This patch adds lowering for global TLS addresses for the TLS models of
InitialExec, GlobalDynamic, LocalExec and LocalDynamic.
LocalExec support required using a 4-operand add instruction, which uses
the fourth operand to express a relocation on the symbol. The necessary
fixup is emitted when the instruction is emitted.
Differential Revision: https://reviews.llvm.org/D55305
llvm-svn: 363771
Lewis Revill