[llvm-commits] [llvm] r123133 - /llvm/trunk/lib/Analysis/ScalarEvolution.cpp

[Chris Lattner]

Author: lattner
Date: Sun Jan  9 16:31:26 2011
New Revision: 123133

URL: http://llvm.org/viewvc/llvm-project?rev=123133&view=rev
Log:
Step #3 to improving trip count analysis: If we fold
a + {b,+,stride} into {a+b,+,stride}  (because a is LIV),
then the resultant AddRec is NUW/NSW if the client says it
is.


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=123133&r1=123132&r2=123133&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sun Jan  9 16:31:26 2011
@@ -1560,10 +1560,14 @@
       AddRecOps[0] = getAddExpr(LIOps);
 
       // Build the new addrec. Propagate the NUW and NSW flags if both the
-      // outer add and the inner addrec are guaranteed to have no overflow.
-      const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop,
-                                         HasNUW && AddRec->hasNoUnsignedWrap(),
-                                         HasNSW && AddRec->hasNoSignedWrap());
+      // outer add and the inner addrec are guaranteed to have no overflow or if
+      // there is no outer part.
+      if (Ops.size() != 1) {
+        HasNUW &= AddRec->hasNoUnsignedWrap();
+        HasNSW &= AddRec->hasNoSignedWrap();
+      }
+      
+      const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, HasNUW, HasNSW);
 
       // If all of the other operands were loop invariant, we are done.
       if (Ops.size() == 1) return NewRec;