The extend instruction is for loading narrower data types into wider
data types, eg, single element into 2, 3, or 4 element types, with a
small set of extension schemes: 0, 1, -1, copy (for 1->any and 2 -> 4).
Possibly most importantly, it works with unaligned data.
Progress towards #30
These add legacy support for basic float bitops (& | ^ ~). Avoiding the
instructions would require tot only the source to be converted, but also
the servers (as they do access those fields), and this seemed to be too
much.
I had forgotten that unsigned division was different from signed
division (rather silly of me). However, with some testing and analysis,
unsigned true modulo is not needed as it's not possible to have
negative inputs and thus it's the same as remainder.
Since the operand types sort out the difference between asr and shr, no
need to give them different opnames. Means qfcc doesn't need to worry
about which one it's searching for.
Yet another redundant addressing mode (since ptr + 0 can be used), so
replace it with a variable-indexed array (same as in v6p). Was forced
into noticing the problem when trying to compile Machine.r.
This fixes Ruamoko's return format string. It looks like it's producing
the correct address (but doesn't show all the information it should),
but the rest of the debug code needs work locals.
ldconst isn't implemented yet but the plan is to load various constants
(eg, 0, 1, 2, pi, e, ...).
Stack adjust is useful for adding an offset to the stack pointer without
having to worry about finding it (and it checks for alignment).
nop is just that :)
It turned out that address mode B was redundant as C with 0 offset
(immediate) was the same (except for the underlying C code of course,
but adding st->b is very cheap). This allowed B to be used for
entity.field for all transfer operations. Thus instructions 0-3 are now
free as load E became load B, and other than the specifics of format
codes for statement printing, transfers+lea are unified.
And other related fields so integer is now int (and uinteger is uint). I
really don't know why I went with integer in the first place, but this
will make using macros easier for dealing with types.
This has been a long-held wishlist item, really, and I thought I might
as well take the opportunity to add the instructions. The double
versions of STATE require both the nextthink field and time global to be
double (but they're not resolved properly yet: marked with
"FIXME double time" comments).
Also, the frame number for double time state is integer rather than
float.
ANY/ALL/NONE have been temporarily removed until I implement the HOPS
(horizontal operations) sub-instructions, which will all both 32-bit and
64-bit operands and several other operations (eg, horizontal add).
All the fancy addressing modes for the conditional branch instructions
have been permanently removed: I decided the gain was too little for the
cost (24 instructions vs 6). JUMP and CALL retain their addressing
modes, though.
Other instructions have been shuffled around a little to fill most of
the holes in the upper block of 256 instructions: just a single small
7-instruction hole.
Rearrangements in the actual engine are mostly just to keep the code
organized. The only real changes were the various IF statements and
dealing with the resulting changes in their addressing.
When creating the tests for lea, I noticed that B was yet another simple
assign, so I decided it was best to drop it and move E into its place
(freeing up another instruction).
I realized that being able to do bit-wise operations with 64-bit values
(and 256-bit vectors) is far more important than some convenient boolean
logic operators. The logic ops can be handled via the bit-wise ops so
long as the values are all properly boolean, and I plan on adding some
boolean conversion ope, so no real loss.
Thanks to Deek for the suggestion: the mode (ie, src and dst types) are
encoded in st->b. Actual code not written yet, but this frees up 13
instructions: now have 74 available for really interesting stuff :)
The call1-8 instructions have been removed as they are really not needed
(they were put in when I had plans of simple translation of v6p progs to
ruamoko, but they joined the dinosaurs).
The call instruction lost mode A (that is now return) and its mode B is
just the regular function access. The important thing is op_c (with
support for with-bases) specifies the location of the return def.
The return instruction packs both its addressing mode and return value
size into st->c as a 3.5 value: 3 bits for the mode (it supports all
five addressing modes with entity.field being mode 4) and 5 for the
size, limiting return sizes to 32 words, which is enough for one 4x4
double matrix.
This, especially with the following convert patch, frees up a lot of
instructions.
Now they're in a much more consistent arrangement, in particular with
the comparison opcodes if the conditional branch instructions are
considered to be fast comparisons with zero (ifnot -> ifeq, if -> ifne,
etc). Unconditional jump and call fill in the gaps. The goal was to get
them all in an arrangement that would work as a small enum for qfcc: it
can use the enum directly for the ruamoko IS, and a small map array for
v6p (except for call).
As I expect to be tweaking things for a while, it's part of the build
process. This will make it a lot easier to adjust mnemonics and argument
formats (tweaking the old table was a pain when conventions changed).
It's not quite done as it still needs arg widths and types.
Bill Currie