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;
}
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