[LLVMdev] Fwd: LLVM IR Branchs

[Rafael Baldiati Parizi]

Sorry, %3 instead of %4.

2011/9/14 Rafael Baldiati Parizi <parizi.computacao at gmail.com>

> Hello,
> I created a new block for execution to continue, but I got the case in
> which a statement defined in a block is used in another, not dominate all
> uses.
> For example:
>
> entry:
>    %n_addr = alloca i32, align 4
>    %retval = alloca i32
>    %"alloca point" = bitcast i32 0 to i32
>   store i32 %n, i32* %n_addr
>    %0 = call i32 (i8*, ...)* @printf(i8* noalias getelementptr inbounds
> ([20 x i8]* @.str, i32 0, i32 0)) nounwind
>    %1 = load i32* %n_addr, align 4
>    %2 = and i32 %1, 1
> *   %3* = icmp eq i32 %2, 0
>    .....
>    br label %new_block
>
> new_block:
>  %4 =  call i32 (i8*, ...)* @printf(i8* noalias getelementptr inbounds ([10
> x i8]* @.str1, i32 0, i32 0), i32 *%3*) nounwind
>  ...
>
>
> How to solve this?
>
> 2011/9/5 Rafael Baldiati Parizi <parizi.computacao at gmail.com>
>
>> Ok!  I do understand.
>> Thanks by help!
>>
>>
>> 2011/9/5 Justin Holewinski <justin.holewinski at gmail.com>
>>
>>> On Mon, Sep 5, 2011 at 8:37 PM, Rafael Baldiati Parizi <
>>> parizi.computacao at gmail.com> wrote:
>>>
>>>> Yes, that's how I'm doing now ... create a new block where the execution
>>>> flow will continue after the shift, following the basics of basic blocks.
>>>> But, I want to find a way to reduce the number of block of my code.
>>>
>>>
>>> Why do you want to reduce the number of LLVM IR blocks?  Just because
>>> LLVM IR does not have fall-through branches does not mean that the generated
>>> code will not have them.  As mentioned before, this is just a level of
>>> abstraction used in the LLVM IR.
>>>
>>>
>>>>
>>>>
>>>> 2011/9/5 Nick Lewycky <nicholas at mxc.ca>
>>>>
>>>>> Rafael Baldiati Parizi wrote:
>>>>>
>>>>>> I have two values and I want see if them are equals. Then, I would a
>>>>>> instruction like
>>>>>> if Value1 != Value2, error
>>>>>> without create a new block, continuing the execution in the same
>>>>>> block,
>>>>>> forcing the LLI to execute this.
>>>>>>
>>>>>
>>>>> You can not. The definition of a "basic block" is a sequence of
>>>>> instructions with a single entry and a single exit. You can not insert
>>>>> multiple exits within a basic block.
>>>>>
>>>>> I realize that this restriction feels arbitrary, but there's a vast
>>>>> amount of research and practical experience in compiler design built around
>>>>> the notion of basic blocks making up a control flow graph.
>>>>>
>>>>> Nick
>>>>>
>>>>>  2011/9/5 Eli Friedman <eli.friedman at gmail.com
>>>>>> <mailto:eli.friedman at gmail.com**>>
>>>>>>
>>>>>>
>>>>>>    On Mon, Sep 5, 2011 at 4:47 PM, Rafael Baldiati Parizi
>>>>>>    <parizi.computacao at gmail.com <mailto:parizi.computacao@**gmail.com<parizi.computacao at gmail.com>
>>>>>> >>
>>>>>>
>>>>>>    wrote:
>>>>>>     > Hello,
>>>>>>     > I would know how can I make a branch in llvm ir without a label
>>>>>> of
>>>>>>     > destination?
>>>>>>     > For example:
>>>>>>     > br i1 %1, label %bb,  NO LABEL HERE
>>>>>>
>>>>>>    What are you trying to do?
>>>>>>
>>>>>>    -Eli
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> */Rafael Parizi/*
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ______________________________**_________________
>>>>>> LLVM Developers mailing list
>>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>>> http://lists.cs.uiuc.edu/**mailman/listinfo/llvmdev<http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> *Rafael Parizi*
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
>>>>
>>>
>>>
>>> --
>>>
>>> Thanks,
>>>
>>> Justin Holewinski
>>>
>>>
>>
>>
>> --
>> *Rafael Parizi*
>>
>>
>>
>>
>
>
> --
> *Rafael Parizi*
>
>
>
>


-- 
*Rafael Parizi*
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