[flang][cuda] Add interface for __saturatef (#153705)

Author: clementval

flang/module/cudadevice.f90

@@ -325,6 +325,13 @@ attributes(device) real(8) function rsqrt(x) bind(c,name='__nv_rsqrt')
     end function
   end interface
 
+  interface saturate
+    attributes(device) real function __saturatef(r) bind(c, name='__nv_saturatef')
+      !dir$ ignore_tkr (d) r
+      real, value :: r
+    end function
+  end interface
+
   interface __sad
     attributes(device) integer function __sad(i,j,k) bind(c, name='__nv_sad')
       !dir$ ignore_tkr (d) i, (d) j, (d) k

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

@@ -162,6 +162,15 @@ end subroutine
 ! CHECK: %{{.*}} = fir.call @__nv_double2ull_ru(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (f64) -> i64
 ! CHECK: %{{.*}} = fir.call @__nv_double2ull_rz(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (f64) -> i64
 
+attributes(global) subroutine test_saturatef()
+  real :: res
+  real :: r
+  res = __saturatef(r)
+end subroutine
+
+! CHECK-LABEL: _QPtest_saturatef
+! CHECK: %{{.*}} = fir.call @__nv_saturatef(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (f32) -> f32
+
 attributes(global) subroutine test_float2ll_rX()
   integer(8) :: res
   real :: r