Bug Summary

File:llvm/lib/Analysis/LoopCacheAnalysis.cpp
Warning:line 429, column 10
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name LoopCacheAnalysis.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -fno-split-dwarf-inlining -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-12/lib/clang/12.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/build-llvm/include -I /build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-12/lib/clang/12.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/build-llvm/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2020-08-29-030604-21646-1 -x c++ /build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp
1//===- LoopCacheAnalysis.cpp - Loop Cache Analysis -------------------------==//
2//
3// The LLVM Compiler Infrastructure
4//
5// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
6// See https://llvm.org/LICENSE.txt for license information.
7// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
8//
9//===----------------------------------------------------------------------===//
10///
11/// \file
12/// This file defines the implementation for the loop cache analysis.
13/// The implementation is largely based on the following paper:
14///
15/// Compiler Optimizations for Improving Data Locality
16/// By: Steve Carr, Katherine S. McKinley, Chau-Wen Tseng
17/// http://www.cs.utexas.edu/users/mckinley/papers/asplos-1994.pdf
18///
19/// The general approach taken to estimate the number of cache lines used by the
20/// memory references in an inner loop is:
21/// 1. Partition memory references that exhibit temporal or spacial reuse
22/// into reference groups.
23/// 2. For each loop L in the a loop nest LN:
24/// a. Compute the cost of the reference group
25/// b. Compute the loop cost by summing up the reference groups costs
26//===----------------------------------------------------------------------===//
27
28#include "llvm/Analysis/LoopCacheAnalysis.h"
29#include "llvm/ADT/BreadthFirstIterator.h"
30#include "llvm/ADT/Sequence.h"
31#include "llvm/ADT/SmallVector.h"
32#include "llvm/Analysis/ScalarEvolutionExpressions.h"
33#include "llvm/Support/CommandLine.h"
34#include "llvm/Support/Debug.h"
35
36using namespace llvm;
37
38#define DEBUG_TYPE"loop-cache-cost" "loop-cache-cost"
39
40static cl::opt<unsigned> DefaultTripCount(
41 "default-trip-count", cl::init(100), cl::Hidden,
42 cl::desc("Use this to specify the default trip count of a loop"));
43
44// In this analysis two array references are considered to exhibit temporal
45// reuse if they access either the same memory location, or a memory location
46// with distance smaller than a configurable threshold.
47static cl::opt<unsigned> TemporalReuseThreshold(
48 "temporal-reuse-threshold", cl::init(2), cl::Hidden,
49 cl::desc("Use this to specify the max. distance between array elements "
50 "accessed in a loop so that the elements are classified to have "
51 "temporal reuse"));
52
53/// Retrieve the innermost loop in the given loop nest \p Loops. It returns a
54/// nullptr if any loops in the loop vector supplied has more than one sibling.
55/// The loop vector is expected to contain loops collected in breadth-first
56/// order.
57static Loop *getInnerMostLoop(const LoopVectorTy &Loops) {
58 assert(!Loops.empty() && "Expecting a non-empy loop vector")((!Loops.empty() && "Expecting a non-empy loop vector"
) ? static_cast<void> (0) : __assert_fail ("!Loops.empty() && \"Expecting a non-empy loop vector\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 58, __PRETTY_FUNCTION__));
59
60 Loop *LastLoop = Loops.back();
61 Loop *ParentLoop = LastLoop->getParentLoop();
62
63 if (ParentLoop == nullptr) {
64 assert(Loops.size() == 1 && "Expecting a single loop")((Loops.size() == 1 && "Expecting a single loop") ? static_cast
<void> (0) : __assert_fail ("Loops.size() == 1 && \"Expecting a single loop\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 64, __PRETTY_FUNCTION__));
65 return LastLoop;
66 }
67
68 return (llvm::is_sorted(Loops,
69 [](const Loop *L1, const Loop *L2) {
70 return L1->getLoopDepth() < L2->getLoopDepth();
71 }))
72 ? LastLoop
73 : nullptr;
74}
75
76static bool isOneDimensionalArray(const SCEV &AccessFn, const SCEV &ElemSize,
77 const Loop &L, ScalarEvolution &SE) {
78 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(&AccessFn);
79 if (!AR || !AR->isAffine())
80 return false;
81
82 assert(AR->getLoop() && "AR should have a loop")((AR->getLoop() && "AR should have a loop") ? static_cast
<void> (0) : __assert_fail ("AR->getLoop() && \"AR should have a loop\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 82, __PRETTY_FUNCTION__));
83
84 // Check that start and increment are not add recurrences.
85 const SCEV *Start = AR->getStart();
86 const SCEV *Step = AR->getStepRecurrence(SE);
87 if (isa<SCEVAddRecExpr>(Start) || isa<SCEVAddRecExpr>(Step))
88 return false;
89
90 // Check that start and increment are both invariant in the loop.
91 if (!SE.isLoopInvariant(Start, &L) || !SE.isLoopInvariant(Step, &L))
92 return false;
93
94 const SCEV *StepRec = AR->getStepRecurrence(SE);
95 if (StepRec && SE.isKnownNegative(StepRec))
96 StepRec = SE.getNegativeSCEV(StepRec);
97
98 return StepRec == &ElemSize;
99}
100
101/// Compute the trip count for the given loop \p L. Return the SCEV expression
102/// for the trip count or nullptr if it cannot be computed.
103static const SCEV *computeTripCount(const Loop &L, ScalarEvolution &SE) {
104 const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(&L);
105 if (isa<SCEVCouldNotCompute>(BackedgeTakenCount) ||
106 !isa<SCEVConstant>(BackedgeTakenCount))
107 return nullptr;
108
109 return SE.getAddExpr(BackedgeTakenCount,
110 SE.getOne(BackedgeTakenCount->getType()));
111}
112
113//===----------------------------------------------------------------------===//
114// IndexedReference implementation
115//
116raw_ostream &llvm::operator<<(raw_ostream &OS, const IndexedReference &R) {
117 if (!R.IsValid) {
118 OS << R.StoreOrLoadInst;
119 OS << ", IsValid=false.";
120 return OS;
121 }
122
123 OS << *R.BasePointer;
124 for (const SCEV *Subscript : R.Subscripts)
125 OS << "[" << *Subscript << "]";
126
127 OS << ", Sizes: ";
128 for (const SCEV *Size : R.Sizes)
129 OS << "[" << *Size << "]";
130
131 return OS;
132}
133
134IndexedReference::IndexedReference(Instruction &StoreOrLoadInst,
135 const LoopInfo &LI, ScalarEvolution &SE)
136 : StoreOrLoadInst(StoreOrLoadInst), SE(SE) {
137 assert((isa<StoreInst>(StoreOrLoadInst) || isa<LoadInst>(StoreOrLoadInst)) &&(((isa<StoreInst>(StoreOrLoadInst) || isa<LoadInst>
(StoreOrLoadInst)) && "Expecting a load or store instruction"
) ? static_cast<void> (0) : __assert_fail ("(isa<StoreInst>(StoreOrLoadInst) || isa<LoadInst>(StoreOrLoadInst)) && \"Expecting a load or store instruction\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 138, __PRETTY_FUNCTION__))
138 "Expecting a load or store instruction")(((isa<StoreInst>(StoreOrLoadInst) || isa<LoadInst>
(StoreOrLoadInst)) && "Expecting a load or store instruction"
) ? static_cast<void> (0) : __assert_fail ("(isa<StoreInst>(StoreOrLoadInst) || isa<LoadInst>(StoreOrLoadInst)) && \"Expecting a load or store instruction\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 138, __PRETTY_FUNCTION__));
139
140 IsValid = delinearize(LI);
141 if (IsValid)
142 LLVM_DEBUG(dbgs().indent(2) << "Succesfully delinearized: " << *thisdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "Succesfully delinearized: "
<< *this << "\n"; } } while (false)
143 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "Succesfully delinearized: "
<< *this << "\n"; } } while (false);
144}
145
146Optional<bool> IndexedReference::hasSpacialReuse(const IndexedReference &Other,
147 unsigned CLS,
148 AliasAnalysis &AA) const {
149 assert(IsValid && "Expecting a valid reference")((IsValid && "Expecting a valid reference") ? static_cast
<void> (0) : __assert_fail ("IsValid && \"Expecting a valid reference\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 149, __PRETTY_FUNCTION__));
150
151 if (BasePointer != Other.getBasePointer() && !isAliased(Other, AA)) {
152 LLVM_DEBUG(dbgs().indent(2)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse: different base pointers\n"
; } } while (false)
153 << "No spacial reuse: different base pointers\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse: different base pointers\n"
; } } while (false);
154 return false;
155 }
156
157 unsigned NumSubscripts = getNumSubscripts();
158 if (NumSubscripts != Other.getNumSubscripts()) {
159 LLVM_DEBUG(dbgs().indent(2)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse: different number of subscripts\n"
; } } while (false)
160 << "No spacial reuse: different number of subscripts\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse: different number of subscripts\n"
; } } while (false);
161 return false;
162 }
163
164 // all subscripts must be equal, except the leftmost one (the last one).
165 for (auto SubNum : seq<unsigned>(0, NumSubscripts - 1)) {
166 if (getSubscript(SubNum) != Other.getSubscript(SubNum)) {
167 LLVM_DEBUG(dbgs().indent(2) << "No spacial reuse, different subscripts: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse, different subscripts: "
<< "\n\t" << *getSubscript(SubNum) << "\n\t"
<< *Other.getSubscript(SubNum) << "\n"; } } while
(false)
168 << "\n\t" << *getSubscript(SubNum) << "\n\t"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse, different subscripts: "
<< "\n\t" << *getSubscript(SubNum) << "\n\t"
<< *Other.getSubscript(SubNum) << "\n"; } } while
(false)
169 << *Other.getSubscript(SubNum) << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse, different subscripts: "
<< "\n\t" << *getSubscript(SubNum) << "\n\t"
<< *Other.getSubscript(SubNum) << "\n"; } } while
(false);
170 return false;
171 }
172 }
173
174 // the difference between the last subscripts must be less than the cache line
175 // size.
176 const SCEV *LastSubscript = getLastSubscript();
177 const SCEV *OtherLastSubscript = Other.getLastSubscript();
178 const SCEVConstant *Diff = dyn_cast<SCEVConstant>(
179 SE.getMinusSCEV(LastSubscript, OtherLastSubscript));
180
181 if (Diff == nullptr) {
182 LLVM_DEBUG(dbgs().indent(2)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse, difference between subscript:\n\t"
<< *LastSubscript << "\n\t" << OtherLastSubscript
<< "\nis not constant.\n"; } } while (false)
183 << "No spacial reuse, difference between subscript:\n\t"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse, difference between subscript:\n\t"
<< *LastSubscript << "\n\t" << OtherLastSubscript
<< "\nis not constant.\n"; } } while (false)
184 << *LastSubscript << "\n\t" << OtherLastSubscriptdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse, difference between subscript:\n\t"
<< *LastSubscript << "\n\t" << OtherLastSubscript
<< "\nis not constant.\n"; } } while (false)
185 << "\nis not constant.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No spacial reuse, difference between subscript:\n\t"
<< *LastSubscript << "\n\t" << OtherLastSubscript
<< "\nis not constant.\n"; } } while (false);
186 return None;
187 }
188
189 bool InSameCacheLine = (Diff->getValue()->getSExtValue() < CLS);
190
191 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { if (InSameCacheLine) dbgs().indent(2
) << "Found spacial reuse.\n"; else dbgs().indent(2) <<
"No spacial reuse.\n"; }; } } while (false)
192 if (InSameCacheLine)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { if (InSameCacheLine) dbgs().indent(2
) << "Found spacial reuse.\n"; else dbgs().indent(2) <<
"No spacial reuse.\n"; }; } } while (false)
193 dbgs().indent(2) << "Found spacial reuse.\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { if (InSameCacheLine) dbgs().indent(2
) << "Found spacial reuse.\n"; else dbgs().indent(2) <<
"No spacial reuse.\n"; }; } } while (false)
194 elsedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { if (InSameCacheLine) dbgs().indent(2
) << "Found spacial reuse.\n"; else dbgs().indent(2) <<
"No spacial reuse.\n"; }; } } while (false)
195 dbgs().indent(2) << "No spacial reuse.\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { if (InSameCacheLine) dbgs().indent(2
) << "Found spacial reuse.\n"; else dbgs().indent(2) <<
"No spacial reuse.\n"; }; } } while (false)
196 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { if (InSameCacheLine) dbgs().indent(2
) << "Found spacial reuse.\n"; else dbgs().indent(2) <<
"No spacial reuse.\n"; }; } } while (false);
197
198 return InSameCacheLine;
199}
200
201Optional<bool> IndexedReference::hasTemporalReuse(const IndexedReference &Other,
202 unsigned MaxDistance,
203 const Loop &L,
204 DependenceInfo &DI,
205 AliasAnalysis &AA) const {
206 assert(IsValid && "Expecting a valid reference")((IsValid && "Expecting a valid reference") ? static_cast
<void> (0) : __assert_fail ("IsValid && \"Expecting a valid reference\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 206, __PRETTY_FUNCTION__));
207
208 if (BasePointer != Other.getBasePointer() && !isAliased(Other, AA)) {
209 LLVM_DEBUG(dbgs().indent(2)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: different base pointer\n"
; } } while (false)
210 << "No temporal reuse: different base pointer\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: different base pointer\n"
; } } while (false);
211 return false;
212 }
213
214 std::unique_ptr<Dependence> D =
215 DI.depends(&StoreOrLoadInst, &Other.StoreOrLoadInst, true);
216
217 if (D == nullptr) {
218 LLVM_DEBUG(dbgs().indent(2) << "No temporal reuse: no dependence\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: no dependence\n"
; } } while (false);
219 return false;
220 }
221
222 if (D->isLoopIndependent()) {
223 LLVM_DEBUG(dbgs().indent(2) << "Found temporal reuse\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "Found temporal reuse\n"
; } } while (false);
224 return true;
225 }
226
227 // Check the dependence distance at every loop level. There is temporal reuse
228 // if the distance at the given loop's depth is small (|d| <= MaxDistance) and
229 // it is zero at every other loop level.
230 int LoopDepth = L.getLoopDepth();
231 int Levels = D->getLevels();
232 for (int Level = 1; Level <= Levels; ++Level) {
233 const SCEV *Distance = D->getDistance(Level);
234 const SCEVConstant *SCEVConst = dyn_cast_or_null<SCEVConstant>(Distance);
235
236 if (SCEVConst == nullptr) {
237 LLVM_DEBUG(dbgs().indent(2) << "No temporal reuse: distance unknown\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: distance unknown\n"
; } } while (false);
238 return None;
239 }
240
241 const ConstantInt &CI = *SCEVConst->getValue();
242 if (Level != LoopDepth && !CI.isZero()) {
243 LLVM_DEBUG(dbgs().indent(2)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: distance is not zero at depth="
<< Level << "\n"; } } while (false)
244 << "No temporal reuse: distance is not zero at depth=" << Leveldo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: distance is not zero at depth="
<< Level << "\n"; } } while (false)
245 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: distance is not zero at depth="
<< Level << "\n"; } } while (false);
246 return false;
247 } else if (Level == LoopDepth && CI.getSExtValue() > MaxDistance) {
248 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: distance is greater than MaxDistance at depth="
<< Level << "\n"; } } while (false)
249 dbgs().indent(2)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: distance is greater than MaxDistance at depth="
<< Level << "\n"; } } while (false)
250 << "No temporal reuse: distance is greater than MaxDistance at depth="do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: distance is greater than MaxDistance at depth="
<< Level << "\n"; } } while (false)
251 << Level << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "No temporal reuse: distance is greater than MaxDistance at depth="
<< Level << "\n"; } } while (false);
252 return false;
253 }
254 }
255
256 LLVM_DEBUG(dbgs().indent(2) << "Found temporal reuse\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "Found temporal reuse\n"
; } } while (false);
257 return true;
258}
259
260CacheCostTy IndexedReference::computeRefCost(const Loop &L,
261 unsigned CLS) const {
262 assert(IsValid && "Expecting a valid reference")((IsValid && "Expecting a valid reference") ? static_cast
<void> (0) : __assert_fail ("IsValid && \"Expecting a valid reference\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 262, __PRETTY_FUNCTION__));
3
←
Assuming field 'IsValid' is true
→
4
←
'?' condition is true
→
263 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs().indent(2) << "Computing cache cost for:\n"
; dbgs().indent(4) << *this << "\n"; }; } } while
(false)
5
←
Assuming 'DebugFlag' is false
→
6
←
Loop condition is false. Exiting loop
→
264 dbgs().indent(2) << "Computing cache cost for:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs().indent(2) << "Computing cache cost for:\n"
; dbgs().indent(4) << *this << "\n"; }; } } while
(false)
265 dbgs().indent(4) << *this << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs().indent(2) << "Computing cache cost for:\n"
; dbgs().indent(4) << *this << "\n"; }; } } while
(false)
266 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs().indent(2) << "Computing cache cost for:\n"
; dbgs().indent(4) << *this << "\n"; }; } } while
(false);
267
268 // If the indexed reference is loop invariant the cost is one.
269 if (isLoopInvariant(L)) {
7
←
Taking false branch
→
270 LLVM_DEBUG(dbgs().indent(4) << "Reference is loop invariant: RefCost=1\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "Reference is loop invariant: RefCost=1\n"
; } } while (false);
271 return 1;
272 }
273
274 const SCEV *TripCount = computeTripCount(L, SE);
275 if (!TripCount) {
8
←
Assuming 'TripCount' is non-null
→
9
←
Taking false branch
→
276 LLVM_DEBUG(dbgs() << "Trip count of loop " << L.getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "Trip count of loop " <<
L.getName() << " could not be computed, using DefaultTripCount\n"
; } } while (false)
277 << " could not be computed, using DefaultTripCount\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "Trip count of loop " <<
L.getName() << " could not be computed, using DefaultTripCount\n"
; } } while (false);
278 const SCEV *ElemSize = Sizes.back();
279 TripCount = SE.getConstant(ElemSize->getType(), DefaultTripCount);
280 }
281 LLVM_DEBUG(dbgs() << "TripCount=" << *TripCount << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "TripCount=" << *
TripCount << "\n"; } } while (false);
10
←
Assuming 'DebugFlag' is false
→
11
←
Loop condition is false. Exiting loop
→
282
283 // If the indexed reference is 'consecutive' the cost is
284 // (TripCount*Stride)/CLS, otherwise the cost is TripCount.
285 const SCEV *RefCost = TripCount;
286
287 if (isConsecutive(L, CLS)) {
12
←
Assuming the condition is true
→
13
←
Taking true branch
→
288 const SCEV *Coeff = getLastCoefficient();
14
←
Calling 'IndexedReference::getLastCoefficient'
→
289 const SCEV *ElemSize = Sizes.back();
290 const SCEV *Stride = SE.getMulExpr(Coeff, ElemSize);
291 const SCEV *CacheLineSize = SE.getConstant(Stride->getType(), CLS);
292 Type *WiderType = SE.getWiderType(Stride->getType(), TripCount->getType());
293 if (SE.isKnownNegative(Stride))
294 Stride = SE.getNegativeSCEV(Stride);
295 Stride = SE.getNoopOrAnyExtend(Stride, WiderType);
296 TripCount = SE.getNoopOrAnyExtend(TripCount, WiderType);
297 const SCEV *Numerator = SE.getMulExpr(Stride, TripCount);
298 RefCost = SE.getUDivExpr(Numerator, CacheLineSize);
299
300 LLVM_DEBUG(dbgs().indent(4)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "Access is consecutive: RefCost=(TripCount*Stride)/CLS="
<< *RefCost << "\n"; } } while (false)
301 << "Access is consecutive: RefCost=(TripCount*Stride)/CLS="do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "Access is consecutive: RefCost=(TripCount*Stride)/CLS="
<< *RefCost << "\n"; } } while (false)
302 << *RefCost << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "Access is consecutive: RefCost=(TripCount*Stride)/CLS="
<< *RefCost << "\n"; } } while (false);
303 } else
304 LLVM_DEBUG(dbgs().indent(4)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "Access is not consecutive: RefCost=TripCount="
<< *RefCost << "\n"; } } while (false)
305 << "Access is not consecutive: RefCost=TripCount=" << *RefCostdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "Access is not consecutive: RefCost=TripCount="
<< *RefCost << "\n"; } } while (false)
306 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "Access is not consecutive: RefCost=TripCount="
<< *RefCost << "\n"; } } while (false);
307
308 // Attempt to fold RefCost into a constant.
309 if (auto ConstantCost = dyn_cast<SCEVConstant>(RefCost))
310 return ConstantCost->getValue()->getSExtValue();
311
312 LLVM_DEBUG(dbgs().indent(4)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "RefCost is not a constant! Setting to RefCost=InvalidCost "
"(invalid value).\n"; } } while (false)
313 << "RefCost is not a constant! Setting to RefCost=InvalidCost "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "RefCost is not a constant! Setting to RefCost=InvalidCost "
"(invalid value).\n"; } } while (false)
314 "(invalid value).\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(4) << "RefCost is not a constant! Setting to RefCost=InvalidCost "
"(invalid value).\n"; } } while (false);
315
316 return CacheCost::InvalidCost;
317}
318
319bool IndexedReference::delinearize(const LoopInfo &LI) {
320 assert(Subscripts.empty() && "Subscripts should be empty")((Subscripts.empty() && "Subscripts should be empty")
? static_cast<void> (0) : __assert_fail ("Subscripts.empty() && \"Subscripts should be empty\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 320, __PRETTY_FUNCTION__));
321 assert(Sizes.empty() && "Sizes should be empty")((Sizes.empty() && "Sizes should be empty") ? static_cast
<void> (0) : __assert_fail ("Sizes.empty() && \"Sizes should be empty\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 321, __PRETTY_FUNCTION__));
322 assert(!IsValid && "Should be called once from the constructor")((!IsValid && "Should be called once from the constructor"
) ? static_cast<void> (0) : __assert_fail ("!IsValid && \"Should be called once from the constructor\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 322, __PRETTY_FUNCTION__));
323 LLVM_DEBUG(dbgs() << "Delinearizing: " << StoreOrLoadInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "Delinearizing: " <<
StoreOrLoadInst << "\n"; } } while (false);
324
325 const SCEV *ElemSize = SE.getElementSize(&StoreOrLoadInst);
326 const BasicBlock *BB = StoreOrLoadInst.getParent();
327
328 if (Loop *L = LI.getLoopFor(BB)) {
329 const SCEV *AccessFn =
330 SE.getSCEVAtScope(getPointerOperand(&StoreOrLoadInst), L);
331
332 BasePointer = dyn_cast<SCEVUnknown>(SE.getPointerBase(AccessFn));
333 if (BasePointer == nullptr) {
334 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "ERROR: failed to delinearize, can't identify base pointer\n"
; } } while (false)
335 dbgs().indent(2)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "ERROR: failed to delinearize, can't identify base pointer\n"
; } } while (false)
336 << "ERROR: failed to delinearize, can't identify base pointer\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "ERROR: failed to delinearize, can't identify base pointer\n"
; } } while (false);
337 return false;
338 }
339
340 AccessFn = SE.getMinusSCEV(AccessFn, BasePointer);
341
342 LLVM_DEBUG(dbgs().indent(2) << "In Loop '" << L->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "In Loop '" <<
L->getName() << "', AccessFn: " << *AccessFn <<
"\n"; } } while (false)
343 << "', AccessFn: " << *AccessFn << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "In Loop '" <<
L->getName() << "', AccessFn: " << *AccessFn <<
"\n"; } } while (false);
344
345 SE.delinearize(AccessFn, Subscripts, Sizes,
346 SE.getElementSize(&StoreOrLoadInst));
347
348 if (Subscripts.empty() || Sizes.empty() ||
349 Subscripts.size() != Sizes.size()) {
350 // Attempt to determine whether we have a single dimensional array access.
351 // before giving up.
352 if (!isOneDimensionalArray(*AccessFn, *ElemSize, *L, SE)) {
353 LLVM_DEBUG(dbgs().indent(2)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "ERROR: failed to delinearize reference\n"
; } } while (false)
354 << "ERROR: failed to delinearize reference\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "ERROR: failed to delinearize reference\n"
; } } while (false);
355 Subscripts.clear();
356 Sizes.clear();
357 return false;
358 }
359
360 // The array may be accessed in reverse, for example:
361 // for (i = N; i > 0; i--)
362 // A[i] = 0;
363 // In this case, reconstruct the access function using the absolute value
364 // of the step recurrence.
365 const SCEVAddRecExpr *AccessFnAR = dyn_cast<SCEVAddRecExpr>(AccessFn);
366 const SCEV *StepRec = AccessFnAR ? AccessFnAR->getStepRecurrence(SE) : nullptr;
367
368 if (StepRec && SE.isKnownNegative(StepRec))
369 AccessFn = SE.getAddRecExpr(AccessFnAR->getStart(),
370 SE.getNegativeSCEV(StepRec),
371 AccessFnAR->getLoop(),
372 AccessFnAR->getNoWrapFlags());
373 const SCEV *Div = SE.getUDivExactExpr(AccessFn, ElemSize);
374 Subscripts.push_back(Div);
375 Sizes.push_back(ElemSize);
376 }
377
378 return all_of(Subscripts, [&](const SCEV *Subscript) {
379 return isSimpleAddRecurrence(*Subscript, *L);
380 });
381 }
382
383 return false;
384}
385
386bool IndexedReference::isLoopInvariant(const Loop &L) const {
387 Value *Addr = getPointerOperand(&StoreOrLoadInst);
388 assert(Addr != nullptr && "Expecting either a load or a store instruction")((Addr != nullptr && "Expecting either a load or a store instruction"
) ? static_cast<void> (0) : __assert_fail ("Addr != nullptr && \"Expecting either a load or a store instruction\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 388, __PRETTY_FUNCTION__));
389 assert(SE.isSCEVable(Addr->getType()) && "Addr should be SCEVable")((SE.isSCEVable(Addr->getType()) && "Addr should be SCEVable"
) ? static_cast<void> (0) : __assert_fail ("SE.isSCEVable(Addr->getType()) && \"Addr should be SCEVable\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 389, __PRETTY_FUNCTION__));
390
391 if (SE.isLoopInvariant(SE.getSCEV(Addr), &L))
392 return true;
393
394 // The indexed reference is loop invariant if none of the coefficients use
395 // the loop induction variable.
396 bool allCoeffForLoopAreZero = all_of(Subscripts, [&](const SCEV *Subscript) {
397 return isCoeffForLoopZeroOrInvariant(*Subscript, L);
398 });
399
400 return allCoeffForLoopAreZero;
401}
402
403bool IndexedReference::isConsecutive(const Loop &L, unsigned CLS) const {
404 // The indexed reference is 'consecutive' if the only coefficient that uses
405 // the loop induction variable is the last one...
406 const SCEV *LastSubscript = Subscripts.back();
407 for (const SCEV *Subscript : Subscripts) {
408 if (Subscript == LastSubscript)
409 continue;
410 if (!isCoeffForLoopZeroOrInvariant(*Subscript, L))
411 return false;
412 }
413
414 // ...and the access stride is less than the cache line size.
415 const SCEV *Coeff = getLastCoefficient();
416 const SCEV *ElemSize = Sizes.back();
417 const SCEV *Stride = SE.getMulExpr(Coeff, ElemSize);
418 const SCEV *CacheLineSize = SE.getConstant(Stride->getType(), CLS);
419
420 Stride = SE.isKnownNegative(Stride) ? SE.getNegativeSCEV(Stride) : Stride;
421 return SE.isKnownPredicate(ICmpInst::ICMP_ULT, Stride, CacheLineSize);
422}
423
424const SCEV *IndexedReference::getLastCoefficient() const {
425 const SCEV *LastSubscript = getLastSubscript();
426 assert(isa<SCEVAddRecExpr>(LastSubscript) &&((isa<SCEVAddRecExpr>(LastSubscript) && "Expecting a SCEV add recurrence expression"
) ? static_cast<void> (0) : __assert_fail ("isa<SCEVAddRecExpr>(LastSubscript) && \"Expecting a SCEV add recurrence expression\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 427, __PRETTY_FUNCTION__))
15
←
Assuming 'LastSubscript' is a 'SCEVAddRecExpr'
→
16
←
'?' condition is true
→
427 "Expecting a SCEV add recurrence expression")((isa<SCEVAddRecExpr>(LastSubscript) && "Expecting a SCEV add recurrence expression"
) ? static_cast<void> (0) : __assert_fail ("isa<SCEVAddRecExpr>(LastSubscript) && \"Expecting a SCEV add recurrence expression\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 427, __PRETTY_FUNCTION__));
428 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LastSubscript);
17
←
Assuming 'LastSubscript' is not a 'SCEVAddRecExpr'
→
18
←
'AR' initialized to a null pointer value
→
429 return AR->getStepRecurrence(SE);
19
←
Called C++ object pointer is null
430}
431
432bool IndexedReference::isCoeffForLoopZeroOrInvariant(const SCEV &Subscript,
433 const Loop &L) const {
434 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(&Subscript);
435 return (AR != nullptr) ? AR->getLoop() != &L
436 : SE.isLoopInvariant(&Subscript, &L);
437}
438
439bool IndexedReference::isSimpleAddRecurrence(const SCEV &Subscript,
440 const Loop &L) const {
441 if (!isa<SCEVAddRecExpr>(Subscript))
442 return false;
443
444 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(&Subscript);
445 assert(AR->getLoop() && "AR should have a loop")((AR->getLoop() && "AR should have a loop") ? static_cast
<void> (0) : __assert_fail ("AR->getLoop() && \"AR should have a loop\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 445, __PRETTY_FUNCTION__));
446
447 if (!AR->isAffine())
448 return false;
449
450 const SCEV *Start = AR->getStart();
451 const SCEV *Step = AR->getStepRecurrence(SE);
452
453 if (!SE.isLoopInvariant(Start, &L) || !SE.isLoopInvariant(Step, &L))
454 return false;
455
456 return true;
457}
458
459bool IndexedReference::isAliased(const IndexedReference &Other,
460 AliasAnalysis &AA) const {
461 const auto &Loc1 = MemoryLocation::get(&StoreOrLoadInst);
462 const auto &Loc2 = MemoryLocation::get(&Other.StoreOrLoadInst);
463 return AA.isMustAlias(Loc1, Loc2);
464}
465
466//===----------------------------------------------------------------------===//
467// CacheCost implementation
468//
469raw_ostream &llvm::operator<<(raw_ostream &OS, const CacheCost &CC) {
470 for (const auto &LC : CC.LoopCosts) {
471 const Loop *L = LC.first;
472 OS << "Loop '" << L->getName() << "' has cost = " << LC.second << "\n";
473 }
474 return OS;
475}
476
477CacheCost::CacheCost(const LoopVectorTy &Loops, const LoopInfo &LI,
478 ScalarEvolution &SE, TargetTransformInfo &TTI,
479 AliasAnalysis &AA, DependenceInfo &DI,
480 Optional<unsigned> TRT)
481 : Loops(Loops), TripCounts(), LoopCosts(),
482 TRT((TRT == None) ? Optional<unsigned>(TemporalReuseThreshold) : TRT),
483 LI(LI), SE(SE), TTI(TTI), AA(AA), DI(DI) {
484 assert(!Loops.empty() && "Expecting a non-empty loop vector.")((!Loops.empty() && "Expecting a non-empty loop vector."
) ? static_cast<void> (0) : __assert_fail ("!Loops.empty() && \"Expecting a non-empty loop vector.\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 484, __PRETTY_FUNCTION__));
485
486 for (const Loop *L : Loops) {
487 unsigned TripCount = SE.getSmallConstantTripCount(L);
488 TripCount = (TripCount == 0) ? DefaultTripCount : TripCount;
489 TripCounts.push_back({L, TripCount});
490 }
491
492 calculateCacheFootprint();
493}
494
495std::unique_ptr<CacheCost>
496CacheCost::getCacheCost(Loop &Root, LoopStandardAnalysisResults &AR,
497 DependenceInfo &DI, Optional<unsigned> TRT) {
498 if (Root.getParentLoop()) {
499 LLVM_DEBUG(dbgs() << "Expecting the outermost loop in a loop nest\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "Expecting the outermost loop in a loop nest\n"
; } } while (false);
500 return nullptr;
501 }
502
503 LoopVectorTy Loops;
504 for (Loop *L : breadth_first(&Root))
505 Loops.push_back(L);
506
507 if (!getInnerMostLoop(Loops)) {
508 LLVM_DEBUG(dbgs() << "Cannot compute cache cost of loop nest with more "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "Cannot compute cache cost of loop nest with more "
"than one innermost loop\n"; } } while (false)
509 "than one innermost loop\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "Cannot compute cache cost of loop nest with more "
"than one innermost loop\n"; } } while (false);
510 return nullptr;
511 }
512
513 return std::make_unique<CacheCost>(Loops, AR.LI, AR.SE, AR.TTI, AR.AA, DI, TRT);
514}
515
516void CacheCost::calculateCacheFootprint() {
517 LLVM_DEBUG(dbgs() << "POPULATING REFERENCE GROUPS\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "POPULATING REFERENCE GROUPS\n"
; } } while (false);
518 ReferenceGroupsTy RefGroups;
519 if (!populateReferenceGroups(RefGroups))
520 return;
521
522 LLVM_DEBUG(dbgs() << "COMPUTING LOOP CACHE COSTS\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "COMPUTING LOOP CACHE COSTS\n"
; } } while (false);
523 for (const Loop *L : Loops) {
524 assert((std::find_if(LoopCosts.begin(), LoopCosts.end(),(((std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const
LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts
.end()) && "Should not add duplicate element") ? static_cast
<void> (0) : __assert_fail ("(std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts.end()) && \"Should not add duplicate element\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 528, __PRETTY_FUNCTION__))
525 [L](const LoopCacheCostTy &LCC) {(((std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const
LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts
.end()) && "Should not add duplicate element") ? static_cast
<void> (0) : __assert_fail ("(std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts.end()) && \"Should not add duplicate element\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 528, __PRETTY_FUNCTION__))
526 return LCC.first == L;(((std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const
LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts
.end()) && "Should not add duplicate element") ? static_cast
<void> (0) : __assert_fail ("(std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts.end()) && \"Should not add duplicate element\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 528, __PRETTY_FUNCTION__))
527 }) == LoopCosts.end()) &&(((std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const
LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts
.end()) && "Should not add duplicate element") ? static_cast
<void> (0) : __assert_fail ("(std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts.end()) && \"Should not add duplicate element\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 528, __PRETTY_FUNCTION__))
528 "Should not add duplicate element")(((std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const
LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts
.end()) && "Should not add duplicate element") ? static_cast
<void> (0) : __assert_fail ("(std::find_if(LoopCosts.begin(), LoopCosts.end(), [L](const LoopCacheCostTy &LCC) { return LCC.first == L; }) == LoopCosts.end()) && \"Should not add duplicate element\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 528, __PRETTY_FUNCTION__));
529 CacheCostTy LoopCost = computeLoopCacheCost(*L, RefGroups);
530 LoopCosts.push_back(std::make_pair(L, LoopCost));
531 }
532
533 sortLoopCosts();
534 RefGroups.clear();
535}
536
537bool CacheCost::populateReferenceGroups(ReferenceGroupsTy &RefGroups) const {
538 assert(RefGroups.empty() && "Reference groups should be empty")((RefGroups.empty() && "Reference groups should be empty"
) ? static_cast<void> (0) : __assert_fail ("RefGroups.empty() && \"Reference groups should be empty\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 538, __PRETTY_FUNCTION__));
539
540 unsigned CLS = TTI.getCacheLineSize();
541 Loop *InnerMostLoop = getInnerMostLoop(Loops);
542 assert(InnerMostLoop != nullptr && "Expecting a valid innermost loop")((InnerMostLoop != nullptr && "Expecting a valid innermost loop"
) ? static_cast<void> (0) : __assert_fail ("InnerMostLoop != nullptr && \"Expecting a valid innermost loop\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 542, __PRETTY_FUNCTION__));
543
544 for (BasicBlock *BB : InnerMostLoop->getBlocks()) {
545 for (Instruction &I : *BB) {
546 if (!isa<StoreInst>(I) && !isa<LoadInst>(I))
547 continue;
548
549 std::unique_ptr<IndexedReference> R(new IndexedReference(I, LI, SE));
550 if (!R->isValid())
551 continue;
552
553 bool Added = false;
554 for (ReferenceGroupTy &RefGroup : RefGroups) {
555 const IndexedReference &Representative = *RefGroup.front().get();
556 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "References:\n"; dbgs
().indent(2) << *R << "\n"; dbgs().indent(2) <<
Representative << "\n"; }; } } while (false)
557 dbgs() << "References:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "References:\n"; dbgs
().indent(2) << *R << "\n"; dbgs().indent(2) <<
Representative << "\n"; }; } } while (false)
558 dbgs().indent(2) << *R << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "References:\n"; dbgs
().indent(2) << *R << "\n"; dbgs().indent(2) <<
Representative << "\n"; }; } } while (false)
559 dbgs().indent(2) << Representative << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "References:\n"; dbgs
().indent(2) << *R << "\n"; dbgs().indent(2) <<
Representative << "\n"; }; } } while (false)
560 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "References:\n"; dbgs
().indent(2) << *R << "\n"; dbgs().indent(2) <<
Representative << "\n"; }; } } while (false);
561
562
563 // FIXME: Both positive and negative access functions will be placed
564 // into the same reference group, resulting in a bi-directional array
565 // access such as:
566 // for (i = N; i > 0; i--)
567 // A[i] = A[N - i];
568 // having the same cost calculation as a single dimention access pattern
569 // for (i = 0; i < N; i++)
570 // A[i] = A[i];
571 // when in actuality, depending on the array size, the first example
572 // should have a cost closer to 2x the second due to the two cache
573 // access per iteration from opposite ends of the array
574 Optional<bool> HasTemporalReuse =
575 R->hasTemporalReuse(Representative, *TRT, *InnerMostLoop, DI, AA);
576 Optional<bool> HasSpacialReuse =
577 R->hasSpacialReuse(Representative, CLS, AA);
578
579 if ((HasTemporalReuse.hasValue() && *HasTemporalReuse) ||
580 (HasSpacialReuse.hasValue() && *HasSpacialReuse)) {
581 RefGroup.push_back(std::move(R));
582 Added = true;
583 break;
584 }
585 }
586
587 if (!Added) {
588 ReferenceGroupTy RG;
589 RG.push_back(std::move(R));
590 RefGroups.push_back(std::move(RG));
591 }
592 }
593 }
594
595 if (RefGroups.empty())
596 return false;
597
598 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
599 dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
600 int n = 1;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
601 for (const ReferenceGroupTy &RG : RefGroups) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
602 dbgs().indent(2) << "RefGroup " << n << ":\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
603 for (const auto &IR : RG)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
604 dbgs().indent(4) << *IR << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
605 n++;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
606 }do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
607 dbgs() << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
)
608 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { { dbgs() << "\nIDENTIFIED REFERENCE GROUPS:\n"
; int n = 1; for (const ReferenceGroupTy &RG : RefGroups)
{ dbgs().indent(2) << "RefGroup " << n << ":\n"
; for (const auto &IR : RG) dbgs().indent(4) << *IR
<< "\n"; n++; } dbgs() << "\n"; }; } } while (false
);
609
610 return true;
611}
612
613CacheCostTy
614CacheCost::computeLoopCacheCost(const Loop &L,
615 const ReferenceGroupsTy &RefGroups) const {
616 if (!L.isLoopSimplifyForm())
617 return InvalidCost;
618
619 LLVM_DEBUG(dbgs() << "Considering loop '" << L.getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "Considering loop '" <<
L.getName() << "' as innermost loop.\n"; } } while (false
)
620 << "' as innermost loop.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs() << "Considering loop '" <<
L.getName() << "' as innermost loop.\n"; } } while (false
);
621
622 // Compute the product of the trip counts of each other loop in the nest.
623 CacheCostTy TripCountsProduct = 1;
624 for (const auto &TC : TripCounts) {
625 if (TC.first == &L)
626 continue;
627 TripCountsProduct *= TC.second;
628 }
629
630 CacheCostTy LoopCost = 0;
631 for (const ReferenceGroupTy &RG : RefGroups) {
632 CacheCostTy RefGroupCost = computeRefGroupCacheCost(RG, L);
633 LoopCost += RefGroupCost * TripCountsProduct;
634 }
635
636 LLVM_DEBUG(dbgs().indent(2) << "Loop '" << L.getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "Loop '" <<
L.getName() << "' has cost=" << LoopCost <<
"\n"; } } while (false)
637 << "' has cost=" << LoopCost << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-cache-cost")) { dbgs().indent(2) << "Loop '" <<
L.getName() << "' has cost=" << LoopCost <<
"\n"; } } while (false);
638
639 return LoopCost;
640}
641
642CacheCostTy CacheCost::computeRefGroupCacheCost(const ReferenceGroupTy &RG,
643 const Loop &L) const {
644 assert(!RG.empty() && "Reference group should have at least one member.")((!RG.empty() && "Reference group should have at least one member."
) ? static_cast<void> (0) : __assert_fail ("!RG.empty() && \"Reference group should have at least one member.\""
, "/build/llvm-toolchain-snapshot-12~++20200828100629+cfde93e5d6b/llvm/lib/Analysis/LoopCacheAnalysis.cpp"
, 644, __PRETTY_FUNCTION__));
1
'?' condition is true
→
645
646 const IndexedReference *Representative = RG.front().get();
647 return Representative->computeRefCost(L, TTI.getCacheLineSize());
2
←
Calling 'IndexedReference::computeRefCost'
→
648}
649
650//===----------------------------------------------------------------------===//
651// LoopCachePrinterPass implementation
652//
653PreservedAnalyses LoopCachePrinterPass::run(Loop &L, LoopAnalysisManager &AM,
654 LoopStandardAnalysisResults &AR,
655 LPMUpdater &U) {
656 Function *F = L.getHeader()->getParent();
657 DependenceInfo DI(F, &AR.AA, &AR.SE, &AR.LI);
658
659 if (auto CC = CacheCost::getCacheCost(L, AR, DI))
660 OS << *CC;
661
662 return PreservedAnalyses::all();
663}