[Bug fortran/109575] Implement runtime check for valid function result
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109575 --- Comment #3 from Steve Kargl --- On Fri, Apr 21, 2023 at 08:24:45PM +, anlauf at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109575 > > --- Comment #2 from anlauf at gcc dot gnu.org --- > I have some idea how (and where) the runtime checks need to be implemented, > but I am confused by the following observations on the occurence of an > explicit RETURN statement and the use of a RESULT variable: > > __attribute__((fn spec (". "))) > integer(kind=4) q2 () > { > integer(kind=4) f; > > f = 2; > return f; > } > > > __attribute__((fn spec (". "))) > integer(kind=4) g () > { > integer(kind=4) __result_g; > > return __result_g; > return __result_g; > } > So, if I follow you correctly, you're worried by about the two 'return __result_g' versus the one 'return f'? Dead code elimination likely removes the second 'return __result_g'. It indeed seems odd!
[Bug fortran/109575] Implement runtime check for valid function result
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109575 --- Comment #2 from anlauf at gcc dot gnu.org --- I have some idea how (and where) the runtime checks need to be implemented, but I am confused by the following observations on the occurence of an explicit RETURN statement and the use of a RESULT variable: function f() integer :: f end function f1() integer :: f1 f1 = 1 end function q() result (f) integer :: f end function q2() result (f) integer :: f f = 2 end function g() integer :: g return end function g3() integer :: g3 g3 = 3 return end function r() result (f) integer :: f return end function r4() result (f) integer :: f f = 4 return end While the dump-fortran-original does not show any surprises, the tree-dump looks somewhat irregular: __attribute__((fn spec (". "))) integer(kind=4) f () { (void) 0; } __attribute__((fn spec (". "))) integer(kind=4) f1 () { integer(kind=4) __result_f1; __result_f1 = 1; return __result_f1; } __attribute__((fn spec (". "))) integer(kind=4) q () { (void) 0; } __attribute__((fn spec (". "))) integer(kind=4) q2 () { integer(kind=4) f; f = 2; return f; } __attribute__((fn spec (". "))) integer(kind=4) g () { integer(kind=4) __result_g; return __result_g; return __result_g; } __attribute__((fn spec (". "))) integer(kind=4) g3 () { integer(kind=4) __result_g3; __result_g3 = 3; return __result_g3; return __result_g3; } __attribute__((fn spec (". "))) integer(kind=4) r () { return; } __attribute__((fn spec (". "))) integer(kind=4) r4 () { integer(kind=4) f; f = 4; return f; return f; } This seems to correspond to two different paths to gfc_generate_return().
[Bug fortran/109575] Implement runtime check for valid function result
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109575 kargl at gcc dot gnu.org changed: What|Removed |Added CC||kargl at gcc dot gnu.org Ever confirmed|0 |1 Status|UNCONFIRMED |NEW Last reconfirmed||2023-04-20 Priority|P3 |P4 --- Comment #1 from kargl at gcc dot gnu.org --- Change status to "new" as I agree with Harald that this would be a nice runtime warning for debugging. Changed to 'P4'