This fixes the bug in 175.vpr. It doesn't fix the

other SPEC breakage.  I'll be reverting all recent
changes shortly, this checking is mostly so this
change doesn't get lost.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61402 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index f38f330f492f936815b070676dd582028803d9fa..fd4cc056271d6b298b65a35b5820d3178e1f77e8 100644 (file)
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1627,10 +1627,17 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
         // The common base is emitted in the loop preheader. But since we
         // are reusing an IV, it has not been used to initialize the PHI node.
         // Add it to the expression used to rewrite the uses.
+        // When this use is outside the loop, we earlier subtracted the
+        // common base, and are adding it back here.  Use the same expression
+        // as before, rather than CommonBaseV, so DAGCombiner will zap it.
         if (!isa<ConstantInt>(CommonBaseV) ||
-            !cast<ConstantInt>(CommonBaseV)->isZero())
-          RewriteExpr = SE->getAddExpr(RewriteExpr,
+            !cast<ConstantInt>(CommonBaseV)->isZero()) {
+          if (L->contains(User.Inst->getParent()))
+            RewriteExpr = SE->getAddExpr(RewriteExpr,
                                        SE->getUnknown(CommonBaseV));
+          else
+            RewriteExpr = SE->getAddExpr(RewriteExpr, CommonExprs);
+        }
       }
 
       // Now that we know what we need to do, insert code before User for the