General offset computation for dynamic slice fusion

This patch adds logic for computing general offset while creating dynamic-slice-fusion.

xla/service/gpu/fusions/dynamic_slice_fusion_test.cc

@@ -27,6 +27,7 @@ limitations under the License.
 #include "xla/ffi/ffi.h"
 #include "xla/ffi/ffi_api.h"
 #include "xla/hlo/ir/hlo_computation.h"
+#include "xla/hlo/ir/hlo_instruction.h"
 #include "xla/hlo/ir/hlo_module.h"
 #include "xla/service/custom_call_target_registry.h"
 #include "xla/service/gpu/backend_configs.pb.h"
@@ -2791,7 +2792,6 @@ TEST_F(DynamicSliceFusionTest, CustomCallDUSTuple) {
   hlo_config.set_debug_options(debug_options);
   TF_ASSERT_OK_AND_ASSIGN(auto hlo_opt, xla::HloModule::CreateFromProto(
                                             computation.proto(), hlo_config));
-
   DynamicSliceFusionRewriter pass(PLATFORM);
   TF_ASSERT_OK_AND_ASSIGN(auto changed, this->RunHloPass(&pass, hlo_opt.get()));
   EXPECT_TRUE(changed);
@@ -3407,6 +3407,100 @@ TEST_F(DynamicSliceFusionTest, OffsetArrayTestU64) {
                ".*");
 }
 
+TEST_F(DynamicSliceFusionTest, TestWithRewriter) {
+  const char* hlo = R"(
+    HloModule test_module, replica_count=2
+
+    add {
+      a = s32[] parameter(0)
+      b = s32[] parameter(1)
+      ROOT add = s32[] add(a, b)
+    }
+
+    Body {
+      param = (s32[], s32[16, 32], s32[8, 32]) parameter(0)
+      i = s32[] get-tuple-element(param), index=0
+      dest = s32[16,32] get-tuple-element(param), index=1
+      src = s32[8,32] get-tuple-element(param), index=2
+      eight = s32[] constant(8)
+      zero = s32[] constant(0)
+      thirty_two = s32[] constant(32)
+      add = s32[] add(eight, i)
+      add.2 = s32[] subtract(add, thirty_two)
+      compare = pred[] compare(add, thirty_two), direction=LT
+      offset = s32[] select(compare, add, add.2)
+      rs = s32[4,32] reduce-scatter(src), channel_id=0, replica_groups={{0,1}}, use_global_device_ids=true, dimensions={0}, to_apply=add
+      fusion = s32[16,32] dynamic-update-slice(dest, rs, offset, zero)
+      one = s32[] constant(1)
+      i_plus_one = s32[] add(i, one)
+      ROOT tuple = tuple(i_plus_one, fusion, src)
+    }
+
+    Cond {
+      param = (s32[], s32[16,32], s32[8,32]) parameter(0)
+      loop_iter = s32[] get-tuple-element(param), index=0
+      four = s32[] constant(32)
+      ROOT compare = pred[] compare(loop_iter, four), direction=LT
+    }
+
+    ENTRY main {
+      zero = s32[] constant(0)
+      dest = s32[16,32] parameter(0)
+      src = s32[8,32] parameter(1)
+      tuple = tuple(zero, dest, src)
+      ROOT while = while(tuple), body=Body, condition=Cond
+    }
+  )";
+
+  HloModuleConfig config;
+  DebugOptions dboptions;
+  dboptions.set_xla_gpu_enable_dynamic_slice_fusion(false);
+  config.set_debug_options(dboptions);
+  TF_ASSERT_OK_AND_ASSIGN(auto module0,
+                          ParseAndReturnVerifiedModule(hlo, config));
+
+  TF_ASSERT_OK_AND_ASSIGN(auto module_without_fusion,
+                          GetOptimizedModule(std::move(module0)));
+  dboptions.set_xla_gpu_enable_dynamic_slice_fusion(true);
+  config.set_debug_options(dboptions);
+  TF_ASSERT_OK_AND_ASSIGN(auto module1,
+                          ParseAndReturnVerifiedModule(hlo, config));
+  TF_ASSERT_OK_AND_ASSIGN(auto module_with_fusion,
+                          GetOptimizedModule(std::move(module1)));
+
+  ASSERT_EQ(GetDynamicSliceFusions(*module_without_fusion).size(), 0);
+  auto fusions = GetDynamicSliceFusions(*module_with_fusion);
+  ASSERT_EQ(fusions.size(), 1);
+  HloPrintOptions options;
+  options.set_print_large_constants(true)
+      .set_print_result_shape(false)
+      .set_print_operand_shape(false);
+  TF_ASSERT_OK_AND_ASSIGN(auto filecheck_fusion,
+                          RunFileCheck(fusions[0]->ToString(options),
+                                       R"(
+      // CHECK-DAG: %[[rs:.+]] = reduce-scatter({{.+}})
+      // CHECK-DAG: %[[offset_vals:.+]] = constant({8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 0, 1, 2, 3, 4, 5, 6, 7})
+      // CHECK-DAG: %[[offset_as_arr:.+]] = dynamic-slice(%[[offset_vals]], {{.+}}), dynamic_slice_sizes={1}
+      // CHECK-DAG: %[[offset:.+]] = reshape(%[[offset_as_arr]])
+      // CHECK-DAG: ROOT %{{.+}} = dynamic-update-slice({{.+}}, %[[rs]], %[[offset]], {{.+}})
+    )"));
+  ASSERT_TRUE(filecheck_fusion);
+  TF_ASSERT_OK_AND_ASSIGN(
+      auto filecheck_while_loop,
+      RunFileCheck(fusions[0]->FusionInstruction()->parent()->ToString(options),
+                   R"(
+      // CHECK-DAG: %[[p:.+]] = parameter(0)
+      // CHECK-DAG: %[[loop_counter:.+]] = get-tuple-element(%[[p]]), index=3
+      // CHECK-DAG: %[[address_computation:.+]] = fusion({{.+}}, %[[loop_counter]]), kind=kCustom
+      // CHECK-DAG: %[[updated_loop_counter:.+]] = add(%[[loop_counter]], {{.+}})
+      // CHECK-DAG: ROOT {{.+}} = tuple({{.+}}, %[[address_computation]], {{.+}}, %[[updated_loop_counter]])
+    )"));
+  ErrorSpec error_spec{/*aabs=*/1e-3, /*arel=*/1e-3};
+  EXPECT_TRUE(RunAndCompareTwoModulesReplicated(
+      std::move(module_without_fusion), std::move(module_with_fusion), false,
+      true, error_spec));
+}
+
 }  // namespace
 }  // namespace gpu
 }  // namespace xla