147 lines
5.5 KiB
C
147 lines
5.5 KiB
C
/*
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* Copyright © 2020 Mike Blumenkrantz
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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* Authors:
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* Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
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*/
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#include "nir.h"
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#include "nir_builder.h"
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/**
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* This pass uses the enabled clip planes from the rasterizer state to rewrite
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* vertex shader store operations and store a 0 to the corresponding gl_ClipDistance[n]
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* value if the plane is disabled
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*/
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/* recursively nest if/else blocks until we get to an array index,
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* then overwrite it if that plane isn't enabled
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*/
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static void
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recursive_if_chain(nir_builder *b, nir_deref_instr *deref, nir_ssa_def *value, unsigned clip_plane_enable, nir_ssa_def *index, unsigned start, unsigned end)
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{
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if (start == end - 1) {
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/* store the original value again if the clip plane is enabled */
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if (clip_plane_enable & (1 << start))
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nir_store_deref(b, deref, value, 1 << start);
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else
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nir_store_deref(b, deref, nir_imm_int(b, 0), 1 << start);
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return;
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}
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unsigned mid = start + (end - start) / 2;
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nir_push_if(b, nir_ilt(b, index, nir_imm_int(b, mid)));
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recursive_if_chain(b, deref, value, clip_plane_enable, index, start, mid);
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nir_push_else(b, NULL);
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recursive_if_chain(b, deref, value, clip_plane_enable, index, mid, end);
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nir_pop_if(b, NULL);
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}
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/* vulkan (and some drivers) provides no concept of enabling clip planes through api,
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* so we rewrite disabled clip planes to a zero value in order to disable them
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*/
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static bool
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lower_clip_plane_store(nir_intrinsic_instr *instr, unsigned clip_plane_enable, nir_builder *b)
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{
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nir_variable *out;
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unsigned plane;
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if (instr->intrinsic != nir_intrinsic_store_deref)
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return false;
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nir_deref_instr *deref = nir_src_as_deref(instr->src[0]);
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out = nir_deref_instr_get_variable(deref);
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if ((out->data.location != VARYING_SLOT_CLIP_DIST0 &&
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out->data.location != VARYING_SLOT_CLIP_DIST1) ||
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out->data.mode != nir_var_shader_out)
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return false;
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b->cursor = nir_after_instr(&instr->instr);
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if (deref->deref_type == nir_deref_type_var) {
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int wrmask = nir_intrinsic_write_mask(instr);
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nir_ssa_def *components[4];
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int start = out->data.location == VARYING_SLOT_CLIP_DIST1 ? 4 : 0;
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/* rewrite components as zeroes for planes that aren't enabled */
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for (int i = 0; i < 4; i++) {
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if (wrmask & (1 << i)) {
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if (!(clip_plane_enable & (1 << (start + i))))
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components[i] = nir_imm_int(b, 0);
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else
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components[i] = nir_channel(b, nir_ssa_for_src(b, instr->src[1], nir_src_num_components(instr->src[1])), i);
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} else
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components[i] = nir_ssa_undef(b, 1, 32);
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}
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nir_store_deref(b, deref, nir_vec(b, components, instr->num_components), wrmask);
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} else if (nir_src_is_const(deref->arr.index)) {
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/* storing using a constant index */
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plane = nir_src_as_uint(deref->arr.index);
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/* no need to make changes if the clip plane is enabled */
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if (clip_plane_enable & (1 << plane))
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return false;
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assert(nir_intrinsic_write_mask(instr) == 1);
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nir_store_deref(b, deref, nir_imm_int(b, 0), 1);
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} else {
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/* storing using a variable index */
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nir_ssa_def *index = nir_ssa_for_src(b, deref->arr.index, 1);
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unsigned length = glsl_get_length(nir_deref_instr_parent(deref)->type);
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recursive_if_chain(b, deref, instr->src[1].ssa, clip_plane_enable, index, 0, length);
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}
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nir_instr_remove(&instr->instr);
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return true;
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}
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bool
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nir_lower_clip_disable(nir_shader *shader, unsigned clip_plane_enable)
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{
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bool progress = false;
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/* if all user planes are enabled in API that are written in the array, always ignore;
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* this explicitly covers the 2x vec4 case
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*/
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if (clip_plane_enable == u_bit_consecutive(0, shader->info.clip_distance_array_size))
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return false;
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nir_foreach_function(function, shader) {
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if (function->impl) {
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nir_builder builder;
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nir_builder_init(&builder, function->impl);
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nir_foreach_block(block, function->impl) {
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nir_foreach_instr_safe(instr, block) {
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if (instr->type == nir_instr_type_intrinsic)
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progress |= lower_clip_plane_store(nir_instr_as_intrinsic(instr),
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clip_plane_enable,
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&builder);
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}
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}
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nir_metadata_preserve(function->impl, nir_metadata_block_index | nir_metadata_dominance);
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}
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}
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return progress;
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}
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