llvm dev - Apr 2007 - [LLVMdev] LLVA and WCET Analysis

Hello everybody,

I'm curious whether there have been any attempts to perform
performance analysis on the LLVA level. I am interested in the
derivation of flow-facts (loop bounds etc. - what about the
value-range-propagation pass I read about on this list some time ago)
but even more I am interested in exec-time modeling (how long does it
take to execute a bunch of LLVA instructions on particular processor)
for the LLVA. I am glad about every pointer I can get.

Thanks in advance, Fabian

On 4/2/07, Fabian Scheler <fabian.scheler at gmail.com>
wrote:
> Hello everybody,
>
> I'm curious whether there have been any attempts to perform
> performance analysis on the LLVA level. I am interested in the
> derivation of flow-facts (loop bounds etc. - what about the
> value-range-propagation pass I read about on this list some time ago)
> but even more I am interested in exec-time modeling (how long does it
> take to execute a bunch of LLVA instructions on particular processor)
> for the LLVA. I am glad about every pointer I can get.
If you are asking about LLVA not LLVM, see
http://llvm.org/pubs/2006-06-18-WIOSCA-LLVAOS.html

LLVA specifically is refering to a research project offshoot of llvm.
LLVM instructions do not have 1:1 mappings to native instructions
(sometimes multiple llvm instructions map to fewer native insts,
sometimes the other way around).

Andrew

On Apr 3, 2007, at 10:55 AM, Andrew Lenharth wrote:
> On 4/2/07, Fabian Scheler <fabian.scheler at gmail.com> wrote:
>> Hello everybody,
>>
>> I'm curious whether there have been any attempts to perform
>> performance analysis on the LLVA level. I am interested in the
>> derivation of flow-facts (loop bounds etc. - what about the
>> value-range-propagation pass I read about on this list some time ago)
>> but even more I am interested in exec-time modeling (how long does it
>> take to execute a bunch of LLVA instructions on particular processor)
>> for the LLVA. I am glad about every pointer I can get.
>
> If you are asking about LLVA not LLVM, see
> http://llvm.org/pubs/2006-06-18-WIOSCA-LLVAOS.html
>
> LLVA specifically is refering to a research project offshoot of llvm.
> LLVM instructions do not have 1:1 mappings to native instructions
> (sometimes multiple llvm instructions map to fewer native insts,
> sometimes the other way around).
That's correct, and furthermore, LLVA (now called SVA = Secure  
Virtual Architecture) uses essentially the same virtual instruction  
set as LLVM, so they have the same difficulty.

--Vikram