[PATCH] Added lowering of dbg.declare in JumpThreading.cpp

[Karl-Johan Karlsson]

Ping.

Regards
/ Karl-Johan Karlsson

On 02/09/2015 03:23 PM, Karl-Johan Karlsson wrote:
> The jumpthreading algorithm might duplicate blocks, including
> dbg.declare instrinsics. Avoid ending up with two dbg.declare
> intrinsics for a single alloca, by using the same method as in
> InstructionCombining. Lower the dbg.declare intrinsics into an
> appropriate set of dbg.value instrinsics.
>
> Regards
> / Karl-Johan Karlsson
>
> On 02/06/2015 09:39 AM, Karl-Johan Karlsson wrote:
>>
>>
>> On 02/05/2015 08:21 PM, Hans Wennborg wrote:
>>> On Thu, Feb 5, 2015 at 4:49 AM, Karl-Johan Karlsson
>>> <karl-johan.karlsson at ericsson.com> wrote:
>>>> I have a small issue with the JumpThreading pass (in opt). As
>>>> described in
>>>> the code (JumpThreading.cpp), the pass may if certain criteria are
>>>> fulfilled
>>>> duplicate the content of a block. If the duplicated block contain a
>>>> call to
>>>> @llvm.dbg.declare() you will end up with invalid code as the intrinsic
>>>> @llvm.dbg.declare() only should occur once for each variable.
>>>>
>>>> I think the JumpThreading pass should lower all llvm.dbg.declare() into
>>>> llvm.dbg.value() the same way as the instcombine pass do (see
>>>> InstructionCombining.cpp):
>>>>
>>>>    // Lower dbg.declare intrinsics otherwise their value may be
>>>> clobbered
>>>>    // by instcombiner.
>>>>    bool DbgDeclaresChanged = LowerDbgDeclare(F);
>>>>
>>>> Do you agree? Ok to commit?
>>>
>>> Did you forget to attach a patch? A patch with a test case showing the
>>> problem you're describing would be great.
>>>
>>> Also, patches should generally be sent to the llvm-commits list, not
>>> llvmdev.
>>
>> I will create a patch with a testcase and send it to llvm-commits.
>>
>> Regards
>> / Karl-Johan Karlsson
>>
>>>
>>> Thanks,
>>> Hans
>>>
>>>
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>>
>
>
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