Date: Thu, 31 Mar 2016 15:25:18 -0400 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Subject: Re: size_t and int64_t on a new platform On Thu, Mar 31, 2016 at 11:20:22AM -0700, Dan Gohman wrote: > I'm working on a new architecture (WebAssembly, aka wasm) and am hoping to > have a compatible ABI at the level of a "freestanding implementation" > between all libc ports. > > The current design would translate into the following in a musl port (in > ..../bits/alltypes.h.in): > > #define _Addr long > #define _Int64 long long > > Both the ILP32 and LP64 platform variants would use the same definitions. > This helps minimize differences between the two variants, which aligns with > an overall goal of the platform. > > However, this differs from musl's convention of using "int" for _Addr on > ILP32 systems and using "long" for _Int64 on LP64 systems. But, as far as I > can tell, no musl code actually depends on this convention. Almost all code > in musl is either fully portable and can't, or is architecture-specific and > can just do the right thing for its own architecture. > > Legacy code may have assumptions, though I'm aware of the issues and don't > believe it's a significant practical problem for WebAssembly. > > If we decide to contribute wasm support upstream to the musl project in the > future, would the musl maintainers expect to be ok with the above > definitions? At some point we'll probably have to make this relaxation anyway. I've heard there's at least one arch we're planning to add (maybe powerpc64? I forget) that's using long instead of int for _Addr types. What would be most helpful to us (to keep things simple) is just ensuring that all the relevant types (size_t, ssize_t, ptrdiff_t, [u]intptr_t, etc.) are defined consistently as int or as long; otherwise we have to pop a hole in the abstraction they're modeled with now. That wouldn't be a huge problem either but it just adds more redundancy to arch/*/bits/alltypes.h.in files. Anyone else have objections to use of long for these types? Rich
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