> On Nov 16, 2023, at 14:33, Fangrui Song <mask...@google.com> wrote: > > On Wed, Nov 15, 2023 at 9:23 PM Jeff Law <jeffreya...@gmail.com> wrote: >> >> >> >> On 11/15/23 18:51, Tatsuyuki Ishi wrote: >>>> On Nov 16, 2023, at 10:07, Jeff Law <jeffreya...@gmail.com> wrote: >> >>> >>> Based on what I have read in the AArch64 backend, there are two ways to >>> do this: introduce a custom calling convention, or put in a RTX insn >>> that covers the whole sequence. Ideally we should do the first, but then >>> there’s the label issue and it’s quite a bit more complicated. So I’m >>> sticking with this for now. >> As I said, I think we're OK here. We can always revamp as we get >> experience with the implementation -- I don't think any of the stuff >> we're talking about is an ABI change, they're just implementation details. >> >>> >>> Sorry for all the delay on this. My progress has been (and still) >>> blocked on supporting relaxation of TLSDESC in binutils (turns out you >>> can’t run static binaries without relaxing it first). But that doesn’t >>> seem exactly easy to do either, because relaxation that involves GOT >>> elimination isn’t something we have in the RISC-V backend. >> Note that binutils is due for another release in the next month or two. >> It'd certainly be helpful to have any issues there resolved in time for >> that release. >> >>> >>> I’ll try to send a new version of this patch and get this unblocked on >>> GCC side first. >> Sounds good. We can always guard its use behind a feature test for GAS >> support. >> >> Jeff > > Agreed. > > > Tatsuyuki, could you also add some tests? For example > > // end of https://maskray.me/blog/2021-02-14-all-about-thread-local-storage > __thread int tls0; > extern __thread int tls1; > int foo() { return ++tls0 + ++tls1; } > static __thread int tls2, tls3; > int bar() { return ++tls2 + ++tls3; } > > I have used this to check rtld and linker behavior. I think we need > some `scan-assembler`. > To make it a runnable test, some assembler feature check may be > needed. Perhaps Jeff can make some suggestion or contribute code! >
I believe there’s existing platform-generic TLS coverage in gcc/testsuite/gcc.dg/torture/tls. GCC's test suite seems pretty sparse, but a lot more testing is done by glibc’s testsuite (which is also where I found the static TLS relaxation issue). Tatsuyuki. > > -- > 宋方睿
