Bug Summary

File:build/source/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp
Warning:line 172, column 38
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 WebAssemblyAsmTypeCheck.cpp -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/source/build-llvm/tools/clang/stage2-bins -resource-dir /usr/lib/llvm-17/lib/clang/17 -D _DEBUG -D _GLIBCXX_ASSERTIONS -D _GNU_SOURCE -D _LIBCPP_ENABLE_ASSERTIONS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I lib/Target/WebAssembly/AsmParser -I /build/source/llvm/lib/Target/WebAssembly/AsmParser -I /build/source/llvm/lib/Target/WebAssembly -I lib/Target/WebAssembly -I include -I /build/source/llvm/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-17/lib/clang/17/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/source/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fmacro-prefix-map=/build/source/= -fcoverage-prefix-map=/build/source/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fcoverage-prefix-map=/build/source/= -source-date-epoch 1680300532 -O2 -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 -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/source/build-llvm/tools/clang/stage2-bins -fdebug-prefix-map=/build/source/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fdebug-prefix-map=/build/source/= -ferror-limit 19 -fvisibility=hidden -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-2023-04-01-083001-16331-1 -x c++ /build/source/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp
1//==- WebAssemblyAsmTypeCheck.cpp - Assembler for WebAssembly -*- 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/// \file
10/// This file is part of the WebAssembly Assembler.
11///
12/// It contains code to translate a parsed .s file into MCInsts.
13///
14//===----------------------------------------------------------------------===//
15
16#include "AsmParser/WebAssemblyAsmTypeCheck.h"
17#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
18#include "MCTargetDesc/WebAssemblyMCTypeUtilities.h"
19#include "MCTargetDesc/WebAssemblyTargetStreamer.h"
20#include "TargetInfo/WebAssemblyTargetInfo.h"
21#include "WebAssembly.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCInst.h"
25#include "llvm/MC/MCInstrInfo.h"
26#include "llvm/MC/MCParser/MCParsedAsmOperand.h"
27#include "llvm/MC/MCParser/MCTargetAsmParser.h"
28#include "llvm/MC/MCSectionWasm.h"
29#include "llvm/MC/MCStreamer.h"
30#include "llvm/MC/MCSubtargetInfo.h"
31#include "llvm/MC/MCSymbol.h"
32#include "llvm/MC/MCSymbolWasm.h"
33#include "llvm/MC/TargetRegistry.h"
34#include "llvm/Support/Compiler.h"
35#include "llvm/Support/Endian.h"
36#include "llvm/Support/SourceMgr.h"
37
38using namespace llvm;
39
40#define DEBUG_TYPE"wasm-asm-parser" "wasm-asm-parser"
41
42extern StringRef GetMnemonic(unsigned Opc);
43
44namespace llvm {
45
46WebAssemblyAsmTypeCheck::WebAssemblyAsmTypeCheck(MCAsmParser &Parser,
47 const MCInstrInfo &MII, bool is64)
48 : Parser(Parser), MII(MII), is64(is64) {
49}
50
51void WebAssemblyAsmTypeCheck::funcDecl(const wasm::WasmSignature &Sig) {
52 LocalTypes.assign(Sig.Params.begin(), Sig.Params.end());
53 ReturnTypes.assign(Sig.Returns.begin(), Sig.Returns.end());
54}
55
56void WebAssemblyAsmTypeCheck::localDecl(
57 const SmallVectorImpl<wasm::ValType> &Locals) {
58 LocalTypes.insert(LocalTypes.end(), Locals.begin(), Locals.end());
59}
60
61void WebAssemblyAsmTypeCheck::dumpTypeStack(Twine Msg) {
62 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("wasm-asm-parser")) { { std::string s; for (auto VT : Stack)
{ s += WebAssembly::typeToString(VT); s += " "; } dbgs() <<
Msg << s << '\n'; }; } } while (false)
63 std::string s;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("wasm-asm-parser")) { { std::string s; for (auto VT : Stack)
{ s += WebAssembly::typeToString(VT); s += " "; } dbgs() <<
Msg << s << '\n'; }; } } while (false)
64 for (auto VT : Stack) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("wasm-asm-parser")) { { std::string s; for (auto VT : Stack)
{ s += WebAssembly::typeToString(VT); s += " "; } dbgs() <<
Msg << s << '\n'; }; } } while (false)
65 s += WebAssembly::typeToString(VT);do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("wasm-asm-parser")) { { std::string s; for (auto VT : Stack)
{ s += WebAssembly::typeToString(VT); s += " "; } dbgs() <<
Msg << s << '\n'; }; } } while (false)
66 s += " ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("wasm-asm-parser")) { { std::string s; for (auto VT : Stack)
{ s += WebAssembly::typeToString(VT); s += " "; } dbgs() <<
Msg << s << '\n'; }; } } while (false)
67 }do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("wasm-asm-parser")) { { std::string s; for (auto VT : Stack)
{ s += WebAssembly::typeToString(VT); s += " "; } dbgs() <<
Msg << s << '\n'; }; } } while (false)
68 dbgs() << Msg << s << '\n';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("wasm-asm-parser")) { { std::string s; for (auto VT : Stack)
{ s += WebAssembly::typeToString(VT); s += " "; } dbgs() <<
Msg << s << '\n'; }; } } while (false)
69 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("wasm-asm-parser")) { { std::string s; for (auto VT : Stack)
{ s += WebAssembly::typeToString(VT); s += " "; } dbgs() <<
Msg << s << '\n'; }; } } while (false);
70}
71
72bool WebAssemblyAsmTypeCheck::typeError(SMLoc ErrorLoc, const Twine &Msg) {
73 // Once you get one type error in a function, it will likely trigger more
74 // which are mostly not helpful.
75 if (TypeErrorThisFunction)
76 return true;
77 // If we're currently in unreachable code, we suppress errors completely.
78 if (Unreachable)
79 return false;
80 TypeErrorThisFunction = true;
81 dumpTypeStack("current stack: ");
82 return Parser.Error(ErrorLoc, Msg);
83}
84
85bool WebAssemblyAsmTypeCheck::popType(SMLoc ErrorLoc,
86 std::optional<wasm::ValType> EVT) {
87 if (Stack.empty()) {
88 return typeError(ErrorLoc,
89 EVT ? StringRef("empty stack while popping ") +
90 WebAssembly::typeToString(*EVT)
91 : StringRef("empty stack while popping value"));
92 }
93 auto PVT = Stack.pop_back_val();
94 if (EVT && *EVT != PVT) {
95 return typeError(ErrorLoc,
96 StringRef("popped ") + WebAssembly::typeToString(PVT) +
97 ", expected " + WebAssembly::typeToString(*EVT));
98 }
99 return false;
100}
101
102bool WebAssemblyAsmTypeCheck::popRefType(SMLoc ErrorLoc) {
103 if (Stack.empty()) {
104 return typeError(ErrorLoc, StringRef("empty stack while popping reftype"));
105 }
106 auto PVT = Stack.pop_back_val();
107 if (!WebAssembly::isRefType(PVT)) {
108 return typeError(ErrorLoc, StringRef("popped ") +
109 WebAssembly::typeToString(PVT) +
110 ", expected reftype");
111 }
112 return false;
113}
114
115bool WebAssemblyAsmTypeCheck::getLocal(SMLoc ErrorLoc, const MCInst &Inst,
116 wasm::ValType &Type) {
117 auto Local = static_cast<size_t>(Inst.getOperand(0).getImm());
118 if (Local >= LocalTypes.size())
119 return typeError(ErrorLoc, StringRef("no local type specified for index ") +
120 std::to_string(Local));
121 Type = LocalTypes[Local];
122 return false;
123}
124
125bool WebAssemblyAsmTypeCheck::checkEnd(SMLoc ErrorLoc, bool PopVals) {
126 if (LastSig.Returns.size() > Stack.size())
127 return typeError(ErrorLoc, "end: insufficient values on the type stack");
128
129 if (PopVals) {
130 for (auto VT : llvm::reverse(LastSig.Returns)) {
131 if (popType(ErrorLoc, VT))
132 return true;
133 }
134 return false;
135 }
136
137 for (size_t i = 0; i < LastSig.Returns.size(); i++) {
138 auto EVT = LastSig.Returns[i];
139 auto PVT = Stack[Stack.size() - LastSig.Returns.size() + i];
140 if (PVT != EVT)
141 return typeError(
142 ErrorLoc, StringRef("end got ") + WebAssembly::typeToString(PVT) +
143 ", expected " + WebAssembly::typeToString(EVT));
144 }
145 return false;
146}
147
148bool WebAssemblyAsmTypeCheck::checkSig(SMLoc ErrorLoc,
149 const wasm::WasmSignature& Sig) {
150 for (auto VT : llvm::reverse(Sig.Params))
151 if (popType(ErrorLoc, VT)) return true;
152 Stack.insert(Stack.end(), Sig.Returns.begin(), Sig.Returns.end());
153 return false;
154}
155
156bool WebAssemblyAsmTypeCheck::getSymRef(SMLoc ErrorLoc, const MCInst &Inst,
157 const MCSymbolRefExpr *&SymRef) {
158 auto Op = Inst.getOperand(0);
159 if (!Op.isExpr())
11
←
Taking false branch
→
160 return typeError(ErrorLoc, StringRef("expected expression operand"));
161 SymRef = dyn_cast<MCSymbolRefExpr>(Op.getExpr());
12
←
Assuming the object is not a 'CastReturnType'
→
13
←
Null pointer value stored to 'SymRef'
→
162 if (!SymRef
13.1
'SymRef' is null
)
14
←
Taking true branch
→
163 return typeError(ErrorLoc, StringRef("expected symbol operand"));
164 return false;
165}
166
167bool WebAssemblyAsmTypeCheck::getGlobal(SMLoc ErrorLoc, const MCInst &Inst,
168 wasm::ValType &Type) {
169 const MCSymbolRefExpr *SymRef;
170 if (getSymRef(ErrorLoc, Inst, SymRef))
10
←
Calling 'WebAssemblyAsmTypeCheck::getSymRef'
→
15
←
Returning from 'WebAssemblyAsmTypeCheck::getSymRef'
→
16
←
Taking false branch
→
171 return true;
172 auto WasmSym = cast<MCSymbolWasm>(&SymRef->getSymbol());
17
←
Called C++ object pointer is null
173 switch (WasmSym->getType().value_or(wasm::WASM_SYMBOL_TYPE_DATA)) {
174 case wasm::WASM_SYMBOL_TYPE_GLOBAL:
175 Type = static_cast<wasm::ValType>(WasmSym->getGlobalType().Type);
176 break;
177 case wasm::WASM_SYMBOL_TYPE_FUNCTION:
178 case wasm::WASM_SYMBOL_TYPE_DATA:
179 switch (SymRef->getKind()) {
180 case MCSymbolRefExpr::VK_GOT:
181 case MCSymbolRefExpr::VK_WASM_GOT_TLS:
182 Type = is64 ? wasm::ValType::I64 : wasm::ValType::I32;
183 return false;
184 default:
185 break;
186 }
187 [[fallthrough]];
188 default:
189 return typeError(ErrorLoc, StringRef("symbol ") + WasmSym->getName() +
190 " missing .globaltype");
191 }
192 return false;
193}
194
195bool WebAssemblyAsmTypeCheck::getTable(SMLoc ErrorLoc, const MCInst &Inst,
196 wasm::ValType &Type) {
197 const MCSymbolRefExpr *SymRef;
198 if (getSymRef(ErrorLoc, Inst, SymRef))
199 return true;
200 auto WasmSym = cast<MCSymbolWasm>(&SymRef->getSymbol());
201 if (WasmSym->getType().value_or(wasm::WASM_SYMBOL_TYPE_DATA) !=
202 wasm::WASM_SYMBOL_TYPE_TABLE)
203 return typeError(ErrorLoc, StringRef("symbol ") + WasmSym->getName() +
204 " missing .tabletype");
205 Type = static_cast<wasm::ValType>(WasmSym->getTableType().ElemType);
206 return false;
207}
208
209bool WebAssemblyAsmTypeCheck::endOfFunction(SMLoc ErrorLoc) {
210 // Check the return types.
211 for (auto RVT : llvm::reverse(ReturnTypes)) {
212 if (popType(ErrorLoc, RVT))
213 return true;
214 }
215 if (!Stack.empty()) {
216 return typeError(ErrorLoc, std::to_string(Stack.size()) +
217 " superfluous return values");
218 }
219 Unreachable = true;
220 return false;
221}
222
223bool WebAssemblyAsmTypeCheck::typeCheck(SMLoc ErrorLoc, const MCInst &Inst,
224 OperandVector &Operands) {
225 auto Opc = Inst.getOpcode();
226 auto Name = GetMnemonic(Opc);
227 dumpTypeStack("typechecking " + Name + ": ");
228 wasm::ValType Type;
229 if (Name == "local.get") {
1
Assuming the condition is false
→
2
←
Taking false branch
→
230 if (getLocal(Operands[1]->getStartLoc(), Inst, Type))
231 return true;
232 Stack.push_back(Type);
233 } else if (Name == "local.set") {
3
←
Assuming the condition is false
→
4
←
Taking false branch
→
234 if (getLocal(Operands[1]->getStartLoc(), Inst, Type))
235 return true;
236 if (popType(ErrorLoc, Type))
237 return true;
238 } else if (Name == "local.tee") {
5
←
Assuming the condition is false
→
6
←
Taking false branch
→
239 if (getLocal(Operands[1]->getStartLoc(), Inst, Type))
240 return true;
241 if (popType(ErrorLoc, Type))
242 return true;
243 Stack.push_back(Type);
244 } else if (Name == "global.get") {
7
←
Assuming the condition is true
→
8
←
Taking true branch
→
245 if (getGlobal(Operands[1]->getStartLoc(), Inst, Type))
9
←
Calling 'WebAssemblyAsmTypeCheck::getGlobal'
→
246 return true;
247 Stack.push_back(Type);
248 } else if (Name == "global.set") {
249 if (getGlobal(Operands[1]->getStartLoc(), Inst, Type))
250 return true;
251 if (popType(ErrorLoc, Type))
252 return true;
253 } else if (Name == "table.get") {
254 if (getTable(Operands[1]->getStartLoc(), Inst, Type))
255 return true;
256 if (popType(ErrorLoc, wasm::ValType::I32))
257 return true;
258 Stack.push_back(Type);
259 } else if (Name == "table.set") {
260 if (getTable(Operands[1]->getStartLoc(), Inst, Type))
261 return true;
262 if (popType(ErrorLoc, Type))
263 return true;
264 if (popType(ErrorLoc, wasm::ValType::I32))
265 return true;
266 } else if (Name == "table.fill") {
267 if (getTable(Operands[1]->getStartLoc(), Inst, Type))
268 return true;
269 if (popType(ErrorLoc, wasm::ValType::I32))
270 return true;
271 if (popType(ErrorLoc, Type))
272 return true;
273 if (popType(ErrorLoc, wasm::ValType::I32))
274 return true;
275 } else if (Name == "drop") {
276 if (popType(ErrorLoc, {}))
277 return true;
278 } else if (Name == "end_block" || Name == "end_loop" || Name == "end_if" ||
279 Name == "else" || Name == "end_try") {
280 if (checkEnd(ErrorLoc, Name == "else"))
281 return true;
282 if (Name == "end_block")
283 Unreachable = false;
284 } else if (Name == "return") {
285 if (endOfFunction(ErrorLoc))
286 return true;
287 } else if (Name == "call_indirect" || Name == "return_call_indirect") {
288 // Function value.
289 if (popType(ErrorLoc, wasm::ValType::I32)) return true;
290 if (checkSig(ErrorLoc, LastSig)) return true;
291 if (Name == "return_call_indirect" && endOfFunction(ErrorLoc))
292 return true;
293 } else if (Name == "call" || Name == "return_call") {
294 const MCSymbolRefExpr *SymRef;
295 if (getSymRef(Operands[1]->getStartLoc(), Inst, SymRef))
296 return true;
297 auto WasmSym = cast<MCSymbolWasm>(&SymRef->getSymbol());
298 auto Sig = WasmSym->getSignature();
299 if (!Sig || WasmSym->getType() != wasm::WASM_SYMBOL_TYPE_FUNCTION)
300 return typeError(Operands[1]->getStartLoc(), StringRef("symbol ") +
301 WasmSym->getName() +
302 " missing .functype");
303 if (checkSig(ErrorLoc, *Sig)) return true;
304 if (Name == "return_call" && endOfFunction(ErrorLoc))
305 return true;
306 } else if (Name == "catch") {
307 const MCSymbolRefExpr *SymRef;
308 if (getSymRef(Operands[1]->getStartLoc(), Inst, SymRef))
309 return true;
310 const auto *WasmSym = cast<MCSymbolWasm>(&SymRef->getSymbol());
311 const auto *Sig = WasmSym->getSignature();
312 if (!Sig || WasmSym->getType() != wasm::WASM_SYMBOL_TYPE_TAG)
313 return typeError(Operands[1]->getStartLoc(), StringRef("symbol ") +
314 WasmSym->getName() +
315 " missing .tagtype");
316 // catch instruction pushes values whose types are specified in the tag's
317 // "params" part
318 Stack.insert(Stack.end(), Sig->Params.begin(), Sig->Params.end());
319 } else if (Name == "unreachable") {
320 Unreachable = true;
321 } else if (Name == "ref.is_null") {
322 if (popRefType(ErrorLoc))
323 return true;
324 Stack.push_back(wasm::ValType::I32);
325 } else {
326 // The current instruction is a stack instruction which doesn't have
327 // explicit operands that indicate push/pop types, so we get those from
328 // the register version of the same instruction.
329 auto RegOpc = WebAssembly::getRegisterOpcode(Opc);
330 assert(RegOpc != -1 && "Failed to get register version of MC instruction")(static_cast <bool> (RegOpc != -1 && "Failed to get register version of MC instruction"
) ? void (0) : __assert_fail ("RegOpc != -1 && \"Failed to get register version of MC instruction\""
, "llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp"
, 330, __extension__ __PRETTY_FUNCTION__));
331 const auto &II = MII.get(RegOpc);
332 // First pop all the uses off the stack and check them.
333 for (unsigned I = II.getNumOperands(); I > II.getNumDefs(); I--) {
334 const auto &Op = II.operands()[I - 1];
335 if (Op.OperandType == MCOI::OPERAND_REGISTER) {
336 auto VT = WebAssembly::regClassToValType(Op.RegClass);
337 if (popType(ErrorLoc, VT))
338 return true;
339 }
340 }
341 // Now push all the defs onto the stack.
342 for (unsigned I = 0; I < II.getNumDefs(); I++) {
343 const auto &Op = II.operands()[I];
344 assert(Op.OperandType == MCOI::OPERAND_REGISTER && "Register expected")(static_cast <bool> (Op.OperandType == MCOI::OPERAND_REGISTER
&& "Register expected") ? void (0) : __assert_fail (
"Op.OperandType == MCOI::OPERAND_REGISTER && \"Register expected\""
, "llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp"
, 344, __extension__ __PRETTY_FUNCTION__));
345 auto VT = WebAssembly::regClassToValType(Op.RegClass);
346 Stack.push_back(VT);
347 }
348 }
349 return false;
350}
351
352} // end namespace llvm