diff --git a/src/nnet3/nnet-am-decodable-simple.cc b/src/nnet3/nnet-am-decodable-simple.cc
index 341f87f0372..d66e24830c6 100644
--- a/src/nnet3/nnet-am-decodable-simple.cc
+++ b/src/nnet3/nnet-am-decodable-simple.cc
@@ -46,7 +46,7 @@ DecodableNnetSimple::DecodableNnetSimple(
       (feats_.NumRows() + opts_.frame_subsampling_factor - 1) /
       opts_.frame_subsampling_factor;
   KALDI_ASSERT(IsSimpleNnet(nnet));
-  ComputeSimpleNnetContext(nnet, &nnet_left_context_, &nnet_right_context_);
+  compiler_.GetSimpleNnetContext(&nnet_left_context_, &nnet_right_context_);
   KALDI_ASSERT(!(ivector != NULL && online_ivectors != NULL));
   KALDI_ASSERT(!(online_ivectors != NULL && online_ivector_period <= 0 &&
                  "You need to set the --online-ivector-period option!"));
diff --git a/src/nnet3/nnet-example-utils.h b/src/nnet3/nnet-example-utils.h
index 81e2882097d..52b2ebbf904 100644
--- a/src/nnet3/nnet-example-utils.h
+++ b/src/nnet3/nnet-example-utils.h
@@ -150,7 +150,6 @@ struct ExampleGenerationConfig {
    struct ChunkTimeInfo is used by class UtteranceSplitter to output
    information about how we split an utterance into chunks.
  */
-
 struct ChunkTimeInfo {
   int32 first_frame;
   int32 num_frames;
diff --git a/src/nnet3/nnet-optimize.cc b/src/nnet3/nnet-optimize.cc
index 63a7e833c74..b0eaa4916ae 100644
--- a/src/nnet3/nnet-optimize.cc
+++ b/src/nnet3/nnet-optimize.cc
@@ -21,6 +21,7 @@
 #include <iomanip>
 #include "nnet3/nnet-optimize.h"
 #include "nnet3/nnet-optimize-utils.h"
+#include "nnet3/nnet-utils.h"
 #include "base/timer.h"
 
 namespace kaldi {
@@ -638,7 +639,8 @@ CachingOptimizingCompiler::CachingOptimizingCompiler(
     seconds_taken_total_(0.0), seconds_taken_compile_(0.0),
     seconds_taken_optimize_(0.0), seconds_taken_expand_(0.0),
     seconds_taken_check_(0.0), seconds_taken_indexes_(0.0),
-    seconds_taken_io_(0.0), cache_(config.cache_capacity) { }
+    seconds_taken_io_(0.0), cache_(config.cache_capacity),
+    nnet_left_context_(-1), nnet_right_context_(-1) { }
 
 CachingOptimizingCompiler::CachingOptimizingCompiler(
     const Nnet &nnet,
@@ -648,8 +650,18 @@ CachingOptimizingCompiler::CachingOptimizingCompiler(
     seconds_taken_total_(0.0), seconds_taken_compile_(0.0),
     seconds_taken_optimize_(0.0), seconds_taken_expand_(0.0),
     seconds_taken_check_(0.0), seconds_taken_indexes_(0.0),
-    seconds_taken_io_(0.0), cache_(config.cache_capacity) { }
+    seconds_taken_io_(0.0), cache_(config.cache_capacity),
+    nnet_left_context_(-1), nnet_right_context_(-1) { }
 
+void CachingOptimizingCompiler::GetSimpleNnetContext(
+    int32 *nnet_left_context, int32 *nnet_right_context) {
+  if (nnet_left_context_ == -1) {
+    ComputeSimpleNnetContext(nnet_, &nnet_left_context_,
+                             &nnet_right_context_);
+  }
+  *nnet_left_context = nnet_left_context_;
+  *nnet_right_context = nnet_right_context_;
+}
 
 void CachingOptimizingCompiler::ReadCache(std::istream &is, bool binary) {
   {
diff --git a/src/nnet3/nnet-optimize.h b/src/nnet3/nnet-optimize.h
index 78763732469..0804729519d 100644
--- a/src/nnet3/nnet-optimize.h
+++ b/src/nnet3/nnet-optimize.h
@@ -242,6 +242,16 @@ class CachingOptimizingCompiler {
   void ReadCache(std::istream &is, bool binary);
   void WriteCache(std::ostream &os, bool binary);
 
+
+  // GetSimpleNnetContext() is equivalent to calling:
+  // ComputeSimpleNnetContext(nnet_, &nnet_left_context,
+  //                          &nnet_right_context)
+  // but it caches it inside this class.  This functionality is independent of
+  // the rest of the functionality of this class; it just happens to be a
+  // convenient place to put this mechanism.
+  void GetSimpleNnetContext(int32 *nnet_left_context,
+                            int32 *nnet_right_context);
+
  private:
 
   // This function just implements the work of Compile(); it's made a separate
@@ -290,6 +300,10 @@ class CachingOptimizingCompiler {
   double seconds_taken_io_;
 
   ComputationCache cache_;
+
+  // These following two variables are only used by the function GetSimpleNnetContext().
+  int32 nnet_left_context_;
+  int32 nnet_right_context_;
 };