[LLVMdev] Shift operation expansion

[Evan Cheng]

You can expand nodes into a serious of instructions, even with control  
flow. Take a look at how the PowerPC target lower atomic operations.  
Look for usesCustomDAGSchedInserter in PPCInstrInfo.td,  
PPCTargetLowering::EmitAtomicBinary.

Evan

On Nov 12, 2008, at 9:14 PM, Sachin.Punyani at microchip.com wrote:

> Hi,
>
> My target supports shift with amount 1 only i.e. to shift a value by  
> 5 bits, I need to have a loop with shift in the body. Similarly for  
> the unknown amount of shift we need to have a loop for shift.
>
> 1)       How can I insert this loop in DAG for shift operation?
> 2)       Is there a way where I can have a call to a function and  
> later expand to the shift code?
>
> Which would be the better way to implement this?
>
> Regards
> Sachin
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