Resurrect some ancient code to add spill ranges without attempting folding, remat, or splitting. This code has been updated to current APIs

in so far as it compiles and, in theory, works, but does not take advantage of recent advancements.  For instance, it could be improved by using
MachineRegisterInfo::use_iterator.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54924 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/LiveIntervalAnalysis.h

@@ -323,6 +323,13 @@ namespace llvm {
     addIntervalsForSpills(const LiveInterval& i,
                           const MachineLoopInfo *loopInfo, VirtRegMap& vrm,
                           float &SSWeight);
+    
+    /// addIntervalsForSpillsFast - Quickly create new intervals for spilled
+    /// defs / uses without remat or splitting.
+    std::vector<LiveInterval*>
+    addIntervalsForSpillsFast(const LiveInterval &li,
+                              const MachineLoopInfo *loopInfo,
+                              VirtRegMap &vrm, float& SSWeight);
 
     /// spillPhysRegAroundRegDefsUses - Spill the specified physical register
     /// around all defs and uses of the specified interval.