1 files changed, 10 insertions, 0 deletions

diff --git a/lib/Target/X86/X86InstrInfo.h b/lib/Target/X86/X86InstrInfo.h
index b83441d89effd..0ab85f4f45b2f 100644
--- a/lib/Target/X86/X86InstrInfo.h
+++ b/lib/Target/X86/X86InstrInfo.h
@@ -448,6 +448,16 @@ public:
                            unsigned &SrcReg, unsigned &DstReg,
                            unsigned &SrcSubIdx, unsigned &DstSubIdx) const;
 
+  /// isCoalescableExtInstr - Return true if the instruction is a "coalescable"
+  /// extension instruction. That is, it's like a copy where it's legal for the
+  /// source to overlap the destination. e.g. X86::MOVSX64rr32. If this returns
+  /// true, then it's expected the pre-extension value is available as a subreg
+  /// of the result register. This also returns the sub-register index in
+  /// SubIdx.
+  virtual bool isCoalescableExtInstr(const MachineInstr &MI,
+                                     unsigned &SrcReg, unsigned &DstReg,
+                                     unsigned &SubIdx) const;
+
   unsigned isLoadFromStackSlot(const MachineInstr *MI, int &FrameIndex) const;
   /// isLoadFromStackSlotPostFE - Check for post-frame ptr elimination
   /// stack locations as well.  This uses a heuristic so it isn't