[llvm-commits] PATCH: BasicBlock metadata

[Ralf Karrenberg]

Hi,

sorry for the last message - there were some things missing, the patch did not compile.
Here is the corrected version.

Sorry again,
Ralf

----- Original Message -----
> From: "Ralf Karrenberg" <karrenberg at cdl.uni-saarland.de>
> To: "Richard Osborne" <richard at xmos.com>
> Cc: llvm-commits at cs.uiuc.edu
> Sent: Dienstag, 8. Mai 2012 23:18:10
> Subject: Re: [llvm-commits] PATCH: BasicBlock metadata
> 
> > On 5/8/12 7:07 AM, Richard Osborne wrote:
>  > > On 08/05/12 11:29, Ralf Karrenberg wrote:
>  > >> On 5/8/12 11:40 AM, Richard Osborne wrote:
>  > >>>> Cheers,
>  > >>>> Ralf
>  > >>>>     /// hasAddressTaken - returns true if there are any uses
>  > >>>>     of
> this basic block
>  > >>>>     /// other than direct branches, switches, etc. to it.
>  > >>>> -  bool hasAddressTaken() const { return
> getSubclassDataFromValue() != 0; }
>  > >>>> +  bool hasAddressTaken() const {
>  > >>>> +    return (getSubclassDataFromValue()&  ~HasMetadataBit) !=
>  > >>>> 0;
>  > >>>> +  }
>  > >>> I think this will result in basic block metadata effecting
>  > >>> optimizations. What would happen if you just ignored metadata
>  > >>> here?
>  > >> It will always treat a block that has metadata attached as a
>  > >> block
>  > >> whose address has been taken, which results in a crash at a
>  > >> later
>  > >> point (don't remember exactly where) because the address was
>  > >> never
> taken.
>  >
>  > I think you might want to update the comment explaining what you
>  > said
>  > above and providing a justification for it.  Developers
>  > misunderstanding
>  > code seems like a flag for a better comment, IMHO.
> 
> That makes sense. I attached the updated patch.
> 
>  > -- John T.
>  >
>  > > Ah sorry, I totally misread this bit of the code. It looks fine
>  > > to me.
> 
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