[llvm-dev] RFC: faster simplifyInstructionsInBlock/SimplifyInstructions pass

[escha via llvm-dev]

> On Sep 13, 2015, at 11:32 AM, Marcello Maggioni <mmaggioni at apple.com> wrote:
> 
>> 
>> On 13 Sep 2015, at 11:11, escha <escha at apple.com <mailto:escha at apple.com>> wrote:
>> 
>>> 
>>> Instead of adding the operands to a list, erase the instruction and add them to the worklist wouldn’t be probably faster something like:
>>> 
>>> if (Instruction *Used = dyn_cast<Instruction>(*OI))
>>>   if (Used->hasOneUse())
>>>     WorkList.insert(Used);
>>> 
>>> If it has one use is going to be the instruction we are going to remove anyway, right?
>> 
>> I don’t think this is strictly true, but someone correct me if I’m wrong: if you have
>> 
>> %y = add i32 %x, %x
>> 
>> %x will have two uses, but it will have zero if %y is deleted. This was the corner case I was worried about.
> 
> Yeah, I think you are right , I didn’t think about this case!
> 
> Marcello
> 
>> 
>> —escha

On this note, I have a feeling that both IR and the DAG could use a hasOneUser() function…

—escha
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