--- /dev/null
+/*
+ * Copyright (C) 2020 Collabora, Ltd.
+ * Copyright (C) 2014 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.
+ *
+ * Authors:
+ * Alyssa Rosenzweig <alyssa@collabora.com>
+ * Jason Ekstrand (jason@jlekstrand.net)
+ *
+ */
+
+#include "nir.h"
+#include "pan_ir.h"
+
+/* Check if a given ALU source is the result of a particular componentwise 1-op
+ * ALU source (principally fneg or fabs). If so, return true and rewrite the
+ * source to be the argument, respecting swizzles as needed. If not (or it
+ * cannot be proven), return false and leave the source untouched.
+*/
+
+bool
+pan_has_source_mod(nir_alu_src *src, nir_op op)
+{
+ if (!src->src.is_ssa || src->src.ssa->parent_instr->type != nir_instr_type_alu)
+ return false;
+
+ nir_alu_instr *alu = nir_instr_as_alu(src->src.ssa->parent_instr);
+
+ if (alu->op != op)
+ return false;
+
+ /* This only works for unary ops */
+ assert(nir_op_infos[op].num_inputs == 1);
+
+ /* If the copied source is not SSA, moving it might not be valid */
+ if (!alu->src[0].src.is_ssa)
+ return false;
+
+ /* Okay - we've found the modifier we wanted. Let's construct the new ALU
+ * src. In a scalar world, this is just psrc, but for vector archs we need
+ * to respect the swizzle, so we compose.
+ */
+
+ nir_alu_src nsrc = {
+ .src = alu->src[0].src,
+ };
+
+ for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; ++i) {
+ /* (a o b)(i) = a(b(i)) ... swizzle composition is intense. */
+ nsrc.swizzle[i] = alu->src[0].swizzle[src->swizzle[i]];
+ }
+
+ *src = nsrc;
+ return true;
+}
+
+/* Check if a given instruction's result will be fed into a
+ * componentwise 1-op ALU instruction (principally fsat without
+ * swizzles). If so, return true and rewrite the destination. The
+ * backend will need to track the new destinations to avoid
+ * incorrect double-emits. */
+
+bool
+pan_has_dest_mod(nir_dest **odest, nir_op op)
+{
+ /* This only works for unary ops */
+ assert(nir_op_infos[op].num_inputs == 1);
+
+ /* If not SSA, this might not be legal */
+ nir_dest *dest = *odest;
+ if (!dest->is_ssa)
+ return false;
+
+ /* Check the uses. We want a single use, with the op `op` */
+ if (!list_is_empty(&dest->ssa.if_uses))
+ return false;
+
+ if (!list_is_singular(&dest->ssa.uses))
+ return false;
+
+ nir_src *use = list_first_entry(&dest->ssa.uses, nir_src, use_link);
+ nir_instr *parent = use->parent_instr;
+
+ /* Check if the op is `op` */
+ if (parent->type != nir_instr_type_alu)
+ return false;
+
+ nir_alu_instr *alu = nir_instr_as_alu(parent);
+ if (alu->op != op)
+ return false;
+
+ /* We can't do expansions without a move in the middle */
+ unsigned nr_components = nir_dest_num_components(alu->dest.dest);
+
+ if (nir_dest_num_components(*dest) != nr_components)
+ return false;
+
+ /* We don't handle swizzles here, so check for the identity */
+ for (unsigned i = 0; i < nr_components; ++i) {
+ if (alu->src[0].swizzle[i] != i)
+ return false;
+ }
+
+ if (!alu->dest.dest.is_ssa)
+ return false;
+
+ /* Otherwise, we're good */
+ *odest = &alu->dest.dest;
+ return true;
+}
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