[LLVMdev] sccp pass with opt

Shuxin Yang
Tue, 16 Apr 2013 19:57:33 -0000

This compiler does not have mem-SSA,  as far as I know, only few pass
can propagate value along memory.

You need to promote those local variable into register first before sccp
is invoked.
  e.g1. opt a.ll -basicaa -gvn -sccp -S
  eg.2. opt a.ll -sroa -sccp -S

On 4/16/13 12:37 PM, Niko Zarzani wrote:
> Hi all,
>
> I am trying to see how single llvm optimizations work by running them
> one by one with opt and looking how the IR changes.
> Since I was interested in seeing how constant propagation was working
> I tried to run opt on the Sparse Conditional Constant Propagation,
> however by passing as argument -S -sccp -die it does not change
> anything in the output IR code. I attached the file with the source
> code I used, I think that the x value in that example should be
> propagated in the mul instruction. What am I missing?
>
> Thank you in advance,
>
> Niko
>
>
>
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