isl: tag unreachable path as such

GCC should be able to figure out that all the possible enum values are
exhausted in the switch() and all the branches return from the function,
but apparently it doesn't, so let's tell the compiler explicitly.

This gets rid of the following warnings in GCC 9:

    [1/24] Compiling C object 'src/intel/isl/60d23f8@@isl@sta/isl.c.o'.
    ../src/intel/isl/isl.c: In function ‘isl_surf_init_s’:
    ../src/intel/isl/isl.c:1569:10: warning: ‘array_pitch_el_rows’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     1569 |    *surf = (struct isl_surf) {
          |    ~~~~~~^~~~~~~~~~~~~~~~~~~~~
     1570 |       .dim = info->dim,
          |       ~~~~~~~~~~~~~~~~~
     1571 |       .dim_layout = dim_layout,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~
     1572 |       .msaa_layout = msaa_layout,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1573 |       .tiling = tiling,
          |       ~~~~~~~~~~~~~~~~~
     1574 |       .format = info->format,
          |       ~~~~~~~~~~~~~~~~~~~~~~~
     1575 |
          |
     1576 |       .levels = info->levels,
          |       ~~~~~~~~~~~~~~~~~~~~~~~
     1577 |       .samples = info->samples,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~
     1578 |
          |
     1579 |       .image_alignment_el = image_align_el,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1580 |       .logical_level0_px = logical_level0_px,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1581 |       .phys_level0_sa = phys_level0_sa,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1582 |
          |
     1583 |       .size_B = size_B,
          |       ~~~~~~~~~~~~~~~~~
     1584 |       .alignment_B = base_alignment_B,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1585 |       .row_pitch_B = row_pitch_B,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1586 |       .array_pitch_el_rows = array_pitch_el_rows,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1587 |       .array_pitch_span = array_pitch_span,
          |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1588 |
          |
     1589 |       .usage = info->usage,
          |       ~~~~~~~~~~~~~~~~~~~~~
     1590 |    };
          |    ~
    ../src/intel/isl/isl.c:1488:24: warning: ‘*((void *)&phys_total_el+4)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     1488 |    struct isl_extent2d phys_total_el;
          |                        ^~~~~~~~~~~~~
    ../src/intel/isl/isl.c:1335:38: warning: ‘phys_total_el’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     1335 |       isl_align_div(phys_total_el->w * tile_el_scale,
          |                     ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
    ../src/intel/isl/isl.c:1488:24: note: ‘phys_total_el’ was declared here
     1488 |    struct isl_extent2d phys_total_el;
          |                        ^~~~~~~~~~~~~

Signed-off-by: Eric Engestrom <[email protected]>
Reviewed-by: Jason Ekstrand <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c
index 2e33031cbbf..43ad8561c7e 100644
--- a/src/intel/isl/isl.c
+++ b/src/intel/isl/isl.c
@@ -1270,6 +1270,8 @@ isl_calc_phys_total_extent_el(const struct isl_device *dev,
                                             total_extent_el);
       return;
    }
+
+   unreachable("invalid value for dim_layout");
 }
 
 static uint32_t