We continue to leak string buffers in trans so this creates a way to get c
string buffers from strings while guaranteeing that they are not freed before
use.
Hopefully this can be made efficient in the istr regime.
The glue-calling will spill the values again anyway. This should
prevent a lot of load/spill junk in the output. It is also necessary
to be able to have unique vecs be immediate values (take must know the
actual address to be able to duplicate).
trans_be now has a precondition that its expression argument
is a call expr. Obviously this code may be going away soon, but
I wanted to exercise typestate somehow and this was an easy one :-)
This patch supports the syntax
unchecked {
...
}
to disable purity checking within a block. Presumably it will only be
used within a declared "pure fn". However, there is no checking that it
doesn't occur elsewhere, and it would be harmless for it to do so.
I went with Lindsey's suggestion for the syntax, but it's subject to
change.
This allows you to write code that uses predicates that call arbitrary
Rust functions, but you must declare your intentions by wrapping it in
an unchecked { ... } block. The test case run-pass/unchecked-predicates.rs
demonstrates how to do that.
You now do
bld::Ret(bcx, someval)
where you used to say
bcx.build.Ret(someval)
Two fewer boxes are allocated for each block context, and build calls
no longer go through a vtable.
This is a preparation for making vectors always-on-the-heap again,
which would cause way too much malloc traffic for this idiom. I will
add an efficient std::vec::push in the future, and migrate += [x] to
that instead.
Reduces compiler code size by 3%
The syntax is
alt x {
mypat where mycond { ... }
}
The condition may refer to any of the variables bound by the pattern.
When a guard fails, pattern-matching continues with the next pattern.
Closes#857
This makes it easier for the caller to optimize the take/drop away for
temporary values, and opens up new possibilities for alias handling.
Breaks tail calls.
If we lose tail calls, this is possible. It simplifies things a lot.
Direct motivation: We want ivecs with pointers pointing into
themselves. When copying those, the pointers have to be adjusted. It
is impossible to this when copying them with Load/Store.
