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

[Daniel Berlin]

reg2mem does not eliminate phi nodes the way codegen does, it just
converts ssa values to non-ssa values.

It's not the same thing.


On Tue, Apr 21, 2015 at 10:14 PM, Eric Lu <eirc.lew at gmail.com> wrote:
> By the way. When I remove these phi nodes with -reg2mem, some new load
> operations will be inserted, but when I try cache load operations with:
> visitFunction
> visitLoadInst
> It seems we can't see these new load operations.
>
> On Wed, Apr 22, 2015 at 1:10 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.
>>
>> 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)
>>
>> 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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>> >
>
>
>
>
> --
> Best Regards!
> Eric Lew