[PATCH] D154488: [PowerPC] Define SchedModel for Power8

[Qiu Chaofan via Phabricator via llvm-commits]

qiucf added inline comments.


================
Comment at: llvm/lib/Target/PowerPC/PPCScheduleP8.td:210
+    (instregex "^(ADD|SUBF)(M|Z)?E(8)?_rec$"),
+    (instregex "^(ADD|SUBF|NEG)(4|8)?_rec$"),
+    NOP, ADDG6S, ADDG6S8, ADDZE, ADDZE8, ADDIC_rec, NEGO_rec, ADDC, ADDC8, SUBFC, SUBFC8,
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shchenz wrote:
> hmm, this change seems still not accurate, below is from PWR8 UM(17 March 2016)
> ```
> addi addis add add. subf subf. addic subfic adde addme subfme subfze neg neg. nego
> FXU (or LU or LSU for non-dot forms)
> ```
> 
> `add.` should be able to use FXU or LU (4 hardware units).
> 
> Maybe we need to define a new unit group like `P8_FX_LU` for this kind of instructions?
> 
> I suggest you check other instructions as well compared with the UM.
> 
> Thanks very much for the big effort.
Per my understanding, only non-dot forms use LU/LSU?


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https://reviews.llvm.org/D154488