This required delaying the setting of the return pointer by call until
after the current pointer had been saved, and thus passing the desired
pointer into PR_CallFunction (which does have some advantages for C
functions calling progs functions, but some dangers too (should ensure a
128 byte (32 word) buffer when calling untrusted code (which is any,
really)).
This fixes the issue of the data stack not being restored properly
because the returning function needs to return a value from its local
variables (stored on the stack) and accessing stack data below the stack
pointer is a bad idea (sure, no interrupts yet, but who knows...).
Call's operand c is used to specify where the return value of the
function is to be stored. This gets both the correct function being
called, and the value being returned correctly. Test still fails due to
the stack restoration issue.
It currently fails for two reasons:
- call's mode selection is incorrect (never updated from when there was
only the one call instruction and the mode was encoded in operand c)
- return should automatically restore the stack pointer to the value it
had on entry to the function, thus allowing local values stored on
the stack to be safely returned.
I don't know why they were ever signed (oversight at id and just
propagated?). Anyway, this resulted in "unsigned" spreading a bit, but
all to reasonable places.
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.
In the end, I decided any/all/none should be separate from the other
horizontal ops, if I even do them (can be implemented by first
converting to bool, then using the appropriate horizontal operation (& |
etc).
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).
Most useful for 64-bit values as only one instruction is needed to move
the data around rather than two, but could be slightly faster for 32-bit
as the addressing is simpler (needs profiling).
The compare/ne operator returns "random" -ve, 0, +ve values (really,
just the numerical difference between the chars of the strings), but all
the rest return -1 for true and 0 for false, as with the rest of the
comparison operators.
Does not include string concatenation because I don't feel like messing
with zone init, but all the other operators are tested (currently
failing due to bool convention)
It calculating only the size of the array (which was often 4 or 8
globals per element) proved to be a pain when I forgot to alter the size
for the new scale tests. Fixing the size calculation even found a bug in
the shiftop tests.
It seems casting from float/double to [unsigned] int/long when the value
doesn't fit is undefined (which would explain the inconsistent results).
Mentioning the possibility seems like a good idea should the results for
such casts change and cause the tests to fail.
Bools turned out to be a problem to due to me wanting any non-zero value
to be treated as true thus had to expand them out as well as the
floating point <-> integral conversions.
They currently fail because for vector values, gcc casts the view, not
the value, so vec4 cast to ivec4 simply views the bits as int rather
than doing the actual conversion.
Rather than specifying that the conversion should be skipped, it now
specifies the mode of the conversions (with 0 being no conversion). This
is in preparation for boolean conversion.
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.
Both float 2,3,4 vectors and double 2,3,4 vectors (1 would be just a
copy of the mul instructions).
This completes the currently planned instructions. Now for testing.
Not all possibilities are supported because converting between int and
uint, and long and ulong is essentially a no-op. However, thanks to
Deek's suggestion, not only are all reasonable conversions available,
conversions for all widths are available, so vector conversions are
supported.
The code for the conversions is generated.
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 :)
