Re: [PATCH v2 03/11] change gdb.base/skip.exp to use finish instead of step

[Bruno Larsen <blarsen@redhat.com>]

Further testing showed that this version of the patch is racy, because of when gdb_test_multiple were getting the outputs. Changing the following regexps:

".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);.*"
".*test_skip_file_and_function \\(\\).*"

with


".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);\r\n$gdb_prompt $"
".*test_skip_file_and_function \\(\\);\r\n$gdb_prompt $"

I've made these changes locally. Please keep this in mind when reviewing the patch.

Cheers!
Bruno Larsen

On 4/11/22 17:13, Bruno Larsen wrote:
> skip.exp was making use of a fixed amount of step commands to exit
> some functions.  This caused some problems when testing GDB with clang,
> as it doesn't add epilogue information for functions, along with some
> unreliable results depending on the version of GCC, as sometimes gdb
> could stop in either of the 2 lines after 2 steps:
> 
> x = bax ((bar (), foo ()))
> test_skip_file_and_function ();
> 
> whereas using clang will always stop on the second line after 1 step.
> To deal with GCC unreliability, this test case used to use the question
> mechanism from gdb_test, but Pedro mentioned that this is a mis-use of
> that feature, and it doesn't deal with the clang case.  This commit
> changes it to use gdb_test_multiple and deal with all possible cases,
> only considering it a pass when test_skip_file_and_function () is
> reached.
> ---
>   gdb/testsuite/gdb.base/skip.exp | 164 +++++++++++++++++++++++++-------
>   1 file changed, 131 insertions(+), 33 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.base/skip.exp b/gdb/testsuite/gdb.base/skip.exp
> index 7c71bb07a84..5021b696668 100644
> --- a/gdb/testsuite/gdb.base/skip.exp
> +++ b/gdb/testsuite/gdb.base/skip.exp
> @@ -117,9 +117,23 @@ with_test_prefix "step after deleting 1" {
>   	return
>       }
>   
> -    gdb_test "step" "foo \\(\\) at.*" "step 1"
> -    gdb_test "step" ".*" "step 2" ; # Return from foo()
> -    gdb_test "step" "main \\(\\) at.*" "step 3"
> +    gdb_test "step" "foo \\(\\) at.*" "step"
> +    # step until we are after foo and bar calls, while making sure that
> +    # we never step into baz.
> +    gdb_test_multiple "step" "step until main" {
> +	# gcc stop in this line before continuing
> +	-re ".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);.*" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*\}\r\n$gdb_prompt $" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*test_skip_file_and_function \\(\\).*" {
> +	    pass "step until main"
> +	}
> +    }
>   }
>   
>   # Now disable the skiplist entry for  skip1.c.  We should now
> @@ -137,13 +151,27 @@ with_test_prefix "step after disabling 3" {
>       }
>   
>       gdb_test "step" "bar \\(\\) at.*" "step 1"
> -    gdb_test "step" ".*" "step 2"; # Return from bar()
> -    # With gcc 9.2.0 we jump once back to main before entering foo here.
> -    # If that happens try to step a second time.
> -    gdb_test "step" "foo \\(\\) at.*" "step 3" \
> -	"main \\(\\) at .*\r\n$gdb_prompt " "step"
> -    gdb_test "step" ".*" "step 4"; # Return from foo()
> -    gdb_test "step" "main \\(\\) at.*" "step 5"
> +    # guarantee that we jump once back to main before entering foo here.
> +    # This makes behavior more consistent over different compilers and
> +    # different compiler versions
> +    gdb_test "finish" ".*" "finish 1"; # Return to main()
> +    gdb_test "step" "foo \\(\\) at.*" "step 2"
> +    # step until we are after foo and bar calls, while making sure that
> +    # we never step into baz.
> +    gdb_test_multiple "step" "step until main" {
> +	# gcc stop in this line before continuing
> +	-re ".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);.*" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*\}\r\n$gdb_prompt $" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*test_skip_file_and_function \\(\\).*" {
> +	    pass "step until main"
> +	}
> +    }
>   }
>   
>   # Enable skiplist entry 3 and make sure we step over it like before.
> @@ -159,9 +187,23 @@ with_test_prefix "step after enable 3" {
>   	return
>       }
>   
> -    gdb_test "step" "foo \\(\\) at.*" "step 1"
> -    gdb_test "step" ".*" "step 2"; # Return from foo()
> -    gdb_test "step" "main \\(\\) at.*" "step 3"
> +    gdb_test "step" "foo \\(\\) at.*" "step"
> +    # step until we are after foo and bar calls, while making sure that
> +    # we never step into baz.
> +    gdb_test_multiple "step" "step until main" {
> +	# gcc stop in this line before continuing
> +	-re ".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);.*" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*\}\r\n$gdb_prompt $" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*test_skip_file_and_function \\(\\).*" {
> +	    pass "step until main"
> +	}
> +    }
>   }
>   
>   # Admin tests (disable,enable,delete).
> @@ -230,9 +272,23 @@ with_test_prefix "step using -fi" {
>   
>       gdb_test_no_output "skip disable"
>       gdb_test_no_output "skip enable 5"
> -    gdb_test "step" "foo \\(\\) at.*" "step 1"
> -    gdb_test "step" ".*" "step 2"; # Return from foo()
> -    gdb_test "step" "main \\(\\) at.*" "step 3"
> +    gdb_test "step" "foo \\(\\) at.*" "step"
> +    # step until we are after foo and bar calls, while making sure that
> +    # we never step into baz.
> +    gdb_test_multiple "step" "step until main" {
> +	# gcc stop in this line before continuing
> +	-re ".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);.*" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*\}\r\n$gdb_prompt $" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*test_skip_file_and_function \\(\\).*" {
> +	    pass "step until main"
> +	}
> +    }
>   }
>   
>   with_test_prefix "step using -gfi" {
> @@ -242,9 +298,23 @@ with_test_prefix "step using -gfi" {
>   
>       gdb_test_no_output "skip disable"
>       gdb_test_no_output "skip enable 6"
> -    gdb_test "step" "foo \\(\\) at.*" "step 1"
> -    gdb_test "step" ".*" "step 2"; # Return from foo()
> -    gdb_test "step" "main \\(\\) at.*" "step 3"
> +    gdb_test "step" "foo \\(\\) at.*" "step"
> +    # step until we are after foo and bar calls, while making sure that
> +    # we never step into baz.
> +    gdb_test_multiple "step" "step until main" {
> +	# gcc stop in this line before continuing
> +	-re ".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);.*" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*\}\r\n$gdb_prompt $" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*test_skip_file_and_function \\(\\).*" {
> +	    pass "step until main"
> +	}
> +    }
>   }
>   
>   with_test_prefix "step using -fu for baz" {
> @@ -255,13 +325,27 @@ with_test_prefix "step using -fu for baz" {
>       gdb_test_no_output "skip disable"
>       gdb_test_no_output "skip enable 7"
>       gdb_test "step" "bar \\(\\) at.*" "step 1"
> -    gdb_test "step" ".*" "step 2"; # Return from bar()
> -    # With gcc 9.2.0 we jump once back to main before entering foo here.
> -    # If that happens try to step a second time.
> -    gdb_test "step" "foo \\(\\) at.*" "step 3" \
> -	"main \\(\\) at .*\r\n$gdb_prompt " "step"
> -    gdb_test "step" ".*" "step 4"; # Return from foo()
> -    gdb_test "step" "main \\(\\) at.*" "step 5"
> +    # guarantee that we jump once back to main before entering foo here.
> +    # This makes behavior more consistent over different compilers and
> +    # different compiler versions
> +    gdb_test "finish" ".*" "finish 1"; # Return to main()
> +    gdb_test "step" "foo \\(\\) at.*" "step 2"
> +    # step until we are after foo and bar calls, while making sure that
> +    # we never step into baz.
> +    gdb_test_multiple "step" "step until main" {
> +	# gcc stop in this line before continuing
> +	-re ".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);.*" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*\}\r\n$gdb_prompt $" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*test_skip_file_and_function \\(\\).*" {
> +	    pass "step until main"
> +	}
> +    }
>   }
>   
>   with_test_prefix "step using -rfu for baz" {
> @@ -272,13 +356,27 @@ with_test_prefix "step using -rfu for baz" {
>       gdb_test_no_output "skip disable"
>       gdb_test_no_output "skip enable 8"
>       gdb_test "step" "bar \\(\\) at.*" "step 1"
> -    gdb_test "step" ".*" "step 2"; # Return from bar()
> -    # With gcc 9.2.0 we jump once back to main before entering foo here.
> -    # If that happens try to step a second time.
> -    gdb_test "step" "foo \\(\\) at.*" "step 3" \
> -	"main \\(\\) at .*\r\n$gdb_prompt " "step"
> -    gdb_test "step" ".*" "step 4"; # Return from foo()
> -    gdb_test "step" "main \\(\\) at.*" "step 5"
> +    # guarantee that we jump once back to main before entering foo here.
> +    # This makes behavior more consistent over different compilers and
> +    # different compiler versions
> +    gdb_test "finish" ".*" "finish 1"; # Return to main()
> +    gdb_test "step" "foo \\(\\) at.*" "step 2"
> +    # step until we are after foo and bar calls, while making sure that
> +    # we never step into baz.
> +    gdb_test_multiple "step" "step until main" {
> +	# gcc stop in this line before continuing
> +	-re ".*x = baz \\(\\(bar \\(\\), foo \\(\\)\\)\\);.*" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*\}\r\n$gdb_prompt $" {
> +	    send_gdb "step\n"
> +	    exp_continue
> +	}
> +	-re ".*test_skip_file_and_function \\(\\).*" {
> +	    pass "step until main"
> +	}
> +    }
>   }
>   
>   # Test -fi + -fu.