[Mesa-dev] [PATCH 2/3] glsl: disable cache if MESA_EXTENSION_OVERRIDE is set

[Timothy Arceri]

On 27/03/17 20:32, Grazvydas Ignotas wrote:
> On Mon, Mar 27, 2017 at 6:14 AM, Timothy Arceri <tarceri at itsqueeze.com> wrote:
>> In the following patch we will stop pre-processing shaders before
>> hashing them, so we just disable the cache if MESA_EXTENSION_OVERRIDE
>> is set.
>
> That's because the extension substitution is done by the preprocessor
> I assume? It's not really obvious for someone who doesn't know the
> code...

Yeah you can do things like take a different path depending on if an 
extension is available or not so we could end up with different programs 
but produce the same hash since we will no longer produce the hash after 
the preprocessor has done its job.

>
> Gražvydas
>
>> ---
>>  src/util/disk_cache.c | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/src/util/disk_cache.c b/src/util/disk_cache.c
>> index d9de8ef..dc883a3 100644
>> --- a/src/util/disk_cache.c
>> +++ b/src/util/disk_cache.c
>> @@ -167,20 +167,29 @@ disk_cache_create(const char *gpu_name, const char *timestamp)
>>  {
>>     void *local;
>>     struct disk_cache *cache = NULL;
>>     char *path, *max_size_str;
>>     uint64_t max_size;
>>     int fd = -1;
>>     struct stat sb;
>>     struct statvfs vfs = { 0 };
>>     size_t size;
>>
>> +   /* We no longer pre-process shaders before hashing them so disable the
>> +    * cache if extensions are overridden.
>> +    *
>> +    * Note: Versions are part of the linked programs hash so we don't need
>> +    * to worry about those here.
>> +    */
>> +   if (getenv("MESA_EXTENSION_OVERRIDE"))
>> +      return NULL;
>> +
>>     /* If running as a users other than the real user disable cache */
>>     if (geteuid() != getuid())
>>        return NULL;
>>
>>     /* A ralloc context for transient data during this invocation. */
>>     local = ralloc_context(NULL);
>>     if (local == NULL)
>>        goto fail;
>>
>>     /* At user request, disable shader cache entirely. */
>> --
>> 2.9.3
>>
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