On 02/05/2014 09:36 AM, Josh Stone wrote:
On 02/05/2014 03:44 AM, Mark Wielaard wrote:
> On Tue, 2014-02-04 at 18:24 -0800, Josh Stone wrote:
>> So now I'm not sure anything needs to change. At least dwarf_formsdata
>> should stay as-is for gcc.
>
> Are you sure? I think your original analysis is correct that
> dwarf_formsdata () is wrong and really should sign-extend.
No, see above; GCC wrote signed index 199 into a data1:199, so it would
be wrong to sign-extend this. We're at the mercy of the producer.
Here's gdb precedent for the status quo, not sign-extending, in the
comment right before dwarf2_const_value_data in gdb/dwarf2read.c:
/* Given an attr with a DW_FORM_dataN value in host byte order,
zero-extend it as appropriate for the symbol's type. The DWARF
standard (v4) is not entirely clear about the meaning of using
DW_FORM_dataN for a constant with a signed type, where the type is
wider than the data. The conclusion of a discussion on the DWARF
list was that this is unspecified. We choose to always zero-extend
because that is the interpretation long in use by GCC. */
current source:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gdb/dwa...
original commit:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;h=0...