[PATCH] D71589: [PowerPC] Adding a match pattern to recognize the and mask with RLWINM8

[Kai Luo via Phabricator via llvm-commits]

lkail added inline comments.


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Comment at: llvm/lib/Target/PowerPC/PPCInstrInfo.td:385
+    uint64_t Mask = (uint64_t)N->getZExtValue();
+    return isUInt<32>(Mask) && isRunOfOnes((unsigned)Mask, mb, me);
+  }
----------------
steven.zhang wrote:
> shchenz wrote:
> > we can only return true  when mb is not bigger than me.  and mask can be 0XF000000F, it becomes to  0XFFFFFFFFF000000F in rlwinm,then we get a 64bit value. This is wrong. 
> Good point. And yes, this is the problem.
Do we have to check `Mask & 0xffffffff00000000 == 0`?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71589/new/

https://reviews.llvm.org/D71589