[Dwarf-Discuss] DW_AT_default_value reference to "subroutine"

Cary Coutant ccoutant at gmail.com
Tue Sep 16 13:40:31 PDT 2014


DWARF v2, Section 4.1:

8. A formal parameter entry describing a formal parameter that has a
default value may have a DW_AT_default_value attribute. The value of
this attribute is a reference to the debugging information entry for a
variable or subroutine. The default value of the parameter is the
value of the variable (which may be constant) or the value returned by
the subroutine. If the value of the DW_AT_default_value attribute is
0, it means that no default value has been specified.

DWARF v3, Section 4.1:

9. A formal parameter entry may have a DW_AT_default_value attribute.
The value of this attribute is a reference to the debugging
information entry for a variable or subroutine, or the value may be a
constant. If it is a reference, the default value of the parameter is
the value of the variable (which may be constant) or the value
returned by the subroutine. If the value of the DW_AT_default_value
attribute is 0, it means that no default value has been specified. If
the value is of form constant, that constant is interpreted as a value
of the type of the formal parameter.

For a constant form there is no way to express the absence of a default value.

DWARF v4, Section 4.1:

9. A DW_AT_default_value attribute for a formal parameter entry. The
value of this attribute is a reference to the debugging information
entry for a variable or subroutine, or the value may be a constant. If
the attribute form is of class reference, the default value of the
parameter is the value of the referenced variable (which may be
constant) or the value returned by the referenced subroutine; a
reference value of 0 means that no default value has been specified.
If the value is of class constant, that constant is interpreted as a
default value of the type of the formal parameter.

For a constant form there is no way to express the absence of a default value.

-cary


On Tue, Sep 16, 2014 at 1:32 PM, David Anderson <davea42 at earthlink.net> wrote:
> On 09/16/2014 12:32 PM, Robinson, Paul wrote:
>> Any old-timers out there who can shed light on the intent of this
>> terminology?  I see similar verbiage all the way back to DWARF 2.
>> Thanks,
>
>
> Paul, could you be more specific about where the 'similar verbiage' is?
> Thanks.
> DavidA.
>
>
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