This should act like range. Previously ConstantRangeList assumed a 64-bit range. Now query from the actual entries. This also means that the empty range has no bitwidth, so move asserts to avoid checking the bitwidth of empty ranges.
Add ConstantRangeList::subtract(ConstantRange). This API will be used in the "initializes" attribute inference as well (for load instructions).
Add ConstantRangeList::unionWith() and ::intersectWith(). These methods will be used in the "initializes" attribute inference. df11106068
df11106068
We propose adding a new LLVM attribute, `initializes((Lo1,Hi1),(Lo2,Hi2),...)`, which expresses the notion of memory space (i.e., intervals, in bytes) that the argument pointing to is initialized in the function. Will commit the attribute inferring in the follow-up PRs. https://discourse.llvm.org/t/rfc-llvm-new-initialized-parameter-attribute-for-improved-interprocedural-dse/77337
