en Copyright 2015 Java http://172.16.0.5:8080/history/llvm-project-15.0.7/llvm/test/CodeGen/SystemZ/int-cmp-55.ll#b32f3656 [SystemZ] Do not use glue to represent condition code dependenciesCurrently, an instruction setting the condition code is linked tothe instruction using the condition code via a "glue" link in theSelectionDAG. This has a number of drawbacks; in particular, itmeans the same CC cannot be used by multiple users. It also makesit more difficult to efficiently implement SADDO et. al.This patch changes the back-end to represent CC dependencies asnormal values during SelectionDAG matching, along the lines ofhow this is handled in the X86 back-end already.In addition to the core mechanics of updating all relevant patterns,this requires a number of additional changes:- We now need to be able to spill/restore a CC value into a GPR if necessary. This means providing a copyPhysReg implementation for moves involving CC, and defining getCrossCopyRegClass.- Since we still prefer to avoid such spills, we provide an override for IsProfitableToFold to avoid creating a merged LOAD / ICMP if this would result in multiple users of the CC.- combineCCMask no longer requires a single CC user, and no longer need to be careful about preventing invalid glue/chain cycles.- emitSelect needs to be more careful in marking CC live-in to the basic block it generates. Also, we can now optimize the case of multiple subsequent selects with the same condition just like X86 does.llvm-svn: 331202 List of files: /llvm-project-15.0.7/llvm/test/CodeGen/SystemZ/int-cmp-55.ll Mon, 30 Apr 2018 17:52:32 +0000 Ulrich Weigand <ulrich.weigand@de.ibm.com>