On Thu, Jun 30, 2011 at 12:02 PM, Richard Henderson <rth@redhat.com> wrote:
> On 06/30/2011 11:23 AM, H.J. Lu wrote:
>> +#ifdef REG_VALUE_IN_UNWIND_CONTEXT
>> +typedef _Unwind_Word _Unwind_Context_Reg_Val;
>> +/* Signal frame context.  */
>> +#define SIGNAL_FRAME_BIT ((_Unwind_Word) 1 >> 0)
>
> There's absolutely no reason to re-define this.
> So what if the value is most-significant-bit set?
>
> Nor do I see any reason not to continue setting E_C_B.

Done.

>> +#define _Unwind_IsExtendedContext(c) 1
>
> Why is this not still an inline function?

It is defined before _Unwind_Context is declared.  I used
macros so that there can be one less "#ifdef".

>> +
>> +static inline _Unwind_Word
>> +_Unwind_Get_Unwind_Word (_Unwind_Context_Reg_Val val)
>> +{
>> +  return val;
>> +}
>> +
>> +static inline _Unwind_Context_Reg_Val
>> +_Unwind_Get_Unwind_Context_Reg_Val (_Unwind_Word val)
>> +{
>> +  return val;
>> +}
>
> I cannot believe this actually works.  I see nowhere that
> you copy the by-address slot out of the stack frame and
> place it into the by-value slot in the unwind context.

I changed the implantation based on the feedback from
Jason.  Now I use the same reg field for both value and
address.

>>    /* This will segfault if the register hasn't been saved.  */
>>    if (size == sizeof(_Unwind_Ptr))
>> -    return * (_Unwind_Ptr *) ptr;
>> +    return * (_Unwind_Ptr *) (_Unwind_Internal_Ptr) val;
>>    else
>>      {
>>        gcc_assert (size == sizeof(_Unwind_Word));
>> -      return * (_Unwind_Word *) ptr;
>> +      return * (_Unwind_Word *) (_Unwind_Internal_Ptr) val;
>>      }
>
> Indeed, this section is both wrong and belies the change
> you purport to make.
>
> You didn't even test this, did you?
>

Here is the updated patch.  It works on simple tests.
I am running full tests.  I kept config/i386/value-unwind.h
since libgcc/md-unwind-support.h is included too late
in unwind-dw2.c and I don't want to move it to be on
the safe side.

OK for trunk?

Thanks.

-- 
H.J.
---
gcc/

2011-06-30  H.J. Lu  <hongjiu.lu@intel.com>

	* config.gcc (libgcc_tm_file): Add i386/value-unwind.h for
	Linux/x86.

	* system.h (REG_VALUE_IN_UNWIND_CONTEXT): Poisoned.

	* unwind-dw2.c (_Unwind_Context_Reg_Val): New.
	(_Unwind_Get_Unwind_Word): Likewise.
	(_Unwind_Get_Unwind_Context_Reg_Val): Likewise.
	(_Unwind_Context): Use _Unwind_Context_Reg_Val on the reg field.
	(_Unwind_IsExtendedContext): Defined as macro.
	(_Unwind_GetGR): Updated.
	(_Unwind_SetGR): Likewise.
	(_Unwind_GetGRPtr): Likewise.
	(_Unwind_SetGRPtr): Likewise.
	(_Unwind_SetGRValue): Likewise.
	(_Unwind_GRByValue): Likewise.
	(__frame_state_for): Likewise.
	(uw_install_context_1): Likewise.

	* doc/tm.texi.in: Document REG_VALUE_IN_UNWIND_CONTEXT.
	* doc/tm.texi: Regenerated.

libgcc/

2011-06-30  H.J. Lu  <hongjiu.lu@intel.com>

	* config/i386/value-unwind.h: New.