[XLA] Simplify BufferAlias class by removing unused member.

Points-to analyis stores buffera aliases in a map:
buffer->(buffer,instruction,index)

Storing buffer in each BufferAlias again is redundant, and it was actually unused.

PiperOrigin-RevId: 156610923

3 files changed, 8 insertions, 15 deletions

diff --git a/tensorflow/compiler/xla/service/tuple_points_to_analysis.cc b/tensorflow/compiler/xla/service/tuple_points_to_analysis.cc
index 554adaf0e3..fe6eadd4db 100644
--- a/tensorflow/compiler/xla/service/tuple_points_to_analysis.cc
+++ b/tensorflow/compiler/xla/service/tuple_points_to_analysis.cc
@@ -33,10 +33,9 @@ limitations under the License.
 namespace xla {
 
 string BufferAlias::ToString() const {
-  return tensorflow::strings::StrCat("BufferAlias(",
-                                     instruction_->FullyQualifiedName(), "[",
-                                     tensorflow::str_util::Join(index_, ","),
-                                     "] => ", buffer_->ToString(), ")");
+  return tensorflow::strings::StrCat(
+      "BufferAlias(", instruction_->FullyQualifiedName(), "[",
+      tensorflow::str_util::Join(index_, ","), "])");
 }
 
 std::ostream& operator<<(std::ostream& out, const BufferAlias& buffer_alias) {
@@ -174,7 +173,7 @@ Status TuplePointsToAnalysis::PopulateDefinedBuffersAndAliases(
         if (buffer_aliases_.count(buffer) == 0) {
           buffer_aliases_.insert({buffer, std::vector<BufferAlias>()});
         }
-        buffer_aliases_[buffer].emplace_back(*buffer, instruction.get(), index);
+        buffer_aliases_[buffer].emplace_back(instruction.get(), index);
       }
       return Status::OK();
     }));
diff --git a/tensorflow/compiler/xla/service/tuple_points_to_analysis.h b/tensorflow/compiler/xla/service/tuple_points_to_analysis.h
index 85a71b56ce..3593cd993d 100644
--- a/tensorflow/compiler/xla/service/tuple_points_to_analysis.h
+++ b/tensorflow/compiler/xla/service/tuple_points_to_analysis.h
@@ -117,27 +117,21 @@ class PointsToSet : public ShapeTree<std::vector<const LogicalBuffer*>> {
 // value.
 class BufferAlias {
  public:
-  BufferAlias(const LogicalBuffer& buffer, HloInstruction* instruction,
-              const ShapeIndex& index)
-      : buffer_(&buffer), instruction_(instruction), index_(index) {}
-
-  // Return the logical buffer aliased at the instruction and index.
-  const LogicalBuffer& buffer() const { return *buffer_; }
+  BufferAlias(HloInstruction* instruction, const ShapeIndex& index)
+      : instruction_(instruction), index_(index) {}
 
   // Return the instruction/index of the subshape.
   HloInstruction* instruction() const { return instruction_; }
   const ShapeIndex& index() const { return index_; }
 
   bool operator==(const BufferAlias& other) const {
-    return buffer_ == other.buffer_ && instruction_ == other.instruction_ &&
-           index_ == other.index_;
+    return instruction_ == other.instruction_ && index_ == other.index_;
   }
   bool operator!=(const BufferAlias& other) const { return !(*this == other); }
 
   string ToString() const;
 
  private:
-  const LogicalBuffer* buffer_;
   HloInstruction* instruction_;
   const ShapeIndex index_;
 };
diff --git a/tensorflow/compiler/xla/service/tuple_points_to_analysis_test.cc b/tensorflow/compiler/xla/service/tuple_points_to_analysis_test.cc
index 87e1b058b7..2a761d70e5 100644
--- a/tensorflow/compiler/xla/service/tuple_points_to_analysis_test.cc
+++ b/tensorflow/compiler/xla/service/tuple_points_to_analysis_test.cc
@@ -111,7 +111,7 @@ class TuplePointsToAnalysisTest : public HloTestBase {
             .ValueOrDie();
     std::vector<BufferAlias> expected_aliases;
     for (auto& pair : expected) {
-      expected_aliases.push_back(BufferAlias(*buffer, pair.first, pair.second));
+      expected_aliases.push_back(BufferAlias(pair.first, pair.second));
     }
     EXPECT_THAT(points_to_analysis_->GetBufferAliases(*buffer),
                 UnorderedElementsAreArray(expected_aliases));