[flang][cuda] Add bind name for __fss interface (#152803)

Author: clementval

flang/module/cudadevice.f90

@@ -743,11 +743,11 @@ attributes(device) real(8) function sinpi(x) bind(c,name='__nv_sinpi')
   end interface
 
   interface __ffs
-    attributes(device) integer function __ffs(i) bind(c)
+    attributes(device) integer function __ffs(i) bind(c, name='__nv_ffs')
       !dir$ ignore_tkr (d) i
       integer, value :: i
     end function
-    attributes(device) integer function __ffsll(i) bind(c)
+    attributes(device) integer function __ffsll(i) bind(c, name='__nv_ffsll')
       !dir$ ignore_tkr (d) i
       integer(8), value :: i
     end function

flang/test/Lower/CUDA/cuda-device-proc.cuf

@@ -53,6 +53,8 @@ attributes(global) subroutine devsub()
 
   res = __popc(ai)
   res = __popc(al)
+  res = __ffs(ai)
+  res = __ffs(al)
 end
 
 ! CHECK-LABEL: func.func @_QPdevsub() attributes {cuf.proc_attr = #cuf.cuda_proc<global>}
@@ -95,6 +97,8 @@ end
 
 ! CHECK: %{{.*}} = fir.call @__nv_popc(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (i32) -> i32
 ! CHECK: %{{.*}} = fir.call @__nv_popcll(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (i64) -> i32
+! CHECK: %{{.*}} = fir.call @__nv_ffs(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (i32) -> i32
+! CHECK: %{{.*}} = fir.call @__nv_ffsll(%{{.*}}) proc_attrs<bind_c> fastmath<contract> : (i64) -> i32
 
 subroutine host1()
   integer, device :: a(32)