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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123133 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index d3d6584..89daec80 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -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;