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nir/algebraic: Lower CS derivatives to zero when no group defined 

In compute shaders if no derivative group is defined, the derivatives
will always be zero.  Specified in NV_compute_shader_derivatives.

To make the check more convenient, add a "info" local variable to the
generated code so we can refer to it in the Python rules.  (Jason)

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This commit is contained in:
Caio Marcelo de Oliveira Filho 2019-03-27 15:07:20 -07:00
parent 3c5ddaeacd
commit d08a74d2bf
2 changed files with 14 additions and 0 deletions
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2
src/compiler/nir/nir_algebraic.py
View File

@ -770,7 +770,9 @@ ${pass_name}(nir_shader *shader)
bool progress = false;
bool condition_flags[${len(condition_list)}];
const nir_shader_compiler_options *options = shader->options;
const shader_info *info = &shader->info;
(void) options;
(void) info;
% for index, condition in enumerate(condition_list):
condition_flags[${index}] = ${condition};

12
src/compiler/nir/nir_opt_algebraic.py
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@ -972,6 +972,18 @@ for op in ['fadd', 'fmul', 'iadd', 'imul']:
((op, ('bcsel(is_used_once)', a, '#b', c), '#d'), ('bcsel', a, (op, b, d), (op, c, d)))
]
# For derivatives in compute shaders, GLSL_NV_compute_shader_derivatives
# states:
#
# If neither layout qualifier is specified, derivatives in compute shaders
# return zero, which is consistent with the handling of built-in texture
# functions like texture() in GLSL 4.50 compute shaders.
for op in ['fddx', 'fddx_fine', 'fddx_coarse',
'fddy', 'fddy_fine', 'fddy_coarse']:
optimizations += [
((op, 'a'), 0.0, 'info->stage == MESA_SHADER_COMPUTE && info->cs.derivative_group == DERIVATIVE_GROUP_NONE')
]
# This section contains "late" optimizations that should be run before
# creating ffmas and calling regular optimizations for the final time.
# Optimizations should go here if they help code generation and conflict