llvm dev - Apr 2009 - [LLVMdev] support for division by constant in APInt

In lib/CodeGen/SelectionDAG/TargetLowering.cpp there are some
functions magic() and magicu() that support optimising division by a
constant. I'd like to use these functions in an LLVM FunctionPass that
I'm working on. The attached patch moves these functions out of
TargetLowering.cpp and into the APInt class, so that I can reuse them
in my pass. What do you think?

It looks to me like these functions were copied straight out of
"Hacker's Delight", Henry S. Warren, Jr., so I added a comment
acknowledging that.

Thanks,
Jay.
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On Apr 23, 2009, at 6:26 AM, Jay Foad wrote:
> In lib/CodeGen/SelectionDAG/TargetLowering.cpp there are some
> functions magic() and magicu() that support optimising division by a
> constant. I'd like to use these functions in an LLVM FunctionPass that
> I'm working on. The attached patch moves these functions out of
> TargetLowering.cpp and into the APInt class, so that I can reuse them
> in my pass. What do you think?
>
> It looks to me like these functions were copied straight out of
> "Hacker's Delight", Henry S. Warren, Jr., so I added a
comment
> acknowledging that.
The patch looks fine to me, does it pass regression tests etc?  If so,  
please apply, or contact me off list if you don't yet have commit  
access.  Thanks Jay!

-Chris

> The patch looks fine to me, does it pass regression tests etc?
Yes, I've just run a successful "make" in the test-suite module.
It
took hours! Is there a smaller set of regression tests I could run for
changes like this in future?

Thanks,
Jay.

> The patch looks fine to me, does it pass regression tests etc?  If so,
> please apply, or contact me off list if you don't yet have commit
> access.  Thanks Jay!
Committed here:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20090427/076916.html

Thanks!
Jay.