They're buggy in that the defspaces for parameters and locals are
incorrect (they need to point to the calling scope's space). Also,
parameters are not yet hooked up correctly. However, errors (because I
need to allow casts from scalars to vectors) do get handled.
xvalue symbols refer to two expressions: an lvalue and an rvalue. They
are meant to be used with xvalue expressions.
xvalue expressions are useful when a distinction must be made between
the behavior of something (eg, a pascal function symbol) must change
depending on whether it's an lvalue (assignment of the function's return
value) or an rvalue (a call to the function, especially when the
function takes no parameters).
The main goal was to make it possible to give generic functions
definitions (since the code would be very dependent on the actual
parameter types), but will also allow for inline functions. It also
helped move a lot of the back-end dependent code out of semantics
processing and almost completely (if not completely) out of the parser.
Possibly more importantly, it gets the dags flushing out of the parser,
which means such is now shared by all front-ends.
There's probably a lot of dead code in expr.c now, but that can be taken
care of another time.
I found a need to check for shifts separately (not sure it's the right
approach for that problem, though), and there are a few more math ops
than just +-*/.
Arrays done via the field code since they use the same opcode and logic.
For now swizzles are just swizzles and don't support zeroing or negating
(but doing one or the other (not both) should be easy).
Explicitly typed compound initializers are what C uses and allows them
to initialized `auto` vars and even pass through `...`. Not tested yet
other than ensuring existing tests didn't break.
I guess that was a mental FIXME for later, but later came sooner. The
declaration doesn't seem to be working properly, but I'll worry about
that later when I can get some automated tests going.
Since spir-v needs actual bools for its conditional instructions, the
time to do bool properly finally came. As expected, the changes caused
quite a mess, but Ruamoko now does bool/true/false.
This required adding a `var` symbol type. For now, it holds just the
storage class, but it might be good for the initializer, too.
Also, clean up some pointer/reference inconsistencies.
I've long felt build_function_call was getting a bit big, and expr.c
especially so. This should make it easier to rewrite build_function_call
for dealing with target-specific code. As a bonus, the int through ...
warning is already cleaned up.
spir-v uses SSA, so temps cannot be assigned to directly, so instead use
the temp expression as a reference for the result id of the rhs of the
assignment. This would get function calls working if the they actually
emitted any code (right now, just a place-holder id so spirv-dis doesn't
fall over).
While a reference var can't be initialized yet, using them seems to work
in that they get dereferenced when the value needs to be read or written
(though I haven't seen any generated code for them yet).
I don't know why the last argument was handled differently. I suspect it
was a hold-over from before I added list handling. Removing it seems to
have made no significant difference (all tests pass still).
I realized that spir-v pointers are essentially references (the way
they're used) since OpVariable requires a pointer type rather than the
base type. Thus, under the hood, references are just pointers with
automatic dereferencing. However, nothing uses references yet, and I
expect to run into issues with is_pointer vs is_reference vs is_ptr
(high-level pointer, reference, low-level pointer, respectively).
Now declarations can be deferred too, thus things like generic/template
and inline functions should be possible. However, the most important
thing is this is a step towards a cleaner middle layer for compilation,
separating front-end language from back-end code-gen.
I don't remember why I thought it was a good idea at the time, but I
decided that having the union was a bit iffy and making the list
"official" would be a good idea. In the end, it removed a nice chunk of
code (redundant list manipulations).
I want to use new_field_expr for specialized field expressions instead.
However, I don't particularly like new_deffield_expr as a name, but I
can't think of anything better just yet.
I plan to do this eventually for Ruamoko, but I need it to keep working
for now; it's rather nice having multiple languages. I expect this will
open up a lot of options for inlining, generic/template function
instantiation, etc. Right now, it's helping with specialization
constants in glsl.
Result type and constant handling is now table-driven, resulting in the
removal of seven switch statements (and thus a lot less hassle when
extending types or expressions). Also, (u)long and (u)short are fully
implemented.
In addition, other than result type handing for boolean results, any
back-end specific implementation is now in the back-end.
It's nowhere near complete, but unary and binary expressions that are
marked as constant will not be subject to constant folding. This is
necessary for proper support of specialization constants.
I don't know why I thought it was a good idea to make sy_var context
dependent. Renaming sy_var to sy_def makes it a little easier to know to
use the def field, too.
Thare are still many const casts, but this does get rid of one set. I
had tried to replace the paren flag with a () unary expression, but that
brought out a whole pile of places that had problems (especially
anything to do with boolean expressions).
It seems it was needed for dealing with the result expression for block
expressions, but it turns out (possibly thanks to dags), that it's easy
to check for the result value and using the appropriate call to emit the
code thus avoiding the non-executable code warning.
Attributes seem appropriate as GLSL's qualifiers affect variables rather
than types (since there's no typedef).
Not much is done with the attributes yet other than some basic error
checking (duplicates of non-layout attributes) and debug output, but
most (if not all) declarations get to the declaration code with
attributes intact.
Their size is now calculated correctly, they can be assigned,
initialized using block initializers (vectors too!), and columns can be
indexed as vector lvalues.
It turned out that for v6 progs (due to lack of double or long) weren't
getting correctly parsed vector literals: incorrect "implicit" flag and
then a lot of brittleness around constant value conversions.
Now parameters can be declared `const`, `@in`, `@out`, `@inout`. `@in`
is redundant as it's the default, but I guess it's nice for
self-documenting code. `const` marks the parameter as read-only in the
function, `@out` and `@inout` allow the parameter to pass the value back
out (by copy), but `@out` does not initialize the parameter before
calling and returning without setting an `@out` parameter is an error
(but unfortunately, currently detected only when optimizing).
Unfortunately, it seems to have broken (only!) v6 progs when optimizing
as the second parameter gets optimized out.
