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/*
* Copyright © 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:
* Jason Ekstrand (jason@jlekstrand.net)
*
*/
#include "nir.h"
/*
* This pass lowers the neg, abs, and sat operations to source modifiers on
* ALU operations to make things nicer for the backend. It's just much
* easier to not have them when we're doing optimizations.
*/
static bool
nir_lower_to_source_mods_block(nir_block *block, void *state)
{
nir_foreach_instr(block, instr) {
if (instr->type != nir_instr_type_alu)
continue;
nir_alu_instr *alu = nir_instr_as_alu(instr);
for (unsigned i = 0; i < nir_op_infos[alu->op].num_inputs; i++) {
if (!alu->src[i].src.is_ssa)
continue;
if (alu->src[i].src.ssa->parent_instr->type != nir_instr_type_alu)
continue;
nir_alu_instr *parent = nir_instr_as_alu(alu->src[i].src.ssa->parent_instr);
if (parent->dest.saturate)
continue;
switch (nir_op_infos[alu->op].input_types[i]) {
case nir_type_float:
if (parent->op != nir_op_fmov)
continue;
break;
case nir_type_int:
if (parent->op != nir_op_imov)
continue;
break;
default:
continue;
}
/* We can only do a rewrite if the source we are copying is SSA.
* Otherwise, moving the read might invalidly reorder reads/writes
* on a register.
*/
if (!parent->src[0].src.is_ssa)
continue;
nir_instr_rewrite_src(instr, &alu->src[i].src, parent->src[0].src);
if (alu->src[i].abs) {
/* abs trumps both neg and abs, do nothing */
} else {
alu->src[i].negate = (alu->src[i].negate != parent->src[0].negate);
alu->src[i].abs |= parent->src[0].abs;
}
for (int j = 0; j < 4; ++j) {
if (!nir_alu_instr_channel_used(alu, i, j))
continue;
alu->src[i].swizzle[j] = parent->src[0].swizzle[alu->src[i].swizzle[j]];
}
if (list_empty(&parent->dest.dest.ssa.uses) &&
list_empty(&parent->dest.dest.ssa.if_uses))
nir_instr_remove(&parent->instr);
}
switch (alu->op) {
case nir_op_fsat:
alu->op = nir_op_fmov;
alu->dest.saturate = true;
break;
case nir_op_ineg:
alu->op = nir_op_imov;
alu->src[0].negate = !alu->src[0].negate;
break;
case nir_op_fneg:
alu->op = nir_op_fmov;
alu->src[0].negate = !alu->src[0].negate;
break;
case nir_op_iabs:
alu->op = nir_op_imov;
alu->src[0].abs = true;
alu->src[0].negate = false;
break;
case nir_op_fabs:
alu->op = nir_op_fmov;
alu->src[0].abs = true;
alu->src[0].negate = false;
break;
default:
break;
}
/* We've covered sources. Now we're going to try and saturate the
* destination if we can.
*/
if (!alu->dest.dest.is_ssa)
continue;
/* We can only saturate float destinations */
if (nir_op_infos[alu->op].output_type != nir_type_float)
continue;
if (!list_empty(&alu->dest.dest.ssa.if_uses))
continue;
bool all_children_are_sat = true;
nir_foreach_use(&alu->dest.dest.ssa, child_src) {
assert(child_src->is_ssa);
nir_instr *child = child_src->parent_instr;
if (child->type != nir_instr_type_alu) {
all_children_are_sat = false;
continue;
}
nir_alu_instr *child_alu = nir_instr_as_alu(child);
if (child_alu->src[0].negate || child_alu->src[0].abs) {
all_children_are_sat = false;
continue;
}
if (child_alu->op != nir_op_fsat &&
!(child_alu->op == nir_op_fmov && child_alu->dest.saturate)) {
all_children_are_sat = false;
continue;
}
}
if (!all_children_are_sat)
continue;
alu->dest.saturate = true;
nir_foreach_use(&alu->dest.dest.ssa, child_src) {
assert(child_src->is_ssa);
nir_instr *child = child_src->parent_instr;
assert(child->type == nir_instr_type_alu);
nir_alu_instr *child_alu = nir_instr_as_alu(child);
child_alu->op = nir_op_fmov;
child_alu->dest.saturate = false;
/* We could propagate the dest of our instruction to the
* destinations of the uses here. However, one quick round of
* copy propagation will clean that all up and then we don't have
* the complexity.
*/
}
}
return true;
}
static void
nir_lower_to_source_mods_impl(nir_function_impl *impl)
{
nir_foreach_block(impl, nir_lower_to_source_mods_block, NULL);
}
void
nir_lower_to_source_mods(nir_shader *shader)
{
nir_foreach_overload(shader, overload) {
if (overload->impl)
nir_lower_to_source_mods_impl(overload->impl);
}
}
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