Allow subtarget selection of the default MachineScheduler and document the interface.

The global registry is used to allow command line override of the
scheduler selection, but does not work well as the normal selection
API. For example, the same LLVM process should be able to target
multiple targets or subtargets.

llvm-svn: 191071

1 files changed, 12 insertions, 4 deletions

diff --git a/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp b/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
index cd96b58e0b6..bb950a0ea75 100644
--- a/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
@@ -102,17 +102,25 @@ class HexagonPassConfig : public TargetPassConfig {
 public:
   HexagonPassConfig(HexagonTargetMachine *TM, PassManagerBase &PM)
     : TargetPassConfig(TM, PM) {
-    // Enable MI scheduler.
-    if (!DisableHexagonMISched) {
+    // FIXME: Rather than calling enablePass(&MachineSchedulerID) below, define
+    // HexagonSubtarget::enableMachineScheduler() { return true; }.
+    // That will bypass the SelectionDAG VLIW scheduler, which is probably just
+    // hurting compile time and will be removed eventually anyway.
+    if (DisableHexagonMISched)
+      disablePass(&MachineSchedulerID);
+    else
       enablePass(&MachineSchedulerID);
-      MachineSchedRegistry::setDefault(createVLIWMachineSched);
-    }
   }
 
   HexagonTargetMachine &getHexagonTargetMachine() const {
     return getTM<HexagonTargetMachine>();
   }
 
+  virtual ScheduleDAGInstrs *
+  createMachineScheduler(MachineSchedContext *C) const {
+    return createVLIWMachineSched(C);
+  }
+
   virtual bool addInstSelector();
   virtual bool addPreRegAlloc();
   virtual bool addPostRegAlloc();