CodeGen: Refactor renameDisconnectedComponents() as a pass

Refactor LiveIntervals::renameDisconnectedComponents() to be a pass.
Also change the name to "RenameIndependentSubregs":

- renameDisconnectedComponents() worked on a MachineFunction at a time
  so it is a natural candidate for a machine function pass.

- The algorithm is testable with a .mir test now.

- This also fixes a problem where the lazy renaming as part of the
  MachineScheduler introduced IMPLICIT_DEF instructions after the number
  of a nodes in a region were counted leading to a mismatch.

Differential Revision: http://reviews.llvm.org/D20507

llvm-svn: 271345

1 files changed, 2 insertions, 10 deletions

diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp
index 5ea20c58620..f3b40d3b28f 100644
--- a/llvm/lib/CodeGen/MachineScheduler.cpp
+++ b/llvm/lib/CodeGen/MachineScheduler.cpp
@@ -882,16 +882,8 @@ void ScheduleDAGMILive::enterRegion(MachineBasicBlock *bb,
   ShouldTrackPressure = SchedImpl->shouldTrackPressure();
   ShouldTrackLaneMasks = SchedImpl->shouldTrackLaneMasks();
 
-  if (ShouldTrackLaneMasks) {
-    if (!ShouldTrackPressure)
-      report_fatal_error("ShouldTrackLaneMasks requires ShouldTrackPressure");
-    // Dead subregister defs have no users and therefore no dependencies,
-    // moving them around may cause liveintervals to degrade into multiple
-    // components. Change independent components to have their own vreg to avoid
-    // this.
-    if (!DisconnectedComponentsRenamed)
-      LIS->renameDisconnectedComponents();
-  }
+  assert((!ShouldTrackLaneMasks || ShouldTrackPressure) &&
+         "ShouldTrackLaneMasks requires ShouldTrackPressure");
 }
 
 // Setup the register pressure trackers for the top scheduled top and bottom