Add support for System z vector language extensions
The z13 vector facility has an associated language extension,
closely modeled on AltiVec/VSX. The main differences are:
- vector long, vector float and vector pixel are not supported
- vector long long and vector double are supported (like VSX)
- comparison operators return a vector rather than a scalar integer
- shift operators behave like the OpenCL shift operators
- vector bool is only supported as argument to certain operators; some operators allow mixing a bool with a non-bool vector
This patch adds clang support for the extension. It is closely modelled
on the AltiVec support. Similarly to the -faltivec option, there's a
new -fzvector option to enable the extensions (as well as an -mzvector
alias for compatibility with GCC). There's also a separate LangOpt.
The extension as implemented here is intended to be compatible with
the -mzvector extension recently implemented by GCC.
Based on a patch by Richard Sandiford.
Differential Revision: http://reviews.llvm.org/D11001