From: Eric Anholt <eric@anholt.net>
Date: Tue, 11 Dec 2018 22:07:52 +0000 (-0800)
Subject: v3d: Avoid assertion failures when removing end-of-shader instructions.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=a7e15a50866cf6bff1114d6e34ee8beab23ee7bb;p=mesa.git

v3d: Avoid assertion failures when removing end-of-shader instructions.

After generating VIR, we leave c->cursor pointing at the end of the
shader.  If the shader had dead code at the end (for example from preamble
instructions in a shader with no side effects), we would assertion fail
that we were leaving the cursor pointing at freed memory.  Since anything
following DCE should be setting up a new cursor anyway, just clear the
cursor at the start.
---

diff --git a/src/broadcom/compiler/vir_opt_dead_code.c b/src/broadcom/compiler/vir_opt_dead_code.c
index 362fc9e52a3..4aedbb6540f 100644
--- a/src/broadcom/compiler/vir_opt_dead_code.c
+++ b/src/broadcom/compiler/vir_opt_dead_code.c
@@ -101,6 +101,12 @@ vir_opt_dead_code(struct v3d_compile *c)
         bool progress = false;
         bool *used = calloc(c->num_temps, sizeof(bool));
 
+        /* Defuse the "are you removing the cursor?" assertion in the core.
+         * You'll need to set up a new cursor for any new instructions after
+         * doing DCE (which we would expect, anyway).
+         */
+        c->cursor.link = NULL;
+
         vir_for_each_inst_inorder(inst, c) {
                 for (int i = 0; i < vir_get_nsrc(inst); i++) {
                         if (inst->src[i].file == QFILE_TEMP)