mirror of
https://github.com/RPCSX/llvm.git
synced 2024-12-14 23:48:49 +00:00
99655e16a6
Final commit for this bug. This removes the last EH holdouts in LLVM
and turns off exception support by using the -fno-exceptions option. This
leads to the following reduction in library and executable sizes:
DEBUG BUILD RELEASE BUILD
before after delta before after delta
lib 162,328K 157,616K 4,712 17,864K 16,416K 1,448K
bin 571,444K 557,156K 14,288 63,296K 56,996K 6,300K
Debug Improvement: 19,000K (2.59%)
Release Improvement: 7,748K (9.55%)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29882 91177308-0d34-0410-b5e6-96231b3b80d8
44 lines
1.9 KiB
Plaintext
44 lines
1.9 KiB
Plaintext
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
|