llvm-6502/lib/System
Chris Lattner 782ab584e5 follow-on to PR6280
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96172 91177308-0d34-0410-b5e6-96231b3b80d8
2010-02-14 18:20:09 +00:00
..
Unix follow-on to PR6280 2010-02-14 18:20:09 +00:00
Win32 Add llvm::Program::ChangeStderrToBinary(). 2010-01-28 06:42:08 +00:00
Alarm.cpp
Atomic.cpp Fixes the Atomic implementation if compiled by MSVC compiler. 2009-12-07 05:29:59 +00:00
CMakeLists.txt Use CMAKE_DL_LIBS instead of raw library name. Fixes bug 5536. 2009-11-19 23:21:43 +00:00
Disassembler.cpp This void is implicit in C++. 2009-08-12 22:10:57 +00:00
DynamicLibrary.cpp Alternative fix to make sure that the extern declarations used by 2009-12-23 19:12:50 +00:00
Errno.cpp
Host.cpp Stubs for getHostCPUFeatures API. This implements part of PR5389. 2010-01-19 21:26:05 +00:00
IncludeFile.cpp
Makefile mark some libraries that currently require RTTI. 2010-01-24 20:22:08 +00:00
Memory.cpp Experimental fix for PR4960. 2009-09-12 23:29:02 +00:00
Mutex.cpp Tweak code into an equivalent form for which icc 2009-09-06 10:53:22 +00:00
Path.cpp Make Path use StringRef instead of std::string where possible. 2009-12-17 21:02:39 +00:00
Process.cpp
Program.cpp Remove duplication in Program::Execute{And,No}Wait. 2009-07-18 21:43:12 +00:00
README.txt
RWMutex.cpp Tweak code into an equivalent form for which icc 2009-09-06 10:53:22 +00:00
Signals.cpp
Threading.cpp No need to double-include config.h 2009-07-06 21:24:37 +00:00
ThreadLocal.cpp
TimeValue.cpp

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</a></li>
 5. Multiple Implementations</a></li>
 6. Minimize Memory Allocation</a></li>
 7. No Virtual Methods