[LLVMdev] Suggestion: Support union types in IR
viridia at gmail.com
Fri May 8 10:07:02 PDT 2009
Nick Lewycky wrote:
> Hi Talin, thanks for looking in to this.
> I think there's already a lot of code that makes the assumption that the
> different members of a StructType represent distinct storage. Why is it
> easier to co-opt StructType than to create a new 'UnionType' under
> CompositeType? What's the tradeoff?
Well, from a pure lines-of-code perspective, the struct and union types
share about 90% of their implementation, and it seemed wrong to
duplicate that code. I thought about factoring out a common base class,
however that seemed more disruptive to the code base than I really
wanted to deal with.
However, I haven't really looked into the parts of LLVM that actually do
the analysis. (I'm mostly a front-end guy.) So I don't yet understand
how much trouble such a change would cause.
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