[PATCH vkd3d 5/6] vkd3d-shader/hlsl: Introduce specialized helpers for arithmetic operations.

[Zebediah Figura]

On 10/14/21 8:37 AM, Giovanni Mascellani wrote:
> In HLSL the rules used to determine the type of a composite expression
> change depending on the operator. This commit changes add_expr so that
> it accepts both the types to which the operands have to be casted
> and the type that the final expression must have (which is not
> necessarily the cast type).
> 
> For example, when comparing a half with an int, both of them will
> have to be casted to float, though the type of the expression as a
> whole will be bool.
> 
> Similarly, it is not always the case that all operands have to be
> casted to the same type, therefore the interface leaves room for
> specifying a different cast type for each operand. For example,
> the first operand of the ternary operator must be casted to bool,
> while the other two must be casted to their common type, which is
> then the output type of the whole expression.

Yeah, but the ternary operator is a special case. I don't think it 
should result in an HLSL_IR_EXPR. Probably we should synthesize a 
temporary variable, store to it inside of a conditional, and load from it.

I'm still not convinced that casting in add_expr() is better than 
casting in the caller, either.

> 
> The add_*_last helpers behave similarly as their counterpart without
> "_last", except that the last node in each instruction list is used
> as an argument.

Yeah, I still don't like this name. "last" makes me think that the 
instruction will be added to the end of a list, or something. "merge" or 
"combine" would be a lot better, but it's a bit awkward for the unary 
helpers. But then again maybe we don't need the unary helpers, and we 
can just as easily just spell out node_from_list() inline. There are 
only three such cases after all (and I guess they're not even all the 
same kind of operation).

Or "parse", I guess, to symbolize it's done as part of parsing, although 
that's not great either.

> 
> Signed-off-by: Giovanni Mascellani <gmascellani at codeweavers.com>
> ---
>   libs/vkd3d-shader/hlsl.y | 144 ++++++++++++++++++---------------------
>   1 file changed, 66 insertions(+), 78 deletions(-)
> 

I think at least splitting the "cast_types" part out of this patch would 
make it easier to read.