some comment improvements.

[oota-llvm.git] / include / llvm / Analysis / ScalarEvolution.h

diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h
index d9104067711f86c58daa0598115f9793d13d3607..d1938061bef6958a462ab726f603680594bd62d6 100644 (file)
--- a/include/llvm/Analysis/ScalarEvolution.h
+++ b/include/llvm/Analysis/ScalarEvolution.h
@@ -537,9 +537,11 @@ namespace llvm {
     ///
     const SCEV *getNotSCEV(const SCEV *V);
 
-    /// getMinusSCEV - Return LHS-RHS.
-    ///
-    const SCEV *getMinusSCEV(const SCEV *LHS, const SCEV *RHS);
+    /// getMinusSCEV - Return LHS-RHS.  Minus is represented in SCEV as A+B*-1,
+    /// and thus the HasNUW and HasNSW bits apply to the resultant add, not
+    /// whether the sub would have overflowed.
+    const SCEV *getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
+                             bool HasNUW = false, bool HasNSW = false);
 
     /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
     /// of the input value to the specified type.  If the type must be