nir: implement lowering for fsin and fcos

Lower sin and cos using Nick's fast sin/cos approximation from
https://web.archive.org/web/20180105155939/http://forum.devmaster.net/t/fast-and-accurate-sine-cosine/9648

It's suitable for GLES2, but it throws warnings in dEQP GLES3 precision tests.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Qiang Yu <yuq825@gmail.com>
Tested-by: Qiang Yu <yuq825@gmail.com>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>

diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index c223e17fa136cb891502bae240d4bf7a3b15bc09..1b6dc25f1edb7cdba1b591bde6a10259a5f430a2 100644 (file)
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -269,6 +269,7 @@ NIR_FILES = \
        nir/nir_lower_regs_to_ssa.c \
        nir/nir_lower_returns.c \
        nir/nir_lower_scratch.c \
+       nir/nir_lower_sincos.c \
        nir/nir_lower_subgroups.c \
        nir/nir_lower_system_values.c \
        nir/nir_lower_tex.c \

diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build
index 505a322caa5e13370219168ab2d07921ae1f2707..69de4121a73dea2f1a6a63cfa659a62a5090131b 100644 (file)
--- a/src/compiler/nir/meson.build
+++ b/src/compiler/nir/meson.build
@@ -150,6 +150,7 @@ files_libnir = files(
   'nir_lower_returns.c',
   'nir_lower_scratch.c',
   'nir_lower_subgroups.c',
+  'nir_lower_sincos.c',
   'nir_lower_system_values.c',
   'nir_lower_tex.c',
   'nir_lower_to_source_mods.c',

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 7de5b51aae755ba84611d94b5542c9dd3527f2e8..301cc76e401474cb5fc8486b646daa387c291e21 100644 (file)
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -3554,6 +3554,8 @@ uint64_t nir_get_single_slot_attribs_mask(uint64_t attribs, uint64_t dual_slot);
 nir_intrinsic_op nir_intrinsic_from_system_value(gl_system_value val);
 gl_system_value nir_system_value_from_intrinsic(nir_intrinsic_op intrin);
 
+bool nir_lower_sincos(nir_shader *shader);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif

diff --git a/src/compiler/nir/nir_lower_sincos.c b/src/compiler/nir/nir_lower_sincos.c
new file mode 100644 (file)
index 0000000..37aa97b
--- /dev/null
+++ b/src/compiler/nir/nir_lower_sincos.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2014 Scott Mansell
+ * Copyright © 2014 Broadcom
+ * Copyright (c) 2019 Vasily Khoruzhick <anarsoul@gmail.com>
+ *
+ * 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 "util/u_math.h"
+#include "nir.h"
+#include "nir_builder.h"
+
+static nir_ssa_def *
+shrink_input(nir_builder *b, nir_ssa_def *x)
+{
+   nir_ssa_def *scaled_x = nir_fmul_imm(b, x, 1.0 / (M_PI * 2));
+
+   nir_ssa_def *xfrac = nir_ffract(b, scaled_x);
+   /* Map [0.5, 1] to [-0.5, 0] */
+   nir_ssa_def *xfrac_0_5_1 = nir_fadd_imm(b, xfrac, -1.0);
+   /* Map [-1, -0.5] to [0, 0.5] */
+   nir_ssa_def *xfrac_n1_n0_5 = nir_fadd_imm(b, xfrac, 1.0);
+
+   nir_ssa_def *geq_0_5 = nir_build_alu(b, nir_op_fge, xfrac, nir_imm_float(b, 0.5), NULL, NULL);
+   nir_ssa_def *less_m0_5 = nir_build_alu(b, nir_op_flt, xfrac, nir_imm_float(b, -0.5), NULL, NULL);
+
+   nir_ssa_def *sel1 = nir_build_alu(b, nir_op_bcsel, geq_0_5, xfrac_0_5_1, xfrac, NULL );
+   nir_ssa_def *sel2 = nir_build_alu(b, nir_op_bcsel, less_m0_5, xfrac_n1_n0_5, sel1, NULL);
+
+   return sel2;
+}
+
+static nir_ssa_def *
+lower_sincos(nir_builder *b, nir_ssa_def *src, bool do_cos)
+{
+   /* Fast sin/cos implementation, see
+    * https://web.archive.org/web/20180105155939/http://forum.devmaster.net/t/fast-and-accurate-sine-cosine/9648
+    */
+   const float B = 8.0; //(M_PI * 2.0) * (4.0 / M_PI);
+   const float C = -16.0; //(M_PI * 2.0) * (M_PI * 2.0) * (-4.0 / (M_PI * M_PI));
+   const float P = 0.225;
+
+   if (do_cos)
+      src = nir_fadd_imm(b, src, M_PI / 2.0);
+
+   nir_ssa_def *x = shrink_input(b, src);
+
+   nir_ssa_def *bx = nir_fmul_imm(b, x, B);
+   nir_ssa_def *cx = nir_fmul_imm(b, x, C);
+   nir_ssa_def *absx = nir_fabs(b, x);
+   nir_ssa_def *cxabsx = nir_fmul(b, cx, absx);
+
+   /* Y1 = B * x + C * x * fabs(x) */
+   nir_ssa_def *y1 = nir_fadd(b, bx, cxabsx);
+
+   /* Precision step: Y = P * (Y1 * fabs(Y1) - Y1) + Y1 */
+   nir_ssa_def *y = nir_fabs(b, y1);
+   y = nir_fmul(b, y, y1);
+   y = nir_fsub(b, y, y1);
+   y = nir_fmul_imm(b, y, P);
+   y = nir_fadd(b, y, y1);
+
+   return y;
+}
+
+static bool
+lower_sincos_impl(nir_function_impl *impl)
+{
+   bool progress = false;
+
+   nir_builder b;
+   nir_builder_init(&b, impl);
+
+   nir_foreach_block(block, impl) {
+      nir_foreach_instr_safe(instr, block) {
+         if (instr->type != nir_instr_type_alu)
+            continue;
+
+         nir_alu_instr *alu_instr = nir_instr_as_alu(instr);
+         nir_ssa_def *lower;
+
+         b.cursor = nir_before_instr(instr);
+
+         switch (alu_instr->op) {
+         case nir_op_fsin:
+            lower = lower_sincos(&b, nir_ssa_for_alu_src(&b, alu_instr, 0), false);
+            break;
+         case nir_op_fcos:
+            lower = lower_sincos(&b, nir_ssa_for_alu_src(&b, alu_instr, 0), true);
+            break;
+         default:
+            continue;
+         }
+
+         nir_ssa_def_rewrite_uses(&alu_instr->dest.dest.ssa,
+                                  nir_src_for_ssa(lower));
+         nir_instr_remove(instr);
+         progress = true;
+      }
+   }
+
+   if (progress) {
+      nir_metadata_preserve(impl, nir_metadata_block_index |
+                                  nir_metadata_dominance);
+   }
+
+   return progress;
+}
+
+bool
+nir_lower_sincos(nir_shader *shader)
+{
+   bool progress = false;
+
+   nir_foreach_function(function, shader) {
+      if (function->impl)
+         progress |= lower_sincos_impl(function->impl);
+   }
+
+   return progress;
+}