1 files changed, 25 insertions, 9 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index 0bd427bf74e..c1ed76256e9 100644
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -1807,6 +1807,23 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
 
 bool SCEVExpander::isHighCostExpansionHelper(
     const SCEV *S, Loop *L, SmallPtrSetImpl<const SCEV *> &Processed) {
+
+  // Zero/One operand expressions
+  switch (S->getSCEVType()) {
+  case scUnknown:
+  case scConstant:
+    return false;
+  case scTruncate:
+    return isHighCostExpansionHelper(cast<SCEVTruncateExpr>(S)->getOperand(), L,
+                                     Processed);
+  case scZeroExtend:
+    return isHighCostExpansionHelper(cast<SCEVZeroExtendExpr>(S)->getOperand(),
+                                     L, Processed);
+  case scSignExtend:
+    return isHighCostExpansionHelper(cast<SCEVSignExtendExpr>(S)->getOperand(),
+                                     L, Processed);
+  }
+
   if (!Processed.insert(S).second)
     return false;
 
@@ -1849,23 +1866,22 @@ bool SCEVExpander::isHighCostExpansionHelper(
     }
   }
 
-  // Recurse past add expressions, which commonly occur in the
+  // HowManyLessThans uses a Max expression whenever the loop is not guarded by
+  // the exit condition.
+  if (isa<SCEVSMaxExpr>(S) || isa<SCEVUMaxExpr>(S))
+    return true;
+
+  // Recurse past nary expressions, which commonly occur in the
   // BackedgeTakenCount. They may already exist in program code, and if not,
   // they are not too expensive rematerialize.
-  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
-    for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();
+  if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(S)) {
+    for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
          I != E; ++I) {
       if (isHighCostExpansionHelper(*I, L, Processed))
         return true;
     }
-    return false;
   }
 
-  // HowManyLessThans uses a Max expression whenever the loop is not guarded by
-  // the exit condition.
-  if (isa<SCEVSMaxExpr>(S) || isa<SCEVUMaxExpr>(S))
-    return true;
-
   // If we haven't recognized an expensive SCEV pattern, assume it's an
   // expression produced by program code.
   return false;