This commit enables ArrangeAccessesHierachically to push down pointer
edges when rearranging accesses hierarchically.
In particular, if an edge N is being pushed down another edge M, and M
is at offset 0, and N reaches a pointer edge PE that points to a
grandparent G of M at offset 0, then we want to push down the pointer
edge PE so that it points to the target of M, unless there is another
edge M' different from M, such that M' has the same properties of M but
target(M) != target(M').
Before this commit, ArrangeAccesseHierachically was removing nodes from
the graph, instead of merging them.
This degraded the information collected on the graph useful for debug.
This commit drops the use of removeNode method, and switches to using
mergeNodes, that preserves the useful debug information when merging.
This commit introduces an additional run of CollapseSingleChild and
DeduplicateFields before CompactCompatibleArrays and
ArrangeAccessesHierarchically.
This is meant to cleanup the graph so that the two latter steps can be
more effective.
Before this commit postProcessMerge was making some strong assumptions
about dla::CollapseSingleChild::collapseSingle that no longer hold.
Namely the (now) wrong assumption is that collapseSingle would not break
post_order iteration, which is now false because collapseSingle can
change the incoming edges of the node it's called on, and those incoming
edges are on the visit stack of the post_order iteration itself.
This required making a copy of the post order, and resulted in dropping
the postProcessMerge function alltogether.
Before this commit we were using int64_t for Offset, Strides, and
TripCounts.
Originally, this choice was intended because for some time we envisioned
actually having a use for negative values, but in the end we decided
there's no use for those.
This commit switches all to unsigned integers, allowing to remove some
static_cast across the codebase, and overall easing typicall computation
we have to perform on those fields.
PromteCSVs creates wrappers around helpers. These helpers used to return
a struct in case the helper was changing a CSV.
In order to simplify the downstream pipeline, we now use out arguments
instead of returning a struct.
In certain code paths, CCodeGenerator would trigger the emission of
`%[number]`, which is very expensive since it requires to assign an ID
to a large amount of `llvm::Value`.
This commit ensure this doesn't happen, unless a logger is active.
Pietro Fezzardi