[LLVMdev] Re : Re : How to assign a constant to a register?

[Matthieu Wipliez]

Yes, because an alloca allocates stack memory for %x, so this means that %x is a 
pointer, not a register in SSA form.
So you need to use "load" and "store" to access the contents of the variable and 
to modify it respectively (as shown in the "Memory in LLVM" section: 
http://llvm.org/docs/tutorial/LangImpl7.html#memory )
Using local registers is less verbose (because you do not have all those 
load/store operations), and is not too hard to generate if you already have a 
representation in SSA form.
On the other hand, using loads and stores does not require the SSA form, and the 
code will use registers anyway once the mem2reg pass is run.

Matthieu



----- Message d'origine ----
> De : leledumbo <leledumbo_cool at yahoo.co.id>
> À : llvmdev at cs.uiuc.edu
> Envoyé le : Jeu 21 octobre 2010, 8h 19min 53s
> Objet : Re: [LLVMdev] Re   :  How to assign a constant to a register?
> 
> 
> > If x is a local variable, it will be stored on the stack. So you need  an
> > alloca for it:
> 
> Aha, I remember this in Kaleidoscope tutorial.  So, after the alloca %x can
> be modified freely (e.g. without adding  suffix)?
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