On Tue, Jul 7, 2020 at 2:52 AM Kito Cheng <kito.ch...@sifive.com> wrote: > gcc/ChangeLog: > * gcc/config/riscv/riscv.md (): New. > (TP_REGNUM): Ditto. > * doc/extend.texi (Target Builtins): Add RISC-V built-in section. > Document __builtin_thread_pointer. > gcc/testsuite/ChangeLog: > * gcc.target/riscv/read-thread-pointer.c: New.
It looks OK to me in general. You added builtin_thread_pointer but not builtin_set_thread_pointer. Maybe we should implement both as long as we are implementing one? If clang only implements one, maybe it should implement the other also? This doesn't have to be part of this patch. This could be a separate issue. The builtin_thread_pointer docs looks out-of-date. It is documented for alpha and SH, but it is implemented in gcc/builtins.c not in the backends. A scan of md files show that quite a few targets support it but don't document it. I think it should be documented in the generic builtins section not in the target dependent builtins sections with some language that says not all targets support it. This doesn't have to be part of this patch. This could be a separate issue. We have two existing undocumented builtins. __builtin_riscv_fsflags and __builtin_riscv_frflags for setting or reading the FP flags. I don't know if anyone uses them though. newlib and glbic both use extended asms for these operations. This doesn't have to be part of this patch. This could be a separate issue. There is a document https://github.com/riscv/riscv-c-api-doc for coordinating gcc and llvm work that has an empty list of builtin functions. I'm not sure if this document is still useful. If this is a RISC-V specific builtin then it should be listed here, but I don't think it should be considered a RISC-V specific builtin. There is an unresolved pull request for the frflags and fsflags builtins. I guess I forgot about that. Jim
