Add TargetInstrInfo::isSafeToMoveRegisterClassDefs. It returns true if it's safe to move an instruction which defines a value in the register class. Replace pre-splitting specific IgnoreRegisterClassBarriers with this new hook.

llvm-svn: 63936
diff --git a/llvm/lib/Target/X86/X86InstrInfo.h b/llvm/lib/Target/X86/X86InstrInfo.h
index 077de56..eba0baf 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.h
+++ b/llvm/lib/Target/X86/X86InstrInfo.h
@@ -406,10 +406,9 @@
   virtual
   bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const;
 
-  /// IgnoreRegisterClassBarriers - Returns true if pre-register allocation
-  /// live interval splitting pass should ignore barriers of the specified
-  /// register class.
-  bool IgnoreRegisterClassBarriers(const TargetRegisterClass *RC) const;
+  /// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine
+  /// instruction that defines the specified register class.
+  bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const;
 
   const TargetRegisterClass *getPointerRegClass() const;