[Mesa-dev] [PATCH 00/56] Die copy-and-paste code, die

[Rob Clark]

On Tue, Jul 19, 2016 at 3:24 PM, Ian Romanick <idr at freedesktop.org> wrote:
> After seeing Dave's series to add support GL_ARB_shader_gpu_int64 and
> thinking about adding support for 8- and  16-bit integers, I decided
> that something had to be done about the cut-and-paste madness that is
> ir_constant_expression.cpp.  I decided to take a page from Jason's book
> and generate it from a machine description of the expressions.  The
> result is this series.

fwiw, I did go down the path of adding half-precision types in IR for
a spell, but ended up deciding it was a maddening explosion of
builtin-types and builtin-functions..

At some point (ie. might be a month or two or more before I get to
it), I was going to go back to my original idea of just keeping things
as-is in glsl IR (as type+precision-qualifier for <=32b types), and
dealing with it in glsl->nir.  Basically just need to add a
precision-visitor (which I think I already pushed on a branch
somewhere) to infer an expression's precision, and wire that up in a
few places (function inlining and various other places where
intermediate vars are created in ir), and mapping type+precision to
nir type in glsl_to_nir.

(Not an argument against autogenerating some of the IR bits..  I think
that would be a really good idea, I'm a much bigger fan of how some of
that is handled in NIR.. maybe there is some room to autogen some of
the builtin-types and builtin-functions, which might make me
reconsider..)

BR,
-R

> You may notice from some of the earlier patches in this series that I
> started this work over a year ago.  The previous work was an attempt to
> generate opt_algebraic.cpp which was ultimately abandonded.  It may be
> worth picking that up again.
>
> I haven't done *anything* for SCons, so hopefully Jose or someone can
> help out there.
>
> All of this is available at:
>
>     https://cgit.freedesktop.org/~idr/mesa/log/?h=generated-glsl-ir
>
> Other possible follow-up work:
>
>  - A few expressions don't have constant evaluation support.  I don't
>    think I've seen a real shader use any of these, so there's a reason
>    we haven't "missed" them.
>
>     - frexp_sig
>     - frexp_exp
>     - vote_any
>     - vote_all
>     - vote_eq
>     - imul_high
>     - carry
>     - borrow
>
>  - Generate validation code for expressions.  A few times while
>    developing this series I had questions about what the IR actually
>    supported.  In quite a few cases the IR support is different from
>    what GLSL supports.  I would often look to ir_validate.cpp to answer
>    these questions, and I was almost always disappointed.  I would
>    really like to see missing type information added to
>    ir_expression_operation.py and generate a much more complete set of
>    validations for ir_expression.  Then the assertions remaining in
>    ir_expression_operation_constant.h could be removed.
>
>  - Generate ir_expression constructors.
>
>  - Generate ir_builder.  We don't support every possible expression in
>    ir_builder, so this may not be worth the effort.
>
>  src/compiler/Android.glsl.gen.mk             |    2 +-
>  src/compiler/Makefile.glsl.am                |   24 +-
>  src/compiler/Makefile.sources                |    8 +-
>  src/compiler/glsl/.gitignore                 |    2 +
>  src/compiler/glsl/ir.cpp                     |  133 +-
>  src/compiler/glsl/ir.h                       |  329 +----
>  src/compiler/glsl/ir_constant_expression.cpp | 1332 ++----------------
>  src/compiler/glsl/ir_expression_operation.py |  738 ++++++++++
>  src/compiler/glsl/ir_print_visitor.cpp       |    2 +-
>  src/compiler/glsl/ir_validate.cpp            |   11 +
>  src/compiler/glsl/lower_mat_op_to_vec.cpp    |    2 +-
>  src/mesa/Makefile.sources                    |    1 +
>  src/mesa/drivers/dri/i965/Makefile.am        |    1 +
>  13 files changed, 901 insertions(+), 1684 deletions(-)
>
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