[LLVMdev] what is the Line number of Phi Node with addr2line

[Daniel Berlin]

On Tue, Apr 21, 2015 at 10:10 PM, Eric Lu <eirc.lew at gmail.com> wrote:
> Hi, Daniel
>
> I want to profile load/store operations, in order to reduce the overhead of
> profiling, I try to instrument the optimized llvm ir, which has phi nodes.

Sure, but if you use -g, it also has debug info metadata attached to
stuff, and will get mostly right answers attached to the output.

>

> BTW, when the value of some load/store operations may have multi-source,
> then the load will be translated into phi nodes, and all phi nodes are
> placed in the front of BB. Sometimes, the position is not where the load
> happens, is there any way to figure out where the load should be placed?( If
> the phi node translated back to load operations)

Can you show me a code example, and i can give you an answer on how to
place them :)

>
> Best Regards!
> Eric Lew
>
> On 周三, 4月 22, 2015 at 12:24 下午, Daniel Berlin <dberlin at dberlin.org> wrote:
>
> Hey Eric,
> phi nodes don't exist for real, so you can't.
> The are removed by PHI elimination as part of codegen.
>
> What are you trying to achieve?
>
>
>
>
> On Tue, Apr 21, 2015 at 9:12 PM, Eric Lu <eirc.lew at gmail.com> wrote:
>> Hi, all
>>
>>    When compiling a program with -g -O0, and if we have a PC, then with
>> addr2line, we can get the line number of the instruction.
>>
>> My quesions are:  what is the result of Phi node instruction, can we get
>> the
>> similar results ?
>>
>> --
>> Best Regards!
>> Eric Lew
>>
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