Add a subtarget hook: enablePostMachineScheduler.

As requested by AArch64 subtargets.

Note that this will have no effect until the
AArch64 target actually enables the pass like this:
substitutePass(&PostRASchedulerID, &PostMachineSchedulerID);

As soon as armv7 switches over, PostMachineScheduler will become the
default postRA scheduler, so this won't be necessary any more.
Targets using the old postRA schedule would then do:
substitutePass(&PostMachineSchedulerID, &PostRASchedulerID);

llvm-svn: 210167

2 files changed, 9 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp
index 6a0a3722ed3..734aba482b9 100644
--- a/llvm/lib/CodeGen/MachineScheduler.cpp
+++ b/llvm/lib/CodeGen/MachineScheduler.cpp
@@ -333,6 +333,12 @@ bool PostMachineScheduler::runOnMachineFunction(MachineFunction &mf) {
   if (skipOptnoneFunction(*mf.getFunction()))
     return false;
 
+  const TargetSubtargetInfo &ST =
+    mf.getTarget().getSubtarget<TargetSubtargetInfo>();
+  if (!ST.enablePostMachineScheduler()) {
+    DEBUG(dbgs() << "Subtarget disables post-MI-sched.\n");
+    return false;
+  }
   DEBUG(dbgs() << "Before post-MI-sched:\n"; mf.print(dbgs()));
 
   // Initialize the context of the pass.
diff --git a/llvm/lib/CodeGen/Passes.cpp b/llvm/lib/CodeGen/Passes.cpp
index b3f719841db..9568e238a2c 100644
--- a/llvm/lib/CodeGen/Passes.cpp
+++ b/llvm/lib/CodeGen/Passes.cpp
@@ -92,9 +92,9 @@ PrintMachineInstrs("print-machineinstrs", cl::ValueOptional,
 
 // Temporary option to allow experimenting with MachineScheduler as a post-RA
 // scheduler. Targets can "properly" enable this with
-// substitutePass(&PostRASchedulerID, &MachineSchedulerID); Ideally it wouldn't
-// be part of the standard pass pipeline, and the target would just add a PostRA
-// scheduling pass wherever it wants.
+// substitutePass(&PostRASchedulerID, &PostMachineSchedulerID); Ideally it
+// wouldn't be part of the standard pass pipeline, and the target would just add
+// a PostRA scheduling pass wherever it wants.
 static cl::opt<bool> MISchedPostRA("misched-postra", cl::Hidden,
   cl::desc("Run MachineScheduler post regalloc (independent of preRA sched)"));