Mesa (master): vc4: Dead code eliminate unused SF instructions.
Eric Anholt
anholt at kemper.freedesktop.org
Thu Oct 9 19:50:06 UTC 2014
Module: Mesa
Branch: master
Commit: b73cab6826b54cdfa138aefb476f1f0d42b87b6a
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=b73cab6826b54cdfa138aefb476f1f0d42b87b6a
Author: Eric Anholt <eric at anholt.net>
Date: Thu Oct 9 14:45:14 2014 +0200
vc4: Dead code eliminate unused SF instructions.
---
src/gallium/drivers/vc4/vc4_opt_dead_code.c | 33 +++++++++++++++++++++------
1 file changed, 26 insertions(+), 7 deletions(-)
diff --git a/src/gallium/drivers/vc4/vc4_opt_dead_code.c b/src/gallium/drivers/vc4/vc4_opt_dead_code.c
index 9f7606f..0c273ff 100644
--- a/src/gallium/drivers/vc4/vc4_opt_dead_code.c
+++ b/src/gallium/drivers/vc4/vc4_opt_dead_code.c
@@ -33,12 +33,25 @@
#include "vc4_qir.h"
+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");
+ }
+ qir_remove_instruction(inst);
+}
+
bool
qir_opt_dead_code(struct vc4_compile *c)
{
bool progress = false;
- bool debug = false;
bool *used = calloc(c->num_temps, sizeof(bool));
+ bool sf_used = false;
struct simple_node *node, *t;
for (node = c->instructions.prev, t = node->prev;
@@ -49,16 +62,22 @@ qir_opt_dead_code(struct vc4_compile *c)
if (inst->dst.file == QFILE_TEMP &&
!used[inst->dst.index] &&
!qir_has_side_effects(inst)) {
- if (debug) {
- fprintf(stderr, "Removing: ");
- qir_dump_inst(c, inst);
- fprintf(stderr, "\n");
- }
- qir_remove_instruction(inst);
+ dce(c, inst);
progress = true;
continue;
}
+ if (qir_depends_on_flags(inst))
+ sf_used = true;
+ if (inst->op == QOP_SF) {
+ if (!sf_used) {
+ dce(c, inst);
+ progress = true;
+ continue;
+ }
+ sf_used = false;
+ }
+
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;
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