Interprets negative values for solver_timeout_in_seconds as disabli…

…ng `solve_nd_sharding_iteratively`.

PiperOrigin-RevId: 692002226

third_party/xla/xla/hlo/experimental/auto_sharding/auto_sharding.cc

@@ -4124,6 +4124,12 @@ absl::StatusOr<bool> AutoSharding::Run(
     }
   }
 
+  // A negative solver timeout means we want to disable iterative ND sharding.
+  if (option_.solver_timeout_in_seconds < 0) {
+    option_.solve_nd_sharding_iteratively = false;
+    option_.solver_timeout_in_seconds *= -1;
+  }
+
   bool module_is_changed = false;
   VLOG(1) << "Original mesh shape "
           << spmd::ToString(option_.device_mesh_shape);

third_party/xla/xla/hlo/experimental/auto_sharding/auto_sharding_test.cc

@@ -1214,6 +1214,43 @@ ENTRY %entry {
                          op::Sharding("{devices=[2,2]<=[4]}")));
 }
 
+TEST_F(AutoShardingTest, NegativeTimeoutDisablesNDIterativeSolve) {
+  constexpr absl::string_view kHloString = R"(
+HloModule module
+ENTRY %entry {
+  %param0 = f32[8192,23]{1,0} parameter(0), sharding={devices=[4,1]0,1,2,3}
+  %param1 = f32[23,23]{1,0} parameter(1)
+  %dot = f32[8192,23]{1,0} dot(%param0, %param1), lhs_contracting_dims={1}, rhs_contracting_dims={1}
+  ROOT %copy = f32[8192,23]{1,0} copy(%dot)
+})";
+
+  TF_ASSERT_OK_AND_ASSIGN(std::unique_ptr<VerifiedHloModule> module,
+                          ParseAndReturnVerifiedModule(kHloString));
+  AutoShardingOption option;
+  option.enable = true;
+  option.device_mesh_shape = {2, 2};
+  option.device_mesh_ids = {0, 1, 2, 3};
+  option.device_mesh_alpha = {1.0, 1.0};
+  option.device_mesh_beta = {0.01, 1.0};
+  option.solve_nd_sharding_iteratively = true;
+  option.solver_timeout_in_seconds = -300;
+  option.preserve_shardings =
+      AutoShardingOption::PreserveShardingsType::kKeepAllShardings;
+  TF_ASSERT_OK_AND_ASSIGN(bool changed, AutoSharding(option).Run(module.get()));
+  VLOG(2) << module->ToString();
+  EXPECT_TRUE(changed);
+  const HloInstruction* param0 = FindInstruction(module.get(), "param0");
+  const HloInstruction* param1 = FindInstruction(module.get(), "param1");
+  const HloInstruction* dot = FindInstruction(module.get(), "dot");
+  ASSERT_NE(param0, nullptr);
+  ASSERT_NE(param1, nullptr);
+  ASSERT_NE(dot, nullptr);
+  EXPECT_THAT(param0, op::Sharding("{devices=[4,1]0,1,2,3}"));
+  EXPECT_THAT(param1, op::Sharding("{replicated}"));
+  EXPECT_THAT(dot, AnyOf(op::Sharding("{devices=[4,1]0,1,2,3}"),
+                         op::Sharding("{devices=[2,2]<=[4]}")));
+}
+
 TEST_F(AutoShardingTest, DotInsertReshardingReshapes) {
   constexpr absl::string_view kHloString = R"(
 HloModule module