This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH v2 13/13] Add hook for modifying debug info for address spaces


On Wed, Oct 21, 2015 at 10:17 AM, Richard Henderson <rth@redhat.com> wrote:
> On 10/21/2015 04:53 AM, H.J. Lu wrote:
>>
>> On Tue, Oct 20, 2015 at 2:27 PM, Richard Henderson <rth@redhat.com> wrote:
>>>
>>> ---
>>>   gcc/config/i386/i386.c | 21 +++++++++++++++++++++
>>>   gcc/doc/tm.texi        |  7 +++++++
>>>   gcc/doc/tm.texi.in     |  2 ++
>>>   gcc/dwarf2out.c        | 48
>>> +++++++++++++++++++++++++++++-------------------
>>>   gcc/target.def         | 10 ++++++++++
>>>   gcc/targhooks.c        |  8 ++++++++
>>>   gcc/targhooks.h        |  1 +
>>>   7 files changed, 78 insertions(+), 19 deletions(-)
>>>
>>> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>>> index 8f833d1..9fb0fac 100644
>>> --- a/gcc/config/i386/i386.c
>>> +++ b/gcc/config/i386/i386.c
>>> @@ -53707,6 +53707,27 @@ ix86_addr_space_convert (rtx op, tree from_type,
>>> tree to_type)
>>>   #undef TARGET_ADDR_SPACE_CONVERT
>>>   #define TARGET_ADDR_SPACE_CONVERT ix86_addr_space_convert
>>>
>>> +static int
>>> +ix86_addr_space_debug (addr_space_t as)
>>> +{
>>> +  /* Represent debugging for address spaces with DW_AT_segment,
>>> +     and the dwarf register for fsbase/gsbase.  */
>>> +  if (as == ADDR_SPACE_SEG_TLS)
>>> +    as = DEFAULT_TLS_SEG_REG;
>>> +
>>> +  /* ??? These register numbers are defined in the x86-64 abi,
>>> +     but there is no corresponding definition for the i386 abi.
>>> +     That said, {58,59} appear to be reserved, so perhaps best
>>> +     to use the same numbers in the 32-bit abi.  */
>>> +  if (as == ADDR_SPACE_SEG_FS)
>>> +    return ~58;  /* dwarf fsbase */
>>> +  else if (as == ADDR_SPACE_SEG_GS)
>>> +    return ~59;  /* dwarf gsbase */
>>> +  gcc_unreachable ();
>>> +}
>>
>>
>> This is wrong for i386 psABI.  Please use the DWARF register
>> numbers listed in Table 2.14: DWARF Register Number Mapping
>> in Intel386 psABI:
>>
>> https://github.com/hjl-tools/x86-psABI/wiki/X86-psABI
>>
>> Segment Register ES 40 %es
>> Segment Register CS 41 %cs
>> Segment Register SS 42 %ss
>> Segment Register DS 43 %ds
>> Segment Register FS 44 %fs
>> Segment Register GS 45 %gs
>
>
> I'm not looking for the segment register (aka descriptor), I'm looking for
> the segment base.  Not the same thing.
>
> As I note in the comment, there is no such definition in the i386 psabi,
> while there is in the x86-64 psabi.

We can define them as 93 and 94.  50-92 were used for other registers
before and have been deprecated now.  But some old tools may
still use them.


-- 
H.J.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]