Geometry shaders that run in "DUAL_INSTANCED" mode store their inputs
in vec4's. This means that when compiling gl_PointSize input
swizzling (a MOV instruction which uses a geometry shader input as
both source and destination), we need to do two things:
- Set force_writemask_all to ensure that the MOV happens regardless of
which channels are enabled.
- Set the source register region to <4;4,1> (instead of <0;4,1> to
satisfy register region restrictions.
---
src/mesa/drivers/dri/i965/brw_vec4_generator.cpp | 17 ++++++++++++++++-
src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp | 8 +++++++-
2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
b/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
index 1b597b5..700da54 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
@@ -858,7 +858,22 @@ vec4_generator::generate_vec4_instruction(vec4_instruction
*instruction,
switch (inst->opcode) {
case BRW_OPCODE_MOV:
- brw_MOV(p, dst, src[0]);
+ if (dst.width == BRW_WIDTH_4) {
+ /* This happens in attribute fixups for "dual instanced" geometry
+ * shaders, since they use attributes that are vec4's. Since the
+ * exec width is only 4, it's essential that the caller set
+ * force_writemask_all in order to make sure the MOV happens
+ * regardless of which channels are enabled.
+ */
+ assert(inst->force_writemask_all);
+
+ /* To satisfy register region restrictions, the source needs a stride
+ * of <4;4,1>.
+ */
+ brw_MOV(p, dst, stride(src[0], 4, 4, 1));
+ } else {
+ brw_MOV(p, dst, src[0]);
+ }
break;
case BRW_OPCODE_ADD:
brw_ADD(p, dst, src[0], src[1]);
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
index 2be2666..5b823c4 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
@@ -210,7 +210,13 @@ vec4_gs_visitor::emit_prolog()
src_reg src(dst);
dst.writemask = WRITEMASK_X;
src.swizzle = BRW_SWIZZLE_WWWW;
- emit(MOV(dst, src));
+ inst = emit(MOV(dst, src));
+
+ /* In dual instanced dispatch mode, dst has a width of 4, so we need
+ * to make sure the MOV happens regardless of which channels are
+ * enabled.
+ */
+ inst->force_writemask_all = true;
}
}
--
1.8.4.1
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