[mlir][ptr] Add ConstantOp with NullAttr and AddressAttr support (#157347)
This patch introduces the `ptr.constant` operation. It also adds the
`NullAttr` and `AddressAttr` for representing null pointers, and integer
raw addresses.
It also implements LLVM IR translation for `ptr.constant` with
`#ptr.null` or `#ptr.address` attributes.
Finally, it extends `FieldParser` to support APInt parsing.
Example:
```mlir
llvm.func @constant_address_op() ->
!llvm.struct<(!ptr.ptr<#llvm.address_space<0>>,
!ptr.ptr<#llvm.address_space<1>>,
!ptr.ptr<#llvm.address_space<2>>)> {
%0 = ptr.constant #ptr.null : !ptr.ptr<#llvm.address_space<0>>
%1 = ptr.constant #ptr.address<0x1000> : !ptr.ptr<#llvm.address_space<1>>
%2 = ptr.constant #ptr.address<3735928559> : !ptr.ptr<#llvm.address_space<2>>
%3 = llvm.mlir.poison : !llvm.struct<(!ptr.ptr<#llvm.address_space<0>>, !ptr.ptr<#llvm.address_space<1>>, !ptr.ptr<#llvm.address_space<2>>)>
%4 = llvm.insertvalue %0, %3[0] : !llvm.struct<(!ptr.ptr<#llvm.address_space<0>>, !ptr.ptr<#llvm.address_space<1>>, !ptr.ptr<#llvm.address_space<2>>)>
%5 = llvm.insertvalue %1, %4[1] : !llvm.struct<(!ptr.ptr<#llvm.address_space<0>>, !ptr.ptr<#llvm.address_space<1>>, !ptr.ptr<#llvm.address_space<2>>)>
%6 = llvm.insertvalue %2, %5[2] : !llvm.struct<(!ptr.ptr<#llvm.address_space<0>>, !ptr.ptr<#llvm.address_space<1>>, !ptr.ptr<#llvm.address_space<2>>)>
llvm.return %6 : !llvm.struct<(!ptr.ptr<#llvm.address_space<0>>, !ptr.ptr<#llvm.address_space<1>>, !ptr.ptr<#llvm.address_space<2>>)>
}
```
Result of translation to LLVM IR:
```llvm
define { ptr, ptr addrspace(1), ptr addrspace(2) } @constant_address_op() {
ret { ptr, ptr addrspace(1), ptr addrspace(2) } { ptr null, ptr addrspace(1) inttoptr (i64 4096 to ptr addrspace(1)), ptr addrspace(2) inttoptr (i64 3735928559 to ptr addrspace(2)) }
}
```
This patch also changes all the `convert*` occurrences in function names
or comments to `translate` in the PtrToLLVM file.
---------
Co-authored-by: Mehdi Amini <joker.eph@gmail.com>
1a65e63c59