Instead of caching alias results globally for the module, make AliasAnalysis a FunctionAnalysisBase which caches the alias results per function.
Why?
* So far the result caches could only grow. They were reset when they reached a certain size. This was not ideal. Now, they are invalidated whenever the function changes.
* It was not possible to actually invalidate an alias analysis result. This is required, for example in TempRValueOpt and TempLValueOpt (so far it was done manually with invalidateInstruction).
* Type based alias analysis results were also cached for the whole module, while it is actually dependent on the function, because it depends on the function's resilience expansion. This was a potential bug.
I also added a new PassManager API to directly get a function-base analysis:
getAnalysis(SILFunction *f)
The second change of this commit is the removal of the instruction-index indirection for the cache keys. Now the cache keys directly work on instruction pointers instead of instruction indices. This reduces the number of hash table lookups for a cache lookup from 3 to 1.
This indirection was needed to avoid dangling instruction pointers in the cache keys. But this is not needed anymore, because of the new delayed instruction deletion mechanism.
introduce a common superclass, SILNode.
This is in preparation for allowing instructions to have multiple
results. It is also a somewhat more elegant representation for
instructions that have zero results. Instructions that are known
to have exactly one result inherit from a class, SingleValueInstruction,
that subclasses both ValueBase and SILInstruction. Some care must be
taken when working with SILNode pointers and testing for equality;
please see the comment on SILNode for more information.
A number of SIL passes needed to be updated in order to handle this
new distinction between SIL values and SIL instructions.
Note that the SIL parser is now stricter about not trying to assign
a result value from an instruction (like 'return' or 'strong_retain')
that does not produce any.
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.
Before this commit all code relating to handling arguments in SILBasicBlock had
somewhere in the name BB. This is redundant given that the class's name is
already SILBasicBlock. This commit drops those names.
Some examples:
getBBArg() => getArgument()
BBArgList => ArgumentList
bbarg_begin() => args_begin()
As there are no instructions left which produce multiple result values, this is a NFC regarding the generated SIL and generated code.
Although this commit is large, most changes are straightforward adoptions to the changes in the ValueBase and SILValue classes.
Revert "Make AADumper and MemoryBehaviorDumper function passes. They do not need to be module passes."
This reverts commit a503269e2d.
This reverts commit 375f525c51.
Turns out we /do/ want these two passes to be module passes so that their output
is independent of how the pass manager schedules function passes.
I tried to just fix the issue in MemBehaviorDumper/AADumper without reverting,
but somehow this caused their tests to start failing?!
I will try separating them again in a subsequent commit.
(libraries now)
It has been generally agreed that we need to do this reorg, and now
seems like the perfect time. Some major pass reorganization is in the
works.
This does not have to be the final word on the matter. The consensus
among those working on the code is that it's much better than what we
had and a better starting point for future bike shedding.
Note that the previous organization was designed to allow separate
analysis and optimization libraries. It turns out this is an
artificial distinction and not an important goal.
