diff --git a/compiler/optimizing/ssa_builder.cc b/compiler/optimizing/ssa_builder.cc
index 6f71ea3..f511603 100644
--- a/compiler/optimizing/ssa_builder.cc
+++ b/compiler/optimizing/ssa_builder.cc
@@ -345,6 +345,33 @@
   }
 }
 
+ArenaVector<HInstruction*>* SsaBuilder::GetLocalsFor(HBasicBlock* block) {
+  DCHECK_LT(block->GetBlockId(), locals_for_.size());
+  ArenaVector<HInstruction*>* locals = &locals_for_[block->GetBlockId()];
+  const size_t vregs = GetGraph()->GetNumberOfVRegs();
+  if (locals->empty() && vregs != 0u) {
+    locals->resize(vregs, nullptr);
+
+    if (block->IsCatchBlock()) {
+      ArenaAllocator* arena = GetGraph()->GetArena();
+      // We record incoming inputs of catch phis at throwing instructions and
+      // must therefore eagerly create the phis. Phis for undefined vregs will
+      // be deleted when the first throwing instruction with the vreg undefined
+      // is encountered. Unused phis will be removed by dead phi analysis.
+      for (size_t i = 0; i < vregs; ++i) {
+        // No point in creating the catch phi if it is already undefined at
+        // the first throwing instruction.
+        if ((*current_locals_)[i] != nullptr) {
+          HPhi* phi = new (arena) HPhi(arena, i, 0, Primitive::kPrimVoid);
+          block->AddPhi(phi);
+          (*locals)[i] = phi;
+        }
+      }
+    }
+  }
+  return locals;
+}
+
 HInstruction* SsaBuilder::ValueOfLocal(HBasicBlock* block, size_t local) {
   ArenaVector<HInstruction*>* locals = GetLocalsFor(block);
   DCHECK_LT(local, locals->size());
diff --git a/compiler/optimizing/ssa_builder.h b/compiler/optimizing/ssa_builder.h
index 804296f..79f1a28 100644
--- a/compiler/optimizing/ssa_builder.h
+++ b/compiler/optimizing/ssa_builder.h
@@ -61,28 +61,9 @@
 
   void BuildSsa();
 
-  ArenaVector<HInstruction*>* GetLocalsFor(HBasicBlock* block) {
-    DCHECK_LT(block->GetBlockId(), locals_for_.size());
-    ArenaVector<HInstruction*>* locals = &locals_for_[block->GetBlockId()];
-    if (locals->empty() && GetGraph()->GetNumberOfVRegs() != 0u) {
-      const size_t vregs = GetGraph()->GetNumberOfVRegs();
-      locals->resize(vregs, nullptr);
-
-      if (block->IsCatchBlock()) {
-        // We record incoming inputs of catch phis at throwing instructions and
-        // must therefore eagerly create the phis. Unused phis will be removed
-        // in the dead phi analysis.
-        ArenaAllocator* arena = GetGraph()->GetArena();
-        for (size_t i = 0; i < vregs; ++i) {
-          HPhi* phi = new (arena) HPhi(arena, i, 0, Primitive::kPrimVoid);
-          block->AddPhi(phi);
-          (*locals)[i] = phi;
-        }
-      }
-    }
-    return locals;
-  }
-
+  // Returns locals vector for `block`. If it is a catch block, the vector will be
+  // prepopulated with catch phis for vregs which are defined in `current_locals_`.
+  ArenaVector<HInstruction*>* GetLocalsFor(HBasicBlock* block);
   HInstruction* ValueOfLocal(HBasicBlock* block, size_t local);
 
   void VisitBasicBlock(HBasicBlock* block);