Add initial support for back-scheduling address computations,
especially in the case of addresses computed from loop induction
variables.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61075 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86Subtarget.h b/lib/Target/X86/X86Subtarget.h
index 5eb89d6..f405ac7 100644
--- a/lib/Target/X86/X86Subtarget.h
+++ b/lib/Target/X86/X86Subtarget.h
@@ -191,6 +191,12 @@
   /// memset with zero passed as the second argument. Otherwise it
   /// returns null.
   const char *getBZeroEntry() const;
+
+  /// getSpecialAddressLatency - For targets where it is beneficial to
+  /// backschedule instructions that compute addresses, return a value
+  /// indicating the number of scheduling cycles of backscheduling that
+  /// should be attempted.
+  unsigned getSpecialAddressLatency() const;
 };
 
 namespace X86 {