[P0] Distinguish the Phi that need ignore one input

[Jackcuii]

The variables out of the loop but used in the loop are assigned by Phi

These Phis should have these semantics: the Phi will always select one of the operands of the Phi for the first time, and choose according to the predicate in the following rounds. (It is exactly the PHI_CONST in VectorCGRA)

However, the current compiled kernels do not distinguish these Phis with the normal Phis.

[tancheng]

@ShangkunLi do you think we are able to distinguish the first phi, and represent it as phi_start?

For nested loop, which phi should be phi_start?

We also need this special phi_start in VectorCGRA. (@ccing @yyan7223)

[ShangkunLi]

@ShangkunLi do you think we are able to distinguish the first phi, and represent it as phi_start?

For nested loop, which phi should be phi_start?

We also need this special phi_start in VectorCGRA. (@ccing @yyan7223)

Yes, we can do that.

But in which case do we need such a phi_start? Could you please provide an example @Jackcuii?

Thanks~

[tancheng]

Based on offline discussion with @ShangkunLi, any phi with reserve op should be replaced with phi_start.

[yyan7223]

@ShangkunLi do you think we are able to distinguish the first phi, and represent it as phi_start?
For nested loop, which phi should be phi_start?
We also need this special phi_start in VectorCGRA. (@ccing @yyan7223)

Yes, we can do that.

But in which case do we need such a phi_start? Could you please provide an example @Jackcuii?

Thanks~

That’s my question too. What's the difference between phi_start and phi_const?

[tancheng]

@ShangkunLi do you think we are able to distinguish the first phi, and represent it as phi_start?
For nested loop, which phi should be phi_start?
We also need this special phi_start in VectorCGRA. (@ccing @yyan7223)

Yes, we can do that.
But in which case do we need such a phi_start? Could you please provide an example @Jackcuii?
Thanks~

That’s my question too. What's the difference between phi_start and phi_const?

for (i = 0; i < BOUND; ++i)

x = y * a[w]
for (i = x; i < BOUND; ++i)

They serve the same purpose, i.e., the main control part of the loop, but could be initialized differently. I also tag you in my PR with a question :-)

[tancheng]

Hi @BenkangPeng, let's make you get familiar with compiler from now on :-) Plz take a look at this issue first.