Matthieu Wipliez
2010-Oct-20 11:31 UTC
[LLVMdev] Re : How to assign a constant to a register?
leledumbo, from what you say, I assume you have some kind of representation (AST or a lower-level intermediate representation) from which you generate LLVM assembly. Is this representation in SSA form? If it is, you might want to do a "copy propagation" transformation that replaces the uses of all variables that are assigned a constant value by their definitions. Example: x = 5 y = x + 1 z = x * y becomes y = 5 + 1 z = 5 * y Cheers Matthieu ----- Message d'origine ----> De : Duncan Sands <baldrick at free.fr> > À : llvmdev at cs.uiuc.edu > Envoyé le : Mer 20 octobre 2010, 11h 59min 32s > Objet : Re: [LLVMdev] How to assign a constant to a register? > > On 20/10/10 11:37, leledumbo wrote: > > > >> Why not just use ConstantInt::get() when you want the number 5? > > > > Because I'm not using LLVM libraries, I'm generating LLVM assembly myself. > > In that case, why not output '5' when you want 5? > > Ciao, > > Duncan. > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >
Hi, If x is a local variable, it will be stored on the stack. So you need an alloca for it: %x = alloca i8 ; <i8*> Then you can just perform a store: Store i8* %x, i8 0 Cheers, James> -----Original Message----- > From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] > On Behalf Of leledumbo > Sent: 20 October 2010 14:39 > To: llvmdev at cs.uiuc.edu > Subject: Re: [LLVMdev] Re : How to assign a constant to a register? > > > > from what you say, I assume you have some kind of representation(AST> or a > > lower-level intermediate representation) from which you generateLLVM> > assembly. > > Is this representation in SSA form? > > Yes, the representation is an AST. It's not in SSA yet, as it's a > direct > representation of the input. I'm confused for this node: > :> / \ > x 0 > > where x is a local variable. > > > If it is, you might want to do a "copy propagation" transformation > that > > replaces > > the uses of all variables that are assigned a constant value bytheir> > definitions. > > I'll consider it, it would useful for constant expression. > > -- > View this message in context: http://old.nabble.com/How-to-assign-a- > constant-to-a-register--tp29987387p30009972.html > Sent from the LLVM - Dev mailing list archive at Nabble.com. > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev-- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
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- [LLVMdev] Re : How to assign a constant to a register?
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- [LLVMdev] Re : How to assign a constant to a register?
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