Paul Berry <stereotype...@gmail.com> writes:
> On 20 February 2013 12:25, Eric Anholt <e...@anholt.net> wrote:
>
>> Matt Turner <matts...@gmail.com> writes:
>>
>> > From: Kenneth Graunke <kenn...@whitecape.org>
>> >
>> > Previously, we had separate constructors for one, two, and four operand
>> > expressions. This patch consolidates them into a single constructor
>> > which uses NULL default parameters.
>> >
>> > The unary and binary operator constructors had assertions to verify that
>> > the caller supplied the correct number of operands for the expression,
>> > but the four-operand version did not. Since get_num_operands for
>> > ir_quadop_vector returns the number of vector_elements, we can safely
>> > add that without breaking the semantics of ir_quadop_vector.
>> >
>> > This also paves the way for expressions with three operands. Currently,
>> > none can be constructed since get_num_operands() never returns 3.
>> >
>> > Reviewed-by: Matt Turner <matts...@gmail.com>
>> > ---
>> > src/glsl/ir.cpp | 34 ++++++----------------------------
>> > src/glsl/ir.h | 13 ++++---------
>> > 2 files changed, 10 insertions(+), 37 deletions(-)
>> >
>> > diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
>> > index 954995d..4ccdc42 100644
>> > --- a/src/glsl/ir.cpp
>> > +++ b/src/glsl/ir.cpp
>> > @@ -234,6 +206,12 @@ ir_expression::ir_expression(int op, const struct
>> glsl_type *type,
>> > this->operands[1] = op1;
>> > this->operands[2] = op2;
>> > this->operands[3] = op3;
>> > +#ifndef NDEBUG
>> > + int num_operands = get_num_operands(this->operation);
>> > + for (int i = num_operands; i < 4; i++) {
>> > + assert(this->operands[i] == NULL);
>> > + }
>> > +#endif
>>
>> Ugh, I don't like seeing #ifdefs for debug around when it's avoidable --
>> we should be able to rely on this stuff getting optimized out. Except
>> that the optimizer doesn't get to know that get_num_operands() has no
>> side effects, unless we annotate it with __attribute__((pure)). I guess
>> I'm fine either way -- this, or adding the attribute.
>>
>
> In i965 I would be a fan of adding the attribute, but since this code is in
> glsl, it needs to be buildable using MSVC, which does not support
> __attribute__ declarations.We #ifdef these things based on __GNUC__, so that lame compilers keep compiling but suffer.
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