+static bool debug;
+
+static void
+dce(struct vc4_compile *c, struct qinst *inst)
+{
+ if (debug) {
+ fprintf(stderr, "Removing: ");
+ qir_dump_inst(c, inst);
+ fprintf(stderr, "\n");
+ }
+ assert(!inst->sf);
+ qir_remove_instruction(c, inst);
+}
+
+static bool
+has_nonremovable_reads(struct vc4_compile *c, struct qinst *inst)
+{
+ for (int i = 0; i < qir_get_op_nsrc(inst->op); i++) {
+ if (inst->src[i].file == QFILE_VPM) {
+ uint32_t attr = inst->src[i].index / 4;
+ uint32_t offset = (inst->src[i].index % 4) * 4;
+
+ if (c->vattr_sizes[attr] != offset + 4)
+ return true;
+
+ /* Can't get rid of the last VPM read, or the
+ * simulator (at least) throws an error.
+ */
+ uint32_t total_size = 0;
+ for (uint32_t i = 0; i < ARRAY_SIZE(c->vattr_sizes); i++)
+ total_size += c->vattr_sizes[i];
+ if (total_size == 4)
+ return true;
+ }
+
+ if (inst->src[i].file == QFILE_VARY &&
+ c->input_slots[inst->src[i].index].slot == 0xff) {
+ return true;
+ }
+ }
+
+ return false;
+}
+