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
