This PR slightly improves the types involved in creating boxed
declarations. Previously the type of
the vdecl used for the return was always `tobj` when returning a boxed
scalar. This is not the most
precise annotation we can give.
This PR lets recursive functions defined by well-founded recursion use a
different `fix` function when the termination measure is of type `Nat`.
This fix-point operator use structural recursion on “fuel”, initialized
by the given measure, and is thus reasonable to reduce, e.g. in `by
decide` proofs.
Extra provisions are in place that the fixpoint operator only starts
reducing when the fuel is fully known, to prevent “accidential” defeqs
when the remaining fuel for the recursive calls match the initial fuel
for that recursive argument.
To opt-out, the idiom `termination_by (n,0)` can be used.
We still use `@[irreducible]` as the default for such recursive
definitions, to avoid unexpected `defeq` lemmas. Making these functions
`@[semireducible]` by default showed performance regressions in lean.
When the measure is of type `Nat`, the system will accept an explicit
`@[semireducible]` without the usual warning.
Fixes#5234. Fixes: #11181.
This PR sorts the declarations fed into ElimDeadBranches in increasing
size. This can improve performance when we are dealing with a lot of
iterations.
The motivation for this change is as follows. Currently the algorithm
for doing one step of abstract interpretation is:
```
for decl in scc do
interpDecl
if summaryChanged decl then
return true
return false
```
whenever we return true we run another step. Now suppose we are in a
situation where we have an SCC with one big decl in the front and then
`n` small ones afterwards. For each time that the small ones change
their summary, we will re-run analysis of the big one in the front.
Currently the ordering is basically at "random" based on how other
compilers inject things into the SCC. This change ensures the behavior
is consistent and at least somewhat intelligent. By putting the small
declarations first, whenever we trigger a rerun of the loop we bias
analyzing the small declarations first, thus decreasing run time.
Note that this change does not have much effect on the current pipeline
because: We usually construct the SCCs in a way such that small ones
happen to be in front anyways. However, with upcomping changes on
specialization this is about to change.
This PR fixes the compilation of structure projections with unboxed
arguments marked `extern`, adding missing `dec` instructions. It led to
leaking single allocations when such functions were used as closures or
in the interpreter.
This is the minimal working fix; `extern` should not replicate parts of
the compilation pipeline, which will be possible via #10291.
This PR is a followup of #11381 and enforces the invariants on ordering
of closed terms and constants required by the EmitC pass properly by
toposorting before saving the declarations into the Environment.
This PR fixes a bug where the closed term extraction does not respect
the implicit invariant of the
c emitter to have closed term decls first, other decls second, within an
SCC. This bug has not yet
been triggered in the wild but was unearthed during work on upcoming
modifications of the
specializer.
This PR accelerates termination of the ElimDeadBranches compiler pass.
The implementation addresses situations such as `choice [none, some
top]` which can be summarized to
`top` because `Option` has only two constructors and all constructor
arguments are `top`.
This PR renames `String.ValidPos` to `String.Pos`, `String.endValidPos`
to `String.endPos` and `String.startValidPos` to `String.startPos`.
Accordingly, the deprecations of `String.Pos` to `String.Pos.Raw` and
`String.endPos` to `String.rawEndPos` are removed early, after an
abbreviated deprecation cycle of two releases.
This PR makes the specializer (correctly) share more cache keys across
invocations, causing us to produce less code bloat.
We observed that in functions with lots of specialization, sometimes
cache keys are defeq but not BEq because one has unused let decls
(introduced by specialization) that the other doesn't. This PR resolves
this conflict by erasing unused let decls from specializer cache keys.
This PR removes all code that sets the `Option.Decl.group` field, which
is unused and has no clearly documented meaning.
The actual removal of the field would be #11305.
This PR replaces `MatcherInfo.numAltParams` with a more detailed data
structure that allows us, in particular, to distinguish between an
alternative for a constructor with a `Unit` field and the alternative
for a nullary constructor, where an artificial `Unit` argument is
introduced.
This PR introduces a function `String.split` which is based on
`String.Slice.split` and therefore supports all pattern types and
returns a `Std.Iter String.Slice`.
This supersedes the functions `String.splitOn` and `String.splitToList`,
and we remove all all uses of these functions from core. They will be
deprecated in a future PR.
Migrating from `String.splitOn` and `String.splitToList` is easy: we
introduce functions `Iter.toStringList` and `Iter.toStringArray` that
can be used to conveniently go from `Std.Iter String.Slice` to `List
String` and `Array String`, so for example `s.splitOn "foo"` can be
replaced by `s.split "foo" |>.toStringList`.
This PR prevents symbol clashes between (non-`@[export]`) definitions
from different Lean packages.
Previously, if two modules define a function with the same name and were
transitively imported (even privately) by some downstream module,
linking would fail due to a symbol clash. Similarly, if a user defined a
symbol with the same name as one in the `Lean` library, Lean would use
the core symbol even if one did not import `Lean`.
This is solved by changing Lean's name mangling algorithm to include an
optional package identifier. This identifier is provided by Lake via
`--setup` when building a module. This information is weaved through the
elaborator, interpreter, and compiler via a persistent environment
extension that associates modules with their package identifier.
With a package identifier, standard symbols have the form
`lp_<pkg-id>_<mangled-def>`. Without one, the old scheme is used (i.e.,
`l_<mangled-def>`). Module initializers are also prefixed with package
identifier (if any). For example, the initializer for a module `Foo` in
a package `test` is now `initialize_test_Foo` (instead of
`initialize_Foo`). Lake's default for native library names has also been
adjusted accordingly, so that libraries can still, by default, be used
as plugins. Thus, the default library name of the `lean_lib Foo` in
`package test` will now be `libtest_Foo`.
When using Lake to build the Lean core (i.e., `bootstrap = true`), no
package identifier will be used. Thus, definitions in user packages can
never have symbol clashes with core.
Closes#222.
This PR redefines `String.take` and variants to operate on
`String.Slice`. While previously functions returning a substring of the
input sometimes returned `String` and sometimes returned
`Substring.Raw`, they now uniformly return `String.Slice`.
This is a BREAKING change, because many functions now have a different
return type. So for example, if `s` is a string and `f` is a function
accepting a string, `f (s.drop 1)` will no longer compile because
`s.drop 1` is a `String.Slice`. To fix this, insert a call to `copy` to
restore the old behavior: `f (s.drop 1).copy`.
Of course, in many cases, there will be more efficient options. For
example, don't write `f <| s.drop 1 |>.copy |>.dropEnd 1 |>.copy`, write
`f <| s.drop 1 |>.dropEnd 1 |>.copy` instead. Also, instead of `(s.drop
1).copy = "Hello"`, write `s.drop 1 == "Hello".toSlice` instead.
This PR fixes a bug in the LCNF simplifier unearthed while working on
#11078. In some situations caused by `unsafeCast`, the simplifier would
record incorrect information about `cases`, leading to further bugs down
the line.
Suppose we have `v : NonScalar` due to an `unsafeCast` and we run
`cases` on it, expecting `Prod.mk fst snd`. The current code attempts to
record both the arguments from the constructor application in the case
arm `fst`, `snd` and the parameters for the type by inspecting the discr
`v`. However, `NonScalar` does of course not have any parameters,
causing the simplifier to record wrong information. This patch makes the
`cases` infrastructure more cautious when extracting information from
the type of `v`.
This PR fixes the `reduceArity` compiler pass to consider
over-applications to functions that have their arity reduced.
Previously, this pass assumed that the amount of arguments to
applications was always the same as the number of parameters in the
signature. This is usually true, since the compiler eagerly introduces
parameters as long as the return type is a function type, resulting in a
function with a return type that isn't a function type. However, for
dependent types that sometimes are function types and sometimes not,
this assumption is broken, resulting in the additional parameters to be
dropped.
Closes#11131
This PR renames `Substring` to `Substring.Raw`.
This is to signify its status as a second-class citizen (not deprecated,
but no real plans for verification, like `String.Pos.Raw`) and to free
up the name `Substring` for a possible future type `String.Substring :
String -> Type` so that `s.Substring` is the type of substrings of `s`.
The functions `String.toSubstring` and `String.toSubstring'` will remain
for now for bootstrapping reasons.
This PR removes all uses of `String.Iterator` from core, preferring
`String.ValidPos` instead.
In an upcoming PR, `String.Iterator` will be renamed to
`String.Legacy.Iterator`.
This PR lets the match compilation procedure use sparse case analysis
when the patterns only match on some but not all constructors of an
inductive type. This way, less code is produce. Before, code handling
each of the other cases was then optimized and commoned-up by later
compilation pipeline, but that is wasteful to do.
In some cases this will prevent Lean from noticing that a match
statement is complete
because it performs less case-splitting for the unreachable case. In
this case, give explicit
patterns to perform the deeper split with `by contradiction` as the
right-hand side.
At least temporarily, there is also the option to disable this behaviour
with
```
set_option backwards.match.sparseCases false
```
This PR adds “sparse casesOn” constructions. They are similar to
`.casesOn`, but have arms only for some constructors and a catch-all
(providing `t.ctorIdx ≠ 42` assumptions). The compiler has native
support for these constructors and now (because of the similarity) also
the per-constructor elimination principles.
This PR enforces users of the constant folder API to provide proofs of
their algebraic properties,
thus hopefully avoiding bugs such as #11042 and #11043 in the future.
This PR fixes a case of overeager constant folding on Nat where the
compiler would mistakenly assume `0 - x = x` (see also #11042 for the
same bug on UInts).
This PR improves the detection of situations where we branch multiple
times on the same value in the
code generator. Previously this would only consider repeated branching
on function arguments, now on
arbitrary values.
Closes: #11018
This PR improves join point finding in the compiler through two means:
1. We now handle situations where a function `f` can only become a join
point when a function `g`
becomes a join point as well correctly.
2. We introduce a second join point finding pass after specialisation
and before the following
simplification pass, as the specialiser might have introduced new join
point opportunities for
the simplifier to exploit.
Notably in the code from #10995 we now correctly detect the missing join
point which required both
of these changes to be made.
Closes: #10995
This PR makes the eager lambda lifting heuristic more predictable by
blocking it from lifting from
any kind of inlineable function, not just `@[inline]`. It also adapts
the doc-string to describe
what is actually going on.
This PR defines `String.Slice.replace` and redefines `String.replace` to
use the `Slice` version.
The new implementation is generic in the pattern, so it supports things
like `"education".replace isVowel "☃!" = "☃!d☃!c☃!t☃!☃!n"`. Since it
uses the `ForwardSearcher` infrastructure, `String` patterns are
searched using KMP, unlike the previous implementation which had
quadratic runtime. As a side effect, the behavior when replacing an
empty string now matches that of most other programming languages,
namely `"abc".replace "" "k" = "kakbkck"`.
This PR adds the basic infrastructure to perform termination proofs
about `String.ValidPos` and `String.Slice.Pos`.
We choose approach where the intended way to do termination arguments is
to argue about the position itself rather than some projection of it
like `remainingBytes`.
The types `String.ValidPos` and `String.Slice.Pos` are equipped with a
`WellFoundedRelation` instance given by the greater-than relation. This
means that if a function takes a position `p` and performs a recursive
call on `q`, then the decreasing obligation will be `p < q`. This works
well in the common case where `q` is `p.next h`, in which case the goal
`p < p.next h` is solved by the simplifier.
For stepping through a string backwards, we introduce a type synonym
with a `WellFoundedRelation` instance given by the less-than relation.
This means that if a function takes a position `p` and performs a
recursive call on `q` and specifies `termination_by p.down`, then the
decreasing obligation will be `q < p`. This works well in the case where
`q` is `p.prev h`, in which case the goal `p.prev h < p` is solved by
the simplifier.
For termination arguments invoving multiple strings, the lower-level
primitive `p.remainingBytes` (landing in `Nat`) is also available.
In a future PR, we will additionally provide the necessary typeclasses
instances to register `String.ValidPos` and `String.Slice.Pos` with
`grind` to make complex termination arguments more convenient in user
code.
This PR performs more widening in ElimDeadBranches in an attempt to
improve performance in situations with a lot of local precision.
While this is not enough to make the compilation instant it pushes
compilation time from 12s to 3s for the example in #10857 and barely
introduces regressions so it seems like a good first step in this
direction.
Closes: #10857
This PR fixes name mangling to be unambiguous / injective by adding `00`
for disambiguation where necessary. Additionally, the inverse function,
`Lean.Name.unmangle` has been added which can be used to unmangle a
mangled identifier. This unmangler has been added to demonstrate the
injectivity but also to allow unmangling identifiers e.g. for debugging
purposes.
Closes#10724
This PR splits some low-hanging fruit out of `Init.Data.String.Basic`:
basic material about `String.Pos.Raw`, `String.Substrig`, and
`String.Iterator`.
More splitting required and the remaining material is quite unorganized,
but it's a start.
This PR implements zero cost `BaseIO` by erasing the `IO.RealWorld`
parameter from argument lists and structures. This is a **major breaking
change for FFI**.
Concretely:
- `BaseIO` is defined in terms of `ST IO.RealWorld`
- `EIO` (and thus `IO`) is defined in terms of `EST IO.RealWorld`
- The opaque `Void` type is introduced and the trivial structure
optimization updated to account for it. Furthermore, arguments of type
`Void s` are removed from the argument lists of the C functions.
- `ST` is redefined as `Void s -> ST.Out s a` where `ST.Out` is a pair
of `Void s` and `a`
This together has the following major effects on our generated code:
- Functions that return `BaseIO`/`ST`/`EIO`/`IO`/`EST` now do not take
the dummy world parameter anymore. To account for this FFI code needs to
delete the dummy world parameter from the argument lists.
- Functions that return `BaseIO`/`ST` now return their wrapped value
directly. In particular `BaseIO UInt32` now returns a `uint32_t` instead
of a `lean_object*`. To account for this FFI code might have to change
the return type and does not need to call `lean_io_result_mk_ok` anymore
but can instead just `return` values right away (same with extracting
values from `BaseIO` computations.
- Functions that return `EIO`/`IO`/`EST` now only return the equivalent
of an `Except` node which reduces the allocation size. The
`lean_io_result_mk_ok`/`lean_io_result_mk_error` functions were updated
to account for this already so no change is required.
Besides improving performance by dropping allocation (sizes) we can now
also do fun new things such as:
```lean
@[extern "malloc"]
opaque malloc (size : USize) : BaseIO USize
```
This PR reduces the amount of symbols in our DLLs by cutting open a
linking cycle of the shape:
`Environment -> Compiler -> Meta -> Environment`
This is achieved by introducing a dynamic call to the compiler hidden
behind a `Ref` as previously
done in the pretty printer.
This PR moves many operations involving `String.Pos.Raw` to a the
`String.Pos.Raw` namespace with the eventual aim of freeing up the
`String` namespace to contain operations using `String.ValidPos` (to be
renamed to `String.Pos`) instead.
This PR adds the `String.ValidPos.set` and `String.ValidPos.modify`
functions.
After this PR, `String.pos_lt_eq` is no longer a `simp` lemma. Add
`String.Pos.Raw.lt_iff` as a `simp` lemma if your proofs break.
