Automated g4 rollback of changelist 188397087

PiperOrigin-RevId: 188503184

2 files changed, 2 insertions, 170 deletions

diff --git a/tensorflow/compiler/xla/service/while_loop_simplifier.cc b/tensorflow/compiler/xla/service/while_loop_simplifier.cc
index 1a93a880dd..c9d77c9376 100644
--- a/tensorflow/compiler/xla/service/while_loop_simplifier.cc
+++ b/tensorflow/compiler/xla/service/while_loop_simplifier.cc
@@ -16,7 +16,6 @@ limitations under the License.
 #include "tensorflow/compiler/xla/service/while_loop_simplifier.h"
 #include "tensorflow/compiler/xla/service/call_inliner.h"
 #include "tensorflow/compiler/xla/service/hlo_evaluator.h"
-#include "tensorflow/core/lib/gtl/flatmap.h"
 #include "tensorflow/core/lib/gtl/optional.h"
 #include "tensorflow/core/lib/strings/str_util.h"
 #include "tensorflow/core/lib/strings/strcat.h"
@@ -606,75 +605,6 @@ static StatusOr<bool> TryRemoveWhileLoop(HloInstruction* while_op) {
   return false;
 }
 
-static StatusOr<bool> TryPropagateConstant(HloInstruction* while_op) {
-  auto while_init = while_op->operand(0);
-  if (while_init->opcode() != HloOpcode::kTuple) {
-    return false;
-  }
-
-  auto while_body = while_op->while_body();
-  auto while_body_root = while_body->root_instruction();
-  if (while_body_root->opcode() != HloOpcode::kTuple) {
-    return false;
-  }
-
-  auto while_body_param = while_body->parameter_instruction(0);
-  const HloInstruction::InstructionVector& root_operands =
-      while_body_root->operands();
-
-  // Find the loop invariant tuple elements with constant init value and
-  // build a map from the tuple element index to the constant value.
-  tensorflow::gtl::FlatMap<int, const HloInstruction*> index_to_constant;
-  for (int i = 0; i < root_operands.size(); i++) {
-    HloInstruction* instr = root_operands[i];
-    if (instr->opcode() == HloOpcode::kGetTupleElement &&
-        instr->tuple_index() == i && instr->operand(0) == while_body_param) {
-      auto tuple_element = while_init->operand(i);
-      if (tuple_element->IsConstant()) {
-        VLOG(3) << "Found loop invariant tuple element " << i << " "
-                << tuple_element->ToString();
-        index_to_constant[i] = tuple_element;
-      }
-    }
-  }
-
-  if (index_to_constant.empty()) {
-    return false;
-  }
-
-  // Replace the use of each constant tuple element in the loop_condition and
-  // loop_body with the corresponding constant value.
-  auto propagate_constant = [&](HloComputation* computation) -> StatusOr<bool> {
-    HloInstruction* param = computation->parameter_instruction(0);
-    bool changed = false;
-    for (auto instr : param->users()) {
-      // Since only a while-loop with a tuple result reaches here, we can safely
-      // assume that `param` is a tuple and the first operand of the
-      // GetTupleElement instruction is a use of `param`.
-      if (instr->opcode() == HloOpcode::kGetTupleElement) {
-        VLOG(3) << "tuple index " << instr->tuple_index() << " "
-                << instr->ToString();
-        auto iter = index_to_constant.find(instr->tuple_index());
-        if (iter != index_to_constant.end()) {
-          const HloInstruction* hlo_constant = (*iter).second;
-          VLOG(3) << "Replace use of " << instr->ToString() << " with "
-                  << hlo_constant->ToString();
-          TF_RETURN_IF_ERROR(instr->ReplaceAllUsesWith(
-              computation->AddInstruction(hlo_constant->Clone())));
-          changed = true;
-        }
-      }
-    }
-    return changed;
-  };
-
-  TF_ASSIGN_OR_RETURN(bool changed_cond,
-                      propagate_constant(while_op->while_condition()));
-  TF_ASSIGN_OR_RETURN(bool changed_body, propagate_constant(while_body));
-
-  return changed_cond || changed_body;
-}
-
 StatusOr<bool> WhileLoopSimplifier::Run(HloModule* module) {
   XLA_VLOG_LINES(3,
                  "WhileLoopSimplifier::Run(), before:\n" + module->ToString());
@@ -705,11 +635,7 @@ StatusOr<bool> WhileLoopSimplifier::Run(HloModule* module) {
       continue;
     }
 
-    StatusOr<bool> result = TryPropagateConstant(while_op);
-    TF_RETURN_IF_ERROR(result.status());
-    changed |= result.ValueOrDie();
-
-    result = TryRemoveWhileLoop(while_op);
+    StatusOr<bool> result = TryRemoveWhileLoop(while_op);
     TF_RETURN_IF_ERROR(result.status());
     if (result.ValueOrDie()) {
       changed = true;
diff --git a/tensorflow/compiler/xla/service/while_loop_simplifier_test.cc b/tensorflow/compiler/xla/service/while_loop_simplifier_test.cc
index 396f942dc0..cbea3e3cf2 100644
--- a/tensorflow/compiler/xla/service/while_loop_simplifier_test.cc
+++ b/tensorflow/compiler/xla/service/while_loop_simplifier_test.cc
@@ -30,11 +30,6 @@ class WhileLoopSimplifierTest : public HloVerifiedTestBase {
  protected:
   // Makes an HloModule that contains a loop with `num_iters` iteration.
   void MakeModuleWithSimpleLoop(int num_iters);
-
-  // Similar to MakeModuleWithSimpleLoop except that the loop bound is passed to
-  // the loop-condition through an element of a tuple which is the
-  // loop-condition parameter.
-  void MakeModuleWithSimpleLoopTupleElementLoopBound(int num_iters);
 };
 
 void WhileLoopSimplifierTest::MakeModuleWithSimpleLoop(int num_iters) {
@@ -71,45 +66,6 @@ void WhileLoopSimplifierTest::MakeModuleWithSimpleLoop(int num_iters) {
   ParseAndVerifyModule(hlo_string.c_str());
 }
 
-void WhileLoopSimplifierTest::MakeModuleWithSimpleLoopTupleElementLoopBound(
-    int num_iters) {
-  string hlo_string_template = R"(
-  HloModule SimpleLoopWithIndirectLoopBound
-  SimpleLoopWithIndirectLoopBound.body {
-    loop_var.1 = (s32[], s32[3]{0}, s32[]) parameter(0)
-    get-tuple-element.1 = s32[] get-tuple-element(loop_var.1), index=0
-    constant.1 = s32[] constant(1)
-    add = s32[] add(get-tuple-element.1, constant.1)
-    get-tuple-element.2 = s32[3]{0} get-tuple-element(loop_var.1), index=1
-    multiply = s32[3]{0} multiply(get-tuple-element.2, get-tuple-element.2)
-    limit = s32[] get-tuple-element(loop_var.1), index=2
-    ROOT tuple = (s32[], s32[3]{0}, s32[]) tuple(add, multiply, limit)
-  }
-  SimpleLoopWithIndirectLoopBound.condition {
-    loop_var.2 = (s32[], s32[3]{0}, s32[]) parameter(0)
-    get-tuple-element.3 = s32[] get-tuple-element(loop_var.2), index=0
-    get-tuple-element.4 = s32[] get-tuple-element(loop_var.2), index=2
-    ROOT less-than = pred[] less-than(get-tuple-element.3, get-tuple-element.4)
-  }
-  ENTRY SimpleLoopWithIndirectLoopBound {
-    constant.3 = s32[] constant(42)
-    constant.4 = s32[3]{0} constant({0, 1, 2})
-    constant.2 = s32[] constant({{LOOP_BOUND}})
-    tuple.1 = (s32[], s32[3]{0}, s32[]) tuple(constant.3, constant.4,
-      constant.2)
-    ROOT while = (s32[], s32[3]{0}, s32[]) while(tuple.1),
-      condition=SimpleLoopWithIndirectLoopBound.condition,
-      body=SimpleLoopWithIndirectLoopBound.body
-  }
-  )";
-
-  string hlo_string = tensorflow::str_util::StringReplace(
-      hlo_string_template, "{{LOOP_BOUND}}",
-      tensorflow::strings::StrCat(42 + num_iters),
-      /*replace_all=*/true);
-  ParseAndVerifyModule(hlo_string.c_str());
-}
-
 TEST_F(WhileLoopSimplifierTest, LoopWithZeroIterationSimiplified) {
   MakeModuleWithSimpleLoop(/*num_iters=*/0);
   HloModule* the_module = &module();
@@ -118,15 +74,6 @@ TEST_F(WhileLoopSimplifierTest, LoopWithZeroIterationSimiplified) {
               op::Tuple(op::Constant(), op::Constant()));
 }
 
-TEST_F(WhileLoopSimplifierTest,
-       LoopWithZeroIterationTupleElementLoopBoundSimplified) {
-  MakeModuleWithSimpleLoopTupleElementLoopBound(/*num_iters=*/0);
-  HloModule* the_module = &module();
-  ASSERT_TRUE(WhileLoopSimplifier().Run(the_module).ValueOrDie());
-  EXPECT_THAT(the_module->entry_computation()->root_instruction(),
-              op::Tuple(op::Constant(), op::Constant(), op::Constant()));
-}
-
 TEST_F(WhileLoopSimplifierTest, LoopWithOneIterationSimplified) {
   MakeModuleWithSimpleLoop(/*num_iters=*/1);
   HloModule* the_module = &module();
@@ -135,15 +82,6 @@ TEST_F(WhileLoopSimplifierTest, LoopWithOneIterationSimplified) {
               op::Tuple(op::Add(), op::Multiply()));
 }
 
-TEST_F(WhileLoopSimplifierTest,
-       LoopWithOneIterationTupleELementLoopBoundSimplified) {
-  MakeModuleWithSimpleLoopTupleElementLoopBound(/*num_iters=*/1);
-  HloModule* the_module = &module();
-  ASSERT_TRUE(WhileLoopSimplifier().Run(the_module).ValueOrDie());
-  EXPECT_THAT(the_module->entry_computation()->root_instruction(),
-              op::Tuple(op::Add(), op::Multiply(), op::Constant()));
-}
-
 TEST_F(WhileLoopSimplifierTest, LoopWithTwoIterationsNotSimplified) {
   MakeModuleWithSimpleLoop(/*num_iters=*/2);
   EXPECT_FALSE(WhileLoopSimplifier().Run(&module()).ValueOrDie());
@@ -426,6 +364,7 @@ TEST_F(WhileLoopSimplifierTest, LoopWithNonTupleBodyShapeNotSimplified) {
   HloModule BodyHasNonTupleRoot
   BodyHasNonTupleRoot.passthrough {
     ROOT param = (s32[], s32[]) parameter(0)
+    get-tuple-element = s32[] get-tuple-element((s32[], s32[]) param), index=1
   }
   BodyHasNonTupleRoot.always_true {
     param.1 = (s32[], s32[]) parameter(0)
@@ -443,38 +382,5 @@ TEST_F(WhileLoopSimplifierTest, LoopWithNonTupleBodyShapeNotSimplified) {
   EXPECT_FALSE(WhileLoopSimplifier().Run(&module()).ValueOrDie());
 }
 
-TEST_F(WhileLoopSimplifierTest,
-       LoopWithNonTupleBodyRootInstructionNotSimplified) {
-  const string hlo_string = R"(
-  HloModule SimpleLoop
-  SimpleLoop.body {
-    loop_var.1 = (s32[], s32[3]{0}) parameter(0)
-    get-tuple-element.1 = s32[] get-tuple-element(loop_var.1), index=0
-    constant.1 = s32[] constant(1)
-    add = s32[] add(get-tuple-element.1, constant.1)
-    get-tuple-element.2 = s32[3]{0} get-tuple-element(loop_var.1), index=1
-    multiply = s32[3]{0} multiply(get-tuple-element.2, get-tuple-element.2)
-    ROOT custom-call = (s32[], s32[3]{0}) custom-call(add, multiply),
-      custom_call_target="x"
-  }
-  SimpleLoop.condition {
-    loop_var.2 = (s32[], s32[3]{0}) parameter(0)
-    get-tuple-element.3 = s32[] get-tuple-element(loop_var.2), index=0
-    constant.2 = s32[] constant(44)
-    ROOT less-than = pred[] less-than(get-tuple-element.3, constant.2)
-  }
-  ENTRY SimpleLoop {
-    constant.3 = s32[] constant(42)
-    constant.4 = s32[3]{0} constant({0, 1, 2})
-    tuple.1 = (s32[], s32[3]{0}) tuple(constant.3, constant.4)
-    ROOT while = (s32[], s32[3]{0}) while(tuple.1), condition=
-      SimpleLoop.condition, body=SimpleLoop.body
-  }
-  )";
-
-  ParseAndVerifyModule(hlo_string.c_str());
-  EXPECT_FALSE(WhileLoopSimplifier().Run(&module()).ValueOrDie());
-}
-
 }  // namespace
 }  // namespace xla