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Re: RFA: GCC stabs don't contain prototype info
- From: Jim Blandy <jimb at zwingli dot cygnus dot com>
- To: gdb-patches at sources dot redhat dot com
- Date: 07 Dec 2001 16:18:43 -0500
- Subject: Re: RFA: GCC stabs don't contain prototype info
- References: <20011127034423.DF2B75E9D8@zwingli.cygnus.com>
I've committed this change.
Jim Blandy <jimb@cygnus.com> writes:
> This comes as a bit of a surprise to me, but it seems that stabs
> generated by GCC don't indicate whether a given function was defined
> with a prototype or not. The argument types should appear after the
> return types, each preceded by a semicolon, but for the following
> input program:
>
> int foo (int a, float b) { return a + b; }
>
> `gcc -save-temps -O2 -g -c' generates the following relevant stabs:
>
> .stabs "int:t(0,1)=r(0,1);0020000000000;0017777777777;",128,0,0,0
> .stabs "float:t(0,12)=r(0,1);4;0;",128,0,0,0
> .stabs "foo:F(0,1)",36,0,1,foo
> .stabs "a:P(0,1)",64,0,1,8
> .stabs "b:P(0,12)",64,0,1,9
> .stabs "",36,0,0,.LLscope0-foo
> .stabs "",100,0,0,.Letext
>
> There is no no prototype info here. There's no way for GDB to know
> that the function expects its second argument to be passed as a float,
> not promoted to a double, as the K&R-style rules specify.
>
> Thus:
>
> 2001-11-26 Jim Blandy <jimb@redhat.com>
>
> * gdb.base/callfuncs.exp: The stabs generated by GCC don't tell us
> whether functions are prototyped or not, so we can't possibly pass
> arguments to t_float_values2 properly.
>
> Index: gdb/testsuite/gdb.base/callfuncs.exp
> ===================================================================
> RCS file: /cvs/cvsfiles/devo/gdb/testsuite/gdb.base/callfuncs.exp,v
> retrieving revision 1.46
> diff -c -r1.46 callfuncs.exp
> *** gdb/testsuite/gdb.base/callfuncs.exp 2001/11/10 00:08:23 1.46
> --- gdb/testsuite/gdb.base/callfuncs.exp 2001/11/27 03:24:59
> ***************
> *** 142,147 ****
> --- 142,150 ----
> gdb_test "p t_float_values(float_val1,-2.3765)" " = 1"
>
> # Test passing of arguments which might not be widened.
> + # Under stabs, GCC doesn't tell us whether the function was
> + # prototyped or not.
> + if {$gcc_compiled} { setup_xfail_format "stabs" }
> gdb_test "p t_float_values2(0.0,0.0)" " = 0"
>
> # Although PR 5318 mentions SunOS specifically, this seems
> ***************
> *** 152,158 ****
> --- 155,166 ----
> setup_xfail "alpha-dec-osf2*" "i*86-*-sysv4*" 5318
> }
> }
> +
> + # Under stabs, GCC doesn't tell us whether the function was
> + # prototyped or not.
> + if {$gcc_compiled} { setup_xfail_format "stabs" }
> gdb_test "p t_float_values2(3.14159,float_val2)" " = 1"
> +
> gdb_test "p t_small_values(1,2,3,4,5,6,7,8,9,10)" " = 55"
>
> gdb_test "p t_double_values(0.0,0.0)" " = 0"
> ***************
> *** 289,294 ****
> --- 297,304 ----
> }
> }
> }
> +
> + get_debug_format
>
> # Make sure that malloc gets called and that the floating point unit
> # is initialized via a call to t_double_values.
>