On Sun, Aug 6, 2017 at 4:26 PM, Luc Van Oostenryck
<luc.vanoostenryck@xxxxxxxxx> wrote:
> Since it seems to be some interest on the subject and
> to avoid duplicated work, here is a rewrite of sparse's
> construction of the SSA form.
>
> It's not using one of the classical algorithm but is
> using something newer, simpler and often faster.
> It's main advantage beyond the simplicity is that you don't
> need to first build the whole CFG & linearized code to
> to directly throw it away (or heavily transform it) as
> it builds the SSA form directly during the linearization.
OK, great.
May I ask the question that, the SSA form you are building
from this codes. Does it violate the SSA dominance property
define as:
==================================
Φ-Functions are placed in all basic blocks of the
Dominance Frontier.
Dominance Property of SSA:
1. If x is used in a Phi-function in block N,
then the definition of x dominates *every* <==== notice "every"
predecessor of N.
2. If x is used in a non-Phi statement in N,
then the definition of x dominates N
==================================
In other word, does it produce the "usage before
define" IR similar to this?
and.32 %r3 <- %r4, $-65
or.32 %r4 <- %r3, $64
> It's not finished code but it's working well (and is
> effectively a bit faster and use less memory).
The correct behavior is the most important one.
Then performance.
> What's interesting for sparse now is that:
> - the phi-noes are correctly placed
In the dominance frontier, right? That is great.
> - uninitialized variables can be handled much more easily.
That I am very curios how it was done. See the above
question. I might not have time to go through your code
very quickly. I will do my best when I have some time.
Chris
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