[LLVMdev] Regression in 3.4's register allocator?

[Quentin Colombet]

Hi Niklas,

This works for me with trunk r207129.

We did fix some register allocation issues recently, don’t know which change fixes the issue though.

Thanks,
-Quentin

On Apr 24, 2014, at 1:07 PM, Niklas Therning <niklas at therning.org> wrote:

> Hi,
> 
> The RoboVM project recently upgraded from LLVM 3.3 to 3.4 and with the new version we are sometimes seeing "ran out of registers during register allocation" errors when targeting x86 32-bit that we haven't seen before. Nothing has changed in our bitcode generator. I have attached an IR file which can be used to reproduce this problem. The problem occurs with -O2 and -disable-fp-elim specified.
> 
> Running llc from 3.3 works without problems:
> $ ~/Downloads/clang+llvm-3.3-x86_64-apple-darwin12/bin/llc -mtriple i386-unknown-macosx -O2 -disable-fp-elim reg-alloc-test.ll
> 
> While llc from 3.4 fails:
> $ ~/Downloads/clang+llvm-3.4-x86_64-apple-darwin10.9/bin/llc -mtriple i386-unknown-macosx -O2 -disable-fp-elim reg-alloc-test.ll
> LLVM ERROR: ran out of registers during register allocation
> 
> I haven't been able to test this with the latest trunk but I got the same error when trying with the 3.4.1 branch.
> 
> Has anyone else seen this? Is it a known bug? Or should I report it?
> 
> Regards,
> Niklas
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