MOVEP's opc itself is always known and used, whether it's a constant
pointer or variable doesn't matter. This fixes the lost pointer calculation
for va_list.list[j] = object_from_plist (item);
Dead nodes are those that generate unused values (unassigned leaf nodes,
expressions or destinationless move(p) nodes). The revoval is done by the
flow analysis code (via the dags code) so that any pre and post removal
flow analysis and manipulation may be done (eg, available expressions).
If MOVEP's destination is variable, then the actual destination isn't (at
this stage) knowable, so it can't be attached to the dagnode and thus must
be a child.
Getting the operands directly from the statement was missing the
destination operand of movep when movep's op_c was a constant pointer and
thus the flowvar wasn't being counted/created early enough. This led to a
segfault in the set code when attempting to add -1 to the set.
Unreachable nodes will cause the first elements of the array to remain
unwritten by df_search. This fixes the segfaults caused by unreachable
nodes (the reason they were an internal error before).
MOVE (static move) and MOVEP to a pointer constant know exactly where their
data is going, so treat them similarly to assignments: save their
distination operands (the addressed def for MOVEP) and mark them as
defined.
I forgot to add func->num_statements :P. Fixes the weirdness where only
some alias temps were being (bogusly) detected as uninitialized. Now they
all are.
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.
Only definitions for the def used in the current statement (whether an
alias or not) are suitable for killing. Doing otherwise defeats the purpose
of this work :P
Fixes the false negatives found in a modified quattest.r (commented out the
"tq.s = 0;" line).
Nicely, the use sets from live_variable analysis can be used too, though
there are some problems with the naive implementation. For:
vector foo (float x, float y, float z)
{
vector v;
v.x = x;
v.y = y;
v.z = z;
return v;
}
qfcc thinks v is uninitialized, but if "if (x) return nil;" (or any other
basic-block splitter) is put just before the return v; qfcc correctly
detects that v is initialized. The reason is that the inits are in the same
basic block as the return, and thus aren't affecting the reaching
definitions, which are stored per-block.
The naive implementation should be good for a fast-cull before doing a
per-statement check.
The exit dummy block is setup to provide dummy uses of global variables to
the live variable analysis doesn't miss global variables. Much cleaner than
the previous code :) There may be some issues with aliases, though.
The entry dummy block is setup to provide dummy definitions of local
variables so the reaching definitions analysis can be used to detect
uninitialized variables (not implemented yet). Fake statement numbers
(func->num_statements + X) are used to represent the definitions. Local
variables (ie, not temp ops) use their offsets (ie, the offset range they
cover) for X. Temp ops use their flowvar number + the size of the
function's defspace for X. flow_kill_aliases() should take care of temp op
aliasing, while the use of the actual offsets spanned by the variable's def
should take care of any wild aliasing so structures and unions should
become a non-issue.
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.
Fixed aliases are those that will never change through the life of the
code. They are generated from structure accesses and thus what they alias
is always known.
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).
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).
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).
