[llvm-commits] [PATCH] thumb t2b fix

[Owen Anderson]

Greg,

This ties in with my earlier comments: the immediate MCOperand on the MCInst is always assumed to contain a pre-encoded value.  The purpose of this is to ensure that it is not possible to represent an unencodable instruction as an MCInst.

--Owen

On Sep 18, 2012, at 5:20 PM, Greg Fitzgerald <garious at gmail.com> wrote:

> A small nitpick from an llvm newb, why these two lines?
> 
> +  let Inst{13} = target{22};
> +  let Inst{11} = target{21};
> 
> These 2 bits require separate logic, which you have.  So should we be
> sure not to reference them in the .td file?  Or better, is there a way
> to do the EOR of S and J1 within the .td file?
> 
> Thanks,
> Greg
> 
> 
> On Tue, Sep 18, 2012 at 9:04 AM, Tim Northover <t.p.northover at gmail.com> wrote:
>> 
>> Hi all,
>> 
>>> Please review and commit this patch.
>>> 
>>> It fixes the thumb t2b instruction, where the immediate value was being
>>> incorrectly encoded and decoded.
>> 
>> I can do the committing again, but is there any chance we could have
>> some non-ARM review on this?
>> 
>> I think it fixes the important codegen errors around the Thumb2 branch
>> instruction, but there's a change to how fixups are handled which is
>> larger than we're comfortable with committing blind and that test is
>> an order of magnitude longer than most (any alternative to .space to
>> make llvm-mc think a label is PC-relative and far away without
>> actually generating the intervening gap?)
>> 
>> Cheers.
>> 
>> Tim.
>> 
>> (Attached file is identical to Chris's original).
>> 
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