[llvm] [SystemZ] Enable liveness reduction in pre-RA sched strategy. (PR #188823)

[Ulrich Weigand via llvm-commits]

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@@ -8,66 +8,27 @@
 
 #include "SystemZMachineScheduler.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
+#include <cmath>
 
 using namespace llvm;
 
 #define DEBUG_TYPE "machine-scheduler"
 
 /// Pre-RA scheduling ///
 
+// Options needed for testing.
+// TopRegionSUs is the number of SUs that are considered to be part of the
+// "top" of a region. Liveness reduction is not done in regions smaller than
+// this. The idea is to prioritize latency more after branches and help
+// liveness only when the decoder is ahead of execution anyway.
+static cl::opt<unsigned> TopRegionSUs("top-region", cl::Hidden, cl::init(36));
+static cl::opt<bool> DisableLatency("disable-latency", cl::Hidden,
+                                    cl::init(false));
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uweigand wrote:

I guess these will be removed before committing?

https://github.com/llvm/llvm-project/pull/188823