issue:
  - 47949
releaseNotes:
  - |
    **Enabled** [Delta xDS](https://www.envoyproxy.io/docs/envoy/latest/api-docs/xds_protocol#incremental-xds) by default. See upgrade notes for more information.
upgradeNotes:
  - title: Delta xDS on by default
    content: |
      In previous versions, Istio used the "State of the world" xDS protocol to configure Envoy.

  }

  /** Returns a new bias. */
  private fun adapt(
    delta: Int,
    numpoints: Int,
    first: Boolean,
  ): Int {
    var delta =
      when {
        first -> delta / DAMP
        else -> delta / 2
      }
    delta += (delta / numpoints)
    var k = 0
    while (delta > ((BASE - TMIN) * TMAX) / 2) {
      delta /= (BASE - TMIN)
      k += BASE
    }

//go:nosplit
//go:noinline
func Xadd(ptr *uint32, delta int32) uint32 {
	new := *ptr + uint32(delta)
	*ptr = new
	return new
}

//go:nosplit
//go:noinline
func Xadd64(ptr *uint64, delta int64) uint64 {
	new := *ptr + uint64(delta)
	*ptr = new
	return new
}

//go:nosplit
//go:noinline
func Xadduintptr(ptr *uintptr, delta uintptr) uintptr {
	new := *ptr + delta
	*ptr = new
	return new
}

	"istio.io/istio/pkg/util/sets"
)

var knownOptimizationGaps = sets.New(
	"BlackHoleCluster",
	"InboundPassthroughCluster",
	"PassthroughCluster",
)

// compareDiff compares a Delta and SotW XDS response. This allows checking that the Delta XDS
// response returned the optimal result. Checks include correctness checks (e.g. if a config changed,
// we must include it) and possible optimizations (e.g. we sent a config, but it was not changed).

  TF_ASSERT_OK(CreateMlirModule("empty_func.mlir"));

  TF_EXPECT_OK(ExportFromTensorflowDialectToExecutor(*mlir_module_));

  EXPECT_EQ(compilation_status.Delta(kExportSuccess), 1);
  EXPECT_EQ(compilation_status.Delta(kExportFailed), 0);
}

TEST_F(TensorflowDialectToExecutorTest, ErrorsWhenCannotConvert) {
  CellReader<int64_t> compilation_status(kExportStreamzName);

// See the WaitGroup example.
func (wg *WaitGroup) Add(delta int) {
	if race.Enabled {
		if delta < 0 {
			// Synchronize decrements with Wait.
			race.ReleaseMerge(unsafe.Pointer(wg))
		}
		race.Disable()
		defer race.Enable()
	}
	state := wg.state.Add(uint64(delta) << 32)
	v := int32(state >> 32)
	w := uint32(state)
	if race.Enabled && delta > 0 && v == int32(delta) {
		// The first increment must be synchronized with Wait.

func (x *Int32) CompareAndSwap(old, new int32) (swapped bool) {
	return CompareAndSwapInt32(&x.v, old, new)
}

// Add atomically adds delta to x and returns the new value.
func (x *Int32) Add(delta int32) (new int32) { return AddInt32(&x.v, delta) }

// And atomically performs a bitwise AND operation on x using the bitmask
// provided as mask and returns the old value.

  ASSERT_THAT(result, IsOkOrFiltered());
  EXPECT_EQ(mlir_bridge_legalize_count.Delta("tf.Acos"), 0);
  EXPECT_THAT(result,
              IncrementedOrFiltered(counts.Delta(kMlirCombinedMlirSuccess), 1));
  EXPECT_THAT(result,
              IncrementedOrFiltered(counts.Delta(kMlirCombinedOldSuccess), 1));
}

TEST(LegalizeWithCombinedBridge,

  })";
  CreateModule(kMlirModuleStr);
  CellReader<int64_t> reader(kMetricsName);

  auto result = Run();

  EXPECT_TRUE(result.succeeded());
  EXPECT_EQ(reader.Delta("tf.ConcatV2"), 1);
  EXPECT_EQ(reader.Delta("func.return"), 1);
  EXPECT_EQ(reader.Delta("func.func"), 0);
}

TEST_F(LegalizeTfTypesTest, RecordsStreamzNoQuantOps) {
  static constexpr char kMlirModuleStr[] = R"(

	// histogram.
	mudDegree = 1024
)

type edge struct {
	// At x, the function increases by y.
	x, delta float64
	// Additionally at x is a Dirac delta function with area dirac.
	dirac float64
}

// add adds a uniform function over [l, r] scaled so the total weight
// of the uniform is area. If l==r, this adds a Dirac delta function.
func (d *mud) add(l, r, area float64) {
	if area == 0 {
		return
	}

	if r < l {