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a8bf06418d
Since header files are not compilation units, CMake does not require
you to specify them in the CMakeLists.txt file. As a result, unless a
header file is explicitly added, CMake won't know about it, and when
generating IDE-based projects, CMake won't put the header files into
the IDE project. LLVM currently tries to deal with this in two ways:
1) It looks for all .h files that are in the project directory, and
adds those.
2) llvm_add_library() understands the ADDITIONAL_HEADERS argument,
which allows one to list an arbitrary list of headers.
This patch takes things one step further. It adds the ability for
llvm_add_library() to take an ADDITIONAL_HEADER_DIRS argument, which
will specify a list of folders which CMake will glob for header files.
Furthermore, it will glob not only for .h files, but also for .inc
files.
Included in this CL is an update to one of the existing users of
ADDITIONAL_HEADERS to use this new argument instead, to serve as an
illustration of how this cleans up the CMake.
The big advantage of this new approach is that until now, there was no
way for the IDE projects to locate the header files that are in the
include tree. In other words, if you are in, for example,
lib/DebugInfo/DWARF, the corresponding includes for this project will
be located under include/llvm/DebugInfo/DWARF. Now, in the
CMakeLists.txt for lib/DebugInfo/DWARF, you can simply write:
ADDITIONAL_HEADER_DIRS
../../include/llvm/DebugInfo/DWARF
as an argument to llvm_add_library(), and all header files will get
added to the IDE project.
Differential Revision: http://reviews.llvm.org/D7460
Reviewed By: Chris Bieneman
llvm-svn: 228670
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