MIsched: add an ILP window property to machine model.
This was an experimental option, but needs to be defined
per-target. e.g. PPC A2 needs to aggressively hide latency.
I converted some in-order scheduling tests to A2. Hal is working on
more test cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171946 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineScheduler.cpp b/lib/CodeGen/MachineScheduler.cpp
index 117b2bd..a32df78 100644
--- a/lib/CodeGen/MachineScheduler.cpp
+++ b/lib/CodeGen/MachineScheduler.cpp
@@ -48,15 +48,6 @@
static bool ViewMISchedDAGs = false;
#endif // NDEBUG
-// Threshold to very roughly model an out-of-order processor's instruction
-// buffers. If the actual value of this threshold matters much in practice, then
-// it can be specified by the machine model. For now, it's an experimental
-// tuning knob to determine when and if it matters.
-static cl::opt<unsigned> ILPWindow("ilp-window", cl::Hidden,
- cl::desc("Allow expected latency to exceed the critical path by N cycles "
- "before attempting to balance ILP"),
- cl::init(10U));
-
// Experimental heuristics
static cl::opt<bool> EnableLoadCluster("misched-cluster", cl::Hidden,
cl::desc("Enable load clustering."), cl::init(true));
@@ -1297,7 +1288,8 @@
if (L > RemLatency)
RemLatency = L;
}
- if (RemLatency + ExpectedLatency >= Rem->CriticalPath + ILPWindow
+ unsigned CriticalPathLimit = Rem->CriticalPath + SchedModel->getILPWindow();
+ if (RemLatency + ExpectedLatency >= CriticalPathLimit
&& RemLatency > Rem->getMaxRemainingCount(SchedModel)) {
Policy.ReduceLatency = true;
DEBUG(dbgs() << "Increase ILP: " << Available.getName() << '\n');