[PATCH] `nonnull` argument attribute.

[Hal Finkel]

----- Original Message -----
> From: "Nick Lewycky" <nicholas at mxc.ca>
> To: reviews+D3389+public+a85d4f162cd7a6e0 at reviews.llvm.org
> Cc: llvm-commits at cs.uiuc.edu
> Sent: Thursday, April 17, 2014 10:52:35 PM
> Subject: Re: [PATCH] `nonnull` argument attribute.
> 
> Your change to lib/IR/Value.cpp is wrong, a nonnull pointer is not
> necessarily dereferenceable.
> 
> %a = inttoptr i32 123456 to i32*
> call void @foo(i32* %a nonnull)
> 
> It's nonnull, but not dereferenceable.

I'll add that we really should have a dereferenceable attribute, IMHO, but as Nick said, it needs to be a separate from notnull. I think that for dereferenceable we'll want to have a more involved discussion because we'll need to decide if it affects derived pointers, should it have a size parameter, etc.

 -Hal

> 
> Nick
> 
> Luqman Aden wrote:
> >    Added test.
> >
> > http://reviews.llvm.org/D3389
> >
> > CHANGE SINCE LAST DIFF
> >    http://reviews.llvm.org/D3389?vs=8552&id=8553#toc
> >
> > Files:
> >    lib/AsmParser/LLToken.h
> >    lib/AsmParser/LLParser.cpp
> >    lib/AsmParser/LLLexer.cpp
> >    lib/Bitcode/Writer/BitcodeWriter.cpp
> >    lib/Bitcode/Reader/BitcodeReader.cpp
> >    lib/IR/Function.cpp
> >    lib/IR/Attributes.cpp
> >    lib/Analysis/ValueTracking.cpp
> >    test/Bitcode/attributes.ll
> >    test/Analysis/BasicAA/nonnull.ll
> >    include/llvm/Bitcode/LLVMBitCodes.h
> >    include/llvm/IR/Attributes.h
> >    include/llvm/IR/Argument.h
> >
> >
> >
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> 
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-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory