[flang][cuda] Add interfaces for int_as_float and float_as_int (#153716)

Author: clementval

flang/module/cudadevice.f90

@@ -471,6 +471,20 @@ attributes(device) real(8) function sinpi(x) bind(c,name='__nv_sinpi')
    end function
   end interface
 
+  interface int_as_float
+    attributes(device) real function __int_as_float(i) bind(c, name='__nv_int_as_float')
+      !dir$ ignore_tkr (d) i
+      integer, value :: i
+    end function
+  end interface
+
+  interface float_as_int
+    attributes(device) integer function __float_as_int(i) bind(c, name='__nv_float_as_int')
+      !dir$ ignore_tkr (d) i
+      real, value :: i
+    end function
+  end interface
+
   interface __float2half_rn
     attributes(device) real(2) function __float2half_rn(r) bind(c, name='__nv_float2half_rn')
       !dir$ ignore_tkr (d) r

flang/test/Lower/CUDA/cuda-libdevice.cuf

@@ -245,6 +245,24 @@ end subroutine
 ! CHECK: %{{.*}} = fir.call @__nv_float2uint_ru(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (f32) -> i32
 ! CHECK: %{{.*}} = fir.call @__nv_float2uint_rz(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (f32) -> i32
 
+attributes(global) subroutine test_int_as_float()
+  integer :: i
+  real :: res
+  res = int_as_float(i)
+end subroutine
+
+! CHECK-LABEL: _QPtest_int_as_float
+! CHECK: %{{.*}} = fir.call @__nv_int_as_float(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (i32) -> f32
+
+attributes(global) subroutine test_float_as_int()
+  integer :: res
+  real :: r
+  res = float_as_int(r)
+end subroutine
+
+! CHECK-LABEL: _QPtest_float_as_int
+! CHECK: %{{.*}} = fir.call @__nv_float_as_int(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (f32) -> i32
+
 attributes(global) subroutine test_double2loint()
   integer :: res
   double precision :: r