[Mesa-dev] [PATCH 1/4] mesa/formats: only do type and component lookup for uncompressed formats

[Chad Versace]

On Tue 11 Aug 2015, Nanley Chery wrote:
> From: Nanley Chery <nanley.g.chery at intel.com>
> 
> Only uncompressed formats have a non-void type and actual components per pixel.
> Rename _mesa_format_to_type_and_comps to
> _mesa_uncompressed_format_to_type_and_comps and require callers to check if
> the format is not compressed.
> 
> Cc: Jason Ekstrand <jason.ekstrand at intel.com>
> Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> ---
>  src/mesa/main/format_utils.c |  2 +-
>  src/mesa/main/formats.c      | 55 ++++++++------------------------------------
>  src/mesa/main/formats.h      |  2 +-
>  src/mesa/main/mipmap.c       |  2 +-
>  4 files changed, 12 insertions(+), 49 deletions(-)

I like several patches in this series, but I don't like this one. It
produces a lot of compiler warnings.

The problem is that the switch in _mesa_format_to_type_and_comps() is
intended to be an exhaustive switch. Removing the compressed format
cases causes a waterfall of compiler warnings like this:

  main/formats.c:1458:4: warning: enumeration value 'MESA_FORMAT_LA_LATC2_UNORM' not handled in switch [-Wswitch]
  main/formats.c:1458:4: warning: enumeration value 'MESA_FORMAT_LA_LATC2_SNORM' not handled in switch [-Wswitch]
  main/formats.c:1458:4: warning: enumeration value 'MESA_FORMAT_ETC1_RGB8' not handled in switch [-Wswitch]
  main/formats.c:1458:4: warning: enumeration value 'MESA_FORMAT_ETC2_RGB8' not handled in switch [-Wswitch]
  main/formats.c:1458:4: warning: enumeration value 'MESA_FORMAT_ETC2_SRGB8' not handled in switch [-Wswitch]
  main/formats.c:1458:4: warning: enumeration value 'MESA_FORMAT_ETC2_RGBA8_EAC' not handled in switch [-Wswitch]
  main/formats.c:1458:4: warning: enumeration value 'MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC' not handled in switch [-Wswitch]

I think you can salvage the patch by following the hint in this deleted
hunk...

> -   case MESA_FORMAT_RGB_FXT1:
> -   case MESA_FORMAT_RGBA_FXT1:
> -   case MESA_FORMAT_RGB_DXT1:
> -   case MESA_FORMAT_RGBA_DXT1:
> -   case MESA_FORMAT_RGBA_DXT3:
> -   case MESA_FORMAT_RGBA_DXT5:
> -   case MESA_FORMAT_SRGB_DXT1:
> -   case MESA_FORMAT_SRGBA_DXT1:
> -   case MESA_FORMAT_SRGBA_DXT3:
> -   case MESA_FORMAT_SRGBA_DXT5:
> -   case MESA_FORMAT_R_RGTC1_UNORM:
> -   case MESA_FORMAT_R_RGTC1_SNORM:
> -   case MESA_FORMAT_RG_RGTC2_UNORM:
> -   case MESA_FORMAT_RG_RGTC2_SNORM:
> -   case MESA_FORMAT_L_LATC1_UNORM:
> -   case MESA_FORMAT_L_LATC1_SNORM:
> -   case MESA_FORMAT_LA_LATC2_UNORM:
> -   case MESA_FORMAT_LA_LATC2_SNORM:
> -   case MESA_FORMAT_ETC1_RGB8:
> -   case MESA_FORMAT_ETC2_RGB8:
> -   case MESA_FORMAT_ETC2_SRGB8:
> -   case MESA_FORMAT_ETC2_RGBA8_EAC:
> -   case MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC:
> -   case MESA_FORMAT_ETC2_R11_EAC:
> -   case MESA_FORMAT_ETC2_RG11_EAC:
> -   case MESA_FORMAT_ETC2_SIGNED_R11_EAC:
> -   case MESA_FORMAT_ETC2_SIGNED_RG11_EAC:
> -   case MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1:
> -   case MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1:
> -   case MESA_FORMAT_BPTC_RGBA_UNORM:
> -   case MESA_FORMAT_BPTC_SRGB_ALPHA_UNORM:
> -   case MESA_FORMAT_BPTC_RGB_SIGNED_FLOAT:
> -   case MESA_FORMAT_BPTC_RGB_UNSIGNED_FLOAT:
> -      /* XXX generate error instead? */
> -      *datatype = GL_UNSIGNED_BYTE;
> -      *comps = 0;
> -      return;
> -

In other words, rename the function to
_mesa_uncompressed_format_to_type_and_comps(); keep all the format
cases; and add an assertion or _mesa_problem() for the compressed cases.