Found with `-fsanitize=undefined`. The only changes that are potentially
bug repairs involve some abuses of pointers that can end up misaligned
(which is not an x86 issue, but might be on other platforms). Most of
the changes involve casting a signed integer to unsigned, which
effectively requests the usual two's complement behavior.
Some undefined behavior still present:
* floating-point operations that can divide by zero or coercions
from `double` to `float` that can fail;
* offset calculations such as `&SCHEME_CDR((Scheme_Object *)0x0)`,
which are supposed to be written with `offsetof`, but using
a NULL address composes better with macros.
* unaligned operations in the JIT for x86 (which are ok, because
they're platform-specific).
Hints for using `-fsanitize=undefined`:
* Add `-fsanitize=undefined` to both CPPFLAGS and LDFLAGS
* Add `-fno-sanitize=alignment -fno-sanitize=null` to CPPFLAGS to
disable those checks.
* Add `-DSTACK_SAFETY_MARGIN=200000` to CPPFLAGS to avoid stack
overflow due to large frames.
* Use `--enable-noopt` so that the JIT compiles.
The `alarm-evt` tests are inherently racy, since they depend on
the scheduler polling quickly enough. The old time values were
close enough that a test failure is particularly likely on
Windows, where the clock resolution is around 16ms. To reduce
failures, make the time differents much bigger.
Closes issue #1232
In some cases, for example while using no_types, the optimizer can try to
add again the type information of a local variable. This creates unnecessary
internal storage to save the repeated information.
A reference to a local may be reduced in a branch to a constant, while it's unchanged in the
other because the optimizer has different type information for each branch. Try to use the
type information of the other branch to see if both branches are actually equivalent.
For example, (if (null? x) x x) is first reduced to (if (null? x) null x) using the type
information of the #t branch. But both branches are equivalent so they can be
reduced to (begin (null? x) x) and then to just x.
The functions expr_implies_predicate was very similar to
expr_produces_local_type, and slighty more general.
Merging them, is possible to use the type information
is expressions where the optimizer used only the
local types that were visible at the definition.
For example, this is useful in this expression to
transform bitwise-xor to it's unsafe version.
(lambda (x)
(when (fixnum? x)
(bitwise-xor x #xff)))
Support "Unix-style" (as opposed to "in-place") installation for
OS X, which is mostly a matter of putting ".app" files in the
right place and correcting relative references.
Intended to fix#1180
