From 5b3ca24a35e91bf9c19af856e7f92c69b17f989e Mon Sep 17 00:00:00 2001 From: Nathan Sidwell Date: Mon, 28 Feb 2022 10:13:44 -0800 Subject: [PATCH] [demangler] Simplify OutputBuffer initialization Every non-testcase use of OutputBuffer contains code to allocate an initial buffer (using either 128 or 1024 as initial guesses). There's now no need to do that, given recent changes to the buffer extension heuristics -- it allocates a 1k(ish) buffer on first need. Just pass in a buffer (if any) to the constructor. Thus the OutputBuffer's ownership of the buffer starts at its own lifetime start. We can reduce the lifetime of this object in several cases. That new constructor takes a 'size_t *' for the size argument, as all uses with a non-null buffer are passing through a malloc'd buffer from their own caller in this manner. The buffer reset member function is never used, and is deleted. The original buffer initialization code would return a failure code if that first malloc failed. Existing code either ignored that, called std::terminate with a FIXME, or returned an error code. But that's not foolproof anyway, as a subsequent buffer extension failure ends up calling std::terminate. I am working on addressing that unfortunate failure mode in a manner more consistent with the C++ ABI design. Reviewed By: dblaikie Differential Revision: https://reviews.llvm.org/D122604 --- libcxxabi/src/cxa_demangle.cpp | 5 +---- libcxxabi/src/demangle/Utility.h | 25 +++---------------------- llvm/include/llvm/Demangle/Utility.h | 25 +++---------------------- llvm/lib/Demangle/DLangDemangle.cpp | 3 --- llvm/lib/Demangle/ItaniumDemangle.cpp | 21 +++++---------------- llvm/lib/Demangle/MicrosoftDemangle.cpp | 17 +---------------- llvm/lib/Demangle/MicrosoftDemangleNodes.cpp | 1 - llvm/lib/Demangle/RustDemangle.cpp | 3 --- 8 files changed, 13 insertions(+), 87 deletions(-) diff --git a/libcxxabi/src/cxa_demangle.cpp b/libcxxabi/src/cxa_demangle.cpp index ddab6d3..7baac68 100644 --- a/libcxxabi/src/cxa_demangle.cpp +++ b/libcxxabi/src/cxa_demangle.cpp @@ -386,15 +386,12 @@ __cxa_demangle(const char *MangledName, char *Buf, size_t *N, int *Status) { int InternalStatus = demangle_success; Demangler Parser(MangledName, MangledName + std::strlen(MangledName)); - OutputBuffer O; - Node *AST = Parser.parse(); if (AST == nullptr) InternalStatus = demangle_invalid_mangled_name; - else if (!initializeOutputBuffer(Buf, N, O, 1024)) - InternalStatus = demangle_memory_alloc_failure; else { + OutputBuffer O(Buf, N); assert(Parser.ForwardTemplateRefs.empty()); AST->print(O); O += '\0'; diff --git a/libcxxabi/src/demangle/Utility.h b/libcxxabi/src/demangle/Utility.h index 6e0fa38..00572880 100644 --- a/libcxxabi/src/demangle/Utility.h +++ b/libcxxabi/src/demangle/Utility.h @@ -69,7 +69,9 @@ class OutputBuffer { public: OutputBuffer(char *StartBuf, size_t Size) - : Buffer(StartBuf), CurrentPosition(0), BufferCapacity(Size) {} + : Buffer(StartBuf), BufferCapacity(Size) {} + OutputBuffer(char *StartBuf, size_t *SizePtr) + : OutputBuffer(StartBuf, StartBuf ? *SizePtr : 0) {} OutputBuffer() = default; // Non-copyable OutputBuffer(const OutputBuffer &) = delete; @@ -77,12 +79,6 @@ public: operator StringView() const { return StringView(Buffer, CurrentPosition); } - void reset(char *Buffer_, size_t BufferCapacity_) { - CurrentPosition = 0; - Buffer = Buffer_; - BufferCapacity = BufferCapacity_; - } - /// If a ParameterPackExpansion (or similar type) is encountered, the offset /// into the pack that we're currently printing. unsigned CurrentPackIndex = std::numeric_limits::max(); @@ -197,21 +193,6 @@ public: ScopedOverride &operator=(const ScopedOverride &) = delete; }; -inline bool initializeOutputBuffer(char *Buf, size_t *N, OutputBuffer &OB, - size_t InitSize) { - size_t BufferSize; - if (Buf == nullptr) { - Buf = static_cast(std::malloc(InitSize)); - if (Buf == nullptr) - return false; - BufferSize = InitSize; - } else - BufferSize = *N; - - OB.reset(Buf, BufferSize); - return true; -} - DEMANGLE_NAMESPACE_END #endif diff --git a/llvm/include/llvm/Demangle/Utility.h b/llvm/include/llvm/Demangle/Utility.h index b17eadc..7025469 100644 --- a/llvm/include/llvm/Demangle/Utility.h +++ b/llvm/include/llvm/Demangle/Utility.h @@ -69,7 +69,9 @@ class OutputBuffer { public: OutputBuffer(char *StartBuf, size_t Size) - : Buffer(StartBuf), CurrentPosition(0), BufferCapacity(Size) {} + : Buffer(StartBuf), BufferCapacity(Size) {} + OutputBuffer(char *StartBuf, size_t *SizePtr) + : OutputBuffer(StartBuf, StartBuf ? *SizePtr : 0) {} OutputBuffer() = default; // Non-copyable OutputBuffer(const OutputBuffer &) = delete; @@ -77,12 +79,6 @@ public: operator StringView() const { return StringView(Buffer, CurrentPosition); } - void reset(char *Buffer_, size_t BufferCapacity_) { - CurrentPosition = 0; - Buffer = Buffer_; - BufferCapacity = BufferCapacity_; - } - /// If a ParameterPackExpansion (or similar type) is encountered, the offset /// into the pack that we're currently printing. unsigned CurrentPackIndex = std::numeric_limits::max(); @@ -197,21 +193,6 @@ public: ScopedOverride &operator=(const ScopedOverride &) = delete; }; -inline bool initializeOutputBuffer(char *Buf, size_t *N, OutputBuffer &OB, - size_t InitSize) { - size_t BufferSize; - if (Buf == nullptr) { - Buf = static_cast(std::malloc(InitSize)); - if (Buf == nullptr) - return false; - BufferSize = InitSize; - } else - BufferSize = *N; - - OB.reset(Buf, BufferSize); - return true; -} - DEMANGLE_NAMESPACE_END #endif diff --git a/llvm/lib/Demangle/DLangDemangle.cpp b/llvm/lib/Demangle/DLangDemangle.cpp index 7cecd80..b747b0f 100644 --- a/llvm/lib/Demangle/DLangDemangle.cpp +++ b/llvm/lib/Demangle/DLangDemangle.cpp @@ -548,9 +548,6 @@ char *llvm::dlangDemangle(const char *MangledName) { return nullptr; OutputBuffer Demangled; - if (!initializeOutputBuffer(nullptr, nullptr, Demangled, 1024)) - return nullptr; - if (strcmp(MangledName, "_Dmain") == 0) { Demangled << "D main"; } else { diff --git a/llvm/lib/Demangle/ItaniumDemangle.cpp b/llvm/lib/Demangle/ItaniumDemangle.cpp index 1c9209d..9b646ea 100644 --- a/llvm/lib/Demangle/ItaniumDemangle.cpp +++ b/llvm/lib/Demangle/ItaniumDemangle.cpp @@ -375,15 +375,12 @@ char *llvm::itaniumDemangle(const char *MangledName, char *Buf, int InternalStatus = demangle_success; Demangler Parser(MangledName, MangledName + std::strlen(MangledName)); - OutputBuffer OB; - Node *AST = Parser.parse(); if (AST == nullptr) InternalStatus = demangle_invalid_mangled_name; - else if (!initializeOutputBuffer(Buf, N, OB, 1024)) - InternalStatus = demangle_memory_alloc_failure; else { + OutputBuffer OB(Buf, N); assert(Parser.ForwardTemplateRefs.empty()); AST->print(OB); OB += '\0'; @@ -427,9 +424,7 @@ bool ItaniumPartialDemangler::partialDemangle(const char *MangledName) { } static char *printNode(const Node *RootNode, char *Buf, size_t *N) { - OutputBuffer OB; - if (!initializeOutputBuffer(Buf, N, OB, 128)) - return nullptr; + OutputBuffer OB(Buf, N); RootNode->print(OB); OB += '\0'; if (N != nullptr) @@ -472,9 +467,7 @@ char *ItaniumPartialDemangler::getFunctionDeclContextName(char *Buf, return nullptr; const Node *Name = static_cast(RootNode)->getName(); - OutputBuffer OB; - if (!initializeOutputBuffer(Buf, N, OB, 128)) - return nullptr; + OutputBuffer OB(Buf, N); KeepGoingLocalFunction: while (true) { @@ -525,9 +518,7 @@ char *ItaniumPartialDemangler::getFunctionParameters(char *Buf, return nullptr; NodeArray Params = static_cast(RootNode)->getParams(); - OutputBuffer OB; - if (!initializeOutputBuffer(Buf, N, OB, 128)) - return nullptr; + OutputBuffer OB(Buf, N); OB += '('; Params.printWithComma(OB); @@ -543,9 +534,7 @@ char *ItaniumPartialDemangler::getFunctionReturnType( if (!isFunction()) return nullptr; - OutputBuffer OB; - if (!initializeOutputBuffer(Buf, N, OB, 128)) - return nullptr; + OutputBuffer OB(Buf, N); if (const Node *Ret = static_cast(RootNode)->getReturnType()) diff --git a/llvm/lib/Demangle/MicrosoftDemangle.cpp b/llvm/lib/Demangle/MicrosoftDemangle.cpp index aca8cf7..26087a5 100644 --- a/llvm/lib/Demangle/MicrosoftDemangle.cpp +++ b/llvm/lib/Demangle/MicrosoftDemangle.cpp @@ -966,9 +966,6 @@ void Demangler::memorizeIdentifier(IdentifierNode *Identifier) { // Render this class template name into a string buffer so that we can // memorize it for the purpose of back-referencing. OutputBuffer OB; - if (!initializeOutputBuffer(nullptr, nullptr, OB, 1024)) - // FIXME: Propagate out-of-memory as an error? - std::terminate(); Identifier->output(OB, OF_Default); StringView Owned = copyString(OB); memorizeString(Owned); @@ -1279,11 +1276,6 @@ Demangler::demangleStringLiteral(StringView &MangledName) { EncodedStringLiteralNode *Result = Arena.alloc(); - // Must happen before the first `goto StringLiteralError`. - if (!initializeOutputBuffer(nullptr, nullptr, OB, 1024)) - // FIXME: Propagate out-of-memory as an error? - std::terminate(); - // Prefix indicating the beginning of a string literal if (!MangledName.consumeFront("@_")) goto StringLiteralError; @@ -1442,9 +1434,6 @@ Demangler::demangleLocallyScopedNamePiece(StringView &MangledName) { // Render the parent symbol's name into a buffer. OutputBuffer OB; - if (!initializeOutputBuffer(nullptr, nullptr, OB, 1024)) - // FIXME: Propagate out-of-memory as an error? - std::terminate(); OB << '`'; Scope->output(OB, OF_Default); OB << '\''; @@ -2307,8 +2296,6 @@ void Demangler::dumpBackReferences() { // Create an output stream so we can render each type. OutputBuffer OB; - if (!initializeOutputBuffer(nullptr, nullptr, OB, 1024)) - std::terminate(); for (size_t I = 0; I < Backrefs.FunctionParamCount; ++I) { OB.setCurrentPosition(0); @@ -2335,7 +2322,6 @@ char *llvm::microsoftDemangle(const char *MangledName, size_t *NMangled, char *Buf, size_t *N, int *Status, MSDemangleFlags Flags) { Demangler D; - OutputBuffer OB; StringView Name{MangledName}; SymbolNode *AST = D.parse(Name); @@ -2360,9 +2346,8 @@ char *llvm::microsoftDemangle(const char *MangledName, size_t *NMangled, int InternalStatus = demangle_success; if (D.Error) InternalStatus = demangle_invalid_mangled_name; - else if (!initializeOutputBuffer(Buf, N, OB, 1024)) - InternalStatus = demangle_memory_alloc_failure; else { + OutputBuffer OB(Buf, N); AST->output(OB, OF); OB += '\0'; if (N != nullptr) diff --git a/llvm/lib/Demangle/MicrosoftDemangleNodes.cpp b/llvm/lib/Demangle/MicrosoftDemangleNodes.cpp index 494cdab..975649f 100644 --- a/llvm/lib/Demangle/MicrosoftDemangleNodes.cpp +++ b/llvm/lib/Demangle/MicrosoftDemangleNodes.cpp @@ -119,7 +119,6 @@ static void outputCallingConvention(OutputBuffer &OB, CallingConv CC) { std::string Node::toString(OutputFlags Flags) const { OutputBuffer OB; - initializeOutputBuffer(nullptr, nullptr, OB, 1024); this->output(OB, Flags); StringView SV = OB; std::string Owned(SV.begin(), SV.end()); diff --git a/llvm/lib/Demangle/RustDemangle.cpp b/llvm/lib/Demangle/RustDemangle.cpp index 32b10db..8c01155 100644 --- a/llvm/lib/Demangle/RustDemangle.cpp +++ b/llvm/lib/Demangle/RustDemangle.cpp @@ -157,9 +157,6 @@ char *llvm::rustDemangle(const char *MangledName) { return nullptr; Demangler D; - if (!initializeOutputBuffer(nullptr, nullptr, D.Output, 1024)) - return nullptr; - if (!D.demangle(Mangled)) { std::free(D.Output.getBuffer()); return nullptr; -- 2.7.4