[RA CopyHints] Fix compile-time regression

This patch makes sure that a register is only hinted once to RA. In extreme
cases the same register can otherwise be hinted numerous times and cause a
compile time slowdown.

Review: Simon Pilgrim
https://reviews.llvm.org/D52826

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343686 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed