pytorch/c10/core/DispatchKeySet.cpp

#include <c10/core/DispatchKeySet.h>

namespace c10 {

// backend_dispatch_keyset should include all runtime backend keys.
// Alias key DispatchKey::CompositeExplicitAutograd maps to
// backend_dispatch_keyset NestedTensor has been explicitly removed due to
// incompatibility with some kernels, such as structured kernels, that use the
// DefaultBackend key.
constexpr DispatchKeySet backend_dispatch_keyset = autogradother_backends |
    DispatchKeySet({
        DispatchKey::CPU,
        DispatchKey::CUDA,
        DispatchKey::XLA,
        DispatchKey::Lazy,
        DispatchKey::XPU,
        DispatchKey::PrivateUse1,
        DispatchKey::PrivateUse2,
        DispatchKey::PrivateUse3,
        DispatchKey::MLC,
        DispatchKey::HPU,
        DispatchKey::Meta,
    });

bool isBackendDispatchKey(DispatchKey t) {
  return t != DispatchKey::Undefined
      // See Note [No Alias Keys in DispatchKeySet]
      && !isAliasDispatchKey(t) && backend_dispatch_keyset.has(t);
}

// math_dispatch_keyset contains all keys in backend_dispatch_keyset and
// autograd_dispatch_keyset Alias key DispatchKey::CompositeImplicitAutograd
// maps to math_dispatch_keyset.
constexpr DispatchKeySet math_dispatch_keyset =
    backend_dispatch_keyset | autograd_dispatch_keyset;

DispatchKeySet getRuntimeDispatchKeySet(DispatchKey t) {
  TORCH_INTERNAL_ASSERT(t != DispatchKey::Undefined);
  switch (t) {
    case DispatchKey::Autograd:
      return autograd_dispatch_keyset;
    case DispatchKey::CompositeImplicitAutograd:
      return math_dispatch_keyset;
    case DispatchKey::CompositeExplicitAutograd:
      return backend_dispatch_keyset;
    default:
      return DispatchKeySet(t);
  }
}

// for a given autograd key, return the (guaranteed nonempty) set of associated
// backend keys. for a non-autograd key, return the empty keyset.
DispatchKeySet getBackendKeySetFromAutograd(DispatchKey t) {
  switch (t) {
    case DispatchKey::AutogradCPU:
      return DispatchKeySet(DispatchKey::CPU);
    case DispatchKey::AutogradCUDA:
      return DispatchKeySet(DispatchKey::CUDA);
    case DispatchKey::AutogradXLA:
      return DispatchKeySet(DispatchKey::XLA);
    case DispatchKey::AutogradLazy:
      return DispatchKeySet(DispatchKey::Lazy);
    case DispatchKey::AutogradMLC:
      return DispatchKeySet(DispatchKey::MLC);
    case DispatchKey::AutogradHPU:
      return DispatchKeySet(DispatchKey::HPU);
    case DispatchKey::AutogradNestedTensor:
      return DispatchKeySet(DispatchKey::NestedTensor);
    case DispatchKey::AutogradXPU:
      return DispatchKeySet(DispatchKey::XPU);
    case DispatchKey::AutogradPrivateUse1:
      return DispatchKeySet(DispatchKey::PrivateUse1);
    case DispatchKey::AutogradPrivateUse2:
      return DispatchKeySet(DispatchKey::PrivateUse2);
    case DispatchKey::AutogradPrivateUse3:
      return DispatchKeySet(DispatchKey::PrivateUse3);
    case DispatchKey::AutogradOther:
      return autogradother_backends;
    default:
      return DispatchKeySet();
  }
}

DispatchKeySet getAutocastRelatedKeySetFromBackend(DispatchKey t) {
  switch (t) {
    case DispatchKey::CPU:
      return DispatchKeySet(DispatchKey::AutocastCPU);
    case DispatchKey::CUDA:
      return DispatchKeySet(DispatchKey::AutocastCUDA);
    default:
      return DispatchKeySet();
  }
}

DispatchKeySet getAutogradRelatedKeySetFromBackend(DispatchKey t) {
  return DispatchKeySet(
      {DispatchKey::ADInplaceOrView, getAutogradKeyFromBackend(t)});
}

bool isIncludedInAlias(DispatchKey k, DispatchKey alias) {
  return k != DispatchKey::Undefined && getRuntimeDispatchKeySet(alias).has(k);
}

std::string toString(DispatchKeySet ts) {
  std::stringstream ss;
  ss << ts;
  return ss.str();
}

std::ostream& operator<<(std::ostream& os, DispatchKeySet ts) {
  if (ts.empty()) {
    os << "DispatchKeySet()";
    return os;
  }
  os << "DispatchKeySet(";
  DispatchKey tid;
  bool first = true;
  while ((tid = ts.highestPriorityTypeId()) != DispatchKey::Undefined) {
    if (!first) {
      os << ", ";
    }
    os << tid;
    ts = ts.remove(tid);
    first = false;
  }
  os << ")";
  return os;
}

} // namespace c10