llvm-6502/lib/System
Duncan Sands 3dc7224379 Rather than using an ifdef on the target to zero out fields,
just use memset to zero the entire struct.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108330 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-14 14:32:33 +00:00
..
Unix Rather than using an ifdef on the target to zero out fields, 2010-07-14 14:32:33 +00:00
Win32 Convert some tab stops into spaces. 2010-07-12 08:16:59 +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 Tell Valgrind when we modify already-executed machine code so it knows 2010-03-15 04:57:55 +00:00
Disassembler.cpp Avoid "variable 'bits' set but not used [-Wunused-but-set-variable]" 2010-06-10 16:23:15 +00:00
DynamicLibrary.cpp Fix a bunch of namespace polution. 2010-04-15 17:08:50 +00:00
Errno.cpp Oops, I #included errno.h from inside the llvm::sys namespace. 2009-07-06 16:50:27 +00:00
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 Tell Valgrind when we modify already-executed machine code so it knows 2010-03-15 04:57:55 +00:00
Mutex.cpp Tweak code into an equivalent form for which icc 2009-09-06 10:53:22 +00:00
Path.cpp Don't bother checking canRead() before calling getMagicNumber(); 2010-05-27 17:12:23 +00:00
Process.cpp
Program.cpp unnest from namespace. 2010-04-18 03:33:55 +00:00
README.txt
RWMutex.cpp Tweak code into an equivalent form for which icc 2009-09-06 10:53:22 +00:00
SearchForAddressOfSpecialSymbol.cpp Make clang bootstrap happier on OSX 10.5 by reducing the number of headers 2010-03-11 06:14:32 +00:00
Signals.cpp
Threading.cpp No need to double-include config.h 2009-07-06 21:24:37 +00:00
ThreadLocal.cpp Try again at making this work on OpenBSD. 2009-07-01 16:19:23 +00:00
TimeValue.cpp
Valgrind.cpp Tell Valgrind when we modify already-executed machine code so it knows 2010-03-15 04:57:55 +00:00

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