On Wed, 13 Oct 2021, Martin Uecker wrote: > There is currently no standard way to set or query > the static chain from C although this is used by > many other languages. Also function pointers in C > usually can not store the static chain. I am going > to propose to WG14 to add some kind of wide function > pointer to address this. I am doing back ground > research to understand whether this exists everywhere.
This doesn't answer your actual question, but: Following discussions of atomics at the last WG14 meeting, I raised the question on the WG14 reflector (and C++ liaison list) of whether it would be useful to have a public list of C-relevant ABIs and their maintainer contacts and ABI-relevant new features in C language versions. I was thinking of such a list as being to help people do due diligence after making ABI-relevant C standard changes (contacting the main ABI maintainers to get them to add ABI specification for the new features) and to help ABI maintainers track new features for which they need to update their ABIs. But such a list could equally be relevant for such research as you mention above in advance of proposing a new feature. There weren't any replies to my message from anyone actually saying they'd find such a list useful. If you think such a list would be useful (for the community of people dealing with maintaining ABIs or ABI implementations or specifying new language features needing corresponding ABIs), then I'd encourage replying to my reflector message of 2 September to say so. Message of 2 September below, for reference of readers not on the WG14 reflector or C++ liaison list: ====================================================================== To expand on something I mentioned in the atomics discussion in today's WG14 meeting: When new ABI-relevant features have been added to C, the community of people involved in C implementations hasn't always done well at updating relevant ABIs to achieve consistency between implementations for those new features (where those implementations aim to allow mixing code built with different implementations for the same architecture/OS - this isn't relevant for all C implementations). Atomics are just one example where the ABI issues are more complicated than usual, and where actual incompatibilities have arisen between implementations as well as between C and C++. Should there be some maintained public list of C-relevant ABI documents (mainly, not entirely, psABI documents for various architectures), and of where they are maintained (if they are) / who the maintainer contacts are? What about lists of ABI-relevant new features in different C versions that ABIs may need to be updated for (and, for that matter, common extensions it may be helpful to consider in ABIs), or some mailing list or other location to help psABI maintainers (and other relevant ABI maintainers - for example, new features often need to be handled by debug info formats such as DWARF as well) track new features they need to pay attention to? Or guidance on issues to consider when writing a psABI document? Do such lists already exist somewhere? As an example of the sort of thing I might hope to find in such a list of ABI documents / contacts: * x86-64: PDFs https://gitlab.com/x86-psABIs/x86-64-ABI/-/wikis/x86-64-psABI repository https://gitlab.com/x86-psABIs/x86-64-ABI mailing list https://groups.google.com/g/x86-64-abi * i386: PDFs https://gitlab.com/x86-psABIs/i386-ABI/-/wikis/Intel386-psABI repository https://gitlab.com/x86-psABIs/i386-ABI/-/tree/hjl/x86/master mailing list https://groups.google.com/g/ia32-abi * Arm and AArch64: PDFs https://github.com/ARM-software/abi-aa/releases repository https://github.com/ARM-software/abi-aa * RISC-V: PDFs https://github.com/riscv/riscv-elf-psabi-doc/releases repository https://github.com/riscv/riscv-elf-psabi-doc (but hopefully covering more architectures than that). -- Joseph S. Myers jos...@codesourcery.com
