The RISC-V psABI pull request is at https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/378 . Pointers to Paul Kirth's corresponding LLVM patches are also there.
On Fri, Apr 28, 2023 at 2:42 PM Hans Boehm <hbo...@google.com> wrote: > The concern with making the new behavior non-default is of course that the > generated code will eventually end up on an A.7-capable platform. > > An A.6-classic option for compiling code that will never run on a newer > machine seems OK. But I'm not sure that seq_cst stores are dynamically > frequent enough in C++ code for this to be worth the trouble. Unlike loads, > they are also costly on x86, programmers may also have been somewhat > trained to avoid them where possible. (And probably where not possible, too > :-( ) > > Hans > > On Fri, Apr 28, 2023 at 10:43 AM Palmer Dabbelt <pal...@rivosinc.com> > wrote: > >> On Fri, 28 Apr 2023 10:40:15 PDT (-0700), jeffreya...@gmail.com wrote: >> > >> > >> > On 4/27/23 10:22, Patrick O'Neill wrote: >> >> This change makes atomic stores strictly stronger than table A.6 of the >> >> ISA manual. This mapping makes the overall patchset compatible with >> >> table A.7 as well. >> >> >> >> 2023-04-27 Patrick O'Neill <patr...@rivosinc.com> >> >> >> >> PR 89835 >> > Should be "PR target/89835" >> > >> >> >> >> gcc/ChangeLog: >> >> >> >> * config/riscv/sync.md: >> > Needs some text here :-) >> > >> > >> > I'm not objecting to this patch, but I think we've got an option >> > question about whether or not this approach is too expensive for >> > existing or soon arriving implementations. >> > >> > If the decision on that topic is to just pay the cost, then this patch >> > is fine. If we decide to make compatibility optional to avoid the >> > additional cost, then this will need suitable adjustments. >> >> IMO the only hardware that's going to be here by gcc-14 and to have >> enough concurrency for these to matter is the Ventana stuff. I think >> you're the only one who can figure out if these are slow, at least until >> that stuff is availiable outside the lab. >> >> So are they too slow for you? >> >> > >> > Jeff >> >
