[Mesa-dev] [PATCH 3/5] i965/fs: Mark last used ip for all regs read in the payload

Connor Abbott cwabbott0 at gmail.com
Wed Jul 1 11:51:37 PDT 2015

From: Jordan Justen <jordan.l.justen at intel.com>

If a source register in the push constant registers uses more than on
register, then we wouldn't update payload_last_use_ip for subsequent

Unlike most uniform data pushed into registers, the CS gl_LocalInvocationID
data varies per execution channel. Therefore for SIMD16 mode, we have vec16
data in the payload. In this case we then need to mark 2 registers in
payload_last_use_ip as last used by the instruction. There's a similar
situation for the z and w coordinates of gl_FragCoord for fragment shaders,
where it had only happened to work before because of some bogus interferences
which the next commit removes.

(Connor: added bit about gl_FragCoord to commit message)

Reviewed-by: Connor Abbott <connor.w.abbott at intel.com>
Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
 src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp b/src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp
index 8e5621d..620fc23 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp
@@ -380,7 +380,10 @@ fs_visitor::setup_payload_interference(struct ra_graph *g,
             if (node_nr >= payload_node_count)
-            payload_last_use_ip[node_nr] = use_ip;
+            for (int j = 0; j < inst->regs_read(i); j++) {
+               payload_last_use_ip[node_nr + j] = use_ip;
+               assert(node_nr + j < payload_node_count);
+            }

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