[XLA] Make some static functions in InstructionFusion members.

PiperOrigin-RevId: 167025880

1 files changed, 13 insertions, 0 deletions

diff --git a/tensorflow/compiler/xla/service/instruction_fusion.h b/tensorflow/compiler/xla/service/instruction_fusion.h
index 3ac13ffda0..0eb8d03489 100644
--- a/tensorflow/compiler/xla/service/instruction_fusion.h
+++ b/tensorflow/compiler/xla/service/instruction_fusion.h
@@ -70,6 +70,19 @@ class InstructionFusion : public HloPassInterface {
   virtual HloInstruction* Fuse(HloInstruction* producer,
                                HloInstruction* consumer);
 
+  // An "effectively unary" operation is one that has one "large"
+  // input with the others being negligible in terms of memory usage.
+  // We use "has a smaller true rank than the output" as a heuristic
+  // for "negligible" memory usage.
+  bool EffectivelyUnary(HloInstruction* hlo);
+
+  // Returns true if fusing producer into consumer would cause producer to be
+  // duplicated. This is the case if producer has uses other than consumer.
+  bool FusionWouldDuplicate(const HloInstruction& producer,
+                            const HloInstruction& consumer) {
+    return !(producer.users().size() == 1 && consumer.IsUserOf(&producer));
+  }
+
   // Current HloComputation instance the loop fuser is traversing.
   HloComputation* computation_;
   HloModule* module_;