[Mesa-dev] [PATCH] mesa: Skip mipmap generation if there is no source image.

[Ian Romanick]

On 10/17/2011 01:59 PM, Brian Paul wrote:
> On 10/17/2011 02:45 PM, Eric Anholt wrote:
>> The spec doesn't explicitly mandate this behavior, but it seems like
>> the only sensible thing to do (as opposed to assertion failing or
>> segfaulting).
>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=40308
>> ---
>>
>> Oops, looks like I never sent this one out for review.
>>
>> src/mesa/main/mipmap.c | 4 +++-
>> 1 files changed, 3 insertions(+), 1 deletions(-)
>>
>> diff --git a/src/mesa/main/mipmap.c b/src/mesa/main/mipmap.c
>> index c2f9226..2b6aead 100644
>> --- a/src/mesa/main/mipmap.c
>> +++ b/src/mesa/main/mipmap.c
>> @@ -2036,7 +2036,9 @@ _mesa_generate_mipmap(struct gl_context *ctx,
>> GLenum target,
>>
>> ASSERT(texObj);
>> srcImage = _mesa_select_tex_image(ctx, texObj, target,
>> texObj->BaseLevel);
>> - ASSERT(srcImage);
>> +
>> + if (!srcImage)
>> + return;
>>
>> maxLevel = _mesa_max_texture_levels(ctx, texObj->Target) - 1;
>> ASSERT(maxLevel>= 0); /* bad target */
>
> I think this check should come sooner. We typically do error checking
> and no-op checking before calling the ctx->Driver.Foobar() functions.
>
> The above fix might work for the fallback path, but what about if
> ctx->Driver.GenerateMipmap points to _mesa_meta_GenerateMipmap() or
> st_generate_mipmap()?
>
> I think I'd try to do the check in _mesa_GenerateMipmapEXT().

Will that also catch the GL_GENERATE_MIPMAP case?  I think that's why 
Eric originally put the check farther down the execution path.  Though, 
you do raise a good point.