The InstId in this field is to an instruction that declares the
function, rather than the function itself, so that diagnostics can print
where the function is coming from. The type of the function (the
FunctionType instruction) is the type (the type_id) of the
function_decl_id. So we rename the field to help make this distinction
more clear.
Followup to #4739
Use it in the instruction namer to make instruction names more stable
across unrelated changes to the toolchain or the prelude.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
* Change `InterfaceWitness` -> `ImplWitness`
* Include a `SpecificId` in the `ImplWitness`. This allows the
`InstBlock` it contains to have its own identity, allowing it to be
changed as the impl is processed. Evaluation only updates the specific.
* Create the `ImplWitness` at the start of the impl definition. In the
future, this will be populated with the values of non-function
associated constants. For now, it starts full of invalid instruction
ids.
* Implements the model suggested in #4672 .
Note that the non-SemIR testdata changes are to these file:
* `toolchain/check/testdata/impl/lookup/fail_todo_undefined_impl.carbon`
* `toolchain/check/testdata/struct/import.carbon`
* `toolchain/check/testdata/tuple/import.carbon`
The last two are due to an import of generics bug exposed by this PR,
which will be fixed in a follow-on.
---------
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Use a deque to maintain the set of instructions to be walked over. so
that the loop can append more instructions (with their related scope)
during iteration without requiring recursion.
---------
Co-authored-by: jonmeow <jperkins@google.com>
I was wondering, instead of treating `misc` differently and enabling
specific checks, maybe we can flip that since we actually seem okay with
most of the checks?
The main check I'm enabling, with significant edits here, is
`misc-no-recursion`. But maybe this is helpful to enable, even with the
necessary NOLINTs, since we want to avoid recursion in the toolchain?
This PR shows some example fixes in subst.cpp (which are more stylistic,
since the code shouldn't actually have recursed due to its structure; I
think we could remove the warning on TryResolveInst the same way). Some
also just don't seem worth fixing, like those in tests files (I didn't
see a way to exclude files in .clang-tidy, so instead I'm using
NOLINTBEGIN). But I think we might actually want to fix inst_namer, and
there's enough in convert that I didn't look closely.
Also, I made some protected -> private style fixes based on
`misc-non-private-member-variables-in-classes` (this is also how I
noticed `class Real` versus `struct Real`). With node_stack, it looks
like the `protected` wasn't even used. [Per
style](https://google.github.io/styleguide/cppguide.html#Access_Control),
data members should be private outside tests. But since we can't
trivially exclude `protected` members in tests, I'm turning it off -- I
don't view it as offering enough benefit on the whole.
migrate_cpp issues are preexisting (I believe we just aren't monitoring
it), but changes there make `bazel build --config=clang-tidy -k //...`
work cleanly.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Instead of treating `Core.Int` as the toolchain's builtin `IntType`,
model it as a class that adapts the builtin type. This aligns us better
with the intended language model, gives an associated library for
`impl`s involving `Core.Int` to live within, and opens the door adding
member functions to `Core.Int` if we decide that is desirable.
Remarkably it also seems to make the formatted SemIR a little smaller,
because a call to a generic class generates less IR than a call to a
function.
When a generic requires a symbolic type to be complete, add a new
`require_complete_type` instruction to the generic eval block. During
monomorphization of such an instruction, require that type to be
complete.
This is a preparation change for adding name poisoning support
(https://github.com/carbon-language/carbon-lang/issues/4622), which is
expected to require more elaborate logic around NameScope since a name
can be not defined yet, defined, or poisoned.
The API separates looking up a name from getting the full entry since we
have cases where the entries are invalidated between the time we're
looking for the name and when we access (and sometimes modify) the
entry.
This change has the following benefits:
* `names` and `name_map` are internal to `NameScope` and are guaranteed
to match.
* `extended_scopes` and `import_ir_scopes` can not be manipulated (only
new scopes can be added).
* `inst_id`, `name_id` and `parent_scope_id` are constants.
* `has_error` can only be mutated from false to true.
---------
Co-authored-by: jonmeow <jperkins@google.com>
The offsets were originally added to deal with churn from builtins in
the raw semir. In textual semir, we mostly see instruction IDs for
imports, and builtins have also settled down more.
On imports, where possible, use the `EntityNameId` for an import instead
of printing an instruction. Next, show the source location if we have a
node. Only show the instruction if there's no location.
This also exposes `Parse::Tree` and `TokenizedBuffer`, so that we can
pass a `SemIR::File` without the component parts. In particular this
allows us to get the `TokenizedBuffer` for import IRs without
substantial structural modifications. We may want to make these optional
for serialized `SemIR` later, but the nodes/tokens contain source
location, which we'd need for debug information -- so it's not clear how
much we can really make them optional without substantial information
loss.
Reduce arguments to just `File` in a few spots, as a result of the
accompanying `TokenizedBuffer` and `Parse::Tree`. Also updates style to
pass around `const File*` where the reference is maintained, instead of
`const File&`.
I was considering keeping a direct reference to the tree and tokens on
`Context`, but initially my thought was it wouldn't make much
difference. I can re-add those if desired, just as direct caching of the
`File` fields.
* Rewrite constraints are stored in a facet type, substituted, imported,
and formatted.
* We now distinguish `.Self` from other symbolic bindings in two ways:
* `.Self` itself now has an invalid compile time binding index (since it
doesn't bind to any of the generic parameters). As a result, we no
longer need to create a generic region in `handle_where.cpp`.
* There is a new phase tracking values that are only symbolic because
they transitively depend on `.Self`. This allows us to give the result
of a `where` expression template phase as long as it doesn't use any
symbolic constants other than `.Self` or other designators.
* `AddConstant` has been removed from `check/context` since it was only
used from `eval`. This meant less plumbing of the phase change.
* Evaluation of `BindSymbolicName` now also performs substitution into
its type.
* Include a bit more information in some diagnostics.
* `StringifyTypeExpr` outputs rewrites, which required adding support
for associated entities as well.
* Associated entities now have an entity name set when importing.
* Adds tests for some interesting cases with rewrites and uses of
`.Self` mixed with other symbolic constants.
Still to do:
* There is no validation that any particular type satisfies rewrite
constraints.
* Access to members of a facet type do not see the rewritten values.
* Impls don't recognize whether associated constants have rewrites
setting their values.
* No support for resolving facet types.
---------
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Goal is to reduce churn in names in test updates (by churning a lot of
them in this PR).
---------
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
This is stamping out the per-instruction structs, similar to what we do
elsewhere. `BuiltinInstKind::label` then finishes shifting to
`InstKind::ir_name`.
For the few remaining uses of the builtin `i32` type, manually build an
`IntType(Signed, 32)` value instead. These are:
- The return type of `Run`.
- The type that int literals in an `if` expression are converted into.
- The type of an array index expression.
We should consider converting those three cases away from `i32` over
time.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This does a few things:
* Replaces the single `TypeId` in the `FacetTypeInfo` struct with a
vector of `InterfaceId`, `SpecificId` pairs (sorted in id order)
representing the set of interface requirements of the facet type. This
will later be used to support facet types with multiple interface
requirements (as in `I & J` or `I where .Self impls J`).
* Replace `InterfaceType` instructions (used as the type of an
`InterfaceDecl` instruction) with `FacetType` instructions (introduced
in #4460) with a (newly introduced) `FacetTypeFromInterface()` function.
* Replace code that consumed `InterfaceType` values with code that
consumed `FaceType` values. I've generally left the assumption in the
code that it is dealing with a single interface, using the (newly
introduced) `FacetTypeInfo::TryAsSingleInterface`, and producing an
error otherwise. There isn't yet support for the `&` operator or `where
.Self impls`, so this is generally a good assumption for now, except you
can get a facet type with no associated interfaces from a `type
where`... expression. In some cases, the facet type value is pulled from
the evaluation of an `InterfaceDecl` instruction, where the single
interface assumption will hold permanently.
* Some related cleans up: nicer stringification and formatting of facet
types, suppression of some errors when there already was an error.
There is still a lot left to do, including:
* Type `type` should be a facet type with a reserved id, replacing the
built-in instruction.
* Code using `TryAsSingleInterface` should generally be upgraded to
handle more than (or less than) one interface. Name lookup should be
particularly exciting.
* Operator `&` should be defined on facet types, unioning their
interface and other requirements.
* Requirements from a `where` clause don't do anything yet.
* Impls and impl lookup need to resolve facet types, and do things like
determine if all the associated constants are given values.
---------
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Geoff Romer <gromer@google.com>
This is in anticipation of making the integer value store be customized
heavily. I'd like to extract it from the common code when doing that, so
first disentangling them here without any intended change in
functionality or behavior to enable that.
I've tried to update `#include`s to be as minimal as I can and added a
few missing includes spotted in the process.
I've split the test for value store to include what was easy focused on
just the value store templates rather than the unified shared value
stores.
This might surface some opportunities for adding more tests, but for
this PR, just doing the minimal restructuring.
- Generate runtime indices as part of pattern matching, rather than as a
separate postprocessing/rewriting step.
- In contexts where runtime parameters aren't permitted, avoid emitting
insts for them to begin with, rather than trying to detect the problem
and rewrite the IR to remove them later on.
Also propagate the pattern IR along with the pattern-match IR, and use
it where appropriate.
Strictly speaking, some parts of the pattern-match IR are allocated
eagerly, while traversing the pattern's parse tree, but they still
aren't actually emitted until we traverse the associated pattern insts.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Update impl handling to more closely match other kinds of declaration,
including support for declaring and defining gneeric `impl`s.
When of performing redeclaration lookup for impls by looking for the
self and constraint type, produce a list of impls rather than a single
impl because it's possible for there to be multiple impls with different
deduced parameters but the same self type and constraint. Following
#3763, only consider impls to be redeclarations if they're spelled the
same, not just if they have the same self and constraint types.
No support yet for impl selection to deduce the arguments of a generic
impl.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Introduces the `BindingPattern` and `SymbolicBindingPattern` insts, and
a separate stack of pattern blocks that they are emitted into. The
intent is to generate the corresponding pattern-matching insts (like
`BindName`) from them in a separate pass, but that is deferred to future
PRs.
See
[here](https://docs.google.com/document/d/1U_vQH17V893J9aF1LJXUnFYBNSs2MjKl4bJPaWCB2zo/edit?usp=sharing&resourcekey=0-w0xGYZ0An31Kpz-wvzSXwQ)
for the design this is based on, but note that during review we have
chosen to deviate from that design by putting the patterns in separate
blocks, and omitting the "forward references" from a `BindingPattern` to
its corresponding `BindName`. This in turn necessitates having separate
inst kinds for symbolic and non-symbolic binding patterns.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This switches `DCHECK` and `FATAL` as well.
The goal is to reduce the code size impact of these assertions so that
we can keep more of them enabled. Currently, the largest cost I see from
`CHECK` is not the actual check or the cold code itself, but actually
the failure to inline trivial functions due to the presence of the cold
code. This means that our goal isn't to reduce apparent code size in the
final binary but the LLVM IR cost assessed for these routines in the
inliner, which closely correlates with code size but is a bit different.
As discussed in #4283, experimentation shows that a single function call
with a minimal number of arguments is the lowest cost model for these.
This is easily achieved with a format-string API that internally uses
`llvm::formatv`. This PR is essentially the `CHECK` version of #4283.
However, the check macros are substantially harder to make work with
both format strings and streaming because they also take a condition.
Also, unexpectedly, I was very successful at devising a regular
expression based automated rewrite from the streaming to the format
string form with only low 10s of manual fixes. This includes compacting
strings broken up across lines, etc. Given how well that went, I've
prepared this PR which just directly switches to the format string API
and migrate everything to use it.
One nice side-effect is that the format string approach ends up greatly
simplifying the implementation here as well.
This is ... *shockingly* effective. Parsing speeds up by more than 3%
with just this change. And checking speeds up by **8%** with this change
alone:
```
BM_CompileAPIFileDenseDecls<Phase::Parse>/256 86.3µs ± 1% 82.9µs ± 1% -3.94% (p=0.000 n=17+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024 431µs ± 1% 415µs ± 1% -3.76% (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096 1.77ms ± 1% 1.71ms ± 1% -3.18% (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384 7.44ms ± 1% 7.17ms ± 2% -3.56% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536 30.7ms ± 1% 29.7ms ± 1% -3.15% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144 131ms ± 1% 127ms ± 1% -2.81% (p=0.000 n=18+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/256 878µs ± 2% 800µs ± 1% -8.91% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/1024 1.88ms ± 2% 1.72ms ± 1% -8.56% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/4096 5.78ms ± 2% 5.28ms ± 1% -8.70% (p=0.000 n=20+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/16384 21.9ms ± 1% 20.1ms ± 1% -8.02% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/65536 90.4ms ± 2% 83.1ms ± 1% -8.04% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/262144 381ms ± 2% 352ms ± 1% -7.79% (p=0.000 n=19+19)
```
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
Instead of reusing instructions from the generic entity in the eval
block, rebuild constants in the same way we rebuild types. The previous
attempt to not rebuild these constants assumed that every constant used
in a generic would be built in that generic, and not referenced directly
or referenced from some enclosing scope, which isn't true in practice
and is a fragile assumption in any case.
We could add back some reuse of instructions from the generic -- if we
happen to see the right instruction to build a constant, we could
opportunistically reuse it -- but given the complexity added by doing
so, I'm not pursuing that here.
Now that the eval block for a generic consists of instructions uniquely
owned by that generic, rather than often being shared with another
entity, include the generic in the formatted SemIR output. I'm using the
same scope name for the generic object itself as for the parameterized
class / function / interface, because there are very frequently
references between them and this keeps the IR simpler and more readable,
and avoids needing to invent a second name for the scope.
Changes crash messages to start printing verbose forms of instructions,
rather than just the ID. Fixes some indentation issues with stacks. Also
switches unexpected inst formatting, because now there are lots, and
it'd be helpful to know where they are.
This uses a pimpl pattern for Formatter due to the number of member
functions on Formatter. Maybe we should refactor that, but this didn't
feel like a good place to do so.
Note, I have two concerns about this change... to note them here, to
make sure others are considering them when evaluating the
implementation:
1. Some instructions are very verbose to print, as evidenced by the
fn_decl printing (which includes function params) or scope printing
(which includes scope members).
- I'm not sure whether there's a way to simply reduce this, as it seems
essential to the requested printing of instructions.
- Long-term, we may at least want to limit the number of lines printed
here. However, I've already spent a fair amount of time here and I think
it's in a good state to evaluate.
2. Increased complexity in the crash handler may result in crash
messages failing to generate.
- For example, a crash in Formatter (and its deps, such as InstNamer or
location handling) prevents a stack from being printed. I'm pretty sure
I've written crashes in Formatter before.
Here's an example crash snippet (generated by adding a crash inside
`return` handling) before:
```
2. NodeStack:
0. FunctionDefinitionStart -> function2
1. ReturnStatementStart -> no value
2. IntLiteral -> inst+26
inst_block_stack_:
0. block<invalid> {inst+0, inst+1, inst+2, inst+23}
1. block9 {inst+26}
param_and_arg_refs_stack:
args_type_info_stack_:
```
And after:
```
2. Check::Context
NodeStack:
0. FunctionDefinitionStart: function2
1. ReturnStatementStart: no value
2. IntLiteral:
unexpected.inst+26.loc12_10: i32 = int_literal 0 [template = constants.%.2]
inst_block_stack_:
0. block<invalid> {
package: <namespace> = namespace [template] {
.Core = unexpected.inst+2
.F = unexpected.inst+23.loc11_22
}
unexpected.inst+1 = import Core
unexpected.inst+2: <namespace> = namespace unexpected.inst+1, [template] {}
unexpected.inst+23.loc11_22: %F.type = fn_decl @F [template = constants.%F] {
unexpected.inst+9.loc11_9: init type = call constants.%Bool() [template = bool]
unexpected.inst+10.loc11_9: type = value_of_initializer unexpected.inst+9.loc11_9 [template = bool]
unexpected.inst+11.loc11_9: type = converted unexpected.inst+9.loc11_9, unexpected.inst+10.loc11_9 [template = bool]
unexpected.inst+12.loc11_6: bool = param b
@F.%b: bool = bind_name b, unexpected.inst+12.loc11_6
unexpected.inst+19.loc11_18: init type = call constants.%Int32() [template = i32]
unexpected.inst+20.loc11_18: type = value_of_initializer unexpected.inst+19.loc11_18 [template = i32]
unexpected.inst+21.loc11_18: type = converted unexpected.inst+19.loc11_18, unexpected.inst+20.loc11_18 [template = i32]
@F.%return: ref i32 = var <return slot>
}
}
1. block9 {
unexpected.inst+26.loc12_10: i32 = int_literal 0 [template = constants.%.2]
}
param_and_arg_refs_stack:
args_type_info_stack_:
```
I'm trying to increase the distinction between BuiltinKind and
BuiltinFunctionKind. BuiltinKind is for instructions,
BuiltinFunctionKind is for function definitions. To get to this point,
I'm doing a few changes:
- BuiltinKind -> BuiltinInstKind
- builtin_kind.* -> builtin_inst_kind.*: filename consistency
- Builtin -> BuiltinInst: mainly for consistency with the above
- Builtin::builtin_kind -> BuiltinInst::builtin_inst_kind: somewhat
repetitive but seems like a consistent edit
- Function::builtin_kind -> Function::builtin_function_kind: seems a
useful distinction
I'm leaving alone things like (and mentioning in case there's a desire
for more renames):
- InstId::BuiltinError, InstId::ForBuiltin: these I think are more
apparent because they're directly associated with Inst.
- GetBuiltinICmpPredicate in lowering: maybe builtin function handling
should be in its own file, but these local names don't feel problematic
to me.
- GetBuiltinType, BuildBuiltinValueRepr, PerformBuiltinIntComparison:
similar to the above, names don't feel too problematic
This executes on a TODO in AddImportRef to add instructions to their own
block instead of the File block. This has an important consequence of
removing a pattern from InstBlockStack that added to blocks not
currently at the top, cleaning up an issue for ArrayStack. The delta
here is then mostly in different formatting of the import refs, a
consequence of the separation.
By adding an `ImportDecl` instruction, this creates something that can
be referenced through `ImportIRInst`.
packages/no_prelude/implicit_imports_entities.carbon is getting a test
of this (import_conflict and import_conflict_reverse).
Also re-packs ImportIR from 24 bytes to 16 on 64-bit, since I'm touching
everywhere that makes one anyways.
Require mapping from a `ConstantId` to an `InstId` to go through the
`ConstantValueStore`.
This is a preparatory step for an upcoming generics change where
symbolic `ConstantId`s are no longer just a thin wrapper around an
`InstId` but instead are indexes into a table with additional
information about the symbolic constant beyond its `InstId`.
This is mostly mechanically duplicating work done for generic classes to
also support generic interfaces.
Also fix both generic interfaces and generic classes to support
importing class and interface types with arguments from another file.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
Don't format the *type of* the function `F` as `"F"`. Instead use
`"<type of F>"`.
Also improve instruction naming for function and generic class name
values: name the value after the function or generic class, and add a
`.type` suffix to the type.
Switch from recursing into non-canonical instruction fields to
separately canonicalizing those fields. This means we now form canonical
`InstBlockId`s, `TypeBlockId`s, `IntId`s, `FloatId`s, and `BindNameId`s
at least in the cases when they're referenced by a constant instruction.
This reduces the overall runtime for @chandlerc's 10MLoC example by
27.5% on my machine.
This adds a `BindExport` instruction in order to better track the
location of the `export` itself, but a `bind_name_id` is also added to
`ImportRef` so that we know quickly where to put it in name lookup.
Merging identical names is a TODO. I haven't quite decided how best to
achieve that, because I do think the BindExport should be what's
actually added to name lookup.
Also, I will probably add a mode to DeclNameStack that blocks
non-namespace scopes. This seems to already be an error, but the wrong
one (maybe due to lack of support for cross-file decl/def support).
This is modeled analogously to FunctionType. So far, GenericClassType
has no operations, but eventually values of that type will be callable
like values of FunctionType.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This was to track use of a declaration after import, prior to a
redeclaration. Per [discussion on
Discord](https://discord.com/channels/655572317891461132/1217182321933815820/1236016521059237962),
we likely don't need this check due to the change in behavior of
`extern`.
Rather than potentially getting one of many `extern` decls and depending
on it by accident, it is now planned to be _required_ to be imported,
and the library doing a non-`extern` decl must _know_ it's importing the
`extern` decl. The stricter requirement on the library means it now
seems more reasonable to use the `extern` decl.
So kind of rolling back #3831, though keeping `ImportIRInstId` (at least
for now) and keeping `Loaded`/`Unloaded` terminology (seems a nicer
fit).
This removes the builtin FunctionType, replacing it with a FunctionType
instruction. The constant for a FunctionDecl is now a StructValue with
type of FunctionType.
Note this means a function declaration produces _both_ a type, and a
value of the type. This has some consequences in terms of circularity,
and makes the importing of function declarations a little more complex.
It'll get particularly peculiar for imports because of the behavior of
the reference, but that's a known issue due to other things such as
`alias`. The impact will hopefully be contained to
ResolvePrevInstForMerge (and ImportRefs).
To note a small formatting change in diagnostics:
```
- // CHECK:STDERR: fail_member_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated <function> in Interface>` is not callable.
+ // CHECK:STDERR: fail_member_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated F in Interface>` is not callable.
- // CHECK:STDERR: fail_todo_facet_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated <function> in Interface>` is not callable.
+ // CHECK:STDERR: fail_todo_facet_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated F in Interface>` is not callable.
```
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Change the names for emitted globals for constants with storage to
include both the name of the constant and the name of the use.
This causes the instructions to also be named in SemIR and in LLVM IR
constants.
Factor out `SemIR::InstNamer` and also use it when lowering to LLVM IR.
Automatically name all instructions created with our `IRBuilder` based
on the name computed by the `InstNamer`, and likewise name basic blocks
using the label generated by the `InstNamer`.
Move some of the existing naming logic out from lower into `InstNamer`
so that it's also used in SemIR. In particular, we now name call
instructions after their callee, or after the builtin name for calls to
builtins.
Computing and adding these names isn't completely free. This instruction
naming is designed to be optional, so that we can turn it off for builds
where the LLVM IR will only be converted to assembly and won't be seen
by a human, but so far it's enabled unconditionally. We can tune that
later as needed.