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Re: [PATCH] testsuite/gdb.dwarf2: Fix for dw2-ifort-parameter failure on ARM


On 19 September 2013 20:30, Omair Javaid <omair.javaid@linaro.org> wrote:
> Yao,
>
> Thanks for your feedback.
>
> Here is the testcase without my patch and breakpoint address gets
> adjusted because an odd address was being used:
>
> (gdb) break func
> warning: Breakpoint address adjusted from 0x000083bd to 0x000083bc.
> Breakpoint 1 at 0x83bc (2 locations)
> (gdb) run
> Starting program:
> /home/linaro/omair/bug_triage/gdb-7.6/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter
> warning: Breakpoint address adjusted from 0x000083bd to 0x000083bc.
> warning: Breakpoint address adjusted from 0x000083bd to 0x000083bc.
> warning: Breakpoint address adjusted from 0x000083bd to 0x000083bc.
> warning: Breakpoint 1 address previously adjusted from 0x000083bd to 0x000083bc.
>
> Breakpoint 1, 0x000083bc in func ()
> (gdb) p/x param
> No symbol "param" in current context.
> (gdb) FAIL: gdb.dwarf2/dw2-ifort-parameter.exp: p/x param
> testcase ./gdb.dwarf2/dw2-ifort-parameter.exp completed in 0 seconds
>
> Can you suggest any other way to fix this issue.
>
> Thanks you for you help.
>
>
> --
> Omair.
>
> On 16 July 2013 03:52, Yao Qi <yao@codesourcery.com> wrote:
>> On 07/15/2013 06:25 PM, Omair Javaid wrote:
>>>
>>> gdb.dwarf2/dw2-ifort-parameter fails on ARM because the dwarf2 debug
>>> information being created by gdb.dwarf2/dw2-ifort-parameter-debug.S
>>> gets corrupted because LSB of function addresses is ON in Thumb mode.
>>> ARM instructions are word aligned and LSB of instruction address is
>>> used to determine whether code being branched to is Thumb or ARM code.
>>> This patch solves the problem by decrementing function address by one
>>> in thumb mode. This patch has been tested on x86_64 and arm7 machines.
>>
>>
>> Omair,
>> IMO, the last bit of "function pointer value" indicates whether the target
>> function is an ARM or a thumb one.  The "address" should still refer to the
>> actual address, as "DWARF should tell the truth".  What is wrong *without*
>> your patch?
>>
>> --
>> Yao (éå)

Ping? Any suggestions? I can actually add labels in c code of this
test case and use those labels instead of function pointer values.
Would that be fine?


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