I decided I want events for VM enter/exit but enter needs to somehow
pass the function which will be executed (even if a builtin). A generic
void * param seemed the best idea, which meant the error string could be
passed via the param instead of a "global" string in the progs struct.
They take a pointer to a free-list used for hashlinks so the hashlink
pools can be per-thread. However, hash tables that are not updated are
always thread-safe, so this affects only updates. progs_t has been set
up such that it is easy for multiple progs within one thread can share
hashlinks.
While there was a breakpoint hook, it was for only breakpoints and more
was needed. Now there's a generic hook that is called for tracing,
breakpoints, watch points, runtime errors and VM errors, with the
"event" type passed as the first parameter and a data pointer in the
second.
The idea is to find th def that contains the address. Had to write my
own bsearch (well... lifted from wikipedia) because libc's is exact. The
defs are assumed to be sorted (which qfcc now ensures when it writes
progs and sym files).
Type encodings are used whenever they are available. For now, if they
are not, then everything is treated as void (which prints <void>, not
very useful). Most return statements and references to .return are now
very readable (excluding structs), and only params going through "..."
are a messy union.
The memset instructions now match the move* instructions other than the
first operand (always int). Probably breaks much, but fixed in next few
commits.
If a temp string is found in the return slot, PR_FreeTempStrings won't
delete the string. However, PR_PopFrame was blindly stomping on the
possibly surviving temp string with the push strings, which would cause
a leak.
This "pushes" a temp string onto the callee's stack frame after removing
it from the caller's stack frame. This is so builtins can pass
auto-freed memory to called progs code. No checking is done, but mayhem
is likely to ensue if a string is pushed that was allocated in an
earlier frame.
PR_AllocTempBlock() works the same way as PR_SetTempString(), except
that it takes a size parameter and always allocates (never tries to
merge). This is, in a way, abusing the string system, but I needed a way
to allocate a block of progs memory that would be automatically freed
when the current frame ended. The biggest abuse is the need to cast away
the const of PR_GetString()'s return value.
Rather than relying on progs code version, use the string to determine
whether PR_Sprintf should behave as if floats have been promoted through
... I imagine I'll get to the rest of the server code at some stage.
With these two changes, nq-x11 works again (teleporters were the
symptom).
With this, the VA is very close to being safe to use in a threaded
environment (so long as each VM is used by only one thread). Just the
debug file hash and source paths to sort out.
The progs execution code will call a breakpoint handler just before
executing an instruction with the flag set. This means there's no need
for the breakpoint handler to mess with execution state or even the
instruction in order to continue past the breakpoint.
The flag being set in a progs file is invalid.
For technical reasons (programmer laziness), qfcc does not fix up local
def type encodings when writing the debug symbols file (type encoding
location not readily accessible).
The debug subsystem now uses the resources system to ensure it cleans
up, and its data is now semi-private. Unfortunately, PR_LoadDebug had to
remain public for qfprogs because using PR_RunLoadFuncs would cause
builtin resolution to complain.
It is now set to 0 when progs are loaded and every time
PR_ExecuteProgram() returns. This takes care of the default case, but
when setting parameters, pr_argc needs to be set correctly in case a
vararg function is called.
PR_SaveParams() is required for implementing the +initialize diversion
used by Objective-QuakeC because builtins do not have local def spaces
(of course, a normal stack calling convention would help). However, it
is entirely possible for a call to +initialize to trigger another call
to +initialize, thus the need for stacking parameter stashes. As a
bonus, this implementation cleans up some fields in progs_t.
The engine now requires non-v6 progs to store the log2 alignment for the
param struct in .param_alignment.
PR_EnterFunction is clearer and possibly more efficient.
Only as scalars, I still need to think about what to do for vectors and
quaternions due to param size issues. Also, doubles are not yet
guaranteed to be correctly aligned.
I've decided that setting pr.max_edicts and pr.zone_size as part of the
local progs initialization rather than in PR_LoadProgsFile makes more
sense. For one, it is unlikely for the limits to change every time progs is
reloaded. Also, they seem to be a property of the VM rather than the progs.
However, there is nothing stopping the caller from updating max_edicts and
zone_size every call.
While scan-build wasn't what I was looking for, it has proven useful
anyway: many of the sizeof errors were just noise, but a few were actual
bugs (allocating too much or too little memory).
The offset to compensate for st++ was missing.
Obviously, the code has never been tested. Found while looking at the
jump code and thinking about using 32-bit addresses for the jump tables.
I'd forgotten that ED_ConvertToPlist mangled light into light_lev and
single component angle values into a vector. This fixes much of the
breakage in qflight (but not the light levels)
It was pointed out by Blub\w (gmqcc) that OP_MUL_FV and friends were buggy
when the operands overlapped (eg, x = x.x * x) as the result would become
'x.x*x.x x.y*x.x*x.x x.z*x.x*x.x' (note the x.x squared for y and z). On
testing, sure enough the bug was present (and is a nice demonstration that
QF's VM does NOT have strict-aliasing bugs). As a very nice benefit: the
code produced by the fixes is actually faster than the broken version :).
The ruamoko code used for testing:
void (string fmt, ...) printf = #0;
vector foo (vector x)
{
x = x * x.x;
return x;
}
vector bar (vector x)
{
x = x.x * x;
return x;
}
int main ()
{
vector x = '2 3 4';
vector y = foo (x);
vector z = bar (x);
printf ("x=%v y=%v z=%v 2*x=%v\n", x, y, z, 2*x);
return 0;
}
Need to up the precision by one due to the difference between g and e, but
much prettier. Might need to rename that function :P I wish I'd thought to
check if g would work, but thanks to divVerent for the suggestion.
Bill Currie