[llvm-commits] [llvm] r126964 - in /llvm/trunk: lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp lib/CodeGen/SelectionDAG/LegalizeTypes.h test/CodeGen/X86/umulo-64.ll

Evan Cheng evan.cheng at apple.com
Fri Mar 4 00:16:14 PST 2011



On Mar 3, 2011, at 4:16 PM, Eric Christopher <echristo at apple.com> wrote:

> 
>> Err, I'm reasonably sure the code has precisely the same issues for
>> 64-bit... narrow my previous example and compile on x86-32, and you
>> end up with the following, which has the exact same issue:
> 
> So I was trying to be clever and have no idea what I was thinking. :)
> 
> Here's a simple patch that fixes the problem in something resembling correctness, but uses divide to do it - so yeah, performance?
> 

Math is hard. But surely it's possible to generate better code. What do other compilers do?

Evan

> Thoughts?
> 
> -eric
> 
> <legalize.diff.txt>
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