[llvm-commits] [Patch] SimplifyCFG: Forward switch condition value to phi node

[Hans Wennborg]

The attached patch is an attempt to fix PR10103.

In cases such as the attached test, where the case value for a switch
destination is used in a phi node that follows the destination, it
might be better to replace that value with the condition value of the
switch, so that more blocks can be folded away with
TryToSimplifyUncondBranchFromEmptyBlock because there are less
conflicts in the phi node.

I'm not familiar with the optimizations code, so please take a look
and let me know if this is a good idea or not. Your comments are most
welcome.

Thanks,
Hans
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