Mesa (master): vc4: Add a constant folding pass.
Eric Anholt
anholt at kemper.freedesktop.org
Mon Mar 30 20:03:26 UTC 2015
Module: Mesa
Branch: master
Commit: 8c5dcdbccb68b73d2856d9c1faafadc536e682e3
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=8c5dcdbccb68b73d2856d9c1faafadc536e682e3
Author: Eric Anholt <eric at anholt.net>
Date: Mon Mar 30 10:38:21 2015 -0700
vc4: Add a constant folding pass.
This cleans up some pointless operations generated by the in-driver mul24
lowering (commonly generated by making a vec4 index for a matrix in a
uniform array).
I could fill in other operations, but pretty much anything else ought to
be getting handled at the NIR level, I think.
total uniforms in shared programs: 13423 -> 13421 (-0.01%)
uniforms in affected programs: 346 -> 344 (-0.58%)
---
src/gallium/drivers/vc4/Makefile.sources | 1 +
src/gallium/drivers/vc4/vc4_opt_constant_folding.c | 110 ++++++++++++++++++++
src/gallium/drivers/vc4/vc4_qir.c | 1 +
src/gallium/drivers/vc4/vc4_qir.h | 1 +
4 files changed, 113 insertions(+)
diff --git a/src/gallium/drivers/vc4/Makefile.sources b/src/gallium/drivers/vc4/Makefile.sources
index c7254ea..ec0f25c 100644
--- a/src/gallium/drivers/vc4/Makefile.sources
+++ b/src/gallium/drivers/vc4/Makefile.sources
@@ -12,6 +12,7 @@ C_SOURCES := \
vc4_fence.c \
vc4_formats.c \
vc4_opt_algebraic.c \
+ vc4_opt_constant_folding.c \
vc4_opt_copy_propagation.c \
vc4_opt_cse.c \
vc4_opt_dead_code.c \
diff --git a/src/gallium/drivers/vc4/vc4_opt_constant_folding.c b/src/gallium/drivers/vc4/vc4_opt_constant_folding.c
new file mode 100644
index 0000000..ac9be5c
--- /dev/null
+++ b/src/gallium/drivers/vc4/vc4_opt_constant_folding.c
@@ -0,0 +1,110 @@
+/*
+ * Copyright © 2015 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_constant_folding.c
+ *
+ * Simple constant folding pass to clean up operations on only constants,
+ * which we might have generated within vc4_program.c.
+ */
+
+#include "vc4_qir.h"
+#include "util/u_math.h"
+
+static bool debug;
+
+static void
+dump_from(struct vc4_compile *c, struct qinst *inst)
+{
+ if (!debug)
+ return;
+
+ fprintf(stderr, "optimizing: ");
+ qir_dump_inst(c, inst);
+ fprintf(stderr, "\n");
+}
+
+static void
+dump_to(struct vc4_compile *c, struct qinst *inst)
+{
+ if (!debug)
+ return;
+
+ fprintf(stderr, "to: ");
+ qir_dump_inst(c, inst);
+ fprintf(stderr, "\n");
+}
+
+static bool
+constant_fold(struct vc4_compile *c, struct qinst *inst)
+{
+ int nsrc = qir_get_op_nsrc(inst->op);
+ uint32_t ui[nsrc];
+
+ for (int i = 0; i < nsrc; i++) {
+ struct qreg reg = inst->src[i];
+ if (reg.file == QFILE_UNIF &&
+ c->uniform_contents[reg.index] == QUNIFORM_CONSTANT) {
+ ui[i] = c->uniform_data[reg.index];
+ } else if (reg.file == QFILE_SMALL_IMM) {
+ ui[i] = reg.index;
+ } else {
+ return false;
+ }
+ }
+
+ uint32_t result = 0;
+ switch (inst->op) {
+ case QOP_SHR:
+ result = ui[0] >> ui[1];
+ break;
+
+ default:
+ return false;
+ }
+
+ dump_from(c, inst);
+
+ inst->src[0] = qir_uniform_ui(c, result);
+ for (int i = 1; i < nsrc; i++)
+ inst->src[i] = c->undef;
+ inst->op = QOP_MOV;
+
+ dump_to(c, inst);
+ return true;
+}
+
+bool
+qir_opt_constant_folding(struct vc4_compile *c)
+{
+ bool progress = false;
+ struct simple_node *node;
+
+ foreach(node, &c->instructions) {
+ struct qinst *inst = (struct qinst *)node;
+ if (constant_fold(c, inst))
+ progress = true;
+ }
+
+ return progress;
+}
diff --git a/src/gallium/drivers/vc4/vc4_qir.c b/src/gallium/drivers/vc4/vc4_qir.c
index e453d84..93be98a 100644
--- a/src/gallium/drivers/vc4/vc4_qir.c
+++ b/src/gallium/drivers/vc4/vc4_qir.c
@@ -512,6 +512,7 @@ qir_optimize(struct vc4_compile *c)
OPTPASS(qir_opt_algebraic);
OPTPASS(qir_opt_cse);
+ OPTPASS(qir_opt_constant_folding);
OPTPASS(qir_opt_copy_propagation);
OPTPASS(qir_opt_dead_code);
OPTPASS(qir_opt_small_immediates);
diff --git a/src/gallium/drivers/vc4/vc4_qir.h b/src/gallium/drivers/vc4/vc4_qir.h
index 4f910e3..6cc8dbe 100644
--- a/src/gallium/drivers/vc4/vc4_qir.h
+++ b/src/gallium/drivers/vc4/vc4_qir.h
@@ -396,6 +396,7 @@ const char *qir_get_stage_name(enum qstage stage);
void qir_optimize(struct vc4_compile *c);
bool qir_opt_algebraic(struct vc4_compile *c);
+bool qir_opt_constant_folding(struct vc4_compile *c);
bool qir_opt_copy_propagation(struct vc4_compile *c);
bool qir_opt_cse(struct vc4_compile *c);
bool qir_opt_dead_code(struct vc4_compile *c);
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