[PATCH] D61114: [SelectionDAG] Use stack load/store in PromoteIntRes_BITCAST when the input needs to be be split and the output type is a vector.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


================
Comment at: llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp:326
+    }
+    break;
   }
----------------
I wonder if there's anything else which would be reasonable to do on a target-independent basis...

I guess on x86, for a bitcast like `bitcast <64 x i1> %1 to <2 x i32>`, the optimal lowering is actually involves splitting the operation: you then have two `bitcast <32 x i1> %1 to i32`, which has an existing efficient custom lowering.  Then you use a BUILD_VECTOR to turn the two results into a `<2 x i32>`.  But I'm not sure that generalizes in a useful way.


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  rL LLVM

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  https://reviews.llvm.org/D61114/new/

https://reviews.llvm.org/D61114