Add more const qualifiers. This fixes build breakage from r59540.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59542 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCInstrInfo.h b/lib/Target/PowerPC/PPCInstrInfo.h
index 2e950a3..909b0c5 100644
--- a/lib/Target/PowerPC/PPCInstrInfo.h
+++ b/lib/Target/PowerPC/PPCInstrInfo.h
@@ -93,8 +93,10 @@
                            unsigned& sourceReg,
                            unsigned& destReg) const;
 
-  unsigned isLoadFromStackSlot(MachineInstr *MI, int &FrameIndex) const;
-  unsigned isStoreToStackSlot(MachineInstr *MI, int &FrameIndex) const;
+  unsigned isLoadFromStackSlot(const MachineInstr *MI,
+                               int &FrameIndex) const;
+  unsigned isStoreToStackSlot(const MachineInstr *MI,
+                              int &FrameIndex) const;
 
   // commuteInstruction - We can commute rlwimi instructions, but only if the
   // rotate amt is zero.  We also have to munge the immediates a bit.