llvm dev - Dec 2009 - [LLVMdev] Possible bug in ExpandShiftWithUnknownAmountBit

Hi Duncan,

Just wondering if you had a chance to look at the expansion.

Thanks,
Javier

On Tue, 01 Dec 2009 20:20:14 +0100, Duncan Sands <baldrick at free.fr>
wrote:
> Hi Javier,
> 
>> It seems that the code you pasted came from the function
>> ExpandShiftByConstant and indeed it looks correct. In my example I used
6
>> as the shift amount but forgot to mention that it's stored in a
register.
> 
> I see, sorry I didn't read your email more carefully.  It does look
like
> ExpandShiftWithUnknownAmountBit is bogus - at a glance it looks like the
> Cmp condition is inverted.  I may have time to take a closer look
tomorrow.
> 
> Best wishes,
> 
> Duncan.

Hi Javier,
> Just wondering if you had a chance to look at the expansion.
I wrote my own fix and committed it in revision 90482.  Do you
have a testcase I can add to the testsuite (preferably not an
execution test, but rather something that checks the assembler
being generated)?

Ciao,

Duncan.

Duncan,

Thanks for committing a fix. I see that you fixed a bug in my patch with
the HiL in the case of an SRA.

The issue with a test case is that it will depend on the target to expose
it. Like you noted in the check-in comment x86 doesn't expose the bug. The
target I'm working on isn't public. Short of writing a new one for the
purpose of a test case I don't know what else to do. Do you have a
suggestion?

Thanks,
Javier 

On Thu, 03 Dec 2009 22:38:44 +0100, Duncan Sands <baldrick at free.fr>
wrote:
> Hi Javier,
> 
>> Just wondering if you had a chance to look at the expansion.
> 
> I wrote my own fix and committed it in revision 90482.  Do you
> have a testcase I can add to the testsuite (preferably not an
> execution test, but rather something that checks the assembler
> being generated)?
> 
> Ciao,
> 
> Duncan.