[llvm-commits] [llvm] r127593 - /llvm/trunk/lib/Analysis/ScalarEvolution.cpp

[Andrew Trick]

Author: atrick
Date: Mon Mar 14 12:38:54 2011
New Revision: 127593

URL: http://llvm.org/viewvc/llvm-project?rev=127593&view=rev
Log:
Negating a recurrence preserves no-self-wrap.

Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=127593&r1=127592&r2=127593&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Mon Mar 14 12:38:54 2011
@@ -1792,6 +1792,17 @@
           if (AnyFolded)
             return getAddExpr(NewOps);
         }
+        else if (const SCEVAddRecExpr *
+                 AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
+          // Negation preserves a recurrence's no self-wrap property.
+          SmallVector<const SCEV *, 4> Operands;
+          for (SCEVAddRecExpr::op_iterator I = AddRec->op_begin(),
+                 E = AddRec->op_end(); I != E; ++I) {
+            Operands.push_back(getMulExpr(Ops[0], *I));
+          }
+          return getAddRecExpr(Operands, AddRec->getLoop(),
+                               AddRec->getNoWrapFlags(SCEV::FlagNW));
+        }
       }
     }