[Hexagon] Adding compare byte/halfword reg-reg/reg-imm forms.  Adding compare to general register reg-imm form.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224991 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Dropping old combine instructions without encodings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224992 91177308-0d34-0410-b5e6-96231b3b80d8
Make the __morestack function available to the JIT memory manager under Linux.

This function's implementation lives in libgcc, a static library, so we need
to expose it explicitly, like the other such functions.

Differential Revision: http://reviews.llvm.org/D6788

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224993 91177308-0d34-0410-b5e6-96231b3b80d8
The __morestack function is only available on i386 and x86_64 architectures.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224994 91177308-0d34-0410-b5e6-96231b3b80d8