[PATCH] D27624: [ARM] Split 128-bit vectors in BUILD_VECTOR lowering

Renato Golin via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Tue Dec 13 07:21:42 PST 2016

rengolin added a comment.

Hi Eli,

This change looks good to me. I just have a small comment inline.


Comment at: lib/Target/ARM/ARMISelLowering.cpp:6232
+      Upper = LowerBUILD_VECTOR(Upper, DAG, ST);
+    if (Lower && Upper)
+      return DAG.getNode(ISD::CONCAT_VECTORS, dl, VT, Lower, Upper);
I'm assuming `LowerBUILD_VECTOR` can return `SDNode()` if there's no need for it, thus the concat only happening if both were lowered.

Is this is your strategy around "we might discover a better way to lower it"?

How can we avoid cases where it doesn't?



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