[Mesa-dev] [PATCH] glsl: make a copy of array indices that are used to deref a function out param

[Ian Romanick]

It seems like this would be much more compact as a
ir_hierarchical_visitor that only implements
visit_leave(ir_dereference_array *).  Is there a reason that doesn't
work that I'm not seeing?

On 07/15/2018 01:04 AM, Timothy Arceri wrote:
> Fixes new piglit test:
> tests/spec/glsl-1.20/execution/qualifiers/vs-out-conversion-int-to-float-vec4-index.shader_test
> ---
>  src/compiler/glsl/ast_function.cpp | 94 ++++++++++++++++++++++++++++++
>  1 file changed, 94 insertions(+)
> 
> diff --git a/src/compiler/glsl/ast_function.cpp b/src/compiler/glsl/ast_function.cpp
> index 127aa1f91c4..97e78f99ea7 100644
> --- a/src/compiler/glsl/ast_function.cpp
> +++ b/src/compiler/glsl/ast_function.cpp
> @@ -348,6 +348,93 @@ verify_parameter_modes(_mesa_glsl_parse_state *state,
>     return true;
>  }
>  
> +static void
> +copy_index_derefs_to_temps(void *mem_ctx, ir_rvalue *param,
> +                           exec_list *before_instructions)
> +{
> +   /* Loop through the IR copying array indices until we find a swizzle,
> +    * costant or variable ref.
> +    */
> +   ir_rvalue *ir = param;
> +   while (ir != NULL) {
> +      switch (ir->ir_type) {
> +      case ir_type_dereference_record: {
> +         ir_dereference_record *r = (ir_dereference_record *) ir;
> +         ir = r->record->as_dereference();
> +         break;
> +      }
> +
> +      case ir_type_swizzle: {
> +         ir_swizzle *s = (ir_swizzle *) ir;
> +         ir = s->val->as_dereference();
> +         break;
> +      }
> +
> +      case ir_type_expression: {
> +         ir_expression *expr = (ir_expression* ) ir;
> +         for (unsigned int i = 0; i < expr->num_operands; i++) {
> +            copy_index_derefs_to_temps(mem_ctx, expr->operands[i],
> +                                       before_instructions);
> +         }
> +
> +         ir = NULL;
> +         break;
> +      }
> +
> +      case ir_type_dereference_array: {
> +         ir_dereference_array *a = (ir_dereference_array *) ir;
> +         ir = a->array->as_dereference();
> +
> +         ir_rvalue *idx = a->array_index;
> +         copy_index_derefs_to_temps(mem_ctx, idx, before_instructions);
> +
> +         if (idx->as_dereference_variable()) {
> +            ir_variable *var = idx->variable_referenced();
> +
> +            /* If the index is read only it cannot change so there is no need
> +             * to copy it.
> +             */
> +            if (var->data.read_only || var->data.memory_read_only)
> +               break;
> +         }
> +
> +         ir_variable *tmp = new(mem_ctx) ir_variable(idx->type, "idx_tmp",
> +                                                     ir_var_temporary);
> +         before_instructions->push_tail(tmp);
> +
> +         ir_dereference_variable *const deref_tmp_1 =
> +            new(mem_ctx) ir_dereference_variable(tmp);
> +         ir_assignment *const assignment =
> +            new(mem_ctx) ir_assignment(deref_tmp_1,
> +                                       idx->clone(mem_ctx, NULL));
> +         before_instructions->push_tail(assignment);
> +
> +         /* Replace the array index with a dereference of the new temporary.
> +          */
> +         ir_dereference_variable *const deref_tmp_2 =
> +            new(mem_ctx) ir_dereference_variable(tmp);
> +         a->array_index = deref_tmp_2;
> +         break;
> +      }
> +
> +      case ir_type_dereference_variable: {
> +         ir = NULL;
> +         break;
> +      }
> +
> +      case ir_type_constant: {
> +         /* Nothing to do for constants */
> +         ir = NULL;
> +         break;
> +      }
> +
> +      default:
> +         unreachable("Unexpected deref type");
> +         break;
> +      }
> +   }
> +}
> +
>  static void
>  fix_parameter(void *mem_ctx, ir_rvalue *actual, const glsl_type *formal_type,
>                exec_list *before_instructions, exec_list *after_instructions,
> @@ -362,6 +449,13 @@ fix_parameter(void *mem_ctx, ir_rvalue *actual, const glsl_type *formal_type,
>         && (expr == NULL || expr->operation != ir_binop_vector_extract))
>        return;
>  
> +   /* An array index could also be an out variable so we need to make a copy
> +    * of them before the function is called.
> +    */
> +   if (!actual->as_dereference_variable()) {
> +      copy_index_derefs_to_temps(mem_ctx, actual, before_instructions);
> +   }
> +
>     /* To convert an out parameter, we need to create a temporary variable to
>      * hold the value before conversion, and then perform the conversion after
>      * the function call returns.
>