[SystemZ] Improve handling of SETCC

We previously used the default expansion to SELECT_CC, which in turn would
expand to "LHI; BRC; LHI".  In most cases it's better to use an IPM-based
sequence instead.

llvm-svn: 192784
diff --git a/llvm/lib/Target/SystemZ/SystemZ.h b/llvm/lib/Target/SystemZ/SystemZ.h
index 4a6b4db..dcebbad 100644
--- a/llvm/lib/Target/SystemZ/SystemZ.h
+++ b/llvm/lib/Target/SystemZ/SystemZ.h
@@ -68,6 +68,9 @@
     const unsigned CCMASK_TM_MSB_1       = CCMASK_2 | CCMASK_3;
     const unsigned CCMASK_TM             = CCMASK_ANY;
 
+    // The position of the low CC bit in an IPM result.
+    const unsigned IPM_CC = 28;
+
     // Mask assignments for PFD.
     const unsigned PFD_READ  = 1;
     const unsigned PFD_WRITE = 2;