Mesa (master): glsl: count atomic counters correctly

[Andres Gomez]

Module: Mesa
Branch: master
Commit: 0f00c6dd7773241b31031f5f77b0e0841a9a9488
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=0f00c6dd7773241b31031f5f77b0e0841a9a9488

Author: Andres Gomez <agomez at igalia.com>
Date:   Thu Jun 30 16:37:11 2016 +0300

glsl: count atomic counters correctly

Currently the linker uses the uniform count for the total number of
atomic counters. However uniforms don't include the innermost array
dimension in their count, but atomic counters are expected to include
them.

Although the spec doesn't directly state this, it's clear how offsets
will be assigned for arrays.

>From OpenGL 4.2 (Core Profile), page 98:

  "  * Arrays of type atomic_uint are stored in memory by element
       order, with array element member zero at the lowest offset. The
       difference in offsets between each pair of elements in the
       array in basic machine units is referred to as the array
       stride, and is constant across the entire array. The stride can
       be queried by calling GetIntegerv with a pname of
       ATOMIC_COUNTER_- ARRAY_STRIDE after a program is linked."

>From that it is clear how arrays of atomic counters will interact with
GL_MAX_ATOMIC_COUNTER_BUFFER_SIZE.

For other kinds of uniforms it's also clear that each entry in an
array counts against the relevant limits.

Hence, although inferred, this is the expected behavior.

Fixes GL44-CTS.arrays_of_arrays_gl.AtomicDeclaration

Reviewed-by: Timothy Arceri <timothy.arceri at collabora.com>
Signed-off-by: Andres Gomez <agomez at igalia.com>

---

 src/compiler/glsl/link_atomics.cpp | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/compiler/glsl/link_atomics.cpp b/src/compiler/glsl/link_atomics.cpp
index fa845e9..05e18db 100644
--- a/src/compiler/glsl/link_atomics.cpp
+++ b/src/compiler/glsl/link_atomics.cpp
@@ -103,9 +103,9 @@ namespace {
                            const unsigned shader_stage)
    {
       /* FIXME: Arrays of arrays get counted separately. For example:
-       * x1[3][3][2] = 9 counters
-       * x2[3][2]    = 3 counters
-       * x3[2]       = 1 counter
+       * x1[3][3][2] = 9 uniforms, 18 atomic counters
+       * x2[3][2]    = 3 uniforms, 6 atomic counters
+       * x3[2]       = 1 uniform, 2 atomic counters
        *
        * However this code marks all the counters as active even when they
        * might not be used.
@@ -129,7 +129,13 @@ namespace {
 
          buf->push_back(*uniform_loc, var);
 
-         buf->stage_references[shader_stage]++;
+         /* When checking for atomic counters we should count every member in
+          * an array as an atomic counter reference.
+          */
+         if (t->is_array())
+            buf->stage_references[shader_stage] += t->length;
+         else
+            buf->stage_references[shader_stage]++;
          buf->size = MAX2(buf->size, *offset + t->atomic_size());
 
          storage->offset = *offset;