llvm dev - Sep 2002 - [LLVMdev] setCC

what's the semantics for setCC if one of the operands is NULL pointer?
%ptr=alloc int
seteq int*, %pt, NULL

what's the result for the second instruction? How about setne, setlt,
setgt, setle, and setge? Thanks!

Jianzhong

It seems like you should be able to statically evaluate these 
if you assume that NULL is zero and alloca returns an unsigned
nonzero pointer value.
> what's the semantics for setCC if one of the operands is NULL pointer?
> %ptr=alloc int
> seteq int*, %pt, NULL
> 
> what's the result for the second instruction? How about setne, setlt,
> setgt, setle, and setge? Thanks!
> 
> Jianzhong
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
-- 
gaeke at uiuc.edu

> what's the result for the second instruction? How about setne, setlt,
> setgt, setle, and setge? Thanks!
You do not consider setgt, setle, setge, setlt. It was mentioned in class
that you would do an assert on those cases.

-Tanya

Only seteq and setne are legal with pointer types.

For a ptr returned by an alloca, seteq ptr, NULL is always false and
setne ptr, NULL is always true.

--Vikram

-------------------------------------------------------------------------
 VIKRAM S. ADVE
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> -----Original Message-----
> From: llvmdev-admin at cs.uiuc.edu [mailto:llvmdev-admin at cs.uiuc.edu]On
> Behalf Of Brian R. Gaeke
> Sent: Saturday, September 28, 2002 12:57 AM
> To: Jianzhong Liu
> Cc: llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] setCC
> 
> 
> It seems like you should be able to statically evaluate these 
> if you assume that NULL is zero and alloca returns an unsigned
> nonzero pointer value.
> 
> > what's the semantics for setCC if one of the operands is NULL
pointer?
> > %ptr=alloc int
> > seteq int*, %pt, NULL
> > 
> > what's the result for the second instruction? How about setne,
setlt,
> > setgt, setle, and setge? Thanks!
> > 
> > Jianzhong
> > 
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
> -- 
> gaeke at uiuc.edu
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
>