS << "Loop is not parallel.\n";
68 }
69 }
70 }
71
checkParallel(Loop * L,isl_pw_aff ** MinDepDistPtr) const72 bool PolyhedralInfo::checkParallel(Loop *L, isl_pw_aff **MinDepDistPtr) const {
73 bool IsParallel;
74 const Scop *S = getScopContainingLoop(L);
75 if (!S)
76 return false;
77 const Dependences &D =
78 DI->getDependences(const_cast<Scop *>(S), Dependences::AL_Access);
79 if (!D.hasValidDependences())
80 return false;
81 POLLY_DEBUG(dbgs() << "Loop :\t" << L->getHeader()->getName() << ":\n");
82
83 isl_union_map *Deps =
84 D.getDependences(Dependences::TYPE_RAW | Dependences::TYPE_WAW |
85 Dependences::TYPE_WAR | Dependences::TYPE_RED)
86 .release();
87
88 POLLY_DEBUG(dbgs() << "Dependences :\t" << stringFromIslObj(Deps, "null")
89 << "\n");
90
91 isl_union_map *Schedule = getScheduleForLoop(S, L);
92 POLLY_DEBUG(dbgs() << "Schedule: \t" << stringFromIslObj(Schedule, "null")
93 << "\n");
94
95 IsParallel = D.isParallel(Schedule, Deps, MinDepDistPtr);
96 isl_union_map_free(Schedule);
97 return IsParallel;
98 }
99
isParallel(Loop * L) const100 bool PolyhedralInfo::isParallel(Loop *L) const { return checkParallel(L); }
101
getScopContainingLoop(Loop * L) const102 const Scop *PolyhedralInfo::getScopContainingLoop(Loop *L) const {
103 assert((SI) && "ScopInfoWrapperPass is required by PolyhedralInfo pass!\n");
104 for (auto &It : *SI) {
105 Region *R = It.first;
106 if (R->contains(L))
107 return It.second.get();
108 }
109 return nullptr;
110 }
111
112 // Given a Loop and the containing SCoP, we compute the partial schedule
113 // by taking union of individual schedules of each ScopStmt within the loop
114 // and projecting out the inner dimensions from the range of the schedule.
115 // for (i = 0; i < n; i++)
116 // for (j = 0; j < n; j++)
117 // A[j] = 1; //Stmt
118 //
119 // The original schedule will be
120 // Stmt[i0, i1] -> [i0, i1]
121 // The schedule for the outer loop will be
122 // Stmt[i0, i1] -> [i0]
123 // The schedule for the inner loop will be
124 // Stmt[i0, i1] -> [i0, i1]
getScheduleForLoop(const Scop * S,Loop * L) const125 __isl_give isl_union_map *PolyhedralInfo::getScheduleForLoop(const Scop *S,
126 Loop *L) const {
127 isl_union_map *Schedule = isl_union_map_empty(S->getParamSpace().release());
128 int CurrDim = S->getRelativeLoopDepth(L);
129 POLLY_DEBUG(dbgs() << "Relative loop depth:\t" << CurrDim << "\n");
130 assert(CurrDim >= 0 && "Loop in region should have at least depth one");
131
132 for (auto &SS : *S) {
133 if (L->contains(SS.getSurroundingLoop())) {
134
135 unsigned int MaxDim = SS.getNumIterators();
136 POLLY_DEBUG(dbgs() << "Maximum depth of Stmt:\t" << MaxDim << "\n");
137 isl_map *ScheduleMap = SS.getSchedule().release();
138 assert(
139 ScheduleMap &&
140 "Schedules that contain extension nodes require special handling.");
141
142 ScheduleMap = isl_map_project_out(ScheduleMap, isl_dim_out, CurrDim + 1,
143 MaxDim - CurrDim - 1);
144 ScheduleMap = isl_map_set_tuple_id(ScheduleMap, isl_dim_in,
145 SS.getDomainId().release());
146 Schedule =
147 isl_union_map_union(Schedule, isl_union_map_from_map(ScheduleMap));
148 }
149 }
150 Schedule = isl_union_map_coalesce(Schedule);
151 return Schedule;
152 }
153
154 char PolyhedralInfo::ID = 0;
155
createPolyhedralInfoPass()156 Pass *polly::createPolyhedralInfoPass() { return new PolyhedralInfo(); }
157
158 INITIALIZE_PASS_BEGIN(PolyhedralInfo, "polyhedral-info",
159 "Polly - Interface to polyhedral analysis engine", false,
160 false);
161 INITIALIZE_PASS_DEPENDENCY(DependenceInfoWrapperPass);
162 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass);
163 INITIALIZE_PASS_DEPENDENCY(ScopInfoWrapperPass);
164 INITIALIZE_PASS_END(PolyhedralInfo, "polyhedral-info",
165 "Polly - Interface to polyhedral analysis engine", false,
166 false)
167
168 //===----------------------------------------------------------------------===//
169
170 namespace {
171 /// Print result from PolyhedralInfo.
172 class PolyhedralInfoPrinterLegacyPass final : public FunctionPass {
173 public:
174 static char ID;
175
PolyhedralInfoPrinterLegacyPass()176 PolyhedralInfoPrinterLegacyPass() : PolyhedralInfoPrinterLegacyPass(outs()) {}
PolyhedralInfoPrinterLegacyPass(llvm::raw_ostream & OS)177 explicit PolyhedralInfoPrinterLegacyPass(llvm::raw_ostream &OS)
178 : FunctionPass(ID), OS(OS) {}
179
runOnFunction(Function & F)180 bool runOnFunction(Function &F) override {
181 PolyhedralInfo &P = getAnalysis<PolyhedralInfo>();
182
183 OS << "Printing analysis '" << P.getPassName() << "' for function '"
184 << F.getName() << "':\n";
185 P.print(OS);
186
187 return false;
188 }
189
getAnalysisUsage(AnalysisUsage & AU) const190 void getAnalysisUsage(AnalysisUsage &AU) const override {
191 FunctionPass::getAnalysisUsage(AU);
192 AU.addRequired<PolyhedralInfo>();
193 AU.setPreservesAll();
194 }
195
196 private:
197 llvm::raw_ostream &OS;
198 };
199
200 char PolyhedralInfoPrinterLegacyPass::ID = 0;
201 } // namespace
202
createPolyhedralInfoPrinterLegacyPass(raw_ostream & OS)203 Pass *polly::createPolyhedralInfoPrinterLegacyPass(raw_ostream &OS) {
204 return new PolyhedralInfoPrinterLegacyPass(OS);
205 }
206
207 INITIALIZE_PASS_BEGIN(
208 PolyhedralInfoPrinterLegacyPass, "print-polyhedral-info",
209 "Polly - Print interface to polyhedral analysis engine analysis", false,
210 false);
211 INITIALIZE_PASS_DEPENDENCY(PolyhedralInfo);
212 INITIALIZE_PASS_END(
213 PolyhedralInfoPrinterLegacyPass, "print-polyhedral-info",
214 "Polly - Print interface to polyhedral analysis engine analysis", false,
215 false)
216