[Mesa-dev] [PATCH 1/2] i965/fs: Don't use backend_visitor::instructions after creating the CFG.

[Matt Turner]

This is a fix for a regression introduced in commit a9f8296d ("i965/fs:
Preserve the CFG in a few more places.").

The errata this code works around is described in a comment before the function:

   "[DevBW, DevCL] Errata: A destination register from a send can not be
    used as a destination register until after it has been sourced by an
    instruction with a different destination register.

The framebuffer write's sources must be in message registers, which SEND
instructions cannot have as a destination. There's no way for this
errata to affect anything at the end of the program. Just remove the
code.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84613
---
Untested on real hardware.

 src/mesa/drivers/dri/i965/brw_fs.cpp | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 9dfb7b7..3f9cd68 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -2925,16 +2925,6 @@ fs_visitor::insert_gen4_post_send_dependency_workarounds(bblock_t *block, fs_ins
       if (i == write_len)
          return;
    }
-
-   /* If we hit the end of the program, resolve all remaining dependencies out
-    * of paranoia.
-    */
-   fs_inst *last_inst = (fs_inst *)this->instructions.get_tail();
-   assert(last_inst->eot);
-   for (int i = 0; i < write_len; i++) {
-      if (needs_dep[i])
-         last_inst->insert_before(block, DEP_RESOLVE_MOV(first_write_grf + i));
-   }
 }
 
 void
-- 
2.0.4