[Mesa-dev] [PATCH 5/5] nir: Add nir_lower_alu_scalar.
Eric Anholt
eric at anholt.net
Wed Jan 21 17:26:01 PST 2015
This is the equivalent of brw_fs_channel_expressions.cpp, which I wanted
for vc4.
---
This series, plus a commit to make i965 use it instead of channel_expressions,
is on the nir-scalarize branch of my mesa tree. With the whole series, there
are 6 regressions, 3 of which are due to lower-vec-to-movs being broken when
faced with "r0 = vec4 r0.yxxx, r0.xxxx, r0.zxxx, r0.wxxx" (fs-swap-problem
test, for example). The other 3 are sampler-nonconst-2d-array and friends,
which I haven't figured out yet.
Full disclosure: I did a cleanup to use nir_alu_ssa_dest_init() more and
haven't repiglited since then.
The full i965 conversion has the following shader-db results for me,
presumably because of losing GLSL-IR-level optimizations due to not splitting
expressions in GLSL IR:
total instructions in shared programs: 137974 -> 139306 (0.97%)
instructions in affected programs: 55959 -> 57291 (2.38%)
src/glsl/Makefile.sources | 1 +
src/glsl/nir/nir.h | 1 +
src/glsl/nir/nir_lower_alu_scalar.c | 287 ++++++++++++++++++++++++++++++++++++
3 files changed, 289 insertions(+)
create mode 100644 src/glsl/nir/nir_lower_alu_scalar.c
diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
index 6237627..9cd1a6a 100644
--- a/src/glsl/Makefile.sources
+++ b/src/glsl/Makefile.sources
@@ -24,6 +24,7 @@ NIR_FILES = \
$(GLSL_SRCDIR)/nir/nir_intrinsics.c \
$(GLSL_SRCDIR)/nir/nir_intrinsics.h \
$(GLSL_SRCDIR)/nir/nir_live_variables.c \
+ $(GLSL_SRCDIR)/nir/nir_lower_alu_scalar.c \
$(GLSL_SRCDIR)/nir/nir_lower_atomics.c \
$(GLSL_SRCDIR)/nir/nir_lower_global_vars_to_local.c \
$(GLSL_SRCDIR)/nir/nir_lower_locals_to_regs.c \
diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
index 7f0aa36..fb42d91 100644
--- a/src/glsl/nir/nir.h
+++ b/src/glsl/nir/nir.h
@@ -1521,6 +1521,7 @@ void nir_lower_vars_to_ssa(nir_shader *shader);
void nir_remove_dead_variables(nir_shader *shader);
void nir_lower_vec_to_movs(nir_shader *shader);
+void nir_lower_ops_scalar(nir_shader *shader);
void nir_lower_samplers(nir_shader *shader,
struct gl_shader_program *shader_program,
diff --git a/src/glsl/nir/nir_lower_alu_scalar.c b/src/glsl/nir/nir_lower_alu_scalar.c
new file mode 100644
index 0000000..e13ad1e
--- /dev/null
+++ b/src/glsl/nir/nir_lower_alu_scalar.c
@@ -0,0 +1,287 @@
+/*
+ * Copyright © 2014-2015 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.
+ */
+
+#include "nir.h"
+
+/** @file nir_lower_alu_scalar.c
+ *
+ * Replaces nir_alu_instr operations with more than one channel used in the
+ * arguments with individual per-channel operations.
+ */
+
+static void
+unsupported(nir_instr *instr)
+{
+ fprintf(stderr, "Unsupported instruction in scalar lowering: ");
+ nir_print_instr(instr, stderr);
+ fprintf(stderr, "\n");
+ abort();
+}
+
+static void
+nir_alu_ssa_dest_init(nir_alu_instr *instr, unsigned num_components)
+{
+ nir_ssa_dest_init(&instr->instr, &instr->dest.dest, num_components, NULL);
+ instr->dest.write_mask = (1 << num_components) - 1;
+}
+
+static void
+reduce_op_replace(nir_alu_instr *instr, nir_ssa_def *def, void *mem_ctx)
+{
+ assert(instr->dest.write_mask == 1);
+
+ if (instr->dest.dest.is_ssa) {
+ nir_src new_src;
+ new_src.is_ssa = true;
+ new_src.ssa = def;
+ nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, new_src, mem_ctx);
+ } else {
+ nir_alu_instr *mov = nir_alu_instr_create(mem_ctx, nir_op_imov);
+ mov->src[0].src.is_ssa = true;
+ mov->src[0].src.ssa = def;
+
+ nir_alu_dest_copy(&mov->dest, &instr->dest, mem_ctx);
+ nir_instr_insert_after(&instr->instr, &mov->instr);
+ }
+
+ nir_instr_remove(&instr->instr);
+}
+
+static void
+lower_reduction(nir_alu_instr *instr, nir_op chan_op, nir_op merge_op,
+ void *mem_ctx)
+{
+ unsigned num_components = nir_op_infos[instr->op].input_sizes[0];
+
+ nir_ssa_def *last = NULL;
+ for (unsigned i = 0; i < num_components; i++) {
+ nir_alu_instr *chan = nir_alu_instr_create(mem_ctx, chan_op);
+ nir_alu_ssa_dest_init(chan, 1);
+ nir_alu_src_copy(&chan->src[0], &instr->src[0], mem_ctx);
+ chan->src[0].swizzle[0] = chan->src[0].swizzle[i];
+ if (nir_op_infos[chan_op].num_inputs > 1) {
+ nir_alu_src_copy(&chan->src[1], &instr->src[1], mem_ctx);
+ chan->src[1].swizzle[0] = chan->src[1].swizzle[i];
+ }
+
+ nir_instr_insert_before(&instr->instr, &chan->instr);
+
+ if (i == 0) {
+ last = &chan->dest.dest.ssa;
+ } else {
+ nir_alu_instr *merge = nir_alu_instr_create(mem_ctx, merge_op);
+ nir_alu_ssa_dest_init(merge, 1);
+ merge->dest.write_mask = 1;
+ merge->src[0].src.is_ssa = true;
+ merge->src[0].src.ssa = last;
+ merge->src[1].src.is_ssa = true;
+ merge->src[1].src.ssa = &chan->dest.dest.ssa;
+ nir_instr_insert_before(&instr->instr, &merge->instr);
+ last = &merge->dest.dest.ssa;
+ }
+ }
+
+ reduce_op_replace(instr, last, mem_ctx);
+}
+
+static void
+lower_alu_instr_scalar(nir_function_impl *impl, nir_alu_instr *instr,
+ void *mem_ctx)
+{
+ unsigned unmodified_chan; /* original instr will still write this channel */
+ if (instr->dest.dest.is_ssa)
+ unmodified_chan = 0;
+ else
+ unmodified_chan = 1 << (ffs(instr->dest.write_mask) - 1);
+ unsigned lower_chans = instr->dest.write_mask & ~unmodified_chan;
+ unsigned num_src = nir_op_infos[instr->op].num_inputs;
+ nir_alu_src src[num_src][4];
+ unsigned i, chan;
+
+ assert(instr->dest.write_mask != 0);
+
+#define LOWER_REDUCTION(name, chan, merge) \
+ case name##2: \
+ case name##3: \
+ case name##4: \
+ lower_reduction(instr, chan, merge, mem_ctx); \
+ break;
+
+ switch (instr->op) {
+ case nir_op_vec4:
+ case nir_op_vec3:
+ case nir_op_vec2:
+ /* We don't need to scalarize these ops, they're the ones generated to
+ * group up outputs into a value that can be SSAed.
+ */
+ return;
+
+ LOWER_REDUCTION(nir_op_fdot, nir_op_fmul, nir_op_fadd);
+ LOWER_REDUCTION(nir_op_ball_fequal, nir_op_feq, nir_op_iand);
+ LOWER_REDUCTION(nir_op_ball_iequal, nir_op_ieq, nir_op_iand);
+ LOWER_REDUCTION(nir_op_bany_fnequal, nir_op_fne, nir_op_ior);
+ LOWER_REDUCTION(nir_op_bany_inequal, nir_op_ine, nir_op_ior);
+ LOWER_REDUCTION(nir_op_fall_equal, nir_op_seq, nir_op_fand);
+ LOWER_REDUCTION(nir_op_fany_nequal, nir_op_sne, nir_op_for);
+ LOWER_REDUCTION(nir_op_ball, nir_op_imov, nir_op_iand);
+ LOWER_REDUCTION(nir_op_bany, nir_op_imov, nir_op_ior);
+ LOWER_REDUCTION(nir_op_fall, nir_op_fmov, nir_op_fand);
+ LOWER_REDUCTION(nir_op_fany, nir_op_fmov, nir_op_for);
+
+ default:
+ break;
+ }
+
+ if (lower_chans == 0 || (instr->dest.dest.is_ssa &&
+ instr->dest.dest.ssa.num_components == 1)) {
+ return;
+ }
+
+ for (i = 0; i < num_src; i++) {
+ bool aliased = (!instr->dest.dest.is_ssa &&
+ !instr->src[i].src.is_ssa &&
+ instr->src[i].src.reg.reg == instr->dest.dest.reg.reg);
+
+ for (unsigned chan = 0; chan < 4; chan++) {
+
+ src[i][chan] = instr->src[i];
+ src[i][chan].swizzle[0] = instr->src[i].swizzle[chan];
+
+ /* Unalias src registers from the destination. */
+ if (aliased) {
+ nir_alu_instr *mov = nir_alu_instr_create(mem_ctx, nir_op_imov);
+ mov->src[0] = src[i][chan];
+ mov->src[0].abs = false;
+ mov->src[0].negate = false;
+ nir_alu_ssa_dest_init(mov, 1);
+
+ nir_instr_insert_before(&instr->instr, &mov->instr);
+
+ src[i][chan].src.is_ssa = true;
+ src[i][chan].src.ssa = &mov->dest.dest.ssa;
+ src[i][chan].swizzle[0] = 0;
+ }
+ }
+ }
+
+ nir_alu_instr *vec_instr = NULL;
+ if (instr->dest.dest.is_ssa) {
+ unsigned num_components = instr->dest.dest.ssa.num_components;
+ static const nir_op nir_op_map[] = {nir_op_vec2, nir_op_vec3, nir_op_vec4};
+ if (num_components < 2)
+ unsupported(&instr->instr);
+ vec_instr = nir_alu_instr_create(mem_ctx, nir_op_map[num_components - 2]);
+ nir_alu_ssa_dest_init(vec_instr, num_components);
+ }
+
+ /* Walk from the end of the channels, so our incremental inserts after the
+ * original instruction end up in a sensible xyzw order.
+ */
+ for (chan = 0; chan < 4; chan++) {
+ if (!(lower_chans & (1 << chan))) {
+ if (instr->dest.dest.is_ssa &&
+ chan < instr->dest.dest.ssa.num_components) {
+ unsupported(&instr->instr);
+ }
+ continue;
+ }
+
+ nir_alu_instr *lower = nir_alu_instr_create(mem_ctx, instr->op);
+ for (i = 0; i < num_src; i++) {
+ /* bcsel and fcsel reuse the same src channel in src[0]. */
+ unsigned src_chan = (nir_op_infos[instr->op].input_sizes[i] == 1 ?
+ 0 : chan);
+
+ lower->src[i].src = nir_src_copy(src[i][src_chan].src, mem_ctx);
+ for (int j = 0; j < 4; j++)
+ lower->src[i].swizzle[j] = src[i][src_chan].swizzle[0];
+ lower->src[i].abs = src[i][src_chan].abs;
+ lower->src[i].negate = src[i][src_chan].negate;
+ }
+
+ if (instr->dest.dest.is_ssa) {
+ nir_alu_ssa_dest_init(lower, 1);
+ vec_instr->src[chan].src.is_ssa = true;
+ vec_instr->src[chan].src.ssa = &lower->dest.dest.ssa;
+ } else {
+ lower->dest.dest.reg.reg = instr->dest.dest.reg.reg;
+ lower->dest.write_mask = 1 << chan;
+ }
+ lower->dest.saturate = instr->dest.saturate;
+
+ nir_instr_insert_before(&instr->instr, &lower->instr);
+ }
+
+ if (instr->dest.dest.is_ssa) {
+ nir_instr_insert_after(&instr->instr, &vec_instr->instr);
+
+ nir_src new_src;
+ new_src.is_ssa = true;
+ new_src.ssa = &vec_instr->dest.dest.ssa;
+ nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, new_src, mem_ctx);
+
+ nir_instr_remove(&instr->instr);
+ } else {
+ instr->dest.write_mask = unmodified_chan;
+ }
+}
+
+struct lower_context {
+ void *mem_ctx;
+ nir_function_impl *impl;
+};
+
+static bool
+lower_ops_scalar_block(nir_block *block, void *data)
+{
+ struct lower_context *lower_context = data;
+
+ nir_foreach_instr_safe(block, instr) {
+ if (instr->type == nir_instr_type_alu)
+ lower_alu_instr_scalar(lower_context->impl,
+ (nir_alu_instr *)instr,
+ lower_context->mem_ctx);
+ }
+
+ return true;
+}
+
+static void
+nir_lower_ops_scalar_impl(nir_function_impl *impl)
+{
+ struct lower_context lower_context;
+
+ lower_context.mem_ctx = ralloc_parent(impl);
+ lower_context.impl = impl;
+
+ nir_foreach_block(impl, lower_ops_scalar_block, &lower_context);
+}
+
+void
+nir_lower_ops_scalar(nir_shader *shader)
+{
+ nir_foreach_overload(shader, overload) {
+ if (overload->impl)
+ nir_lower_ops_scalar_impl(overload->impl);
+ }
+}
--
2.1.3
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