Bug Summary

File:mlir/lib/Rewrite/PatternApplicator.cpp
Warning:line 194, column 7
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 -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name PatternApplicator.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 -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/build-llvm/tools/clang/stage2-bins -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D MLIR_CUDA_CONVERSIONS_ENABLED=1 -D MLIR_ROCM_CONVERSIONS_ENABLED=1 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I tools/mlir/lib/Rewrite -I /build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/mlir/lib/Rewrite -I include -I /build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/llvm/include -I /build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/mlir/include -I tools/mlir/include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fmacro-prefix-map=/build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/= -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/build-llvm/tools/clang/stage2-bins -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-01-19-134126-35450-1 -x c++ /build/llvm-toolchain-snapshot-14~++20220119111520+da61cb019eb2/mlir/lib/Rewrite/PatternApplicator.cpp
1//===- PatternApplicator.cpp - Pattern Application Engine -------*- C++ -*-===//
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// This file implements an applicator that applies pattern rewrites based upon a
10// user defined cost model.
11//
12//===----------------------------------------------------------------------===//
13
14#include "mlir/Rewrite/PatternApplicator.h"
15#include "ByteCode.h"
16#include "llvm/Support/Debug.h"
17
18#define DEBUG_TYPE"pattern-application" "pattern-application"
19
20using namespace mlir;
21using namespace mlir::detail;
22
23PatternApplicator::PatternApplicator(
24 const FrozenRewritePatternSet &frozenPatternList)
25 : frozenPatternList(frozenPatternList) {
26 if (const PDLByteCode *bytecode = frozenPatternList.getPDLByteCode()) {
27 mutableByteCodeState = std::make_unique<PDLByteCodeMutableState>();
28 bytecode->initializeMutableState(*mutableByteCodeState);
29 }
30}
31PatternApplicator::~PatternApplicator() = default;
32
33#ifndef NDEBUG
34/// Log a message for a pattern that is impossible to match.
35static void logImpossibleToMatch(const Pattern &pattern) {
36 llvm::dbgs() << "Ignoring pattern '" << pattern.getRootKind()
37 << "' because it is impossible to match or cannot lead "
38 "to legal IR (by cost model)\n";
39}
40
41/// Log IR after pattern application.
42static Operation *getDumpRootOp(Operation *op) {
43 return op->getParentWithTrait<mlir::OpTrait::IsIsolatedFromAbove>();
44}
45static void logSucessfulPatternApplication(Operation *op) {
46 llvm::dbgs() << "// *** IR Dump After Pattern Application ***\n";
47 op->dump();
48 llvm::dbgs() << "\n\n";
49}
50#endif
51
52void PatternApplicator::applyCostModel(CostModel model) {
53 // Apply the cost model to the bytecode patterns first, and then the native
54 // patterns.
55 if (const PDLByteCode *bytecode = frozenPatternList.getPDLByteCode()) {
56 for (const auto &it : llvm::enumerate(bytecode->getPatterns()))
57 mutableByteCodeState->updatePatternBenefit(it.index(), model(it.value()));
58 }
59
60 // Copy over the patterns so that we can sort by benefit based on the cost
61 // model. Patterns that are already impossible to match are ignored.
62 patterns.clear();
63 for (const auto &it : frozenPatternList.getOpSpecificNativePatterns()) {
64 for (const RewritePattern *pattern : it.second) {
65 if (pattern->getBenefit().isImpossibleToMatch())
66 LLVM_DEBUG(logImpossibleToMatch(*pattern))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { logImpossibleToMatch(*pattern); } }
while (false)
;
67 else
68 patterns[it.first].push_back(pattern);
69 }
70 }
71 anyOpPatterns.clear();
72 for (const RewritePattern &pattern :
73 frozenPatternList.getMatchAnyOpNativePatterns()) {
74 if (pattern.getBenefit().isImpossibleToMatch())
75 LLVM_DEBUG(logImpossibleToMatch(pattern))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { logImpossibleToMatch(pattern); } }
while (false)
;
76 else
77 anyOpPatterns.push_back(&pattern);
78 }
79
80 // Sort the patterns using the provided cost model.
81 llvm::SmallDenseMap<const Pattern *, PatternBenefit> benefits;
82 auto cmp = [&benefits](const Pattern *lhs, const Pattern *rhs) {
83 return benefits[lhs] > benefits[rhs];
84 };
85 auto processPatternList = [&](SmallVectorImpl<const RewritePattern *> &list) {
86 // Special case for one pattern in the list, which is the most common case.
87 if (list.size() == 1) {
88 if (model(*list.front()).isImpossibleToMatch()) {
89 LLVM_DEBUG(logImpossibleToMatch(*list.front()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { logImpossibleToMatch(*list.front()
); } } while (false)
;
90 list.clear();
91 }
92 return;
93 }
94
95 // Collect the dynamic benefits for the current pattern list.
96 benefits.clear();
97 for (const Pattern *pat : list)
98 benefits.try_emplace(pat, model(*pat));
99
100 // Sort patterns with highest benefit first, and remove those that are
101 // impossible to match.
102 std::stable_sort(list.begin(), list.end(), cmp);
103 while (!list.empty() && benefits[list.back()].isImpossibleToMatch()) {
104 LLVM_DEBUG(logImpossibleToMatch(*list.back()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { logImpossibleToMatch(*list.back())
; } } while (false)
;
105 list.pop_back();
106 }
107 };
108 for (auto &it : patterns)
109 processPatternList(it.second);
110 processPatternList(anyOpPatterns);
111}
112
113void PatternApplicator::walkAllPatterns(
114 function_ref<void(const Pattern &)> walk) {
115 for (const auto &it : frozenPatternList.getOpSpecificNativePatterns())
116 for (const auto &pattern : it.second)
117 walk(*pattern);
118 for (const Pattern &it : frozenPatternList.getMatchAnyOpNativePatterns())
119 walk(it);
120 if (const PDLByteCode *bytecode = frozenPatternList.getPDLByteCode()) {
121 for (const Pattern &it : bytecode->getPatterns())
122 walk(it);
123 }
124}
125
126LogicalResult PatternApplicator::matchAndRewrite(
127 Operation *op, PatternRewriter &rewriter,
128 function_ref<bool(const Pattern &)> canApply,
129 function_ref<void(const Pattern &)> onFailure,
130 function_ref<LogicalResult(const Pattern &)> onSuccess) {
131 // Before checking native patterns, first match against the bytecode. This
132 // won't automatically perform any rewrites so there is no need to worry about
133 // conflicts.
134 SmallVector<PDLByteCode::MatchResult, 4> pdlMatches;
135 const PDLByteCode *bytecode = frozenPatternList.getPDLByteCode();
1
'bytecode' initialized here
136 if (bytecode)
2
Assuming 'bytecode' is null
3
Taking false branch
137 bytecode->match(op, rewriter, pdlMatches, *mutableByteCodeState);
138
139 // Check to see if there are patterns matching this specific operation type.
140 MutableArrayRef<const RewritePattern *> opPatterns;
141 auto patternIt = patterns.find(op->getName());
142 if (patternIt != patterns.end())
4
Taking false branch
143 opPatterns = patternIt->second;
144
145 // Process the patterns for that match the specific operation type, and any
146 // operation type in an interleaved fashion.
147 unsigned opIt = 0, opE = opPatterns.size();
148 unsigned anyIt = 0, anyE = anyOpPatterns.size();
149 unsigned pdlIt = 0, pdlE = pdlMatches.size();
150 LogicalResult result = failure();
151 do {
152 // Find the next pattern with the highest benefit.
153 const Pattern *bestPattern = nullptr;
154 unsigned *bestPatternIt = &opIt;
155 const PDLByteCode::MatchResult *pdlMatch = nullptr;
156
157 /// Operation specific patterns.
158 if (opIt < opE)
5
Assuming 'opIt' is < 'opE'
6
Taking true branch
159 bestPattern = opPatterns[opIt];
160 /// Operation agnostic patterns.
161 if (anyIt < anyE &&
7
Assuming 'anyIt' is >= 'anyE'
162 (!bestPattern ||
163 bestPattern->getBenefit() < anyOpPatterns[anyIt]->getBenefit())) {
164 bestPatternIt = &anyIt;
165 bestPattern = anyOpPatterns[anyIt];
166 }
167 /// PDL patterns.
168 if (pdlIt < pdlE && (!bestPattern || bestPattern->getBenefit() <
8
Assuming 'pdlIt' is < 'pdlE'
9
Assuming 'bestPattern' is null
10
Taking true branch
169 pdlMatches[pdlIt].benefit)) {
170 bestPatternIt = &pdlIt;
171 pdlMatch = &pdlMatches[pdlIt];
172 bestPattern = pdlMatch->pattern;
173 }
174 if (!bestPattern)
11
Assuming 'bestPattern' is non-null
12
Taking false branch
175 break;
176
177 // Update the pattern iterator on failure so that this pattern isn't
178 // attempted again.
179 ++(*bestPatternIt);
180
181 // Check that the pattern can be applied.
182 if (canApply && !canApply(*bestPattern))
13
Assuming the condition is false
183 continue;
184
185 // Try to match and rewrite this pattern. The patterns are sorted by
186 // benefit, so if we match we can immediately rewrite. For PDL patterns, the
187 // match has already been performed, we just need to rewrite.
188 rewriter.setInsertionPoint(op);
189#ifndef NDEBUG
190 // Operation `op` may be invalidated after applying the rewrite pattern.
191 Operation *dumpRootOp = getDumpRootOp(op);
192#endif
193 if (pdlMatch
13.1
'pdlMatch' is non-null
) {
14
Taking true branch
194 bytecode->rewrite(rewriter, *pdlMatch, *mutableByteCodeState);
15
Called C++ object pointer is null
195 result = success(!onSuccess || succeeded(onSuccess(*bestPattern)));
196 } else {
197 const auto *pattern = static_cast<const RewritePattern *>(bestPattern);
198
199 LLVM_DEBUG(llvm::dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { llvm::dbgs() << "Trying to match \""
<< pattern->getDebugName() << "\"\n"; } } while
(false)
200 << "Trying to match \"" << pattern->getDebugName() << "\"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { llvm::dbgs() << "Trying to match \""
<< pattern->getDebugName() << "\"\n"; } } while
(false)
;
201 result = pattern->matchAndRewrite(op, rewriter);
202 LLVM_DEBUG(llvm::dbgs() << "\"" << pattern->getDebugName() << "\" result "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { llvm::dbgs() << "\"" <<
pattern->getDebugName() << "\" result " << succeeded
(result) << "\n"; } } while (false)
203 << succeeded(result) << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { llvm::dbgs() << "\"" <<
pattern->getDebugName() << "\" result " << succeeded
(result) << "\n"; } } while (false)
;
204
205 if (succeeded(result) && onSuccess && failed(onSuccess(*pattern)))
206 result = failure();
207 }
208 if (succeeded(result)) {
209 LLVM_DEBUG(logSucessfulPatternApplication(dumpRootOp))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("pattern-application")) { logSucessfulPatternApplication(dumpRootOp
); } } while (false)
;
210 break;
211 }
212
213 // Perform any necessary cleanups.
214 if (onFailure)
215 onFailure(*bestPattern);
216 } while (true);
217
218 if (mutableByteCodeState)
219 mutableByteCodeState->cleanupAfterMatchAndRewrite();
220 return result;
221}