misched: Added CanHandleTerminators.

This is a special flag for targets that really want their block
terminators in the DAG. The default scheduler cannot handle this
correctly, so it becomes the specialized scheduler's responsibility to
schedule terminators.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154712 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/ScheduleDAGInstrs.h b/include/llvm/CodeGen/ScheduleDAGInstrs.h
index c8de7bc8f8922aba49bb38ddf060b9fea6e76f3c..4fee108cd2be0d5991821f4e6b3b1c914d3f159f 100644 (file)
--- a/include/llvm/CodeGen/ScheduleDAGInstrs.h
+++ b/include/llvm/CodeGen/ScheduleDAGInstrs.h
@@ -181,6 +181,13 @@ namespace llvm {
     /// the def-side latency only.
     bool UnitLatencies;
 
+    /// The standard DAG builder does not normally include terminators as DAG
+    /// nodes because it does not create the necessary dependencies to prevent
+    /// reordering. A specialized scheduler can overide
+    /// TargetInstrInfo::isSchedulingBoundary then enable this flag to indicate
+    /// it has taken responsibility for scheduling the terminator correctly.
+    bool CanHandleTerminators;
+
     /// State specific to the current scheduling region.
     /// ------------------------------------------------
 

diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index 6be1ab7f5b08fc090fe787486d6830aa8bb2f59a..d46eb896e549e51b09780a893b988415b1797d17 100644 (file)
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -39,8 +39,8 @@ ScheduleDAGInstrs::ScheduleDAGInstrs(MachineFunction &mf,
                                      LiveIntervals *lis)
   : ScheduleDAG(mf), MLI(mli), MDT(mdt), MFI(mf.getFrameInfo()),
     InstrItins(mf.getTarget().getInstrItineraryData()), LIS(lis),
-    IsPostRA(IsPostRAFlag), UnitLatencies(false), LoopRegs(MLI, MDT),
-    FirstDbgValue(0) {
+    IsPostRA(IsPostRAFlag), UnitLatencies(false), CanHandleTerminators(false),
+    LoopRegs(MLI, MDT), FirstDbgValue(0) {
   assert((IsPostRA || LIS) && "PreRA scheduling requires LiveIntervals");
   DbgValues.clear();
   assert(!(IsPostRA && MRI.getNumVirtRegs()) &&
@@ -554,7 +554,7 @@ void ScheduleDAGInstrs::buildSchedGraph(AliasAnalysis *AA) {
       continue;
     }
 
-    assert(!MI->isTerminator() && !MI->isLabel() &&
+    assert((!MI->isTerminator() || CanHandleTerminators) && !MI->isLabel() &&
            "Cannot schedule terminators or labels!");
 
     SUnit *SU = MISUnitMap[MI];