[Mesa-dev] [PATCH v2] glsl: move uniform calculation to link_uniforms

[Ilia Mirkin]

On Wed, Jan 20, 2016 at 6:35 AM, Tapani Pälli <tapani.palli at intel.com> wrote:
> On 01/20/2016 01:11 PM, Ilia Mirkin wrote:
>>
>> On Wed, Jan 20, 2016 at 6:02 AM, Tapani Pälli <tapani.palli at intel.com>
>> wrote:
>>>>
>>>> Unfortunately putting such a shader together is a bit of a pain, since
>>>> all the uniforms have to be used. I still really think you need to
>>>> build a heap. Or at least store a "first empty slot" so that you don't
>>>> repeat the iteration *every* time.
>>>
>>>
>>> Yeah, I agree "first empty slot" would be good addition and will already
>>> help a lot in problematic cases.
>>
>> Actually it's still not so great, since you can have stupid situations
>> which won't fit into the first empty position. e.g. one empty
>> location, and a bunch of foo[2] things. That's why I like using a heap
>> :)

With this shader: http://hastebin.com/sisomonenu.avrasm and this patch:

diff --git a/src/glsl/link_uniforms.cpp b/src/glsl/link_uniforms.cpp
index 76ee70d..a826e63 100644
--- a/src/glsl/link_uniforms.cpp
+++ b/src/glsl/link_uniforms.cpp
@@ -1066,10 +1066,12 @@ find_empty_block(struct gl_shader_program *prog,
                  struct gl_uniform_storage *uniform)
 {
    const unsigned entries = MAX2(1, uniform->array_elements);
+static int loops = 0;
    for (unsigned i = 0, j; i < prog->NumUniformRemapTable; i++) {
       /* We found empty space in UniformRemapTable. */
       if (prog->UniformRemapTable[i] == NULL) {
-         for (j = i; j < entries && j < prog->NumUniformRemapTable; j++) {
+         for (j = i; j - i < entries && j < prog->NumUniformRemapTable; j++) {
+loops++;
             if (prog->UniformRemapTable[j] != NULL) {
                /* Entries do not fit in this space, continue searching
                 * after this location.
@@ -1080,10 +1082,12 @@ find_empty_block(struct gl_shader_program *prog,
          }
          /* Entries fit, we can return this location. */
          if (i != j + 1) {
+printf("loops: %d\n", loops);
             return i;
          }
-      }
+      } else loops++;
    }
+printf("loops: %d (fail)\n", loops);
    return -1;
 }

I get loops going up to 8386560. Which is roughly what I expected.
This doesn't concern you at all?

  -ilia