Bug Summary

File:llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp
Warning:line 253, column 26
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 SVEIntrinsicOpts.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 -fhalf-no-semantic-interposition -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~++20210107111113+c9154e8fa377/build-llvm/lib/Target/AArch64 -I /build/llvm-toolchain-snapshot-12~++20210107111113+c9154e8fa377/llvm/lib/Target/AArch64 -I /build/llvm-toolchain-snapshot-12~++20210107111113+c9154e8fa377/build-llvm/include -I /build/llvm-toolchain-snapshot-12~++20210107111113+c9154e8fa377/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~++20210107111113+c9154e8fa377/build-llvm/lib/Target/AArch64 -fdebug-prefix-map=/build/llvm-toolchain-snapshot-12~++20210107111113+c9154e8fa377=. -ferror-limit 19 -fvisibility hidden -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-2021-01-08-143434-21064-1 -x c++ /build/llvm-toolchain-snapshot-12~++20210107111113+c9154e8fa377/llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp
1//===----- SVEIntrinsicOpts - SVE ACLE Intrinsics Opts --------------------===//
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// Performs general IR level optimizations on SVE intrinsics.
11//
12// The main goal of this pass is to remove unnecessary reinterpret
13// intrinsics (llvm.aarch64.sve.convert.[to|from].svbool), e.g:
14//
15// %1 = @llvm.aarch64.sve.convert.to.svbool.nxv4i1(<vscale x 4 x i1> %a)
16// %2 = @llvm.aarch64.sve.convert.from.svbool.nxv4i1(<vscale x 16 x i1> %1)
17//
18// This pass also looks for ptest intrinsics & phi instructions where the
19// operands are being needlessly converted to and from svbool_t.
20//
21//===----------------------------------------------------------------------===//
22
23#include "Utils/AArch64BaseInfo.h"
24#include "llvm/ADT/PostOrderIterator.h"
25#include "llvm/ADT/SetVector.h"
26#include "llvm/IR/Constants.h"
27#include "llvm/IR/Dominators.h"
28#include "llvm/IR/IRBuilder.h"
29#include "llvm/IR/Instructions.h"
30#include "llvm/IR/IntrinsicInst.h"
31#include "llvm/IR/IntrinsicsAArch64.h"
32#include "llvm/IR/LLVMContext.h"
33#include "llvm/IR/PatternMatch.h"
34#include "llvm/InitializePasses.h"
35#include "llvm/Support/Debug.h"
36
37using namespace llvm;
38using namespace llvm::PatternMatch;
39
40#define DEBUG_TYPE"aarch64-sve-intrinsic-opts" "aarch64-sve-intrinsic-opts"
41
42namespace llvm {
43void initializeSVEIntrinsicOptsPass(PassRegistry &);
44}
45
46namespace {
47struct SVEIntrinsicOpts : public ModulePass {
48 static char ID; // Pass identification, replacement for typeid
49 SVEIntrinsicOpts() : ModulePass(ID) {
50 initializeSVEIntrinsicOptsPass(*PassRegistry::getPassRegistry());
51 }
52
53 bool runOnModule(Module &M) override;
54 void getAnalysisUsage(AnalysisUsage &AU) const override;
55
56private:
57 static IntrinsicInst *isReinterpretToSVBool(Value *V);
58
59 static bool optimizeIntrinsic(Instruction *I);
60
61 bool optimizeFunctions(SmallSetVector<Function *, 4> &Functions);
62
63 static bool optimizeConvertFromSVBool(IntrinsicInst *I);
64 static bool optimizePTest(IntrinsicInst *I);
65
66 static bool processPhiNode(IntrinsicInst *I);
67};
68} // end anonymous namespace
69
70void SVEIntrinsicOpts::getAnalysisUsage(AnalysisUsage &AU) const {
71 AU.addRequired<DominatorTreeWrapperPass>();
72 AU.setPreservesCFG();
73}
74
75char SVEIntrinsicOpts::ID = 0;
76static const char *name = "SVE intrinsics optimizations";
77INITIALIZE_PASS_BEGIN(SVEIntrinsicOpts, DEBUG_TYPE, name, false, false)static void *initializeSVEIntrinsicOptsPassOnce(PassRegistry &
Registry) {
78INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);;
79INITIALIZE_PASS_END(SVEIntrinsicOpts, DEBUG_TYPE, name, false, false)PassInfo *PI = new PassInfo( name, "aarch64-sve-intrinsic-opts"
, &SVEIntrinsicOpts::ID, PassInfo::NormalCtor_t(callDefaultCtor
<SVEIntrinsicOpts>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeSVEIntrinsicOptsPassFlag
; void llvm::initializeSVEIntrinsicOptsPass(PassRegistry &
Registry) { llvm::call_once(InitializeSVEIntrinsicOptsPassFlag
, initializeSVEIntrinsicOptsPassOnce, std::ref(Registry)); }
80
81namespace llvm {
82ModulePass *createSVEIntrinsicOptsPass() { return new SVEIntrinsicOpts(); }
83} // namespace llvm
84
85/// Returns V if it's a cast from <n x 16 x i1> (aka svbool_t), nullptr
86/// otherwise.
87IntrinsicInst *SVEIntrinsicOpts::isReinterpretToSVBool(Value *V) {
88 IntrinsicInst *I = dyn_cast<IntrinsicInst>(V);
89 if (!I)
90 return nullptr;
91
92 if (I->getIntrinsicID() != Intrinsic::aarch64_sve_convert_to_svbool)
93 return nullptr;
94
95 return I;
96}
97
98/// The function will remove redundant reinterprets casting in the presence
99/// of the control flow
100bool SVEIntrinsicOpts::processPhiNode(IntrinsicInst *X) {
101
102 SmallVector<Instruction *, 32> Worklist;
103 auto RequiredType = X->getType();
104
105 auto *PN = dyn_cast<PHINode>(X->getArgOperand(0));
106 assert(PN && "Expected Phi Node!")((PN && "Expected Phi Node!") ? static_cast<void>
(0) : __assert_fail ("PN && \"Expected Phi Node!\"",
"/build/llvm-toolchain-snapshot-12~++20210107111113+c9154e8fa377/llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp"
, 106, __PRETTY_FUNCTION__));
107
108 // Don't create a new Phi unless we can remove the old one.
109 if (!PN->hasOneUse())
110 return false;
111
112 for (Value *IncValPhi : PN->incoming_values()) {
113 auto *Reinterpret = isReinterpretToSVBool(IncValPhi);
114 if (!Reinterpret ||
115 RequiredType != Reinterpret->getArgOperand(0)->getType())
116 return false;
117 }
118
119 // Create the new Phi
120 LLVMContext &Ctx = PN->getContext();
121 IRBuilder<> Builder(Ctx);
122 Builder.SetInsertPoint(PN);
123 PHINode *NPN = Builder.CreatePHI(RequiredType, PN->getNumIncomingValues());
124 Worklist.push_back(PN);
125
126 for (unsigned I = 0; I < PN->getNumIncomingValues(); I++) {
127 auto *Reinterpret = cast<Instruction>(PN->getIncomingValue(I));
128 NPN->addIncoming(Reinterpret->getOperand(0), PN->getIncomingBlock(I));
129 Worklist.push_back(Reinterpret);
130 }
131
132 // Cleanup Phi Node and reinterprets
133 X->replaceAllUsesWith(NPN);
134 X->eraseFromParent();
135
136 for (auto &I : Worklist)
137 if (I->use_empty())
138 I->eraseFromParent();
139
140 return true;
141}
142
143bool SVEIntrinsicOpts::optimizePTest(IntrinsicInst *I) {
144 IntrinsicInst *Op1 = dyn_cast<IntrinsicInst>(I->getArgOperand(0));
145 IntrinsicInst *Op2 = dyn_cast<IntrinsicInst>(I->getArgOperand(1));
146
147 if (Op1 && Op2 &&
148 Op1->getIntrinsicID() == Intrinsic::aarch64_sve_convert_to_svbool &&
149 Op2->getIntrinsicID() == Intrinsic::aarch64_sve_convert_to_svbool &&
150 Op1->getArgOperand(0)->getType() == Op2->getArgOperand(0)->getType()) {
151
152 Value *Ops[] = {Op1->getArgOperand(0), Op2->getArgOperand(0)};
153 Type *Tys[] = {Op1->getArgOperand(0)->getType()};
154 Module *M = I->getParent()->getParent()->getParent();
155
156 auto Fn = Intrinsic::getDeclaration(M, I->getIntrinsicID(), Tys);
157 auto CI = CallInst::Create(Fn, Ops, I->getName(), I);
158
159 I->replaceAllUsesWith(CI);
160 I->eraseFromParent();
161 if (Op1->use_empty())
162 Op1->eraseFromParent();
163 if (Op1 != Op2 && Op2->use_empty())
164 Op2->eraseFromParent();
165
166 return true;
167 }
168
169 return false;
170}
171
172bool SVEIntrinsicOpts::optimizeConvertFromSVBool(IntrinsicInst *I) {
173 assert(I->getIntrinsicID() == Intrinsic::aarch64_sve_convert_from_svbool &&((I->getIntrinsicID() == Intrinsic::aarch64_sve_convert_from_svbool
&& "Unexpected opcode") ? static_cast<void> (0
) : __assert_fail ("I->getIntrinsicID() == Intrinsic::aarch64_sve_convert_from_svbool && \"Unexpected opcode\""
, "/build/llvm-toolchain-snapshot-12~++20210107111113+c9154e8fa377/llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp"
, 174, __PRETTY_FUNCTION__))
174 "Unexpected opcode")((I->getIntrinsicID() == Intrinsic::aarch64_sve_convert_from_svbool
&& "Unexpected opcode") ? static_cast<void> (0
) : __assert_fail ("I->getIntrinsicID() == Intrinsic::aarch64_sve_convert_from_svbool && \"Unexpected opcode\""
, "/build/llvm-toolchain-snapshot-12~++20210107111113+c9154e8fa377/llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp"
, 174, __PRETTY_FUNCTION__));
175
176 // If the reinterpret instruction operand is a PHI Node
177 if (isa<PHINode>(I->getArgOperand(0)))
178 return processPhiNode(I);
179
180 // If we have a reinterpret intrinsic I of type A which is converting from
181 // another reinterpret Y of type B, and the source type of Y is A, then we can
182 // elide away both reinterprets if there are no other users of Y.
183 auto *Y = isReinterpretToSVBool(I->getArgOperand(0));
184 if (!Y)
185 return false;
186
187 Value *SourceVal = Y->getArgOperand(0);
188 if (I->getType() != SourceVal->getType())
189 return false;
190
191 I->replaceAllUsesWith(SourceVal);
192 I->eraseFromParent();
193 if (Y->use_empty())
194 Y->eraseFromParent();
195
196 return true;
197}
198
199bool SVEIntrinsicOpts::optimizeIntrinsic(Instruction *I) {
200 IntrinsicInst *IntrI = dyn_cast<IntrinsicInst>(I);
201 if (!IntrI)
202 return false;
203
204 switch (IntrI->getIntrinsicID()) {
205 case Intrinsic::aarch64_sve_convert_from_svbool:
206 return optimizeConvertFromSVBool(IntrI);
207 case Intrinsic::aarch64_sve_ptest_any:
208 case Intrinsic::aarch64_sve_ptest_first:
209 case Intrinsic::aarch64_sve_ptest_last:
210 return optimizePTest(IntrI);
211 default:
212 return false;
213 }
214
215 return true;
216}
217
218bool SVEIntrinsicOpts::optimizeFunctions(
219 SmallSetVector<Function *, 4> &Functions) {
220 bool Changed = false;
221 for (auto *F : Functions) {
222 DominatorTree *DT = &getAnalysis<DominatorTreeWrapperPass>(*F).getDomTree();
223
224 // Traverse the DT with an rpo walk so we see defs before uses, allowing
225 // simplification to be done incrementally.
226 BasicBlock *Root = DT->getRoot();
227 ReversePostOrderTraversal<BasicBlock *> RPOT(Root);
228 for (auto *BB : RPOT)
229 for (Instruction &I : make_early_inc_range(*BB))
230 Changed |= optimizeIntrinsic(&I);
231 }
232 return Changed;
233}
234
235bool SVEIntrinsicOpts::runOnModule(Module &M) {
236 bool Changed = false;
237 SmallSetVector<Function *, 4> Functions;
238
239 // Check for SVE intrinsic declarations first so that we only iterate over
240 // relevant functions. Where an appropriate declaration is found, store the
241 // function(s) where it is used so we can target these only.
242 for (auto &F : M.getFunctionList()) {
243 if (!F.isDeclaration())
1
Assuming the condition is false
→
2
←
Taking false branch
→
244 continue;
245
246 switch (F.getIntrinsicID()) {
3
←
Control jumps to 'case aarch64_sve_ptest_last:' at line 250
→
247 case Intrinsic::aarch64_sve_convert_from_svbool:
248 case Intrinsic::aarch64_sve_ptest_any:
249 case Intrinsic::aarch64_sve_ptest_first:
250 case Intrinsic::aarch64_sve_ptest_last:
251 for (auto I = F.user_begin(), E = F.user_end(); I != E;) {
4
←
Loop condition is true. Entering loop body
→
252 auto *Inst = dyn_cast<Instruction>(*I++);
5
←
Assuming the object is not a 'Instruction'
→
6
←
'Inst' initialized to a null pointer value
→
253 Functions.insert(Inst->getFunction());
7
←
Called C++ object pointer is null
254 }
255 break;
256 default:
257 break;
258 }
259 }
260
261 if (!Functions.empty())
262 Changed |= optimizeFunctions(Functions);
263
264 return Changed;
265}