Fix a bug where we were counting the alias sets as completely used

registers for fast allocation.

Fixes rdar://9207598


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129408 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/RegAllocFast.cpp

@@ -442,8 +442,6 @@ unsigned RAFast::calcSpillCost(unsigned PhysReg) const {
   unsigned Cost = 0;
   for (const unsigned *AS = TRI->getAliasSet(PhysReg);
        unsigned Alias = *AS; ++AS) {
-    if (UsedInInstr.test(Alias))
-      return spillImpossible;
     switch (unsigned VirtReg = PhysRegState[Alias]) {
     case regDisabled:
       break;