If an lvalue DeclRefExpr doesn't have a local VarLocs entry in the current SILGen function, assume it's a global variable and generate a constant_ref to get at its address. Eventually there should be a SILGenModule with which we can check that the global access is valid. Either ConstantRef should be renamed or a new GlobalVarRef instruction should be added as well.
Swift SVN r3319
Remove the AllocTmp instruction and represent MaterializeExpr allocations using 'alloc_var stack'/'dealloc_var stack' instructions. Rename Dealloc to DeallocVar, and add an AllocKind attribute to AllocVar and DeallocVar. Update MaterializeExpr SILGen to generate an AllocVar with a DeallocVar cleanup instead of AllocTmp. Tweak SILPrinter's presentation of AllocVar and DeallocVar to be in line with what SIL.rst claims.
Swift SVN r3311
Add RetainInst, ReleaseInst, DeallocInst for managing object lifetimes, and CopyInst and DestroyInst for indirectly managing resilient types and other non-materializable types.
Swift SVN r3159
