In a pattern like
a*b
a naive attempt to match will take quadratic time on an input that
contains all "a"s an no "b". To improve that case, the regexp compiler
detects that a match will require a "b" and checks the input for a "b"
to enable linear-time failure.
That optimization mishandled `(?!...)` and `(?<!...)` patterns,
treating the must-not-match subpatterns as things that must match.
So,
(regexp-match "a*(?!b)" "aaaxy")
returned false, because the input doesn't contain "b".
Thie commit repairs the optimization.
Closes#1468
Fix a regression relative to v6.4 caused by a refactoring of the
compiler between v6.4 and v6.5. The refactoring lost information about
letrecs that are converted internally to let* when a mutable variable
is involved, and it ends up allocating a closure before the box of a
mutable variable that is referenced by the closure. Something like
`with-continuation-mark` is needed around the closure's `lambda` to
prevent other optimizations from hiding the bug.
Closes#1462
lookup-errno now returns #f when given an unknown symbol instead
of raising a contract error. It should not return #f for any
symbol that it previously accepted.
The `if` case of the compiler's space-safety pass abused its "last
non-tail call relative to the closest enclosing binding" state as
"last non-tail call relative to the enclosing run time", which could
cause it to not clear a stack position as needed to maintain space
safety.
* add lang-reader-module-paths to syntax/module-reader
to be used as the third argument to make-meta-reader in lang-extensions
like at-exp
* document lang-reader-module-paths
* use lang-reader-module-paths in at-exp
This makes two changes to the forms in racket/splicing to adjust how
syntax properties are propagated through expansion:
1. Uses of make-syntax-introducer are passed #t as the first argument,
which causes the introduced scope to be consider a use-site rather
than macro-introduction scope. This prevents syntax objects from
being unnecessarily marked as unoriginal, in the syntax-original?
sense.
2. Uses of syntax/loc have been adjusted to copy syntax properties
from original syntax objects, which were previously discared. Forms
that were spliced into the surrounding context, such as begin,
define-values, and define-syntaxes, recreated the top-level syntax
objects, which did not preserve syntax properties from the
originals.
This is not a perfect solution, mostly because it potentially elides
properties that may be associated with captured literals (that is,
properties attached directly to begin, define-values, or define-syntaxes
identifiers themselves). However, it seems to accommodate most of the
common use-cases: propagation of syntax-original?-ness and forms like
`struct`, which attach properties like 'sub-range-binders.
fixes#1410
A `struct-copy` form can generates a call for a constructor that
includes a sequence of `unsafe-struct-ref` arguments. Each
`unsafe-struct-ref` must still check for a chaperone. Make the JIT
recognize that pattern an turn it into a single test instead of
one test per `unsafe-struct-ref`.
http-proxy/ contains a suite of almost useful (but mostly useless) servers.
These can be used to test http-client, and url.rkt
git proxy is not tested yet -- I really wouldn’t know how
Make the optimizer recognize and track `make-struct-property-type`
values, and use that information to recognize `make-struct-type`
calls that will defnitely succeed because a property that hs no
guard is given a value in the list of properties.
Combined with the change to require-keyword expansion, this
change allows the optimizer to inline `f` in
(define (g y)
(f #:x y))
(define (f #:x x)
(list x))
because the `make-struct-type` that appears between `g` and `f`
is determined to have no side-effect that would prevent `f` from
having its expected value.
When a module defines and exports an identifier at two phases,
and when another module imports both of them at the same phase,
an error was not reported as it should have been.
Some expressions are omittable only when the arguments have certain types.
In this case the application is marked with APPN_FLAG_OMITTABLE instead of relaying on the flags of the primitive.
The optimizer can't use this flag to move the expression inside a lamba or across a potential continuation capture, unlike other omittable expressions. They can be moved
only in more restricted conditions.
For example, in this program
#lang racket/base
(define n 10000)
(define m 10000)
(time
(define xs (build-list n (lambda (x) 0)))
(length xs)
(define ws (list->vector xs)) ; <-- omittable
(for ([i (in-range m)])
(vector-ref ws 0))) ; <-- ws is used once
If the optimizer moves the expression in the definition of ws inside the recursive
lambda that is created by the for, then the code is equivalent to:
#lang racket/base
(define n 10000)
(define m 10000)
(time
(define xs (build-list n (lambda (x) 0)))
(length xs)
(for ([i (in-range m)])
(vector-ref (list->vector xs) 0))) ; <-- moved here
And the new code is O(n*m) instead of O(n+m). This example is a minimized version
of the function kde from the plot package, where n=m and the bug changed the run
time from linear to quadratic.
The application of some procedures are omittables when the arguments have
certain properties. Check the arity of the procedure before marking the application as omittable.
The only case that appears to be relevant is the expression (-).
The relevant predicates are almost disjoint. The superposition
is solved with predicate_implies and predicate_implies_not.
This is also valid considering the equivalence classes modulo
eqv? and equal?. So if the optimizer knows that two expressions
X and Y have different relevant types, then it can reduce
(equal? X Y) ==> (begin X Y #f).
Changes signatures in `syntax/modcode` to accept `path-string?` arguments
instead of `path?`.
Before, the docs listed `path-string?` but the contracts used `path?`.
Now they agree.
Allow a `struct` form to be recognized when it provides
a number as the 8th argument to `make-struct-type`. In
particular, that change allows the construction of
optional-keyword functions to be recognized as a
purely functional operation.
Also, allow the optimizer to use information about imports
when deciding whether a module-level form is functional.
It's ok to use that information, because the validator has
it, too.
This combination of changes allows something like
(define (f #:optional [x #f])
(later))
(define (later) ....)
to compile to a reference to `later` wihout a check.
Due to an obvious problem in the setup, the letrec-check pass wasn't
running an intended dead-code pruning pass. Correcting the problem
cuases one test in "optimize.rktl" to change, because the letrec-check
pass can see more in one case than thanother.
(Problem discovered by accidentally fixing the setup in a Racket
branch based on "linklets".)
Along with the `PLT_COMPILED_FILE_CHECK` environment variable, allows
the timestamp check to be disabled when deciding whether to use a
compiled bytecode file.
In accomodating this change, `raco make` and `raco setup` in all modes
check whether the SHA1 hash of a module source matches the one
recorded in its ".dep" file, even if the timestamp on the bytecode
file is newer. (If the compile-file check mode is 'exists, the
timestamp is completely ignored.)
1. Changed the API documentation for scheme_make_hash_tree, adding primitives for:
* SCHEME_hashtr_eq
* SCHEME_hashtr_equal
* SCHEME_hashtr_eqv
2. Changed direct uses of scheme_make_hash_tree to use these enumed values.
3. Fixed bugs in documentation
4. Defaults to racket/interactive (and racket/gui/interactive) if there is nothing in the config file
Now accepts any whitespace, not just spaces, ignores both leading and
trailing whitespace, and accepts multiple whitespace characters
separating subterms.
After refactoring the test for the inferred types of some procedures that
use vector?/bytes?/string?/list? it was easier to spot the missing information.
Note that in the documentation, some arguments like the position in
(vector-ref <vector> <position>)
are documented as exact-nonnegative-integer? but due to the implementation
details they are actually in a subset of fixnum?s.
When `read` parses a literal hash table, it inserts an placeholder
just in case it's needed for cycles. The `unsafe-immutable-hash-...`
operations in some cases did not detect and remove the placeholder.
Closes#1376
Merge to v6.6
The namespace returned by `variable-reference->namespace` (or
`namespace-anchor->namespace`) may be used via `eval` to define new
bindings, so enable top-level binding support for the namespace.
for example, make the optimizer convert something like
(struct a (x))
(lambda (v) (if (a? v) (a-x v) #f))
to
(struct a (x))
(lambda (v) (if (a? v) (unsafe-struct-ref v 0) #f))
The optimizer change in e887fa56d1 recognized struct declarations that
involved only whitelisted properties to guarantee that constructor
properties are preserved --- while `prop:chaperone-unsafe-undefined`
can affect the constructor, and other properties might imply that one.
But the optimizer's transformer aren't actually invalidated by
`prop:chaperone-unsafe-undefined`; the JIT's assumptions are affected,
but that's handled in a different way. So, remove the whitelist and
allow any property list.
This change permits EH patterns like (~once <nullable>), because the
match will happen at most once, so there is no danger of divergence.
Thanks to Alex Knauth for pointing out this special case.
Merge to release branch.
The optimizer tries to reduce the `if` assuming that the result will be used.
In case it later detects that the result will be ignored, it can try to
apply some additional reductions to the branches and to the whole expression.
This function exposes the fast subset operation that is built in for
immutable hash tables (and used by the set-of-scopes implementation).
Also, make the space optimization implicit for `eq?`-based hash tables
that contain only #t values (instead of explicit and only available
internally). It turns out to be easy and efficient to make the
representation automatic, because the HAMT implementation can support
a mixture of nodes with some containing explicit values and some
containing implicit #t values.
Now with-disappeared-uses surrounds its body with let, so it can contain
multiple body expressions. The record-disappeared-use function is like
record-disappeared-uses but for a single identifier.
The `#%linklet` module is intended to eventually provide
a simplified compiler for the core Racket language. For
now, it provides minimal hooks for bootstrapping an
expander implementation.
When the properties argument for `make-struct-type` is non-empty,
then we cant; guarantee that `make-struct-type` succeeds, but
if it does, then we can still know that the result is a structure
type and (as long as `prop:chaperone-unsafe-undefined` is not
involved) the properties don't affect the constructor, predicate,
selector, or mutators.
The resolve-module-path-* functions effectively already had a default argument,
which is #f, this allows you to just directly call it with one argument.
This fixes an immediate problem, but the macro expander should have
complained about an unbound `maybe` at phase 2. (A new implementation
of the macro expander detected the unbound `maybe`.)
In (~and p1 p2), a failure in p2 now always dominates a failure in p1.
Consequently, if a pattern succeeds, its failures don't matter.
Add {pat,hpat,action}:ord wrappers, ord prframes. Apply ordering to
main pattern and side clauses. Add better progress analysis to
eliminate order wrapping.
When an array value is provided, make sure that it's an array
with at least the expected length (or longer) and same element
layout. That's weaker than checking that the array elements have
the right type, because an `eq?` check at the ctype layer seems
too strong, and the ctype API doesn't provide enough information
for a more flexible equality.
Avoid creating a result that is intended as a module path but
has elements that are not syntactically allowed, such as a "."
in a collection-path element.
A phase shift was mising on `begin-for-syntax`es introduced by
`syntax-local-lift-module-end-declaration`, which is in turn
used to implement` module+`, so `module+` didn't work under
two or more `begin-for-syntaxes`.
Closes#1312
Syntax objects generally make sense as properties in other syntax
objects, but they require special care when marshaling to bytecode
(as syntax objects do in general). To make that special handling
possible and reliable, constrain the shape of allowed values.
The name `path-extension` created a conflict for an existing
registered package, so it should not have been added to
`racket/path`.
Also, `path-get-extension` was intended to work on a path
that is syntactically a directory, so fix and test that.
Change the one expansion mode as far as I can tell) that disables
lifts so that lifts are now allowed, which means that
`(syntax-transforming?)` implies `(syntax-transforming--with-lifts?)`.
The old documentation incorrectly characterized when lifts
were allowed. Ryan noticed the documentation problem, and that
observation led to this simplication.
