Re: [RFA] Accept compiler internal use of memcpy/bcopy for structs

[Michael Snyder <msnyder@redhat.com>]

Fred Fish wrote:
> 
> For cases where the compiler uses memcpy/bcopy to copy structs around,
> and those calls are found in a library for which debugging line number
> information is available, attempting to step into a function where a
> large struct is passed by value will first stop at the memcpy/bcopy
> call that the compiler calls prior to the user function.
> 
> The comment in step-test.exp says that "opinion is bitterly divided
> about whether this is the right behavior for GDB or not".  Regardless
> of which opinion you have, you would probably have to agree that gdb
> is currently behaving as designed, in the absence of additional
> code to not stop in functions used internally by the compiler.  Thus
> I believe the correct behavior of the test suite is to accept the
> cases where gdb stops in memcpy/bcopy.
> 
> Here is a patch to fix the testsuite.
> 
> -Fred

I like the fix -- but could you maybe use exp_continue instead of
duplicating the code for the pass condition?

> 
> 2002-01-08  Fred Fish  <fnf@redhat.com>
> 
>         * gdb.base/step-test.exp: Accept stopping in memcpy/bcopy when we
>         have debugging info for those functions and the compiler uses them
>         internally to copy structs around.
> 
> Index: gdb.base/step-test.exp
> ===================================================================
> RCS file: /cvs/src/src/gdb/testsuite/gdb.base/step-test.exp,v
> retrieving revision 1.3
> diff -c -p -r1.3 step-test.exp
> *** step-test.exp       2001/03/06 08:21:51     1.3
> --- step-test.exp       2002/01/08 16:51:30
> *************** gdb_test \
> *** 212,220 ****
>   gdb_test "continue" \
>            ".*Breakpoint ${decimal},.*large_struct_by_value.*" \
>          "run to pass large struct"
> ! gdb_test "step" \
> !          ".*step-test.exp: arrive here 1.*" \
> !          "large struct by value"
> 
>   gdb_continue_to_end "step-test.exp"
> 
> --- 212,244 ----
>   gdb_test "continue" \
>            ".*Breakpoint ${decimal},.*large_struct_by_value.*" \
>          "run to pass large struct"
> ! send_gdb "step\n"
> ! gdb_expect {
> !     -re ".*step-test.exp: arrive here 1.*$gdb_prompt $" {
> !       pass "large struct by value"
> !     }
> !     -re ".*(memcpy|bcopy).*$gdb_prompt $" {
> !       send_gdb "finish\n" ; gdb_expect -re "$gdb_prompt $"
> !       send_gdb "step\n"
> !       gdb_expect {
> !           -re ".*step-test.exp: arrive here 1.*$gdb_prompt $" {
> !               pass "large struct by value"
> !           }
> !           -re ".*$gdb_prompt $" {
> !               fail "large struct by value"
> !           }
> !           timeout {
> !               fail "large struct by value (timeout)"
> !           }
> !       }
> !     }
> !     -re ".*$gdb_prompt $" {
> !       fail "large struct by value"
> !     }
> !     timeout {
> !       fail "large struct by value (timeout)"
> !     }
> ! }
> 
>   gdb_continue_to_end "step-test.exp"
>