Cleaning up in preparation for making changes that improve
compile-time issues in AccessEnforcementOpts.
This is a simple but important enum with a handful of cases. The cases
need to be easily referenced from the header. Don't define them in a
separate .def. Remove the visitor biolerplate because it doesn't serve
any purpose.
This enum is meant to be used with covered switches. The enum cases do
not have their own types, so there's no performance reason to use a
Visitor pattern.
It should not be possible to add a case to this enum without carefully
considering the impact on the encoding of this class and the impact on
each and every one of the uses. We always want covered switches at the
use sites.
This is a major improvement in readability and usability both in the
definition of the class and in the one place where a visitor was used.
I have been meaning to do this change for a minute, but kept on putting it off.
This describes what is actually happening and is a better name for the option.
This is the first in a sequence of patches that implement various optimizations
to transform load [copy] into load_borrow.
The optimization works by looking for a load [copy] that:
1. Only has destroy_value as consuming users. This implies that we do not need
to pass off the in memory value at +1 and that we can use a +0 value.
2. Is loading from a memory location that is never written to or only written to
after all uses of the load [copy].
and then RAUW the load [copy] with a load_borrow and convertes the destroy_value
to end_borrow.
NOTE: I also a .def file for AccessedStorage so we can do visitors over the
kinds. The reason I want to do this is to ensure that people update these
optimizations if we add new storage kinds.
I am doing this for two reasons:
1. I want to use this in a different optimization where we optimize load [copy]
=> load_borrow.
2. This will ensure that if/when the ownership APIs change to use isConsume/etc
instead of the current operand ownership map, the optimization will be easy to
update.
This takes advantage of my restricting Semantic ARC Opts to run only on the
stdlib since we know it passes the ownership verifier. Using that I
reimplemented this optimization in a more robust, elegant, general
way. Specifically, we now will eliminate any SILGen copy_value on a guaranteed
argument all of whose uses are either destroy_values or instructions that can
accept guaranteed parameters. To be clear: This means that the value must be
consumed in the same function only be destroy_value.
Since we know that the lifetime of the guaranteed parameter will be larger than
any owned value created/destroyed in the body, we do not need to check that the
copy_value's destroy_value set is joint post-dominated by the set of end_borrows.
That will have to be added to turn this into a general optimization.
NOTE: This is not the final form of how operand ownership restraints will be
represented. This patch is instead an incremental change that extracts out this
functionality from the ownership verifier as a pure refactor.
rdar://44667493
The reason why I am doing this is now that once we have the
OperandOwnershipKindMap I can write this optimization in a more robust,
aggressive manner. My hope is that I can eliminate all copy_value of guaranteed
parameters all of whose uses could accept a guaranteed parameter. This is given
to me by the OperandOwnershipKindMap.
Additionally, I found that the way the analysis was using the OwnershipVerifier
was not sound on non-ownership verified SIL. Rather than fix it, I just turned
it off for that case.
rdar://44667493
This does not eliminate the entrypoints on SILBuilder yet. I want to do this in
two parts so that it is functionally easier to disentangle changing the APIs
above SILBuilder and changing the underlying instruction itself.
rdar://33440767
At some point, pass definitions were heavily macro-ized. Pass
descriptive names were added in two places. This is not only redundant
but a source of confusion. You could waste a lot of time grepping for
the wrong string. I removed all the getName() overrides which, at
around 90 passes, was a fairly significant amount of code bloat.
Any pass that we want to be able to invoke by name from a tool
(sil-opt) or pipeline plan *should* have unique type name, enum value,
commend-line string, and name string. I removed a comment about the
various inliner passes that contradicted that.
Side note: We should be consistent with the policy that a pass is
identified by its type. We have a couple passes, LICM and CSE, which
currently violate that convention.
I am going to run it very early and use it to ensure that extra copies due to my
refactoring of SILGenPattern do not cause COW copies to be introduced.
For now, it does a very simple optimization, namely, it eliminates a copy_value,
with only a destroy_value user on a guaranteed parameter.
It is now disabled behind a flag.
