mesa: remove fallback RefCount == 0 pattern

We should never get here if this is 0 unless there is a
bug. Replace the check with an assert.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

src/mesa/main/arrayobj.c

@@ -208,16 +208,10 @@ _mesa_reference_vao_(struct gl_context *ctx,
    if (vao) {
       /* reference new array object */
       mtx_lock(&vao->Mutex);
-      if (vao->RefCount == 0) {
-         /* this array's being deleted (look just above) */
-         /* Not sure this can every really happen.  Warn if it does. */
-         _mesa_problem(NULL, "referencing deleted array object");
-         *ptr = NULL;
-      }
-      else {
-         vao->RefCount++;
-         *ptr = vao;
-      }
+      assert(vao->RefCount > 0);
+
+      vao->RefCount++;
+      *ptr = vao;
       mtx_unlock(&vao->Mutex);
    }
 }

src/mesa/main/bufferobj.c

@@ -511,16 +511,10 @@ _mesa_reference_buffer_object_(struct gl_context *ctx,
    if (bufObj) {
       /* reference new buffer */
       mtx_lock(&bufObj->Mutex);
-      if (bufObj->RefCount == 0) {
-         /* this buffer's being deleted (look just above) */
-         /* Not sure this can every really happen.  Warn if it does. */
-         _mesa_problem(NULL, "referencing deleted buffer object");
-         *ptr = NULL;
-      }
-      else {
-         bufObj->RefCount++;
-         *ptr = bufObj;
-      }
+      assert(bufObj->RefCount > 0);
+
+      bufObj->RefCount++;
+      *ptr = bufObj;
       mtx_unlock(&bufObj->Mutex);
    }
 }

src/mesa/main/pipelineobj.c

@@ -206,16 +206,10 @@ _mesa_reference_pipeline_object_(struct gl_context *ctx,
    if (obj) {
       /* reference new pipeline object */
       mtx_lock(&obj->Mutex);
-      if (obj->RefCount == 0) {
-         /* this pipeline's being deleted (look just above) */
-         /* Not sure this can ever really happen.  Warn if it does. */
-         _mesa_problem(NULL, "referencing deleted pipeline object");
-         *ptr = NULL;
-      }
-      else {
-         obj->RefCount++;
-         *ptr = obj;
-      }
+      assert(obj->RefCount > 0);
+
+      obj->RefCount++;
+      *ptr = obj;
       mtx_unlock(&obj->Mutex);
    }
 }

src/mesa/main/samplerobj.c

@@ -97,16 +97,10 @@ _mesa_reference_sampler_object_(struct gl_context *ctx,
    if (samp) {
       /* reference new sampler */
       mtx_lock(&samp->Mutex);
-      if (samp->RefCount == 0) {
-         /* this sampler's being deleted (look just above) */
-         /* Not sure this can every really happen.  Warn if it does. */
-         _mesa_problem(NULL, "referencing deleted sampler object");
-         *ptr = NULL;
-      }
-      else {
-         samp->RefCount++;
-         *ptr = samp;
-      }
+      assert(samp->RefCount > 0);
+
+      samp->RefCount++;
+      *ptr = samp;
       mtx_unlock(&samp->Mutex);
    }
 }

src/mesa/main/texobj.c

@@ -566,16 +566,10 @@ _mesa_reference_texobj_(struct gl_texture_object **ptr,
       /* reference new texture */
       assert(valid_texture_object(tex));
       mtx_lock(&tex->Mutex);
-      if (tex->RefCount == 0) {
-         /* this texture's being deleted (look just above) */
-         /* Not sure this can every really happen.  Warn if it does. */
-         _mesa_problem(NULL, "referencing deleted texture object");
-         *ptr = NULL;
-      }
-      else {
-         tex->RefCount++;
-         *ptr = tex;
-      }
+      assert(tex->RefCount > 0);
+
+      tex->RefCount++;
+      *ptr = tex;
       mtx_unlock(&tex->Mutex);
    }
 }

src/mesa/main/transformfeedback.c

@@ -110,16 +110,12 @@ reference_transform_feedback_object(struct gl_transform_feedback_object **ptr,
    assert(!*ptr);
 
    if (obj) {
+      assert(obj->RefCount > 0);
+
       /* reference new object */
-      if (obj->RefCount == 0) {
-         _mesa_problem(NULL, "referencing deleted transform feedback object");
-         *ptr = NULL;
-      }
-      else {
-         obj->RefCount++;
-         obj->EverBound = GL_TRUE;
-         *ptr = obj;
-      }
+      obj->RefCount++;
+      obj->EverBound = GL_TRUE;
+      *ptr = obj;
    }
 }