[PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Jin Ma]

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;
+}
+
 /* Auxiliary function to emit RISC-V ELF attribute. */
 static void
 riscv_emit_attribute ()
@@ -7671,6 +7689,9 @@ riscv_vectorize_related_mode (machine_mode vector_mode, scalar_mode element_mode
 #undef TARGET_SCHED_ISSUE_RATE
 #define TARGET_SCHED_ISSUE_RATE riscv_issue_rate
 
+#undef  TARGET_SCHED_VARIABLE_ISSUE
+#define TARGET_SCHED_VARIABLE_ISSUE riscv_sched_variable_issue
+
 #undef TARGET_FUNCTION_OK_FOR_SIBCALL
 #define TARGET_FUNCTION_OK_FOR_SIBCALL riscv_function_ok_for_sibcall
 
-- 
2.17.1

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Jeff Law]

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;

Jeff

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Jeff Law]

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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

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commit f088b768d01ae42385697584a2bcac141685dce2
Author: Jin Ma <jinma@linux.alibaba.com>
Date:   Wed Aug 9 13:52:06 2023 -0600

    RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.
    
    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.
    
            Co-authored-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
            Co-authored-by: Jeff Law <jlaw@ventanamicro.com>

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 7f2041a54ba..dfb519ab9a8 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -6698,6 +6698,31 @@ 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;
+
+  /* GHOST insns are used for blockage and similar cases which
+     effectively end a cycle.  */
+  if (get_attr_type (insn) == TYPE_GHOST)
+    return 0;
+
+#if 0
+  /* If we ever encounter an insn with an unknown type, trip
+     an assert so we can find and fix this problem.  */
+  gcc_assert (get_attr_type (insn) != TYPE_UNKNOWN);
+#endif
+
+  return more - 1;
+}
+
 /* Auxiliary function to emit RISC-V ELF attribute. */
 static void
 riscv_emit_attribute ()
@@ -8420,6 +8445,9 @@ riscv_frame_pointer_required (void)
 #undef TARGET_SCHED_ISSUE_RATE
 #define TARGET_SCHED_ISSUE_RATE riscv_issue_rate
 
+#undef  TARGET_SCHED_VARIABLE_ISSUE
+#define TARGET_SCHED_VARIABLE_ISSUE riscv_sched_variable_issue
+
 #undef TARGET_FUNCTION_OK_FOR_SIBCALL
 #define TARGET_FUNCTION_OK_FOR_SIBCALL riscv_function_ok_for_sibcall
 

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Jin Ma]

> 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 :)

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Palmer Dabbelt]

On Thu, 10 Aug 2023 19:12:06 PDT (-0700), gcc-patches@gcc.gnu.org wrote:
>> 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.

Sorry for being lost here, but I'm not sure where TYPE_UNKNOWN comes 
from.  There's not a whole lot of instances in the code, and they all 
seem to be doing something very special.  Is it just something we didn't 
do a '(set_attr "type" ...)' on?

In that case it seems reasonable to have a dev-mode early failure: we've 
got some odd types now (like just the broad "bitmanip" one), but those 
can be split later.  At least having some classification seems like the 
way to go, it's just an internal interface so we can make it better 
later.

That said, it also smells like this is something that should be more 
generic than backend code?

>> > 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;

Lost again, here, there's almost no references to TYPE_GHOST (aside from 
a MIPS-ism that looks to have ended up in Loongarch).

>> 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 :)

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Jeff Law]

On 8/10/23 20:30, Palmer Dabbelt wrote:

> 
> Sorry for being lost here, but I'm not sure where TYPE_UNKNOWN comes 
> from.  There's not a whole lot of instances in the code, and they all 
> seem to be doing something very special.  Is it just something we didn't 
> do a '(set_attr "type" ...)' on?
Yup.  TYPE_UNKNOWN means we don't have a type associated with the insn. 
As I've mentioned before this isn't a major problem if there's one or 
two here and there.  But if most are TYPE_UNKNOWN, the the scheduler is 
going to do highly unnatural things.

> 
> In that case it seems reasonable to have a dev-mode early failure: we've 
> got some odd types now (like just the broad "bitmanip" one), but those 
> can be split later.  At least having some classification seems like the 
> way to go, it's just an internal interface so we can make it better later.
> 
> That said, it also smells like this is something that should be more 
> generic than backend code?
No, it's really a target issue.  And what I was suggesting is that we 
get to the point where we can enable the currently #if 0'd assert so 
that if we introduce insns without an associated type, we get a nice 
early warning.  I wasn't up for tackling that this week ;-)


> 
>>> > 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;
> 
> Lost again, here, there's almost no references to TYPE_GHOST (aside from 
> a MIPS-ism that looks to have ended up in Loongarch).
Search for "ghost" in riscv.md ;-)

Jeff

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Palmer Dabbelt]

On Thu, 10 Aug 2023 20:19:02 PDT (-0700), jeffreyalaw@gmail.com wrote:
>
>
> On 8/10/23 20:30, Palmer Dabbelt wrote:
>
>>
>> Sorry for being lost here, but I'm not sure where TYPE_UNKNOWN comes
>> from.  There's not a whole lot of instances in the code, and they all
>> seem to be doing something very special.  Is it just something we didn't
>> do a '(set_attr "type" ...)' on?
> Yup.  TYPE_UNKNOWN means we don't have a type associated with the insn.
> As I've mentioned before this isn't a major problem if there's one or
> two here and there.  But if most are TYPE_UNKNOWN, the the scheduler is
> going to do highly unnatural things.

OK, that seems like the way to go.  I still think it's likely we'll need 
to split up these types more, but that's something we can only deal with 
when there's HW that behaves oddly.

>> In that case it seems reasonable to have a dev-mode early failure: we've
>> got some odd types now (like just the broad "bitmanip" one), but those
>> can be split later.  At least having some classification seems like the
>> way to go, it's just an internal interface so we can make it better later.
>>
>> That said, it also smells like this is something that should be more
>> generic than backend code?
> No, it's really a target issue.  And what I was suggesting is that we
> get to the point where we can enable the currently #if 0'd assert so
> that if we introduce insns without an associated type, we get a nice
> early warning.  I wasn't up for tackling that this week ;-)

I was thinking of some sort of "TARGET_ALLOWS_UNKNOWN_INSNS" hook, but 
poking around the uses that might not be meaningfully simpler than just 
rejecting these in the backend -- certainly simpler if we're just 
worried about RISC-V ;)

This seems pretty mechinacial: just scrub through our MDs to check for 
any un-typed insns, then add the assert and fix the failures.  You're 
more than welcome to have at it, but LMK if you want me to try and find 
some time for someone to do it -- certainly seems like a good way for 
someone new to dig in a bit.

>>>> > 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;
>>
>> Lost again, here, there's almost no references to TYPE_GHOST (aside from
>> a MIPS-ism that looks to have ended up in Loongarch).
> Search for "ghost" in riscv.md ;-)

Thanks, the "return 0" makes sense.

>
> Jeff

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Jeff Law]

On 8/10/23 20:12, Jin Ma wrote:

> 
> My fault, I'm very sorry for not replying to the patch follow-up, I just
> forgot this :)
No worries.  We're tracking it in patchwork and it also overlaps with 
some work we had internally at Ventana.  So it was trivial to pick it up 
once it was clear it'd fallen through the cracks.

jeff

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Jeff Law]

On 8/10/23 21:45, Palmer Dabbelt wrote:
> 
> OK, that seems like the way to go.  I still think it's likely we'll need 
> to split up these types more, but that's something we can only deal with 
> when there's HW that behaves oddly.
Yea, but I think we can fault this in as problematic hardware arrives.


>> No, it's really a target issue.  And what I was suggesting is that we
>> get to the point where we can enable the currently #if 0'd assert so
>> that if we introduce insns without an associated type, we get a nice
>> early warning.  I wasn't up for tackling that this week ;-)
> 
> I was thinking of some sort of "TARGET_ALLOWS_UNKNOWN_INSNS" hook, but 
> poking around the uses that might not be meaningfully simpler than just 
> rejecting these in the backend -- certainly simpler if we're just 
> worried about RISC-V ;)
Not all ports have types at all.  Some use types for things other than 
scheduling.  It'd be a huge can of worms.

> 
> This seems pretty mechinacial: just scrub through our MDs to check for 
> any un-typed insns, then add the assert and fix the failures.  You're 
> more than welcome to have at it, but LMK if you want me to try and find 
> some time for someone to do it -- certainly seems like a good way for 
> someone new to dig in a bit.
Yes, definitely mechanical.  And yes, it's a good way for someone to 
start to get familiar with these bits -- I used the lack of types on 
some of the bitmanip insns to help ramp up Raphael and one of the RAU 
guys in this space.

Jeff

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Edwin Lu]

On 8/11/2023 6:29 AM, Jeff Law via Gcc-patches wrote:
>
>
> On 8/10/23 21:45, Palmer Dabbelt wrote:
>
>>
>> This seems pretty mechinacial: just scrub through our MDs to check 
>> for any un-typed insns, then add the assert and fix the failures.  
>> You're more than welcome to have at it, but LMK if you want me to try 
>> and find some time for someone to do it -- certainly seems like a 
>> good way for someone new to dig in a bit.
> Yes, definitely mechanical.  And yes, it's a good way for someone to 
> start to get familiar with these bits -- I used the lack of types on 
> some of the bitmanip insns to help ramp up Raphael and one of the RAU 
> guys in this space.
>
> Jeff

Hi, Palmer sent me this thread to take a look at. I can start working on 
this.

Edwin Lu

Re: [PATCH] RISC-V: Handle no_insn in TARGET_SCHED_VARIABLE_ISSUE.

[Jeff Law]

On 8/14/23 14:33, Edwin Lu wrote:
> 
> On 8/11/2023 6:29 AM, Jeff Law via Gcc-patches wrote:
>>
>>
>> On 8/10/23 21:45, Palmer Dabbelt wrote:
>>
>>>
>>> This seems pretty mechinacial: just scrub through our MDs to check 
>>> for any un-typed insns, then add the assert and fix the failures. 
>>> You're more than welcome to have at it, but LMK if you want me to try 
>>> and find some time for someone to do it -- certainly seems like a 
>>> good way for someone new to dig in a bit.
>> Yes, definitely mechanical.  And yes, it's a good way for someone to 
>> start to get familiar with these bits -- I used the lack of types on 
>> some of the bitmanip insns to help ramp up Raphael and one of the RAU 
>> guys in this space.
>>
>> Jeff
> 
> Hi, Palmer sent me this thread to take a look at. I can start working on 
> this.
Sounds good.  The goal is to make sure that every insn has a type and 
once we hit that milestone we can enable the currently #if 0'd assert in 
riscv_sched_variable_issue to help ensure we don't introduce any new 
insns without types in the future.

If you have any questions, don't hesitate to reach out.

jeff