> On 5/29/23 06:46, Jeff Law wrote: > > > > > > On 5/29/23 05:01, Jin Ma wrote: > >> Reference: > >> https://github.com/gcc-mirror/gcc/commit/d0bc0cb66bcb0e6a5a5a31a9e900e8ccc98e34e5 > >> > >> RISC-V should also be implemented to handle no_insn patterns for > >> pipelining. > >> > >> gcc/ChangeLog: > >> > >> * config/riscv/riscv.cc (riscv_sched_variable_issue): New function. > >> (TARGET_SCHED_VARIABLE_ISSUE): New macro. > >> --- > >> gcc/config/riscv/riscv.cc | 21 +++++++++++++++++++++ > >> 1 file changed, 21 insertions(+) > >> > >> diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc > >> index 3954fc07a8b..559fa9cd7e0 100644 > >> --- a/gcc/config/riscv/riscv.cc > >> +++ b/gcc/config/riscv/riscv.cc > >> @@ -6225,6 +6225,24 @@ riscv_issue_rate (void) > >> return tune_param->issue_rate; > >> } > >> +/* Implement TARGET_SCHED_VARIABLE_ISSUE. */ > >> + > >> +static int > >> +riscv_sched_variable_issue (FILE *, int, rtx_insn *insn, int more) > >> +{ > >> + if (DEBUG_INSN_P (insn)) > >> + return more; > >> + > >> + rtx_code code = GET_CODE (PATTERN (insn)); > >> + if (code == USE || code == CLOBBER) > >> + return more; > >> + > >> + if (get_attr_type (insn) == TYPE_UNKNOWN) > >> + return more; > >> + > >> + return more - 1; > >> +} > > The problem is that INSN is *much* more likely to be a real instruction > > that takes real resources, even if it is TYPE_UNKNOWN. > > TYPE_UNKNOWN here is actually an indicator of what I would consider a > > bug in the backend, specifically that we have INSNs that do not provide > > a mapping for the schedulers to suitable types. > > > > With that in mind I'd much rather get to the point where we can do > > something like this for TYPE_UNKNOWN: > > > > type = get_attr_type (insn); > > gcc_assert (type != TYPE_UNKNOWN); > > > > That way if we ever encounter a TYPE_UNKNOWN during development, we can > > fix it in the md files in a sensible manner. I don't know if we are > > close to being able to do that. We fixed a ton of stuff in bitmanip.md, > > but I don't think there's been a thorough review of the port to find > > other instances of TYPE_UNKNOWN INSNs. > > > > > > The other thing if this code probably wants to handle GHOST type > > instructions. While GHOST is used for instructions which generate no > > code, it might seem they should return "more" as those INSNs take no > > resources. But GHOST is actually used for things like the blockage insn > > which should end a cycle from an issue standpoint. So the right > > handling of a GHOST is something like this: > > > > if (type == TYPE_GHOST) > > return 0; > So there wasn't ever any follow-up. Given this was something Ventana > was also carrying locally (with very minor differences) I went ahead and > merged up the implementations and pushed the final result to the trunk. > > > Attached is the patch that was actually committed. > > Jeff
My fault, I'm very sorry for not replying to the patch follow-up, I just forgot this :)
