Branch: refs/heads/master
Revision: 5492b6b
Author: ekayrakli
Log Message:
Merge pull request #16218 from ekayrakli/constdomain
Propagate constness of domain variables into the instance implementation
Add a definedConst
field in BaseDom
and adjust how we create domains to
set that field for const
domains. Also, use that information to avoid
tracking arrays for const
domains, which is the main motivation for this PR.
Implementation details:

Many module helper functions that create domains have a new argument
definedConst
. These helpers include,chpl__initCopy
,chpl__autoCopy
,
chpl__coerceCopy
andchpl__coerceMove

BaseDom
has a new fielddefinedConst
.This field is currently
var
because there are cases where we need to fix it
up after initialization. I’ll check if we can handle that case differently
and can make the fieldconst
. See future work for more. 
Many places in the compiler that create/modify/analyze
chpl__initCopy
et al
are adjusted to use the new signature. 
Coercion helpers (
chpl__coerceCopy
andchpl__coerceMove
) are modified to
use a new helper to callchpl__convertRuntimeTypeToValue
and pass constness
information to that directly. 
For optimization: adds a simple check around where we add/remove arrays to the
domains set of arrays to avoid doing that.
Future work
The implementation was challenging and there are some future steps that we
should take to make the implementation cleaner:

See if we can make the
definedConst
fieldconst
orparam
.param
ness makes sense however it has some difficulties as it’ll create a
completely different type. I am not sure how we can do that without adding
some notion betweenconst
andparam
for userdefined types that only used
by the compiler.const
is probably more doable but there are two major questions that we need
to address if we want to go in that direction:
Can/should we change dsiNewRectangularDomain to accept a new
definedConst
argument? I think the answer to this question should be
“no”, because we don’t want the implementer of the dmap to deal with
constness. However, that means that we can’t propogate the information in
newRectangularDom
unless we set it after initialization. 
Can/should we put the constness information in the privatization data? I
think the answer is “no” because of similar reasons. Then the question is
how to propagate the constness information to the privatized instances.
This PR handles it in ChapelArray after privatized instances are inited.
Thus, it needs the field to bevar
.


Can we also determine constness by static code analysis even if the domain was
declared asvar
? 
Domain arguments passed to
const in
formals are not recognized as constant
within the function body.
Further optimization oppurtunities:

Instead of doing lockincrementunlock, we can use an atomic integer for
tracking the number of arrays using a domain.Arguably an easy change to make. However, will reauire adding one more
redundant field to theBaseDom
class. 
Can we make use of this information in irregular domains? If we create
var
sparse domain, add indices to it, and then assign it to aconst
sparse
domain; can we make thatconst
sparse domain and its arrays work faster in
some cases?
Other Alternative Implementations Considered

We thought about adding a
param
field torecord _domain
, but didn’t do it: The information is needed in the domain instance and not in the domain
record, even though adding a field in the record would be easier.  We try to keep the footprint of these records small.
 The information is needed in the domain instance and not in the domain

Thought about adding “fixups” after all domain initializations, but didn’t do
it: This would have avoided the need to tinker with
chpl__initCopy
et al.
However, it would separate how we set constness from the initialization
itself. That could cause some issues where we do pattern detection and
change AST around DefExpr’s.
 This would have avoided the need to tinker with

Thought about adding
definedConst
argument as the first argument and not the
last.There is no ideal choice as to where we add this argument. And I initially
added it as a first argument. However, there are way too many places in the
compiler where the 1st and 2nd argument of these functions are used. Whereas,
the number of places where the arguments are counted from back is very
limited.The only potential confusion with adding this argument as the last is when the
compiler changes these functions to return via an RVV. In that scenario, the
definedConst
argument is in the middle of arguments. Currently there’s only
one place in the compiler where this surfaces and that’s in split
initialization support.
[Reviewed by @mppf]
Test status:
 [x] standard
 [x] gasnet
Modified Files:
A test/optimizations/constDomain/arrayOfArrays.chpl
A test/optimizations/constDomain/arrayOfArrays.good
A test/optimizations/constDomain/basic.chpl
A test/optimizations/constDomain/basic.good
A test/optimizations/constDomain/constPrimitiveDecl.chpl
A test/optimizations/constDomain/constPrimitiveDecl.good
A test/optimizations/constDomain/ifExpr.chpl
A test/optimizations/constDomain/ifExpr.good
A test/optimizations/constDomain/inIntents.bad
A test/optimizations/constDomain/inIntents.chpl
A test/optimizations/constDomain/inIntents.future
A test/optimizations/constDomain/inIntents.good
A test/optimizations/constDomain/lowLevel.chpl
A test/optimizations/constDomain/lowLevel.good
A test/optimizations/constDomain/privatization.chpl
A test/optimizations/constDomain/privatization.good
A test/optimizations/constDomain/privatization.numlocales
A test/optimizations/constDomain/privatization.skipif
M compiler/AST/AggregateType.cpp
M compiler/AST/AstToText.cpp
M compiler/AST/build.cpp
M compiler/include/bisonchapel.h
M compiler/include/resolution.h
M compiler/main/checks.cpp
M compiler/optimizations/removeUnnecessaryAutoCopyCalls.cpp
M compiler/parser/bisonchapel.cpp
M compiler/parser/chapel.ypp
M compiler/passes/errorHandling.cpp
M compiler/passes/parallel.cpp
M compiler/passes/splitInit.cpp
M compiler/resolution/callDestructors.cpp
M compiler/resolution/functionResolution.cpp
M compiler/resolution/initializerResolution.cpp
M compiler/resolution/lowerIterators.cpp
M compiler/resolution/preFold.cpp
M compiler/resolution/resolveFunction.cpp
M compiler/resolution/tuples.cpp
M compiler/resolution/wrappers.cpp
M modules/internal/ArrayViewRankChange.chpl
M modules/internal/ByteBufferHelpers.chpl
M modules/internal/CString.chpl
M modules/internal/ChapelArray.chpl
M modules/internal/ChapelBase.chpl
M modules/internal/ChapelDistribution.chpl
M modules/internal/ChapelIteratorSupport.chpl
M modules/internal/ChapelSyncvar.chpl
M modules/internal/DefaultRectangular.chpl
M modules/internal/LocaleModelHelpRuntime.chpl
M modules/internal/OwnedObject.chpl
M modules/packages/Futures.chpl
M test/arrays/slices/commCounts/sliceBlockWithRanges.nanone.good
M test/distributions/bradc/wrongDomForDist/DummyArithDist.chpl
M test/distributions/robust/arithmetic/performance/multilocale/assignReindex.block.good
M test/distributions/robust/arithmetic/performance/multilocale/assignReindex.block.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/assignReindex.cyclic.good
M test/distributions/robust/arithmetic/performance/multilocale/assignReindex.cyclic.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/assignReindex.replicated.good
M test/distributions/robust/arithmetic/performance/multilocale/assignReindex.replicated.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/assignSlice.block.good
M test/distributions/robust/arithmetic/performance/multilocale/assignSlice.block.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/assignSlice.cyclic.good
M test/distributions/robust/arithmetic/performance/multilocale/assignSlice.cyclic.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/assignSlice.replicated.good
M test/distributions/robust/arithmetic/performance/multilocale/assignSlice.replicated.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/reduceSlice.block.good
M test/distributions/robust/arithmetic/performance/multilocale/reduceSlice.block.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/reduceSlice.cyclic.good
M test/distributions/robust/arithmetic/performance/multilocale/reduceSlice.cyclic.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/reduceSlice.replicated.good
M test/distributions/robust/arithmetic/performance/multilocale/reduceSlice.replicated.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignReindex.block.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignReindex.block.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignReindex.cyclic.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignReindex.cyclic.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignReindex.replicated.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignReindex.replicated.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignSlice.block.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignSlice.block.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignSlice.cyclic.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignSlice.cyclic.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignSlice.replicated.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/assignSlice.replicated.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/reduceSlice.block.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/reduceSlice.block.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/reduceSlice.cyclic.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/reduceSlice.cyclic.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/reduceSlice.replicated.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/reduceSlice.replicated.nanone.good
M test/distributions/robust/arithmetic/performance/multilocale/rvfSlices/reduceSlice2.good
M test/functions/iterators/ferguson/noleakrecordbug.chpl
M test/functions/iterators/ferguson/noleakyieldrecord.chpl
M test/types/records/ferguson/dynamicdispatchautocopy.chpl
M test/types/records/ferguson/missingautocopy.chpl
Compare: https://github.com/chapellang/chapel/compare/d59235aaca86...5492b6b941c4