All parameters with a structure type in extern functions are marked as
`byref` instead of `byval`, as most ABIs require the first several
arguments to be passed in registers before spilling into the stack.
`byval` breaks this contract by explicitly requiring all arguments to be
passed in the stack, breaking interop with libraries written in other
languages.
In LLVM, i1 represents a 1-byte integer with a single valid bit; The
rest of the 7 upper bits are undefined. This causes problems when
using these variables in memory operations (e.g. memcpy/memmove as
needed by List slicing and assignment).
We fix this by treating all local boolean variables as i8 so that they
are well-defined for memory operations. Function ABIs will continue to
use i1, as memory operations cannot be directly performed on function
arguments or return types, instead they are always converted back into
local boolean variables (which are i8s anyways).
Fixes#315.
Previously, the final value of the target expression would be one after
the last element of the loop, which does not match Python's behavior.
This commit fixes this problem while also preserving the last assigned
value of the loop beyond the loop, matching Python's behavior.
The current default prefix is only derived from the instruction type,
which is not helpful during the comprehension of the IR. Changing to
anonymous names (e.g. %1) helps understand that the variable is only
needed as part of a larger (possibly named) expression.
Because it is unclear which variables are expressions and
subexpressions, all variables which are previously anonymous are named
using (1) the control flow statement if available, (2) the possible name
of the variable as inferred from the variable name in Rust, and (3) the
"addr" prefix to indicate that the values are pointers. These three
strings are joint together using '.', forming "for.i.addr" for instance.
