Mesa (master): i965/fs: fix FS_OPCODE_CINTERP for unpacked double input varyings

[Samuel Iglesias Gonsálvez]

Module: Mesa
Branch: master
Commit: cb30727648fea301cfff1647d947bfab540c3bf6
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=cb30727648fea301cfff1647d947bfab540c3bf6

Author: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Date:   Thu May 26 07:56:38 2016 +0200

i965/fs: fix FS_OPCODE_CINTERP for unpacked double input varyings

Data starts at suboffet 3 in 32-bit units (12 bytes), so it is not
64-bit aligned and the current implementation fails to read the data
properly. Instead, when there is is a double input varying, read it as
vector of floats with twice the number of components.

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Reviewed-by: Timothy Arceri <timothy.arceri at collabora.com>
Cc: "12.0" <mesa-stable at lists.freedesktop.org>

---

 src/mesa/drivers/dri/i965/brw_fs.cpp | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 366d9ff..4b29ee5 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1189,7 +1189,18 @@ fs_visitor::emit_general_interpolation(fs_reg *attr, const char *name,
           * handed us defined values in only the constant offset
           * field of the setup reg.
           */
-         for (unsigned int i = 0; i < type->vector_elements; i++) {
+         unsigned vector_elements = type->vector_elements;
+
+         /* Data starts at suboffet 3 in 32-bit units (12 bytes), so it is not
+          * 64-bit aligned and the current implementation fails to read the
+          * data properly. Instead, when there is is a double input varying,
+          * read it as vector of floats with twice the number of components.
+          */
+         if (attr->type == BRW_REGISTER_TYPE_DF) {
+            vector_elements *= 2;
+            attr->type = BRW_REGISTER_TYPE_F;
+         }
+         for (unsigned int i = 0; i < vector_elements; i++) {
             struct brw_reg interp = interp_reg(*location, i);
             interp = suboffset(interp, 3);
             interp.type = attr->type;