From: Eric Anholt <eric@anholt.net>
Date: Fri, 12 Jan 2018 23:35:04 +0000 (-0800)
Subject: broadcom/vc5: Use MSF to ignore discards/non-dispatched channels in loops.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=5bc0b63799dd23c7c1d150e83770d79bdca00a62;p=mesa.git

broadcom/vc5: Use MSF to ignore discards/non-dispatched channels in loops.

Prevents potential infinite loops when a non-dispatched or discarded
channel never triggers the loop break condition.
---

diff --git a/src/broadcom/compiler/nir_to_vir.c b/src/broadcom/compiler/nir_to_vir.c
index bc18b19f802..68e86f3a1c2 100644
--- a/src/broadcom/compiler/nir_to_vir.c
+++ b/src/broadcom/compiler/nir_to_vir.c
@@ -1780,7 +1780,11 @@ ntq_emit_loop(struct v3d_compile *c, nir_loop *loop)
 
         vir_PF(c, c->execute, V3D_QPU_PF_PUSHZ);
 
-        vir_BRANCH(c, V3D_QPU_BRANCH_COND_ANYA);
+        struct qinst *branch = vir_BRANCH(c, V3D_QPU_BRANCH_COND_ANYA);
+        /* Pixels that were not dispatched or have been discarded should not
+         * contribute to looping again.
+         */
+        branch->qpu.branch.msfign = V3D_QPU_MSFIGN_P;
         vir_link_blocks(c->cur_block, c->loop_cont_block);
         vir_link_blocks(c->cur_block, c->loop_break_block);