[Mesa-dev] [PATCH] glsl: fix lower jumps for nested non-void returns

[Roland Scheidegger]

Looks alright to me though I still don't really understand this code :-)

Reviewed-by: Roland Scheidegger <sroland at vmware.com>

Am 07.04.2017 um 03:24 schrieb Timothy Arceri:
> Fixes the case were a loop contains a return and the loop is
> nested inside an if.
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=100303
> ---
>  src/compiler/glsl/lower_jumps.cpp                        | 6 ++++++
>  src/compiler/glsl/tests/lower_jumps/create_test_cases.py | 5 ++++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/src/compiler/glsl/lower_jumps.cpp b/src/compiler/glsl/lower_jumps.cpp
> index e165172..7dc3405 100644
> --- a/src/compiler/glsl/lower_jumps.cpp
> +++ b/src/compiler/glsl/lower_jumps.cpp
> @@ -938,20 +938,26 @@ lower_continue:
>               * those instructions into the else clause of the generated if
>               * statement.
>               */
>              move_outer_block_inside(ir, &return_if->else_instructions);
>  
>              /* In case the loop is embedded inside an if add a new return to
>               * the return flag then branch and let a future pass tidy it up.
>               */
>              if (this->function.signature->return_type->is_void())
>                 return_if->then_instructions.push_tail(new(ir) ir_return(NULL));
> +            else {
> +               assert(this->function.return_value);
> +               ir_variable* return_value = this->function.return_value;
> +               return_if->then_instructions.push_tail(
> +                  new(ir) ir_return(new(ir) ir_dereference_variable(return_value)));
> +            }
>           }
>  
>           ir->insert_after(return_if);
>        }
>  
>        this->loop = saved_loop;
>        --this->function.nesting_depth;
>     }
>  
>     virtual void visit(ir_function_signature *ir)
> diff --git a/src/compiler/glsl/tests/lower_jumps/create_test_cases.py b/src/compiler/glsl/tests/lower_jumps/create_test_cases.py
> index 20f5ace..623487e 100644
> --- a/src/compiler/glsl/tests/lower_jumps/create_test_cases.py
> +++ b/src/compiler/glsl/tests/lower_jumps/create_test_cases.py
> @@ -621,21 +621,24 @@ def test_lower_return_non_void_at_end_of_loop():
>              assign_x('b', const_float(3)) +
>              return_(const_float(4))
>              ))
>      expected_sexp = make_test_case('sub', 'float', (
>              declare_execute_flag() +
>              declare_return_value() +
>              declare_return_flag() +
>              loop(assign_x('a', const_float(1)) +
>                   lowered_return_simple(const_float(2)) +
>                   break_()) +
> -            if_not_return_flag(assign_x('b', const_float(3)) +
> +            if_return_flag(assign_x('return_value', '(var_ref return_value)') +
> +                           assign_x('return_flag', const_bool(1)) +
> +                           assign_x('execute_flag', const_bool(0)),
> +                           assign_x('b', const_float(3)) +
>                                 lowered_return(const_float(4))) +
>              final_return()
>              ))
>      create_test_case(doc_string, input_sexp, input_sexp, 'return_non_void_at_end_of_loop_lower_nothing')
>      create_test_case(doc_string, input_sexp, expected_sexp, 'return_non_void_at_end_of_loop_lower_return',
>                       lower_sub_return=True)
>      create_test_case(doc_string, input_sexp, expected_sexp, 'return_non_void_at_end_of_loop_lower_return_and_break',
>                       lower_sub_return=True, lower_break=True)
>  
>  if __name__ == '__main__':
>