Francisco Jerez <curroje...@riseup.net> writes:
> Tapani Pälli <tapani.pa...@intel.com> writes:
>
>> Desktop GLSL < 130 and GLSL ES < 300 allow sampler array indexing where
>> index can contain a loop induction variable. This extra check will warn
>> during linking if some of the indexes could not be turned in to constant
>> expressions.
>>
>> v2: warning instead of error for backends that did not enable
>> UnrollSamplerArrayDynamicIndexing option (have dynamic indexing)
>>
>> Signed-off-by: Tapani Pälli <tapani.pa...@intel.com>
>> Cc: "10.5" and "10.6" <mesa-sta...@lists.freedesktop.org>
>> ---
>> src/glsl/linker.cpp | 77
>> +++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 77 insertions(+)
>>
>> diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
>> index 9978380..27d7c18 100644
>> --- a/src/glsl/linker.cpp
>> +++ b/src/glsl/linker.cpp
>> @@ -346,6 +346,39 @@ private:
>> bool uses_non_zero_stream;
>> };
>>
>> +/* Class that finds array derefs and check if indexes are dynamic. */
>> +class dynamic_sampler_array_indexing_visitor : public
>> ir_hierarchical_visitor
>> +{
>> +public:
>> + dynamic_sampler_array_indexing_visitor() :
>> + dynamic_sampler_array_indexing(false)
>> + {
>> + }
>> +
>> + ir_visitor_status visit_enter(ir_dereference_array *ir)
>> + {
>> + if (!ir->variable_referenced())
>> + return visit_continue;
>> +
>> + if (!ir->variable_referenced()->type->contains_sampler())
>> + return visit_continue;
>> +
>> + if (!ir->array_index->constant_expression_value()) {
>> + dynamic_sampler_array_indexing = true;
>> + return visit_stop;
>> + }
>> + return visit_continue;
>> + }
>> +
>> + bool uses_dynamic_sampler_array_indexing()
>> + {
>> + return dynamic_sampler_array_indexing;
>> + }
>> +
>> +private:
>> + bool dynamic_sampler_array_indexing;
>> +};
>> +
>> } /* anonymous namespace */
>>
>> void
>> @@ -2736,6 +2769,40 @@ build_program_resource_list(struct gl_context *ctx,
>> */
>> }
>>
>> +/**
>> + * This check is done to make sure we allow only constant expression
>> + * indexing and "constant-index-expression" (indexing with an expression
>> + * that includes loop induction variable).
>> + */
>> +static bool
>> +validate_sampler_array_indexing(struct gl_context *ctx,
>> + struct gl_shader_program *prog)
>> +{
>> + dynamic_sampler_array_indexing_visitor v;
>> + for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
>> + if (prog->_LinkedShaders[i] == NULL)
>> + continue;
>> +
>> + bool no_dynamic_indexing =
>> +
>> ctx->Const.ShaderCompilerOptions[i].UnrollSamplerArrayDynamicIndexing;
>> +
>> + /* Search for array derefs in shader. */
>> + v.run(prog->_LinkedShaders[i]->ir);
>> + if (v.uses_dynamic_sampler_array_indexing()) {
>> + const char *msg = "sampler arrays indexed with non-constant "
>> + "expressions is forbidden in GLSL %s %u";
>
> For the sake of clarity, maybe add that it's sampler array indexing with
> *general* non-constant expressions what is forbidden, loop induction
> variables are allowed and they are technically a kind of non-constant
> expression.
>
>> + /* Backend has indicated that it has no dynamic indexing support.
>> */
>> + if (no_dynamic_indexing) {
>> + linker_error(prog, msg, prog->IsES ? "ES" : "", prog->Version);
>> + return false;
>> + } else {
>> + linker_warning(prog, msg, prog->IsES ? "ES" : "",
>> prog->Version);
>
> It seems a bit mean to spam the user with another warning at link time,
> you've already warned in PATCH 01 that this feature will be removed in
> more recent GLSL versions. If you drop the warning:
>
Er, nevermind, the warning here is indeed subtly different (you are
doing a kind of indexing not considered under the
constant-index-expression wording), disregard my comment about dropping
the warning, it seems fine to warn the user twice.
> Reviewed-by: Francisco Jerez <curroje...@riseup.net>
>
>> + }
>> + }
>> + }
>> + return true;
>> +}
>> +
>>
>> void
>> link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
>> @@ -2954,6 +3021,16 @@ link_shaders(struct gl_context *ctx, struct
>> gl_shader_program *prog)
>> lower_const_arrays_to_uniforms(prog->_LinkedShaders[i]->ir);
>> }
>>
>> + /* Validation for special cases where we allow sampler array indexing
>> + * with loop induction variable. This check emits a warning or error
>> + * depending if backend can handle dynamic indexing.
>> + */
>> + if ((!prog->IsES && prog->Version < 130) ||
>> + (prog->IsES && prog->Version < 300)) {
>> + if (!validate_sampler_array_indexing(ctx, prog))
>> + goto done;
>> + }
>> +
>> /* Check and validate stream emissions in geometry shaders */
>> validate_geometry_shader_emissions(ctx, prog);
>>
>> --
>> 2.1.0
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