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[Demangle] make llvm::demangle take std::string_view rather than const std::string&
As suggested by @erichkeane in https://reviews.llvm.org/D141451#inline-1429549 There's potential for a lot more cleanups around these APIs. This is just a start. Callers need to be more careful about sub-expressions producing strings that don't outlast the expression using ``llvm::demangle``. Add a release note. Reviewed By: MaskRay, #lld-macho Differential Revision: https://reviews.llvm.org/D149104
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16 files changed

+52
-60
lines changed

16 files changed

+52
-60
lines changed

‎clang/lib/CodeGen/CodeGenAction.cpp

Lines changed: 4 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -633,9 +633,8 @@ BackendConsumer::StackSizeDiagHandler(const llvm::DiagnosticInfoStackSize &D) {
633633
return false;
634634

635635
Diags.Report(*Loc, diag::warn_fe_frame_larger_than)
636-
<< D.getStackSize()
637-
<< D.getStackLimit()
638-
<< llvm::demangle(D.getFunction().getName().str());
636+
<< D.getStackSize() << D.getStackLimit()
637+
<< llvm::demangle(D.getFunction().getName());
639638
return true;
640639
}
641640

@@ -649,7 +648,7 @@ bool BackendConsumer::ResourceLimitDiagHandler(
649648

650649
Diags.Report(*Loc, DiagID)
651650
<< D.getResourceName() << D.getResourceSize() << D.getResourceLimit()
652-
<< llvm::demangle(D.getFunction().getName().str());
651+
<< llvm::demangle(D.getFunction().getName());
653652
return true;
654653
}
655654

@@ -854,7 +853,7 @@ void BackendConsumer::DontCallDiagHandler(const DiagnosticInfoDontCall &D) {
854853
Diags.Report(LocCookie, D.getSeverity() == DiagnosticSeverity::DS_Error
855854
? diag::err_fe_backend_error_attr
856855
: diag::warn_fe_backend_warning_attr)
857-
<< llvm::demangle(D.getFunctionName().str()) << D.getNote();
856+
<< llvm::demangle(D.getFunctionName()) << D.getNote();
858857
}
859858

860859
void BackendConsumer::MisExpectDiagHandler(

‎lld/COFF/Symbols.cpp

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -38,9 +38,9 @@ static std::string maybeDemangleSymbol(const COFFLinkerContext &ctx,
3838
StringRef demangleInput = prefixless;
3939
if (ctx.config.machine == I386)
4040
demangleInput.consume_front("_");
41-
std::string demangled = demangle(demangleInput.str());
41+
std::string demangled = demangle(demangleInput);
4242
if (demangled != demangleInput)
43-
return prefix + demangle(demangleInput.str());
43+
return prefix + demangled;
4444
return (prefix + prefixless).str();
4545
}
4646
return std::string(symName);

‎lld/ELF/SymbolTable.cpp

Lines changed: 9 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -145,13 +145,16 @@ StringMap<SmallVector<Symbol *, 0>> &SymbolTable::getDemangledSyms() {
145145
if (canBeVersioned(*sym)) {
146146
StringRef name = sym->getName();
147147
size_t pos = name.find('@');
148+
std::string substr;
148149
if (pos == std::string::npos)
149-
demangled = demangle(name.str());
150-
else if (pos + 1 == name.size() || name[pos + 1] == '@')
151-
demangled = demangle(name.substr(0, pos).str());
152-
else
153-
demangled =
154-
(demangle(name.substr(0, pos).str()) + name.substr(pos)).str();
150+
demangled = demangle(name);
151+
else if (pos + 1 == name.size() || name[pos + 1] == '@') {
152+
substr = name.substr(0, pos);
153+
demangled = demangle(substr);
154+
} else {
155+
substr = name.substr(0, pos);
156+
demangled = (demangle(substr) + name.substr(pos)).str();
157+
}
155158
(*demangledSyms)[demangled].push_back(sym);
156159
}
157160
}

‎lld/ELF/Symbols.cpp

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -45,9 +45,7 @@ LLVM_ATTRIBUTE_UNUSED static inline void assertSymbols() {
4545

4646
// Returns a symbol for an error message.
4747
static std::string maybeDemangleSymbol(StringRef symName) {
48-
if (elf::config->demangle)
49-
return demangle(symName.str());
50-
return symName.str();
48+
return elf::config->demangle ? demangle(symName.str()) : symName.str();
5149
}
5250

5351
std::string lld::toString(const elf::Symbol &sym) {

‎lld/MachO/Symbols.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -32,7 +32,7 @@ static_assert(sizeof(SymbolUnion) == sizeof(Defined),
3232
static std::string maybeDemangleSymbol(StringRef symName) {
3333
if (config->demangle) {
3434
symName.consume_front("_");
35-
return demangle(symName.str());
35+
return demangle(symName);
3636
}
3737
return symName.str();
3838
}

‎lld/wasm/Symbols.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -35,7 +35,7 @@ std::string maybeDemangleSymbol(StringRef name) {
3535
if (name == "__main_argc_argv")
3636
return "main";
3737
if (wasm::config->demangle)
38-
return demangle(name.str());
38+
return demangle(name);
3939
return name.str();
4040
}
4141

‎llvm/docs/ReleaseNotes.rst

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -292,6 +292,11 @@ Changes to Sanitizers
292292
Other Changes
293293
-------------
294294

295+
* ``llvm::demangle`` now takes a ``std::string_view`` rather than a
296+
``const std::string&``. Be careful passing temporaries into
297+
``llvm::demangle`` that don't outlive the expression using
298+
``llvm::demangle``.
299+
295300
External Open Source Projects Using LLVM 15
296301
===========================================
297302

‎llvm/include/llvm/Demangle/Demangle.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,7 @@
1111

1212
#include <cstddef>
1313
#include <string>
14+
#include <string_view>
1415

1516
namespace llvm {
1617
/// This is a llvm local version of __cxa_demangle. Other than the name and
@@ -62,7 +63,7 @@ char *dlangDemangle(const char *MangledName);
6263
/// \param MangledName - reference to string to demangle.
6364
/// \returns - the demangled string, or a copy of the input string if no
6465
/// demangling occurred.
65-
std::string demangle(const std::string &MangledName);
66+
std::string demangle(const std::string_view MangledName);
6667

6768
bool nonMicrosoftDemangle(const char *MangledName, std::string &Result);
6869

‎llvm/lib/DebugInfo/LogicalView/Readers/LVCodeViewVisitor.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1605,7 +1605,7 @@ Error LVSymbolVisitor::visitKnownRecord(CVSymbol &Record, ProcSym &Proc) {
16051605

16061606
// We don't have a way to see if the symbol is compiler generated. Use
16071607
// the linkage name, to detect `scalar deleting destructor' functions.
1608-
std::string DemangledSymbol = demangle(std::string(LinkageName));
1608+
std::string DemangledSymbol = demangle(LinkageName);
16091609
if (DemangledSymbol.find("scalar deleting dtor") != std::string::npos) {
16101610
Function->setIsArtificial();
16111611
} else {

‎llvm/lib/Demangle/Demangle.cpp

Lines changed: 14 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -11,24 +11,14 @@
1111
//===----------------------------------------------------------------------===//
1212

1313
#include "llvm/Demangle/Demangle.h"
14+
#include "llvm/Demangle/StringViewExtras.h"
1415
#include <cstdlib>
15-
#include <cstring>
1616

17-
static bool isItaniumEncoding(const char *S) {
18-
// Itanium encoding requires 1 or 3 leading underscores, followed by 'Z'.
19-
return std::strncmp(S, "_Z", 2) == 0 || std::strncmp(S, "___Z", 4) == 0;
20-
}
21-
22-
static bool isRustEncoding(const char *S) { return S[0] == '_' && S[1] == 'R'; }
23-
24-
static bool isDLangEncoding(const std::string &MangledName) {
25-
return MangledName.size() >= 2 && MangledName[0] == '_' &&
26-
MangledName[1] == 'D';
27-
}
17+
using llvm::itanium_demangle::starts_with;
2818

29-
std::string llvm::demangle(const std::string &MangledName) {
19+
std::string llvm::demangle(const std::string_view MangledName) {
3020
std::string Result;
31-
const char *S = MangledName.c_str();
21+
const char *S = MangledName.data();
3222

3323
if (nonMicrosoftDemangle(S, Result))
3424
return Result;
@@ -39,12 +29,20 @@ std::string llvm::demangle(const std::string &MangledName) {
3929
if (char *Demangled = microsoftDemangle(S, nullptr, nullptr)) {
4030
Result = Demangled;
4131
std::free(Demangled);
42-
return Result;
32+
} else {
33+
Result = MangledName;
4334
}
35+
return Result;
36+
}
4437

45-
return MangledName;
38+
static bool isItaniumEncoding(std::string_view S) {
39+
return starts_with(S, "_Z") || starts_with(S, "___Z");
4640
}
4741

42+
static bool isRustEncoding(std::string_view S) { return starts_with(S, "_R"); }
43+
44+
static bool isDLangEncoding(std::string_view S) { return starts_with(S, "_D"); }
45+
4846
bool llvm::nonMicrosoftDemangle(const char *MangledName, std::string &Result) {
4947
char *Demangled = nullptr;
5048
if (isItaniumEncoding(MangledName))

‎llvm/lib/IR/DiagnosticInfo.cpp

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -441,8 +441,7 @@ void llvm::diagnoseDontCall(const CallInst &CI) {
441441
}
442442

443443
void DiagnosticInfoDontCall::print(DiagnosticPrinter &DP) const {
444-
DP << "call to " << demangle(getFunctionName().str())
445-
<< " marked \"dontcall-";
444+
DP << "call to " << demangle(getFunctionName()) << " marked \"dontcall-";
446445
if (getSeverity() == DiagnosticSeverity::DS_Error)
447446
DP << "error\"";
448447
else

‎llvm/tools/llvm-objdump/ELFDump.cpp

Lines changed: 1 addition & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -108,10 +108,7 @@ static Error getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
108108
Expected<StringRef> SymName = SI->getName();
109109
if (!SymName)
110110
return SymName.takeError();
111-
if (Demangle)
112-
Fmt << demangle(std::string(*SymName));
113-
else
114-
Fmt << *SymName;
111+
Fmt << (Demangle ? demangle(*SymName) : *SymName);
115112
}
116113
} else {
117114
Fmt << "*ABS*";

‎llvm/tools/llvm-objdump/XCOFFDump.cpp

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -32,10 +32,8 @@ Error objdump::getXCOFFRelocationValueString(const XCOFFObjectFile &Obj,
3232
if (!SymNameOrErr)
3333
return SymNameOrErr.takeError();
3434

35-
std::string SymName = (*SymNameOrErr).str();
36-
if (Demangle)
37-
SymName = demangle(SymName);
38-
35+
std::string SymName =
36+
Demangle ? demangle(*SymNameOrErr) : SymNameOrErr->str();
3937
if (SymbolDescription)
4038
SymName = getXCOFFSymbolDescription(createSymbolInfo(Obj, *SymI), SymName);
4139

‎llvm/tools/llvm-objdump/llvm-objdump.cpp

Lines changed: 6 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -1548,7 +1548,7 @@ static void disassembleObject(const Target *TheTarget, ObjectFile &Obj,
15481548
if (Demangle) {
15491549
// Fetch the demangled names and store them locally.
15501550
for (const SymbolInfoTy &Symbol : SymbolsHere)
1551-
DemangledSymNamesHere.push_back(demangle(Symbol.Name.str()));
1551+
DemangledSymNamesHere.push_back(demangle(Symbol.Name));
15521552
// Now we've finished modifying that vector, it's safe to make
15531553
// a vector of StringRefs pointing into it.
15541554
SymNamesHere.insert(SymNamesHere.begin(), DemangledSymNamesHere.begin(),
@@ -1909,9 +1909,8 @@ static void disassembleObject(const Target *TheTarget, ObjectFile &Obj,
19091909
if (TargetSym != nullptr) {
19101910
uint64_t TargetAddress = TargetSym->Addr;
19111911
uint64_t Disp = Target - TargetAddress;
1912-
std::string TargetName = TargetSym->Name.str();
1913-
if (Demangle)
1914-
TargetName = demangle(TargetName);
1912+
std::string TargetName = Demangle ? demangle(TargetSym->Name)
1913+
: TargetSym->Name.str();
19151914

19161915
*TargetOS << " <";
19171916
if (!Disp) {
@@ -2511,10 +2510,8 @@ void objdump::printSymbol(const ObjectFile &O, const SymbolRef &Symbol,
25112510

25122511
if (NameOrErr) {
25132512
outs() << " (csect:";
2514-
std::string SymName(NameOrErr.get());
2515-
2516-
if (Demangle)
2517-
SymName = demangle(SymName);
2513+
std::string SymName =
2514+
Demangle ? demangle(*NameOrErr) : NameOrErr->str();
25182515

25192516
if (SymbolDescription)
25202517
SymName = getXCOFFSymbolDescription(createSymbolInfo(O, *SymRef),
@@ -2568,10 +2565,7 @@ void objdump::printSymbol(const ObjectFile &O, const SymbolRef &Symbol,
25682565
outs() << " .hidden";
25692566
}
25702567

2571-
std::string SymName(Name);
2572-
if (Demangle)
2573-
SymName = demangle(SymName);
2574-
2568+
std::string SymName = Demangle ? demangle(Name) : Name.str();
25752569
if (O.isXCOFF() && SymbolDescription)
25762570
SymName = getXCOFFSymbolDescription(createSymbolInfo(O, Symbol), SymName);
25772571

‎llvm/tools/llvm-readobj/ELFDumper.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -908,7 +908,7 @@ ELFDumper<ELFT>::getShndxTable(const Elf_Shdr *Symtab) const {
908908
}
909909

910910
static std::string maybeDemangle(StringRef Name) {
911-
return opts::Demangle ? demangle(std::string(Name)) : Name.str();
911+
return opts::Demangle ? demangle(Name) : Name.str();
912912
}
913913

914914
template <typename ELFT>

‎llvm/tools/llvm-tli-checker/llvm-tli-checker.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -107,7 +107,7 @@ static std::string getPrintableName(StringRef Name) {
107107
std::string OutputName = "'";
108108
OutputName += Name;
109109
OutputName += "'";
110-
std::string DemangledName(demangle(Name.str()));
110+
std::string DemangledName(demangle(Name));
111111
if (Name != DemangledName) {
112112
OutputName += " aka ";
113113
OutputName += DemangledName;

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