[PATCH] D154306: [InstCombine] Generalise ((x1 ^ y1) | (x2 ^ y2)) == 0 transform to more than two pairs of variables

[Maksim Kita via Phabricator via llvm-commits]

kitaisreal marked an inline comment as done.
kitaisreal added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp:2038
+  // ((X1 ^ X2) || (X3 ^ X4) || (X5 ^ X6)) == 0 --> (X1 == X2) && (X3 == X4) && (X5 == X6)
+  // ((X1 ^ X2) || (X3 ^ X4) || (X5 ^ X6)) != 0 --> (X1 != X2) || (X3 != X4) || (X5 != X6)
+  bool Match = false;
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goldstein.w.n wrote:
> Maybe add as a todo, but this also works for `sub` (or implement in a follow up patch!)
I can implement this in follow up patch.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp:2066
+
+    if (!OrLhsIsXor && !OrRhsIsXor) {
+      break;
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goldstein.w.n wrote:
> There could we a case where we have:
> 
> `(or (or (xor A, B), (xor C, D)), (or (xor E, F), (xor G, H)))`.
> Not sure if it worth handling this case, but maybe switch this to a worklist algo so you can arbitrarily add `Or` ops.
Updated implementation to support such case.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D154306/new/

https://reviews.llvm.org/D154306