[PATCH] D67664: [ARM] Ensure we do not attempt to create lsll #0

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


================
Comment at: llvm/lib/Target/ARM/ARMISelLowering.cpp:6013
     if (ShAmt->getValueType(0).getSizeInBits() > 64 ||
-        (Con && Con->getZExtValue() >= 32))
+        (Con && (Con->getZExtValue() == 0 || Con->getZExtValue() >= 32)))
       return SDValue();
----------------
What happens if we discover the shift amount is zero after legalization?

If MVE_LSLLi doesn't accept arbitrary immediates, the isel pattern should reflect that.  (With only that fix, I think we still end up with an MVE_LSLLr, but that's not a correctness issue, just a missed optimization, I think.)


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D67664/new/

https://reviews.llvm.org/D67664