[PATCH] D55444: AMDGPU: Fix DPP combiner

Thu Jan 10 08:42:19 PST 2019

vpykhtin added a comment.

In D55444#1352866 <https://reviews.llvm.org/D55444#1352866>, @vpykhtin wrote:

> > Anyways, the other cases look like maybe some other clever optimization for the immediate is hindering this one, for example this with signed minimum:
> > 
> >   	v_bfrev_b32_e32 v8, -2                                        ; 7E1058C2
> >   	s_nop 1                                                       ; BF800001
> >   	v_mov_b32_dpp v8, v2  row_bcast:15 row_mask:0xa bank_mask:0xf ; 7E1002FA AF014202
> >   	v_min_i32_e32 v2, v2, v8                                      ; 18041102
> > 
> > 
> > Maybe this pass needs to be moved earlier in the pipeline?
>
> I'm not sure I can insert the pass that high, I'll think of how it can be skipped.

This kind of immediate init optimization is performed by SIShrinkInstructions pass and it runs after the DPP combiner pass, so the issue is different here, would be nice to have .ll file.

Repository:
  rL LLVM

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  https://reviews.llvm.org/D55444/new/

https://reviews.llvm.org/D55444