[Release-2.1]Add finfo properties for float8 dtypes (#109808)

Add float8 finfo checks to `test_type_info.py`
Fixes #109737
Cherry-pick of #109744 into release/2.1 branch
Approved by: https://github.com/drisspg

(cherry picked from commit cddd0db)

aten/src/ATen/Dispatch.h

@@ -371,6 +371,22 @@ inline void deprecated_AT_DISPATCH_ALL_TYPES_AND_HALF_AND_COMPLEX() {}
       AT_DISPATCH_CASE_FLOATING_AND_COMPLEX_TYPES_AND3(     \
           SCALARTYPE1, SCALARTYPE2, SCALARTYPE3, __VA_ARGS__))
 
+#define AT_DISPATCH_CASE_FLOATING_AND_COMPLEX_TYPES_AND4(    \
+    SCALARTYPE1, SCALARTYPE2, SCALARTYPE3, SCALARTYPE4, ...) \
+  AT_DISPATCH_CASE_FLOATING_AND_COMPLEX_TYPES(__VA_ARGS__)   \
+  AT_DISPATCH_CASE(SCALARTYPE1, __VA_ARGS__)                 \
+  AT_DISPATCH_CASE(SCALARTYPE2, __VA_ARGS__)                 \
+  AT_DISPATCH_CASE(SCALARTYPE3, __VA_ARGS__)                 \
+  AT_DISPATCH_CASE(SCALARTYPE4, __VA_ARGS__)
+
+#define AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND4(                     \
+    SCALARTYPE1, SCALARTYPE2, SCALARTYPE3, SCALARTYPE4, TYPE, NAME, ...) \
+  AT_DISPATCH_SWITCH(                                                    \
+      TYPE,                                                              \
+      NAME,                                                              \
+      AT_DISPATCH_CASE_FLOATING_AND_COMPLEX_TYPES_AND4(                  \
+          SCALARTYPE1, SCALARTYPE2, SCALARTYPE3, SCALARTYPE4, __VA_ARGS__))
+
 #define AT_DISPATCH_CASE_INTEGRAL_TYPES(...)          \
   AT_DISPATCH_CASE(at::ScalarType::Byte, __VA_ARGS__) \
   AT_DISPATCH_CASE(at::ScalarType::Char, __VA_ARGS__) \

test/test_type_info.py

@@ -72,5 +72,25 @@ def test_finfo(self):
         # Restore the default type to ensure that the test has no side effect
         torch.set_default_dtype(initial_default_type)
 
+        # Special test case for Float8_E5M2
+        xinfo = torch.finfo(torch.float8_e5m2)
+        self.assertEqual(xinfo.bits, 8)
+        self.assertEqual(xinfo.max, 57344.0)
+        self.assertEqual(xinfo.min, -57344.0)
+        self.assertEqual(xinfo.eps, .25)
+        self.assertEqual(xinfo.tiny, 6.10352e-05)
+        self.assertEqual(xinfo.resolution, 1.0)
+        self.assertEqual(xinfo.dtype, "float8_e5m2")
+
+        # Special test case for Float8_E4M3FN
+        xinfo = torch.finfo(torch.float8_e4m3fn)
+        self.assertEqual(xinfo.bits, 8)
+        self.assertEqual(xinfo.max, 448.0)
+        self.assertEqual(xinfo.min, -448.0)
+        self.assertEqual(xinfo.eps, .125)
+        self.assertEqual(xinfo.tiny, 0.015625)
+        self.assertEqual(xinfo.resolution, 1.0)
+        self.assertEqual(xinfo.dtype, "float8_e4m3fn")
+
 if __name__ == '__main__':
     run_tests()

torch/csrc/TypeInfo.cpp

@@ -113,25 +113,43 @@ static PyObject* THPDTypeInfo_bits(THPDTypeInfo* self, void*) {
 }
 
 static PyObject* THPFInfo_eps(THPFInfo* self, void*) {
-  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND2(
-      at::kHalf, at::ScalarType::BFloat16, self->type, "epsilon", [] {
+  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND4(
+      at::kHalf,
+      at::ScalarType::BFloat16,
+      at::ScalarType::Float8_e4m3fn,
+      at::ScalarType::Float8_e5m2,
+      self->type,
+      "epsilon",
+      [] {
         return PyFloat_FromDouble(
             std::numeric_limits<
                 at::scalar_value_type<scalar_t>::type>::epsilon());
       });
 }
 
 static PyObject* THPFInfo_max(THPFInfo* self, void*) {
-  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND2(
-      at::kHalf, at::ScalarType::BFloat16, self->type, "max", [] {
+  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND4(
+      at::kHalf,
+      at::ScalarType::BFloat16,
+      at::ScalarType::Float8_e4m3fn,
+      at::ScalarType::Float8_e5m2,
+      self->type,
+      "max",
+      [] {
         return PyFloat_FromDouble(
             std::numeric_limits<at::scalar_value_type<scalar_t>::type>::max());
       });
 }
 
 static PyObject* THPFInfo_min(THPFInfo* self, void*) {
-  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND2(
-      at::kHalf, at::ScalarType::BFloat16, self->type, "lowest", [] {
+  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND4(
+      at::kHalf,
+      at::ScalarType::BFloat16,
+      at::ScalarType::Float8_e4m3fn,
+      at::ScalarType::Float8_e5m2,
+      self->type,
+      "lowest",
+      [] {
         return PyFloat_FromDouble(
             std::numeric_limits<
                 at::scalar_value_type<scalar_t>::type>::lowest());
@@ -170,8 +188,14 @@ static PyObject* THPIInfo_dtype(THPIInfo* self, void*) {
 }
 
 static PyObject* THPFInfo_smallest_normal(THPFInfo* self, void*) {
-  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND2(
-      at::kHalf, at::ScalarType::BFloat16, self->type, "min", [] {
+  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND4(
+      at::kHalf,
+      at::ScalarType::BFloat16,
+      at::ScalarType::Float8_e4m3fn,
+      at::ScalarType::Float8_e5m2,
+      self->type,
+      "smallest",
+      [] {
         return PyFloat_FromDouble(
             std::numeric_limits<at::scalar_value_type<scalar_t>::type>::min());
       });
@@ -183,8 +207,14 @@ static PyObject* THPFInfo_tiny(THPFInfo* self, void*) {
 }
 
 static PyObject* THPFInfo_resolution(THPFInfo* self, void*) {
-  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND2(
-      at::kHalf, at::ScalarType::BFloat16, self->type, "digits10", [] {
+  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND4(
+      at::kHalf,
+      at::ScalarType::BFloat16,
+      at::ScalarType::Float8_e4m3fn,
+      at::ScalarType::Float8_e5m2,
+      self->type,
+      "digits10",
+      [] {
         return PyFloat_FromDouble(std::pow(
             10,
             -std::numeric_limits<
@@ -194,9 +224,11 @@ static PyObject* THPFInfo_resolution(THPFInfo* self, void*) {
 
 static PyObject* THPFInfo_dtype(THPFInfo* self, void*) {
   auto primary_name = torch::utils::getDtypeNames(self->type).first;
-  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND2(
+  return AT_DISPATCH_FLOATING_AND_COMPLEX_TYPES_AND4(
       at::kHalf,
       at::ScalarType::BFloat16,
+      at::ScalarType::Float8_e4m3fn,
+      at::ScalarType::Float8_e5m2,
       self->type,
       "dtype",
       [&primary_name] { return PyUnicode_FromString(primary_name.data()); });