MachineSink: make shouldSink a TII target hook

Some targets may disagree on what they want sunk or not sunk,
so make this a target hook instead of hardcoded.

llvm-svn: 264799

1 files changed, 2 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/MachineSink.cpp b/llvm/lib/CodeGen/MachineSink.cpp
index 18aecdaba84..07fbd3d36ab 100644
--- a/llvm/lib/CodeGen/MachineSink.cpp
+++ b/llvm/lib/CodeGen/MachineSink.cpp
@@ -472,10 +472,6 @@ bool MachineSinking::PostponeSplitCriticalEdge(MachineInstr *MI,
   return true;
 }
 
-static bool AvoidsSinking(MachineInstr *MI, MachineRegisterInfo *MRI) {
-  return MI->isInsertSubreg() || MI->isSubregToReg() || MI->isRegSequence();
-}
-
 /// collectDebgValues - Scan instructions following MI and collect any
 /// matching DBG_VALUEs.
 static void collectDebugValues(MachineInstr *MI,
@@ -724,9 +720,8 @@ static bool SinkingPreventsImplicitNullCheck(MachineInstr *MI,
 /// instruction out of its current block into a successor.
 bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore,
                                      AllSuccsCache &AllSuccessors) {
-  // Don't sink insert_subreg, subreg_to_reg, reg_sequence. These are meant to
-  // be close to the source to make it easier to coalesce.
-  if (AvoidsSinking(MI, MRI))
+  // Don't sink instructions that the target prefers not to sink.
+  if (!TII->shouldSink(*MI))
     return false;
 
   // Check if it's safe to move the instruction.