[Mesa-dev] [PATCH V2] i965: enable STD430 packing by default on IVB+

[Timothy Arceri]

v2: Add full description of the SNB issue to the TODO.
---
 src/mesa/drivers/dri/i965/brw_context.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index d97a24fbf8..11cb2f7226 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -668,20 +668,32 @@ brw_initialize_context_constants(struct brw_context *brw)
       ctx->Const.MaxVertexStreams = MIN2(4, MAX_VERTEX_STREAMS);
 
    /* ARB_framebuffer_no_attachments */
    ctx->Const.MaxFramebufferWidth = 16384;
    ctx->Const.MaxFramebufferHeight = 16384;
    ctx->Const.MaxFramebufferLayers = ctx->Const.MaxArrayTextureLayers;
    ctx->Const.MaxFramebufferSamples = max_samples;
 
    /* OES_primitive_bounding_box */
    ctx->Const.NoPrimitiveBoundingBoxOutput = true;
+
+   /* TODO: We should be able to use STD430 packing by default on all hardware
+    * but some piglit tests e.g. [1] currently fail on SNB when this is
+    * enabled. The problem is the messages we're using for doing uniform pulls
+    * in the vec4 back-end on SNB is the OWORD block load instruction, which
+    * takes its offset in units of OWORDS (16 bytes).  On IVB+, we use the
+    * sampler which doesn't have these restrictions.
+    *
+    * [1] glsl-1.40/uniform_buffer/vs-float-array-variable-index.shader_test
+    */
+   if (brw->gen >= 7)
+      ctx->Const.UseSTD430AsDefaultPacking = true;
 }
 
 static void
 brw_initialize_cs_context_constants(struct brw_context *brw)
 {
    struct gl_context *ctx = &brw->ctx;
    const struct intel_screen *screen = brw->screen;
    struct gen_device_info *devinfo = &brw->screen->devinfo;
 
    /* FINISHME: Do this for all platforms that the kernel supports */
-- 
2.13.4