llvm-mirror/lib/System
Duncan Sands de498ef6ec Revert commit 81144, and add a comment. It caused bugpoint timeouts
not to work any more on linux.

llvm-svn: 86481
2009-11-08 20:55:48 +00:00
..
Unix Revert commit 81144, and add a comment. It caused bugpoint timeouts 2009-11-08 20:55:48 +00:00
Win32 Path::createDirectoryOnDisk should ignore existing directories on win32 too. 2009-11-05 14:32:40 +00:00
Alarm.cpp
Atomic.cpp
CMakeLists.txt
Disassembler.cpp This void is implicit in C++. 2009-08-12 22:10:57 +00:00
DynamicLibrary.cpp Remove unused includes. 2009-10-25 22:38:41 +00:00
Errno.cpp
Host.cpp
IncludeFile.cpp
Makefile MingW build fixes 2009-10-02 19:36:31 +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 Remove unused includes. 2009-10-25 22:38:41 +00:00
Process.cpp
Program.cpp
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
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