This patch eanble register coalescing to coalesce the following:

  %vreg2<def> = MOVi32imm 1; GPR32:%vreg2
  %W1<def> = COPY %vreg2; GPR32:%vreg2
into:
  %W1<def> = MOVi32imm 1
Patched by Lawrence Hu (lawrence@codeaurora.org)

llvm-svn: 243033