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Both GCC and LLVM will implicitly define __ppc__ and __powerpc__ for all PowerPC targets, whether 32- or 64-bit. They will both implicitly define __ppc64__ and __powerpc64__ for 64-bit PowerPC targets, and not for 32-bit targets. We cannot be sure that all other possible compilers used to compile Clang/LLVM define both __ppc__ and __powerpc__, for example, so it is best to check for both when relying on either inside the Clang/LLVM code base. This patch makes sure we always check for both variants. In addition, it fixes one unnecessary check in lib/Target/PowerPC/PPCJITInfo.cpp. (At least one of __ppc__ and __powerpc__ should always be defined when compiling for a PowerPC target, no matter which compiler is used, so testing for them is unnecessary.) There are some places in the compiler that check for other variants, like __POWERPC__ and _POWER, and I have left those in place. There is no need to add them elsewhere. This seems to be in Apple-specific code, and I won't take a chance on breaking it. There is no intended change in behavior; thus, no test cases are added. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187248 91177308-0d34-0410-b5e6-96231b3b80d8
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