llvm-project/llvm/lib/Demangle/Demangle.cpp
Nathan Sidwell 201c4b9cc4 [demangler] Rust demangler buffer return
The rust demangler has some odd buffer handling code, which will copy
the demangled string into the provided buffer, if it will fit.
Otherwise it uses the allocated buffer it made.  But the length of the
incoming buffer will have come from a previous call, which was the
length of the demangled string -- not the buffer size.  And of course,
we're unconditionally allocating a temporary buffer in the first
place.  So we don't actually get buffer reuse, and we get a memcpy in
somecases.

However, nothing in LLVM ever passes in a non-null pointer.  Neither
does anything pass in a status pointer that is then made use of.  The
only exercise these have is in the test suite.

So let's just make the rust demangler have the same API as the dlang
demangler.

Reviewed By: tmiasko

Differential Revision: https://reviews.llvm.org/D123420
2022-04-13 08:50:04 -07:00

65 lines
1.9 KiB
C++

//===-- Demangle.cpp - Common demangling functions ------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file This file contains definitions of common demangling functions.
///
//===----------------------------------------------------------------------===//
#include "llvm/Demangle/Demangle.h"
#include <cstdlib>
#include <cstring>
static bool isItaniumEncoding(const char *S) {
// Itanium encoding requires 1 or 3 leading underscores, followed by 'Z'.
return std::strncmp(S, "_Z", 2) == 0 || std::strncmp(S, "___Z", 4) == 0;
}
static bool isRustEncoding(const char *S) { return S[0] == '_' && S[1] == 'R'; }
static bool isDLangEncoding(const std::string &MangledName) {
return MangledName.size() >= 2 && MangledName[0] == '_' &&
MangledName[1] == 'D';
}
std::string llvm::demangle(const std::string &MangledName) {
std::string Result;
const char *S = MangledName.c_str();
if (nonMicrosoftDemangle(S, Result))
return Result;
if (S[0] == '_' && nonMicrosoftDemangle(S + 1, Result))
return Result;
if (char *Demangled =
microsoftDemangle(S, nullptr, nullptr, nullptr, nullptr)) {
Result = Demangled;
std::free(Demangled);
return Result;
}
return MangledName;
}
bool llvm::nonMicrosoftDemangle(const char *MangledName, std::string &Result) {
char *Demangled = nullptr;
if (isItaniumEncoding(MangledName))
Demangled = itaniumDemangle(MangledName, nullptr, nullptr, nullptr);
else if (isRustEncoding(MangledName))
Demangled = rustDemangle(MangledName);
else if (isDLangEncoding(MangledName))
Demangled = dlangDemangle(MangledName);
if (!Demangled)
return false;
Result = Demangled;
std::free(Demangled);
return true;
}