[Mesa-dev] [PATCH 01/11] intel/compiler: lower 16-bit integer extended math instructions
Jason Ekstrand
jason at jlekstrand.net
Wed Apr 25 03:11:38 UTC 2018
On April 24, 2018 18:38:33 Rob Clark <robdclark at gmail.com> wrote:
On Tue, Apr 24, 2018 at 5:45 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
On Tue, Apr 24, 2018 at 7:38 AM, Rob Clark <robdclark at gmail.com> wrote:
side-note, not sure if it really effects what you are doing here, but
karol ran into some cases, like 8bit signed imax, which needs to be
"lowered" to 16b (or 32b) and converted back for hw that doesn't
support smaller than 16b (or 32b). I think I have the same case with
ir3, which also has 16b but no 8b, (but he is a bit further along cl
cts than I am)..
I think there will be more of this sort of thing coming for more
instructions and for more than just 16b vs 32b. So not sure if
writing rules for each in nir_opt_algebraic.py will be so fun..
Yeah, it may be that what we want is a generic "lower this to something with
more bits" pass. If this is a problem for the CL people, maybe we just want
some way to make it configurable and put it in core NIR. I don't really
have a huge preference. I'm just trying to make sure we explore the
solution space.
something generic/configurable in core nir seems more sane..
ofc, do what you need to do in the short term, I just mentioned this
to point out that more of this sort of "handle fewer bits in more
bits" stuff is coming down the pipe as we start seeing more 8b stuff..
if needed we can refactor..
Yeah, maybe the best thing to do then would be to just leave this as is and
plan to pull it into core NIR and generalize it when the time comes. One
idea for generalizing would be to have a callback that returns the bit size
to lower to or zero for "leave it alone".
I suspect we'll need more stuff like this for 8-bit integers and 16-bit
floats. I'll review the original for real in the morning.
--Jason
BR,
-R
--Jason
BR,
-R
On Tue, Apr 24, 2018 at 9:56 AM, Jason Ekstrand <jason at jlekstrand.net>
wrote:
It may be useful to just use nir_algebraic for this. We already do for
trig
workarounds. It's more painful from a build-system perspective but, in
general, the fewer hand-rolled algebraic lowering passes we have, the
better.
On Wed, Apr 11, 2018 at 12:20 AM, Iago Toral Quiroga <itoral at igalia.com>
wrote:
The hardware doesn't support 16-bit integer types, so we need to
implement
these using 32-bit integer instructions and then convert the result
back
to 16-bit.
---
src/intel/Makefile.sources | 1 +
src/intel/compiler/brw_nir.c | 2 +
src/intel/compiler/brw_nir.h | 2 +
src/intel/compiler/brw_nir_lower_16bit_int_math.c | 108
++++++++++++++++++++++
src/intel/compiler/meson.build | 1 +
5 files changed, 114 insertions(+)
create mode 100644 src/intel/compiler/brw_nir_lower_16bit_int_math.c
diff --git a/src/intel/Makefile.sources b/src/intel/Makefile.sources
index 91c71a8dfaf..2cd76961ea4 100644
--- a/src/intel/Makefile.sources
+++ b/src/intel/Makefile.sources
@@ -79,6 +79,7 @@ COMPILER_FILES = \
compiler/brw_nir_analyze_boolean_resolves.c \
compiler/brw_nir_analyze_ubo_ranges.c \
compiler/brw_nir_attribute_workarounds.c \
+ compiler/brw_nir_lower_16bit_int_math.c \
compiler/brw_nir_lower_cs_intrinsics.c \
compiler/brw_nir_opt_peephole_ffma.c \
compiler/brw_nir_tcs_workarounds.c \
diff --git a/src/intel/compiler/brw_nir.c
b/src/intel/compiler/brw_nir.c
index 69ab162f888..2e5754076ed 100644
--- a/src/intel/compiler/brw_nir.c
+++ b/src/intel/compiler/brw_nir.c
@@ -638,6 +638,8 @@ brw_preprocess_nir(const struct brw_compiler
*compiler, nir_shader *nir)
nir_lower_isign64 |
nir_lower_divmod64);
+ brw_nir_lower_16bit_int_math(nir);
+
nir = brw_nir_optimize(nir, compiler, is_scalar);
if (is_scalar) {
diff --git a/src/intel/compiler/brw_nir.h
b/src/intel/compiler/brw_nir.h
index 03f52da08e5..6ba1a8bc654 100644
--- a/src/intel/compiler/brw_nir.h
+++ b/src/intel/compiler/brw_nir.h
@@ -152,6 +152,8 @@ void brw_nir_analyze_ubo_ranges(const struct
brw_compiler *compiler,
bool brw_nir_opt_peephole_ffma(nir_shader *shader);
+bool brw_nir_lower_16bit_int_math(nir_shader *shader);
+
nir_shader *brw_nir_optimize(nir_shader *nir,
const struct brw_compiler *compiler,
bool is_scalar);
diff --git a/src/intel/compiler/brw_nir_lower_16bit_int_math.c
b/src/intel/compiler/brw_nir_lower_16bit_int_math.c
new file mode 100644
index 00000000000..6876309a822
--- /dev/null
+++ b/src/intel/compiler/brw_nir_lower_16bit_int_math.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * 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 "brw_nir.h"
+#include "nir_builder.h"
+
+/**
+ * Intel hardware doesn't support 16-bit integer Math instructions so
this
+ * pass implements them in 32-bit and then converts the result back to
16-bit.
+ */
+static void
+lower_math_instr(nir_builder *bld, nir_alu_instr *alu, bool is_signed)
+{
+ const nir_op op = alu->op;
+
+ bld->cursor = nir_before_instr(&alu->instr);
+
+ nir_ssa_def *srcs_32[4] = { NULL, NULL, NULL, NULL };
+ const uint32_t num_inputs = nir_op_infos[op].num_inputs;
+ for (uint32_t i = 0; i < num_inputs; i++) {
+ nir_ssa_def *src = nir_ssa_for_alu_src(bld, alu, i);
+ srcs_32[i] = is_signed ? nir_i2i32(bld, src) : nir_u2u32(bld,
src);
+ }
+
+ nir_ssa_def *dst_32 =
+ nir_build_alu(bld, op, srcs_32[0], srcs_32[1], srcs_32[2],
srcs_32[3]);
+
+ nir_ssa_def *dst_16 =
+ is_signed ? nir_i2i16(bld, dst_32) : nir_u2u16(bld, dst_32);
+
+ nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa,
nir_src_for_ssa(dst_16));
+}
+
+static bool
+lower_instr(nir_builder *bld, nir_alu_instr *alu)
+{
+ assert(alu->dest.dest.is_ssa);
+ if (alu->dest.dest.ssa.bit_size != 16)
+ return false;
+
+ bool is_signed = false;
+ switch (alu->op) {
+ case nir_op_idiv:
+ case nir_op_imod:
+ is_signed = true;
You can get is_signed from nit_op_infos
+ /* Fallthrough */
+ case nir_op_udiv:
+ case nir_op_umod:
+ case nir_op_irem:
How is irem unsigned?
+ lower_math_instr(bld, alu, is_signed);
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool
+lower_impl(nir_function_impl *impl)
+{
+ nir_builder b;
+ nir_builder_init(&b, impl);
+ bool progress = false;
+
+ nir_foreach_block(block, impl) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type == nir_instr_type_alu)
+ progress |= lower_instr(&b, nir_instr_as_alu(instr));
+ }
+ }
+
+ nir_metadata_preserve(impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+
+ return progress;
+}
+
+bool
+brw_nir_lower_16bit_int_math(nir_shader *shader)
+{
+ bool progress = false;
+
+ nir_foreach_function(function, shader) {
+ if (function->impl)
+ progress |= lower_impl(function->impl);
+ }
+
+ return progress;
+}
diff --git a/src/intel/compiler/meson.build
b/src/intel/compiler/meson.build
index 72b7a6796cb..d80fcd6e31b 100644
--- a/src/intel/compiler/meson.build
+++ b/src/intel/compiler/meson.build
@@ -76,6 +76,7 @@ libintel_compiler_files = files(
'brw_nir_analyze_boolean_resolves.c',
'brw_nir_analyze_ubo_ranges.c',
'brw_nir_attribute_workarounds.c',
+ 'brw_nir_lower_16bit_int_math.c',
'brw_nir_lower_cs_intrinsics.c',
'brw_nir_opt_peephole_ffma.c',
'brw_nir_tcs_workarounds.c',
--
2.14.1
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