mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-02-25 03:30:37 +00:00
3f8a26f6fe
This class is generally useful. In breaking it out, the primary change is that it has been made non-virtual. It seems like being abstract led to there being 3 different (2 in llvm + 1 in clang) concrete implementations which disagreed about the ownership of the saved strings (see the manual call to free() in the unittest StrDupSaver; yes this is different from the CommandLine.cpp StrDupSaver which owns the stored strings; which is different from Clang's StringSetSaver which just holds a reference to a std::set<std::string> which owns the strings). I've identified 2 other places in the codebase that are open-coding this pattern: memcpy(Alloc.Allocate<char>(strlen(S)+1), S, strlen(S)+1) I'll be switching them over. They are * llvm::sys::Process::GetArgumentVector * The StringAllocator member of YAMLIO's Input class This also will allow simplifying Clang's driver.cpp quite a bit. Let me know if there are any other places that could benefit from StringSaver. I'm also thinking of adding a saveStringRef member for getting a stable StringRef. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215784 91177308-0d34-0410-b5e6-96231b3b80d8
Design Of lib/System
====================
The software in this directory is designed to completely shield LLVM from any
and all operating system specific functionality. It is not intended to be a
complete operating system wrapper (such as ACE), but only to provide the
functionality necessary to support LLVM.
The software located here, of necessity, has very specific and stringent design
rules. Violation of these rules means that cracks in the shield could form and
the primary goal of the library is defeated. By consistently using this library,
LLVM becomes more easily ported to new platforms since the only thing requiring
porting is this library.
Complete documentation for the library can be found in the file:
llvm/docs/SystemLibrary.html
or at this URL:
http://llvm.org/docs/SystemLibrary.html
While we recommend that you read the more detailed documentation, for the
impatient, here's a high level summary of the library's requirements.
1. No system header files are to be exposed through the interface.
2. Std C++ and Std C header files are okay to be exposed through the interface.
3. No exposed system-specific functions.
4. No exposed system-specific data.
5. Data in lib/System classes must use only simple C++ intrinsic types.
6. Errors are handled by returning "true" and setting an optional std::string
7. Library must not throw any exceptions, period.
8. Interface functions must not have throw() specifications.
9. No duplicate function impementations are permitted within an operating
system class.
To accomplish these requirements, the library has numerous design criteria that
must be satisfied. Here's a high level summary of the library's design criteria:
1. No unused functionality (only what LLVM needs)
2. High-Level Interfaces
3. Use Opaque Classes
4. Common Implementations
5. Multiple Implementations
6. Minimize Memory Allocation
7. No Virtual Methods