[RV64_DYNAREC] Added 66 0F D4 PADDQ opcode for vector and fixes SEW cache transform

[ptitSeb]

Why is the ordering of the sewTranform maters?

[ksco]

Why is the ordering of the sewTranform maters?

Because it changes the runtime effective sew of the vector unit, but do not change our compile time tracking of sew for current instruction.

So for example, if the current compile time sew is 64, and it changed to 32 in the sew transformation, if there is a VLE instruction in the fpu transformation it will be VLE64 as the compile time sew is 64, so the instruction will SIGILL because it runtime sew has already changed to 32. (It may seems strange, but VLE64 requires current sew to be 64.)

[ptitSeb]

Why is the ordering of the sewTranform maters?

Because it changes the runtime effective sew of the vector unit, but do not change our compile time tracking of sew for current instruction.

So for example, if the current compile time sew is 64, and it changed to 32 in the sew transformation, if there is a VLE instruction in the fpu transformation it will be VLE64 as the compile time sew is 64, so the instruction will SIGILL because it runtime sew has already changed to 32. (It may seems strange, but VLE64 requires current sew to be 64.)

Ok, but what happens if the sew needs change in fpuTransform but sewTransform is not needed?

[ksco]

Why is the ordering of the sewTranform maters?

Because it changes the runtime effective sew of the vector unit, but do not change our compile time tracking of sew for current instruction. So for example, if the current compile time sew is 64, and it changed to 32 in the sew transformation, if there is a VLE instruction in the fpu transformation it will be VLE64 as the compile time sew is 64, so the instruction will SIGILL because it runtime sew has already changed to 32. (It may seems strange, but VLE64 requires current sew to be 64.)

Ok, but what happens if the sew needs change in fpuTransform but sewTransform is not needed?

The fpuTransform is and will always be sew agnostic, meaning any valid sew is okay for it, so there will never be any sew changes in fpuTransform.

[ptitSeb]

This seems a bit odd to me, but that's ok. a SIGILL is easy enough to catch and diagnose if something goes wrong later.

[ksco]

This seems a bit odd to me, but that's ok.

Things in the fpuCacheTransform are basically moves, loads and stores, so it’s natural that it’s not bound to a specific SEW, which is also good for performance.

[ptitSeb]

This seems a bit odd to me, but that's ok.

Things in the fpuCacheTransform are basically moves, loads and stores, so it’s natural that it’s not bound to a specific SEW, which is also good for performance.

But yet, it still needs sewTranform to be done after and not before?

[ksco]

I guess we can “fix” this by actually change the compile time sew in sewTransform in and only in pass3.

[ptitSeb]

that's not really my point. I'm just woried that this "need" is just the manifastation of an issue where some needed sew tranform is needed and missed...

[ksco]

ah ok, got it.