[llvm-dev] virtual registers

Laura personen via llvm-dev llvm-dev at lists.llvm.org
Thu Feb 18 10:17:41 PST 2016


Thank you for your swift reply.

I also need some reference about instruction sequence in llvm. I mean, do
the order of instructions remain the same as they appear in a .ll file? or
do they change by different optimizations (e.g. SSA-based Machine Code
Optimizations
<http://llvm.org/docs/CodeGenerator.html#ssa-based-machine-code-optimizations>,
Late Machine Code Optimizations
<http://llvm.org/docs/CodeGenerator.html#late-machine-code-optimizations>,
etc.)?

If they change, which algorithms are used for reordering instructions? I
appreciate a reference that explains them or just gives the name of the
algorithms that are used.

BR
Laura

On Thu, Feb 18, 2016 at 6:45 PM, John Criswell <jtcriswel at gmail.com> wrote:

> On 2/18/16 12:03 PM, Laura personen via llvm-dev wrote:
>
> Hi,
>
> Is there any way to detect which virtual registers are assigned to
> physical registers and which ones are assigned to memory slots?
>
>
> At the LLVM IR level, no.  However, it might be possible for a
> MachineFunctionPass to determine this or to modify the register allocator
> to record this information somewhere for query by a MachineFunctionPass
> later.
>
> Regards,
>
> John Criswell
>
>
>
> BR
> Laura
>
>
> _______________________________________________
> LLVM Developers mailing listllvm-dev at lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
>
> --
> John Criswell
> Assistant Professor
> Department of Computer Science, University of Rochesterhttp://www.cs.rochester.edu/u/criswell
>
>
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