--- /dev/null
+/*
+ * Copyright © 2014 Broadcom
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/**
+ * @file vc4_opt_dead_code.c
+ *
+ * This is a simmple dead code eliminator for QIR with no control flow.
+ *
+ * It walks from the bottom of the instruction list, removing instructions
+ * with a destination that is never used, and marking the sources of non-dead
+ * instructions as used.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "vc4_qir.h"
+
+bool
+qir_opt_dead_code(struct qcompile *c)
+{
+ bool progress = false;
+ bool debug = false;
+ bool *used = calloc(c->num_temps, sizeof(bool));
+
+ struct simple_node *node, *t;
+ for (node = c->instructions.prev, t = node->prev;
+ &c->instructions != node;
+ node = t, t = t->prev) {
+ struct qinst *inst = (struct qinst *)node;
+
+ if (inst->dst.file == QFILE_TEMP &&
+ !used[inst->dst.index] &&
+ !qir_has_side_effects(inst)) {
+ if (debug) {
+ fprintf(stderr, "Removing: ");
+ qir_dump_inst(inst);
+ fprintf(stderr, "\n");
+ }
+ remove_from_list(&inst->link);
+ free(inst);
+ progress = true;
+ continue;
+ }
+
+ for (int i = 0; i < qir_get_op_nsrc(inst->op); i++) {
+ if (inst->src[i].file == QFILE_TEMP)
+ used[inst->src[i].index] = true;
+ }
+ }
+
+ free(used);
+
+ return progress;
+}
struct qir_op_info {
const char *name;
uint8_t ndst, nsrc;
+ bool has_side_effects;
};
static const struct qir_op_info qir_op_info[] = {
[QOP_LOG2] = { "log2", 1, 2 },
[QOP_PACK_COLORS] = { "pack_colors", 1, 4 },
[QOP_PACK_SCALED] = { "pack_scaled", 1, 2 },
- [QOP_VPM_WRITE] = { "vpm_write", 0, 1 },
- [QOP_VPM_READ] = { "vpm_read", 0, 1 },
- [QOP_TLB_COLOR_WRITE] = { "tlb_color", 0, 1 },
+ [QOP_VPM_WRITE] = { "vpm_write", 0, 1, true },
+ [QOP_VPM_READ] = { "vpm_read", 0, 1, true },
+ [QOP_TLB_COLOR_WRITE] = { "tlb_color", 0, 1, true },
[QOP_VARY_ADD_C] = { "vary_add_c", 1, 1 },
};
abort();
}
+bool
+qir_has_side_effects(struct qinst *inst)
+{
+ for (int i = 0; i < qir_get_op_nsrc(inst->op); i++) {
+ if (inst->src[i].file == QFILE_VARY ||
+ inst->src[i].file == QFILE_UNIF)
+ return true;
+ }
+
+ return qir_op_info[inst->op].has_side_effects;
+}
+
static void
qir_print_reg(struct qreg reg)
{
bool progress = false;
OPTPASS(qir_opt_algebraic);
+ OPTPASS(qir_opt_dead_code);
if (!progress)
break;
struct qreg qir_get_temp(struct qcompile *c);
int qir_get_op_nsrc(enum qop qop);
bool qir_reg_equals(struct qreg a, struct qreg b);
+bool qir_has_side_effects(struct qinst *inst);
void qir_dump(struct qcompile *c);
void qir_dump_inst(struct qinst *inst);
void qir_optimize(struct qcompile *c);
bool qir_opt_algebraic(struct qcompile *c);
+bool qir_opt_dead_code(struct qcompile *c);
#define QIR_ALU1(name) \
static inline struct qreg \
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