I always suspected the overflow conversions were UB, but with gcc doing
different things on arm, I thought it was about time to abandon those
particular tests. What I was not expecting was for the return value of
strcmp to be "UB" (in that there's no guarantee of the exact value, just
< = > 0). Fortunately, nothing actually relies on the value of the op
other than the tests, so modify the test to make the behavior well
defined.
The inconsistencies in clang's handling of casts was bad enough, and its
silliness with certain extensions, but discovering that it doesn't
support raw strings was just too much. Yes, it gives a 3s boost to qfvis
on gmsp3v2.bsp, but it's not worth the hassle.
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
Most were pretty easy and fairly logical, but gib's regex was a bit of a
pain until I figured out the real problem was the conditional
assignments.
However, libs/gamecode/test/test-conv4 fails when optimizing due to gcc
using vcvttps2dq (which is nice, actually) for vector forms, but not the
single equivalent other times. I haven't decided what to do with the
test (I might abandon it as it does seem to be UD).
This is an extremely extensive patch as it hits every cvar, and every
usage of the cvars. Cvars no longer store the value they control,
instead, they use a cexpr value object to reference the value and
specify the value's type (currently, a null type is used for strings).
Non-string cvars are passed through cexpr, allowing expressions in the
cvars' settings. Also, cvars have returned to an enhanced version of the
original (id quake) registration scheme.
As a minor benefit, relevant code having direct access to the
cvar-controlled variables is probably a slight optimization as it
removed a pointer dereference, and the variables can be located for data
locality.
The static cvar descriptors are made private as an additional safety
layer, though there's nothing stopping external modification via
Cvar_FindVar (which is needed for adding listeners).
While not used yet (partly due to working out the design), cvars can
have a validation function.
Registering a cvar allows a primary listener (and its data) to be
specified: it will always be called first when the cvar is modified. The
combination of proper listeners and direct access to the controlled
variable greatly simplifies the more complex cvar interactions as much
less null checking is required, and there's no need for one cvar's
callback to call another's.
nq-x11 is known to work at least well enough for the demos. More testing
will come.
The tests fail due to differences in how clang and gcc treat floating
point to unsigned integral type conversions when the values overflow. It
wouldn't be so bad if clang was consistent with conversions to 32-bit
unsigned integers, like it seems to be with conversion to 64-bit
unsigned integers.
With this, the "get QF building with clang" mini-project is done and I
won't have to panic when someone comes to me and asks if it will work.
At worst, there'll be a little bit-rot.
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.
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 cleans up dprograms_t, making it easier to read and see what chunks
are in it (I was surprised to see only 6, the explicit pairs made it
seem to have more).
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.
They are both gone, and pr_pointer_t is now pr_ptr_t (pointer may be a
little clearer than ptr, but ptr is consistent with things like intptr,
and keeps the type name short).
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.
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).
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.
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.
While working on the new opcode table, I decided a lot of the names were
not to my liking. Part of the problem was the earlier clash with the
v6p opcode names, but that has been resolved via the v6p tag.
