> -----Original Message-----
> From: Richard Earnshaw
> Sent: Wednesday, April 16, 2014 6:21 PM
> To: Joey Ye
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: [patch] Disable if_conversion2 for Og
>
> On 16/04/14 11:17, Joey Ye wrote:
> >> -----Original Message-----
> >> From: Richard Earnshaw
> >> Sent: Wednesday, April 16, 2014 6:04 PM
> >> To: Joey Ye
> >> Cc: gcc-patches@gcc.gnu.org
> >> Subject: Re: [patch] Disable if_conversion2 for Og
> >>
> >> On 16/04/14 11:02, Joey Ye wrote:
> >>>
> >>>
> >>>> -----Original Message-----
> >>>> From: Richard Earnshaw
> >>>> Sent: Wednesday, April 16, 2014 5:44 PM
> >>>> To: Joey Ye
> >>>> Cc: gcc-patches@gcc.gnu.org
> >>>> Subject: Re: [patch] Disable if_conversion2 for Og
> >>>>
> >>>> Arguably, this is a bug in gdb. The debugger should understand
> >>>> when a breakpointed conditional instruction is not going to execute
> >>>> and silently continue. That preserves the illusion of not
> >>>> executing the code without requiring the compiler to de-optimize
> things.
> >>>>
> >>>> R.
> >>> Or compiler just optimizes it, and emits generic DWARFx information
> >>> to help GDB handle it in more target independently?
> >>>
> >>> - Joey
> >>>
> >>
> >> I'm not sure extra dwarf info would help much. The debugger still
> >> has to understand that the breakpoint has not really been hit.
> >>
> >> R.
> > Yes, it is inevitable. But without extra dwarf info it will be even more
painful:
> each time setting break-point or break-point hits it has to decode the
break-
> pointed instructions and its context to search for conditional execution
and IT
> blocks.
> >
>
> For thumb code it can get the conditional information it needs from the IT
> state in the PSR; for ARM code it has to look no further than the
instruction
> itself.
>
> R.
The thing is, debugger has to do this for every breakpoint, even though more
of them are not conditional execution, which isn't efficient.
