This patch paves the way for allowing varying structs by generalizing
varying_matches::compute_packing_order to handle any type of varying.
Previously, we packed in the order (vec4, vec2, float, vec3), with
matrices being packed according to the size of their columns. Now, we
pack everything according to its number of components mod 4, in the
order (0, 2, 1, 3).
There is no behavioural change for vectors. Matrices are now packed
slightly differently:
- mat2x2 gets assigned PACKING_ORDER_VEC4 instead of
PACKING_ORDER_VEC2. This is slightly better, because it guarantees
that the matrix occupies a single varying slot.
- mat2x3 gets assigned PACKING_ORDER_VEC2 instead of
PACKING_ORDER_VEC3. This is kind of a wash. Previously, mat2x3 had
a 25% chance of having neither of its columns double parked, a 50%
chance of having exactly one of its columns double parked, and a 25%
chance of having both of its columns double parked. Now it always
has exactly one of its columns double parked.
- mat3x3 gets assigned PACKING_ORDER_SCALAR instead of
PACKING_ORDER_VEC3. This doesn't affect much, since in both cases
there is no guarantee of how the matrix will be aligned.
- mat4x2 gets assigned PACKING_ORDER_VEC4 instead of
PACKING_ORDER_VEC2. This is slightly better for the same reason as
in mat2x2.
- mat4x3 gets assigned PACKING_ORDER_VEC4 instead of
PACKING_ORDER_VEC3. This is slightly better for the same reason as
in mat2x2.
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
This patch replaces the three ir_variable_mode enums:
- ir_var_in
- ir_var_out
- ir_var_inout
with the following five:
- ir_var_shader_in
- ir_var_shader_out
- ir_var_function_in
- ir_var_function_out
- ir_var_function_inout
This eliminates a frustrating ambiguity: it used to be impossible to
tell whether an ir_var_{in,out} variable was a shader in/out or a
function in/out without seeing where the variable was declared in the
IR. This complicated some optimization and lowering passes, and would
have become a problem for implementing varying structs.
In the lisp-style serialization of GLSL IR to strings performed by
ir_print_visitor.cpp and ir_reader.cpp, I've retained the names "in",
"out", and "inout" for function parameters, to avoid introducing code
churn to the src/glsl/builtins/ir/ directory.
Note: a couple of comments in the code seemed to indicate that we were
planning for a possible future in which geometry shaders could have
shader-scope inout variables. Our GLSL grammar rejects shader-scope
inout variables, and I've been unable to find any evidence in the GLSL
standards documents (or extensions) that this will ever be allowed, so
I've eliminated these comments.
Reviewed-by: Carl Worth <cworth@cworth.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
This patch enhances the varying packing code so that flat varyings of
uint, int, and float types can be packed together.
We accomplish this in lower_packed_varyings.cpp by making the type of
all flat varyings ivec4, and then using information-preserving type
conversions (e.g. ir_unop_bitcast_f2i) to convert all other types to
ints.
The varying_matches::compute_packing_class() function is updated to
reflect the fact that varying packing no longer needs to segregate
varyings of different base types.
Fixes piglit test varying-packing-mixed-types.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
v2: Split lower_packed_varyings_visitor::bitwise_assign into
pack/unpack variants.
linker.cpp is getting pretty big, and we're about to add even more
varying packing code, so split out the linker code that concerns
varyings to its own file.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
