[XLA:GPU] Update FindNonTrivialHero to work with HloInstructionAdaptor.

third_party/xla/xla/service/gpu/hlo_fusion_analysis.cc

@@ -139,7 +139,7 @@ HloFusionAnalysis HloFusionAnalysis::Create(
  std::vector<const HloInstruction*> heroes;
  for (auto root : fusion->GetRoots()) {
  roots.push_back(&root.instruction());
- heroes.push_back(&FindNonTrivialHero(*roots.back(), *fusion));
+ heroes.push_back(&FindNonTrivialHero(root).instruction());
  }
 
  std::vector<const HloInstruction*> fusion_arguments;

third_party/xla/xla/service/gpu/hlo_traversal.h

@@ -57,6 +57,7 @@ class HloInstructionAdaptor {
 
  // Use sparingly; prefer extending the interface.
  const HloInstruction& instruction() const { return *instruction_; }
+ const HloFusionAdaptor& parent() const { return *parent_; }
 
  private:
  const HloInstruction* instruction_;

third_party/xla/xla/service/gpu/ir_emission_utils.cc

@@ -688,7 +688,7 @@ bool IsIntermediate(const HloInstruction* instr, int allowed_operand_count,
 }
 
 static std::optional<HloInstructionAdaptor> FindNonTrivialHero(
- HloInstructionAdaptor root, const HloFusionAdaptor& fusion,
+ const HloInstructionAdaptor& root,
  const std::function<bool(const HloInstruction&)>& predicate) {
  std::optional<HloInstructionAdaptor> hero = std::nullopt;
  auto visitor = [&](HloInstructionAdaptor node) {
@@ -710,7 +710,7 @@ static std::optional<HloInstructionAdaptor> FindNonTrivialHero(
  }
  return TraversalResult::kAdvance;
  };
- HloBfsConsumersFirstTraversal({root}, fusion, visitor);
+ HloBfsConsumersFirstTraversal({root}, root.parent(), visitor);
  if (!hero) {
  return std::nullopt;
  }
@@ -727,23 +727,23 @@ static std::optional<HloInstructionAdaptor> FindNonTrivialHero(
  /*add_single_user_check=*/true);
  };
  bool visit_operands = false;
- if (HloAnyOf(hero->GetUsers(), fusion, is_nontrivial, visit_operands)) {
+ if (HloAnyOf(hero->GetUsers(), hero->parent(), is_nontrivial,
+ visit_operands)) {
  return std::nullopt;
  }
 
  return hero;
 }
 
-const HloInstruction& FindNonTrivialHero(const HloInstruction& instr,
- const HloFusionAdaptor& fusion) {
- HloInstructionAdaptor hero{instr, &fusion};
+HloInstructionAdaptor FindNonTrivialHero(const HloInstructionAdaptor& instr) {
+ HloInstructionAdaptor hero = instr;
 
  // Go up the chain of trivial element-wise(+bitcast, -copy) operations. Note
  // that no memoization is needed due to number of operands constraints: we
  // never have to revisit same nodes.
  while (IsIntermediate(&hero.instruction(), /*allowed_operand_count=*/1,
- &fusion) &&
- fusion.ContainsInstruction(hero.GetOperand(0))) {
+ &hero.parent()) &&
+ hero.parent().ContainsInstruction(hero.GetOperand(0))) {
  hero = hero.GetOperand(0);
  }
 
@@ -753,25 +753,26 @@ const HloInstruction& FindNonTrivialHero(const HloInstruction& instr,
  auto is_transpose = [](const HloInstruction& node) {
  return FindTiledLogicalTranspose(node).has_value();
  };
- if (auto transpose = FindNonTrivialHero(hero, fusion, is_transpose)) {
- return transpose->instruction();
+ if (auto transpose = FindNonTrivialHero(hero, is_transpose)) {
+ return *transpose;
  }
  auto is_concatenate = [](const HloInstruction& node) {
  return node.opcode() == HloOpcode::kConcatenate;
  };
- if (auto concatenate = FindNonTrivialHero(hero, fusion, is_concatenate)) {
- return concatenate->instruction();
+ if (auto concatenate = FindNonTrivialHero(hero, is_concatenate)) {
+ return *concatenate;
  }
  if (hero.opcode() != HloOpcode::kReduce) {
  return instr;
  }
- return hero.instruction();
+ return hero;
 }
 
 const HloInstruction& FindNonTrivialHero(const HloInstruction& instr) {
  CHECK_NE(instr.opcode(), HloOpcode::kFusion);
- return FindNonTrivialHero(instr,
- *HloFusionAdaptor::ForComputation(instr.parent()));
+ auto fusion_adaptor = HloFusionAdaptor::ForComputation(instr.parent());
+ HloInstructionAdaptor instr_adaptor(instr, fusion_adaptor.get());
+ return FindNonTrivialHero(instr_adaptor).instruction();
 }
 
 void VLogModule(int level, const llvm::Module& module) {

third_party/xla/xla/service/gpu/ir_emission_utils.h

@@ -149,16 +149,12 @@ std::vector<const HloInstruction*> GetOutputDefiningDynamicUpdateSlices(
 
 Shape GetShape(mlir::Value value);
 
-// `is_boundary` returns `true` for edges that are on the boundary of the
-// fusion, i.e., they go from an instruction inside the fusion to one outside,
-// or vice versa.
-// Note: when this is called with a fusion instruction, it will traverse into
-// the fusion (unless the boundary function stops it).
-const HloInstruction& FindNonTrivialHero(const HloInstruction& instr,
- const HloFusionAdaptor& fusion);
-
-// Like above, but assumes the instruction is inside an HloFusionInstruction.
-// Returns the instruction itself if it is an HloFusionInstruction.
+// Returns the first hero instruction reachable from `instr` as root. Hero
+// instruction can be in a different computation if the parent HloFusionAdaptor
+// is a producer-consumer fusion.
+HloInstructionAdaptor FindNonTrivialHero(const HloInstructionAdaptor& instr);
+
+// Same as above, but fusion is the parent computation of the hlo instruction.
 const HloInstruction& FindNonTrivialHero(const HloInstruction& instr);
 
 /// Description of how to emit a given transposition.

third_party/xla/xla/service/gpu/ir_emission_utils_test.cc

@@ -152,8 +152,7 @@ TEST_F(IrEmissionUtilsTest, FindReduceHeroEpilogueFusion) {
 
  HloInstruction* r = module->entry_computation()->root_instruction();
  auto fusion = HloFusionAdaptor::ForInstruction(r);
- const auto& result =
- FindNonTrivialHero(fusion->GetRoots()[0].instruction(), *fusion);
+ const auto& result = FindNonTrivialHero(fusion->GetRoots()[0]);
  EXPECT_EQ(result.name(), "reduce.0");
 }
 
@@ -187,11 +186,9 @@ TEST_F(IrEmissionUtilsTest, FindReduceHeroEpilogueFusionTwoRootUsers) {
 
  HloInstruction* r = module->entry_computation()->root_instruction();
  auto fusion = HloFusionAdaptor::ForInstruction(r);
- const auto& result =
- FindNonTrivialHero(fusion->GetRoots()[1].instruction(), *fusion);
+ const auto& result = FindNonTrivialHero(fusion->GetRoots()[1]);
  EXPECT_EQ(result.name(), "reduce.1");
- const auto& result2 =
- FindNonTrivialHero(fusion->GetRoots()[2].instruction(), *fusion);
+ const auto& result2 = FindNonTrivialHero(fusion->GetRoots()[2]);
  EXPECT_EQ(result2.name(), "reduce.1");
 }
 
@@ -225,13 +222,11 @@ TEST_F(IrEmissionUtilsTest, FindReduceHeroEpilogueFusionHeroAlsoUsedAsNonHero) {
 
  HloInstruction* r = module->entry_computation()->root_instruction();
  auto fusion = HloFusionAdaptor::ForInstruction(r);
- const auto& result =
- FindNonTrivialHero(fusion->GetRoots()[1].instruction(), *fusion);
+ const auto& result = FindNonTrivialHero(fusion->GetRoots()[1]);
  // reduce.0 is also an operand of broadcast, but it is not a hero for that
  // root.
  EXPECT_EQ(result.name(), "broadcast");
- const auto& result2 =
- FindNonTrivialHero(fusion->GetRoots()[2].instruction(), *fusion);
+ const auto& result2 = FindNonTrivialHero(fusion->GetRoots()[2]);
  EXPECT_EQ(result2.name(), "reduce.0");
 }
 
@@ -258,11 +253,9 @@ TEST_F(IrEmissionUtilsTest, DoNotFindTransposeHeroEpilogueFusionTwoRootUsers) {
 
  HloInstruction* r = module->entry_computation()->root_instruction();
  auto fusion = HloFusionAdaptor::ForInstruction(r);
- const auto& result =
- FindNonTrivialHero(fusion->GetRoots()[0].instruction(), *fusion);
+ const auto& result = FindNonTrivialHero(fusion->GetRoots()[0]);
  EXPECT_EQ(result.name(), "bitcast.1");
- const auto& result2 =
- FindNonTrivialHero(fusion->GetRoots()[1].instruction(), *fusion);
+ const auto& result2 = FindNonTrivialHero(fusion->GetRoots()[1]);
  EXPECT_EQ(result2.name(), "sign.1");
 }
 
@@ -370,14 +363,16 @@ ENTRY entry {
  TF_ASSERT_OK_AND_ASSIGN(std::unique_ptr<HloModule> module,
  ParseAndReturnVerifiedModule(hlo));
 
- HloInstruction* r = module->GetComputationWithName("f")->root_instruction();
  HloInstruction* transpose =
  module->entry_computation()->GetInstructionWithName("t");
  HloInstruction* fusion =
  module->entry_computation()->GetInstructionWithName("fusion");
  auto fusion_adaptor =
  HloFusionAdaptor::ForProducerConsumer(transpose, fusion);
- EXPECT_EQ(&FindNonTrivialHero(*r, *fusion_adaptor), transpose);
+ HloInstructionAdaptor r(
+ *module->GetComputationWithName("f")->root_instruction(),
+ fusion_adaptor.get());
+ EXPECT_EQ(&FindNonTrivialHero(r).instruction(), transpose);
 }
 
 TEST_F(IrEmissionUtilsTest, FindNonTrivialHeroInsideFusion) {
@@ -409,7 +404,9 @@ ENTRY entry {
  HloInstruction* fusion =
  module->entry_computation()->GetInstructionWithName("fusion");
  auto fusion_adaptor = HloFusionAdaptor::ForProducerConsumer(fusion, r);
- EXPECT_EQ(&FindNonTrivialHero(*r, *fusion_adaptor), transpose);
+ EXPECT_EQ(&FindNonTrivialHero(HloInstructionAdaptor(*r, fusion_adaptor.get()))
+ .instruction(),
+ transpose);
 }
 
 TEST_F(IrEmissionUtilsTest, TransposeReachableViaTrivialAndNontrivialOps) {

third_party/xla/xla/service/gpu/rename_fusions.cc

@@ -56,8 +56,7 @@ std::string MakeFusionHeroNames(const HloInstruction* instruction) {
  absl::btree_set<absl::string_view> heroes;
 
  for (auto root : fusion_adaptor->GetRoots()) {
- heroes.insert(HloOpcodeString(
- FindNonTrivialHero(root.instruction(), *fusion_adaptor).opcode()));
+ heroes.insert(HloOpcodeString(FindNonTrivialHero(root).opcode()));
  }
  return absl::StrReplaceAll(absl::StrJoin(heroes, "_"), {{"-", "_"}});
 }