qfcc now does local common subexpression elimination. It seems to work, but
is optional (default off): use -O to enable. Also, uninitialized variable
detection is finally back :)
The progs engine now has very basic valgrind-like functionality for
checking pointer accesses. Enable with pr_boundscheck 2
When an alais def (or aliased def) is used, any overlapping aliases that
have previously been assigned need to be marked as live, and edges to the
aliases added to the new node. However, when assigned to, live-forcing
needs to be turned off.
This fixes the lost assignments to .super.
When the naive uninitialized variable detection finds a node with possible
uses of uninitialized variables, the statements in the node are scanned one
at a time checking each usage and removing uninitialized definitions as
appropriate. vectest.r now compiles without warnings. As an added bonus,
accurate line number information is reported for uninitialized variables.
Unfortunately, there is still a problem with uninitialized temps in
switch.r, but that might just be poor handling of temp op aliases.
The dummy nodes are for detectining uninitialized variables (entry dummy)
and making globals live at function exit (exit dummy). The reaching defs
and live vars code currently seg because neither node has had its sets
initialized.
Also move the ALLOC/FREE macros from qfcc.h to QF/alloc.h (needed to for
set.c).
Both modules are more generally useful than just for qfcc (eg, set
builtins for ruamoko).
Set of everything is implemented by inverting the meaning of bits in the
bitmap: 1 becomes non-member, 0 member. This means that set_size and
set_first/set_next become inverted and represent non-members as counting
members becomes impossible :)
With the need to handle aliasing in the optimizer, it has become apparent
that having the flow data attached to symbols is not nearly as useful as
having it attached to defs (which are views of the actual variables).
This also involves a bit of a cleanup of operand types: op_pointer and
op_alias are gone (this seems to greatly simplify the optimizer)
There is a bit of a problem with enums in switch statements, but this might
actually be a sign that something is not quite right in the switch code
(other than enums not being recognized as ints for jump table
optimization).
Simply "backed" and "virutal". Backed spaces have memory allocated to them
while virtual spaces do not. Virtual spaces are intended for local
variables and entity fields.
With this, alias defs become singletons based on the def they alias and the
type and offset of the alias. Thus, the removal of the free_def call in
emit.c.
alias_def now always creates an offset def (though the usual case has an
offset of 0). The if the alias escapes the bounds of the base def, an
internal error will be generated.
It really doesn't seem wise to allow the compiler to do so as it would
overwrite unrelated defs. The only time such a thing is valid is the return
statement (silly vm design), and that's read-only.
Also remove the extern for current_storage as it belongs in shared.h.
I'm not satisfied with the documentation for initialize_def, but it will do
for now. I probably have to rewrite the thing as it's a bit of a beast.
With the intoduction of the statement type enum came a prefix clash. As
"st" makes sense for "statement type", I decided that "storage class"
should be "sc". Although there haven't been any problems as of yet, I
decided it would be a good idea to clean up the clash now. It also helps
avoid confusion (I was a bit surprised after working with st_assign etc to
be reminded of st_extern etc).
It doesn't quite work yet, but...
It has proven necessary to know what type .return has at any point in the
function. The segfault in ctf is caused by the return statement added to
the end of the void function messing with the expr pointer stored in the
daglabel for .return. While this is actually by design (though the
statement really should have a valid expr pointer rather than), it actually
highlights a bigger problem: there's no stable knowledge of the current
type of .return. This is not a problem in expression statements as the
dagnodes for expression statements store the desired types of all operands.
However, when assigning from .return to attached variables in a leaf node,
the type of .return is not stored anywhere but the expression last
accessing .return.
Now information like dags or live variables are dumped separately, and the
live variable information replaces the flow node in the diagram (like dags
have recently).
They really should have been in statements.[ch] in the first place
(actually, they sort of were: is_goto etc, so some redundant code has been
removed, too).
