I'm surprised it took almost two years to discover that I had no
quaternion multiplications in any test code, but getting an ICE for a
quaternion-vector product, and the Hadamard product for
quaternion-quaternion was a bit of a nasty surprise.
This makes a slight improvement to the commutator product in that it
removes the expand statement, but there's still the problem of (a+a)/2.
However, at least now the product is correct and slightly less abysmal.
This takes advantage of evaluate_constexpr to do all the work. Necessary
for use of basis blade constants in algebra contexts (avoids an internal
error).
This fixes the upostop-- test by auto-casting implicit constants to
unsigned (and it gives a warning for signed-unsigned comparisons
otherwise). The generated code isn't quite the best, but the fix for
that is next.
Also clean up the resulting mess, though not properly. There are a few
bogus warnings, and the legit ones could do with a review.
This fixes the really odd bug of certain string values getting swapped
in vkgen when DEBUG_QF_MEMORY was defined in expr.c. It will also
prevent a lot of fun with floats in the future, I imagine.
It's now meant only for ALLOC. Interestingly, when DEBUG_QF_MEMORY is
defined in expr.c, something breaks badly with vkgen (no sniffles out of
valgrind, though), but everything is fine with it not defined. It seems
there may be some unpleasant UB going on somewhere.
I'm not sure why this showed up now (I guess just not enough large
immediate values), but this fixes a segfault in the algtypes test (the
mystery is why it showed up this late).
This gets my `m * p * ~m` code as optimal as possible if my counting is
correct (this does not include the extra extends and add needed to merge
the values). Also, there might be a possibility of recombining some ops
into a vector op, but I'm happy with this.
That is, `x+x -> 2*x` (and similar for higher counts). Doesn't make much
difference for just 2, but it will make collecting scales easier and I
remember some testing showing that `2*x` is faster than `x+x` for
floating point.
Of course, motor-point keeps bouncing around numerically :/
This fixes the motor-point.r test (ie, the sub-type field selector works
on mono-group types now). Still need to sort out something for scalars
(but I imagine that can work only in an @algebra context).
This allows them to be matched with cancelling factors. My fancy zero
test is now just that: a fancy zero:
typedef @algebra(float(3,0,1)) PGA;
typedef PGA.group_mask(0xa) bivector_t;
typedef PGA.group_mask(0x1e) motor_t;
typedef PGA.tvec point_t;
typedef PGA.vec plane_t;
plane_t
apply_motor (motor_t m, point_t p)
{
return (m * p * ~m).vec;
}
0000 nop there were plums...
0001 adjstk 0, 0
apply_motor:
motor.r:32:{
0002 with 2, 0, 1
motor.r:33: return (m * p * ~m).vec;
0003 return (<void>)
The motor-point.r test fails because it uses (m * p * ~m).tvec to get
the value but the type system is slightly broken in that a mono-group
algebra type does not have a structure associated with it and thus the
"missing" field results in 0. Yes, I spent too long chasing that one,
too.
I'd missed this in the previous commit, which was a good thing, really,
as it turns out this was the trigger of the bug that causes my fancy
zero test to become non-zero. It seems the bug is in either
component_sum or in the extend merging.
Or really, the implementers. This gets my fancy zero test down to just
unrecognized permutations of commutative multiplies and dot products
(with the multiplies above the dot products).
While this does "explode" the instruction count (I'll have to collect
like terms later), it does allow for many more opportunities for things
to cancel out to 0 (once (pseudo)commutativity is taken care of).
That is, dot(scale(A,a),scale(B,b)) -> (a*b)*dot(A,B). Does the right
thing when only one side is a scale. No change to the instruction count
in my fancy zero, but it does open more opportunities when I distribute
products.
That is, scale(scale(A,b),c) becomes scale(A,b*c), thus giving the
expression dag more opportunities to find common sub-expressions. My
fancy zero test is down to 20 total instructions (including overhead, or
16 for the actual algebra).
While splitting up the scaled vector into scaled xyz and scaled w does
cost an extra instruction, it allows for other optimizations to be
applied. For one, extends get all the way to the top now, and there are
at most two (in my test cases), thus either break-even or even a slight
reduction in instruction count. However, in the initial implementation,
I forgot to do the actual scaling, and 12 instructions were removed from
my fancy zero case, but real tests failed :P It looks like it's just
distributivity and commutativity holding things back (eg,
omega*gamma*sigma - gamma*omega*sigma: should be 0, but not recognized
as that).
This fixes the motor test :) It turns out that every lead I had
previously was due to the disabling of that feature "breaking" dags
(such that expressions wouldn't be found) and it was the dagged
multi-vector components getting linked by expr->next that made a mess of
things.
Or at least mostly so (there are a few casts). This doesn't fix the
motor bug, but I've wanted to do this for over twenty years and at least
I know what's not causing the bug. However, disabling fold_constants in
expr_algebra.c does "fix" things, so it's still a good place to look.
This doesn't fix the motor bug, but it doesn't make it worse. However,
it does simplify the trees quite a bit, so it should be easier to debug.
It seems the problem has something to do with fold_constants messing up
dagged aliases: in particular, const-folding multiplication by e0123 in
3d PGA as fold_constants sees it as 1.
They should be treated as such only when merging vector components. This
fixes a bug that doesn't actually exist (it's in experimental code),
where the sum of two 3-component vectors was getting lost.
For cross products: remove any a from a×(...+/-a...)
For dot products: remove any a×b from a•(...+/-a×b...) (or b×a)
This removed another 2 instructions :)
They don't have much effect that I've noticed, but the expression dags
code does check for commutative expressions. The algebra code uses the
anticommutative flag for cross, wedge and subtract (unconditional at
this stage). Integer ops that are commutative are always commutative (or
anticommutative). Floating point ops can be controlled (default to non),
but no way to set the options currently.
This takes advantage of the expression dag to detect when an expression
is on both sides of a cross product (which always results in 0). This
removes 3 instructions from my motor test (28 to go).
Especially binary expressions. That expressions can now be reused is
what caused the need to make expression lists non-invasive: the reuse
resulted in loops in the lists. This doesn't directly affect code
generation at this stage but it will help with optimizing algebraic
expressions.
The dags are per sequence point (as per my reading of the C spec).
The removal of the e tag from expr_t necessitated making convert_name
return a new expressions which resulted in get_type no longer being
enough to both convert a name expression and get the type. This was just
another missed spot. With this, all of game-source except ctf builds.
