When a path is made relative for marshaling to bytecode, record
a list of byte strings in stead of a platform-specific relative
path.
For syntax-object source locations, convert any non-relative path to a
string that shows just the last couple of path elements preceded by
".../". This conversion avoids embedding absolute paths in bytecode,
but at the cost of some information. A more complete and consistent
solution would invove using a module-path index instead of a path, but
that would be a big change at several layers.
The `prop:expansion-contexts` property can control the expansion
of a rename transformer in much the same that conditionals on
`(syntax-local-context)` can control the expansion of other
transformers.
The `from` string argument is converted to a regexp and cached. When `from` is
a mutable string this can cause wrong results in the following calls
to string-replace. So the string is first converted to an immutable string to
be used as the key for the cache.
Progress toward making the bytecode compiler deterministic, so that a
fresh `make base` always produces exactly the same bytecode from the
same sources. Most changes involve avoiding hash-table order
dependencies and adjusting scope identity. The namespace used to load
a reader extension is also better defined. Plus many other little
changes.
The identity of a scope that is unmarshaled from a bytecode file now
incorporates the hash of the file, and the relative order of scopes is
preserved in a bytecode file. This combination allows compilation to
start with modules that loaded and compiled in different orders
(including delayed loading of bytecode fragments within one file).
Formerly, a reader extension triggered by `#lang` or `#reader` was
loaded in whatever namespace happens to be current. That's
unpredictable and can pollute a module build at the level of bytecode.
To help make builds deterministic, reader extensions are now loaded in
a root namespace of the current namespace.
Deterministic compilation in general relies on deterministic macros.
The two most common ways for a macro to be non-deterministic are by
using `gensym` (use `generate-temporaries`, instead) and by using an
unsorted hash-table traversal (don't do that).
At this point, bytecode generation is unlikely to be completely
deterministic, since I uncovered non-determinism mostly by iterating
attempts over the base collections. For now, the intent is not to
provide guarantees outside of the compilation of the base collections
--- but "more deterministic" is likely to be useful in the short run,
and we can improve further in the long run.
Nested splicing forms would lead to an "ambigious binding" error
when the nested forms bind the same name, such as in
(splicing-let ([a 1])
(splicing-let ([a 2])
(define x a)))
The problem is that splicing is implemented by adding a scope to
everything in the form's body, but removing it back off the
identifiers of a definition (so the `x` above ends up with no new
scopes). Meanwhile, a splicing form expands to a set of definitions,
where the locally bound identifier keeps the extra scope (unlike
definitions from the body). A local identifier for a nested splicing
form would then keep the inner scope but lose the outer scope, while
a local identifier from the outer splicing form would keep the outer
scope but no have the inner one --- leading to ambiguity.
The solution in this commit is to annotate a local identifier for a
splicing form with a property that says "intended to be local", so the
nested definition will keep the scope for the outer splicing form as
well as the inner one. It's not clear that this is the right approach,
but it's the best idea I have for now.
Although `eval-syntax` is not supposed to add the current namespace's
"outer edge" scope, it must add the "inner edge" scope to be consistent
with adding the inner edge to every intermediate expansion (as in
other definition contexts).
In addition, `eval`, `eval-syntax`, `expand`, and `expand-syntax`
did not cooperate properly with `local-expand` on the inner edge.
Genereating a use-site scope, instead of a macro-introduction scope,
prevents the scope's presense from triggering a #f result from
`syntax-original?`.
Formerly, compiling a definition in one namespace and evaluating it in
another would cause the definition to take place in the original
namespace --- unless the compiled code is marshaled to a byte string
and back. Adjust the "linking" process to redirect the variable
definition and any references to the new namespace. (This is a change
relative to the compiler with the old macro expander.)
Also, repair a compiled `require` form along similar lines. (This is
*not* a change relative to the compiler with the old macro expander;
the mismatch is part of the motivation for changing `define`
handling.)
Add the current definition context's scope to any expression that is
produced by macro expansion before trying to expand again, in case the
expansion needs to refer to a definition introduced by a previous
expansion.
Previously, the scope was added before any expansion and after any
expansion, but that misses intermediate points.
The old expander had this bug, too (some of the new tests fail there),
but it showed up less often and was sometimes considered correct, for
various reasons.
The `eval-syntax` function (which is used by other functions, such as
loading a module) should not install fallback-binding scopes from
the current namespace.
When `(let ([x ...]) (let ([y x]) ... y ... y ...))` turns into
`(let ([x ...]) ... x ... x ...)`, make sure that `x` is not
still marked as single-use. Incorrect marking as single-use could
cause the optimizer to inline too much, for example.
Thanks to Gustavo for tracking down the problem.
Previously all the predicates recognized only non-#f things, so ´not´ can be
added to the list of disjoint predicates. But many of the parts of the code
relied on the non-#f property and had to be modified.
In (if (eq? x <pred?-expr>) <tbranch> <fbranch>) infer that the type of
x is pred? in the tbranch.
Also, reduce (eq? x y) => #f when the types are different.
The optimizer reduces the variables with a known type to #t in a Boolean context.
But some predicates imply that the variable has a definite values, so they can be
reduced in a non-Boolean context too.
For example, in (lambda (x) (if (null? x) x 0))) reduce the last x ==> null.
This fixes the bug twice:
* Don't reduce mutable variables with a type to #t in a Boolean context.
* Don't record the type of mutable variables when a predicate is
checked in a test condition.
While reducing some ignored constructors, the optimizer may wrap the arguments
<expr> in (values <expr>) to ensure that it's a single value non-cm expression.
This avoids the unnecessary nesting of (values (values <expr>)).
Similarly, add the cases for begin and begin0 to single_valued_noncm_expression
The optimizer was able to use the type information gained outside
the let's to reduce expressions inside the lets. For example, in
(lambda (z) (car z) (let ([o (random)]) (pair? z)))
it reduces (pair? z) ==> #t.
This enable the propagation in the other direction so in
(lambda (z) (let ([o (random)]) (car z)) (pair? z))
it reduces (pair? z) ==> #t too.
When `local-require` is used in a non-phase-0 position and it is
`expand`ed (as opposed to compiled directly), then the generated
`#%require` form had the wrong binding phase.
Merge to v6.2
In many use cases the length of the vector is fixed and know,
so we are sure that make-vector will not raise an error and
we can recognize these expressions as omittable and drop
them when the result is ignored.
The result of some procedures is a vector, but they are not omittable
because they may rise an error. With the recent changes of the
predicate reduction these cases are correctly handled.
Adds a sealing and unsealing function to attach (or detach)
seals onto a class via impersonator properties. Since these
properties override, they do not accumulate wrappers.
Calling seal multiple times will still accumulate multiple seal
values inside the property.
A sealed class cannot be instantiated and a subclass may not
add class members that match any of the sealed names in its
sealed parent.
These functions are intended for use by TR's `sealing->/c`
contract, but are parameterized over checking functions and
could be used for other purposes.
The optimizer checks the type of the argument of some unary procedures and
uses the gathered information to replace them by the unsafe version, reduce
predicates and detect type errors. This extends the checks to more procedures
that have no unsafe version and procedures that have more than one argument.
Use the given readtable more consistently to parse
delimiters in the top-level form. This change particularly
addresses problems with trying to restore the original
`(` when parsing a hash table, but allowing nested
forms to still use a different `(` mapping.
When determing whether expressions can be reordered, a reference to a
module-defined variable was considered unreorderable when it is
known to have a value and no further mutation, but the value isn't
constant across all runs.
The optimizer had some reductions of predicates applications, like (pair? X),
only when X was very simple and the type of X was obvious.
Use expr_implies_predicate and make_discarding_sequence to allow
the reduction of more complex expressions.
Also, the reduction of procedure? and fixnum? were special cases in
optimize_application2. Move the checks to expr_implies_predicate
to take advantage of the reductions in more general cases.
Use `syntax-track-origin` and 'disappeared-use properties to
communicate `require` and `provide` form bindings to tools such as
Check Syntax.
Relevant to PR 13186
When a structure type has `prop:inpersonator-of`, follow it
when attemptng to access imperonator properties.
This change fixes a problem with `impersonate-procedure` as
reported by Scott Moore.
scheme_optimize_apply_values reduces (call-with-values gen proc)
to (#%apply-values proc gen) when recognizes proc as a procedure.
This extends the expressions that are recognized as procedures.
Instead of delaying the registration of some constants until a
group of expressions is re-optimized, add constant information as
it is discovered, which can expose some additional optimizations.
The old grouping was probably aimed at avoiding excessive code growth,
but I think that other and better controls are now in place. The
overall size of ".zo" files in an installation did not grow
significantly with this change.
Closes PR 14978
This allows to define the offsets for each field instead
of relying on the calculated ones - useful when struct might
be defined differently across platforms.
Racket has a minimal support to read and write `extflonum`s when the `exflonums`
are not available. In this configuration they use a different path code, so it's
necessary to test this version of the code too.
The macro expander formerly put all lifted requires at the start of a
module, but that doesn't work with re-expansion if a module has
submodules and lifted requires that refer to submodules. Put lifted
submodules in the right place, instead: just before the form whose
expansion added the lifted require.
Even when `(variable-reference-constant? (#%variable-reference ....))`
cannot be optimized to a boolean, the expression should not retain a
reference to the enclosing namespace. That space guarantee is
important for the compilation of calls to keyword-accepting functions.
The handling of `for-template` imports by `namespace-attach-module`
didn't match the docs. The actual handling was to refrain from
attaching instances of a phase-0 module if the instance was reachable
only through a `for-template`. The rationale had to do with such
modules instances being created only through instantiation of
phase-1 modules, and phase-1 module instances aren't attached;
it doesn't work well that way, though, when different modules
are attached with intervening `namespace-require`s on the target
namespace.
The change includes a documentation correction. Previously and still,
only modules at the same phase as the attached module (as opposed to
the same phase or less) are instantiated in the target namespace.
Closes PR 14938
If a file or directory delete fails, try adjusting the file or directory
permissions to allow writes, then try deleting again. This process should
provide a more Unix-like experience and make programs behave more
consistently.
A new `current-force-delete-permissions` parameter provides access to
the raw native behavior.
If the slow path has to be taken because the number of
list elements is greater than the stack size, then the
old implementation would copy all the arguments --- which
still might be too much for the available stack space.
Avoid that copy.
Also, add pad word to the end of the stack to help detect
overflow.
For example, reduce (begin x (error 'e) y) ==> (begin x (error 'e)) and
(f (error 'e) y ) ==> (begin f (error 'e)).
Also, reduce (if (error 'e) x y) ==> (error 'e) and propagate the type information
and clocks when only one branch produce an error.
This required moving some tests to "racket-test", and putting them
in modules that use `rackunit`. Also, some uses of rackunit were
removed and switched to more primitive systems. Some improvements
here, particularly in "foreign-test.rktl", would still be good,
but everything passes at the moment.
The test tried to detect separate evaluations by using the
result of `(current-inexact-milliseconds)`, but a clock's
resolution might not be high enough. Use `(gensym)`, instead.
This supports running the core tests on systems which can't run
or don't want to install all the dependencies of the "racket-test"
package.
The "racket-test-core" pkg stil depends on "sandbox-lib" because
the sandbox tests live with the core tests. Hopefully I'll be able
to fix that eventually.
