================ @@ -650,48 +650,127 @@ literal types are uniqued in recent versions of LLVM. .. _nointptrtype: -Non-Integral Pointer Type -------------------------- +Non-Integral and Unstable Pointer Types +--------------------------------------- -Note: non-integral pointer types are a work in progress, and they should be -considered experimental at this time. +Note: non-integral/unstable pointer types are a work in progress, and they +should be considered experimental at this time. LLVM IR optionally allows the frontend to denote pointers in certain address -spaces as "non-integral" via the :ref:`datalayout string<langref_datalayout>`. -Non-integral pointer types represent pointers that have an *unspecified* bitwise -representation; that is, the integral representation may be target dependent or -unstable (not backed by a fixed integer). +spaces as "non-integral" or "unstable" (or both "non-integral" and "unstable") +via the :ref:`datalayout string<langref_datalayout>`. + +The exact implications of these properties are target-specific, but the +following IR semantics and restrictions to optimization passes apply: + +Unstable pointer representation +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Pointers in this address space have an *unspecified* bitwise representation +(i.e. not backed by a fixed integer). The bitwise pattern of such pointers is +allowed to change in a target-specific way. For example, this could be a pointer +type used with copying garbage collection where the garbage collector could +update the pointer at any time in the collection sweep. ``inttoptr`` and ``ptrtoint`` instructions have the same semantics as for integral (i.e. normal) pointers in that they convert integers to and from -corresponding pointer types, but there are additional implications to be -aware of. Because the bit-representation of a non-integral pointer may -not be stable, two identical casts of the same operand may or may not +corresponding pointer types, but there are additional implications to be aware +of. + +For "unstable" pointer representations, the bit-representation of the pointer +may not be stable, so two identical casts of the same operand may or may not ---------------- arsenm wrote:
So this applies to only an SSA value of an unstable pointer type? What about an in-memory value with the unstable pointer type? https://github.com/llvm/llvm-project/pull/105735 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits