llvm dev - Sep 2009 - [LLVMdev] creating a loop in lowering code

The MSP430 only has 1-bit shifts.  In the lowering code, I would like to create 
a small loop to do multiple bit shifts.  I assume that I have to create a new 
basic block, and figure out the chain stuff.

Is there code in some backend, or generic lowering support, that does a similar 
thing?  Could someone point me to it?

thanks,
bagel

Hello
> The MSP430 only has 1-bit shifts.  In the lowering code, I would like to
create
> a small loop to do multiple bit shifts.  I assume that I have to create a
new
> basic block, and figure out the chain stuff.
This might be tricky in general. Why cannot you just emit a libcall?

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

On Sep 27, 2009, at 3:05 PMPDT, Bagel wrote:
> The MSP430 only has 1-bit shifts.  In the lowering code, I would  
> like to create
> a small loop to do multiple bit shifts.  I assume that I have to  
> create a new
> basic block, and figure out the chain stuff.
>
> Is there code in some backend, or generic lowering support, that  
> does a similar
> thing?  Could someone point me to it?
It doesn't work exactly like that, but see the handling of ATOMICs on  
PPC.