Recognize n/1 in the SCEV divide function

n/1 generates a quotient equal to n and a remainder of 0.
If this case is not recognized, then the SCEV divide() function
can return a remainder that is greater than or equal to the
denominator, which means the delinearized subscripts for the
test case will be incorrect.

Differential Revision: http://reviews.llvm.org/D9003

llvm-svn: 235311

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 37377f0b859..d88b0268651 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -726,6 +726,13 @@ public:
       return;
     }
 
+    // A simple case when N/1. The quotient is N.
+    if (Denominator->isOne()) {
+      *Quotient = Numerator;
+      *Remainder = D.Zero;
+      return;
+    }
+
     // Split the Denominator when it is a product.
     if (const SCEVMulExpr *T = dyn_cast<const SCEVMulExpr>(Denominator)) {
       const SCEV *Q, *R;