Merged r14545 into 3.18 branch.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index d1312202bcf6b038b34bcaec75ebf3359091f0aa..ec98dc64a2d72495ba0a979ed8bd7b8322b2b953 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5380,6 +5380,9 @@ void HGraph::DeadCodeElimination() {
 
   while (!worklist.is_empty()) {
     HInstruction* instr = worklist.RemoveLast();
+    // This happens when an instruction is used multiple times as operand. That
+    // in turn could happen through GVN.
+    if (!instr->IsLinked()) continue;
     if (FLAG_trace_dead_code_elimination) {
       HeapStringAllocator allocator;
       StringStream stream(&allocator);