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

[escha via llvm-dev]

> 
> 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.

—escha
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