/* * Copyright 2018 Collabora Ltd. * * 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 * on the rights to use, copy, modify, merge, publish, distribute, sub * license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL * THE AUTHOR(S) AND/OR THEIR SUPPLIERS 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 "nir.h" #include "compiler/nir/nir_builder.h" static bool lower_discard_if_instr(nir_builder *b, nir_instr *instr_, UNUSED void *cb_data) { if (instr_->type != nir_instr_type_intrinsic) return false; nir_intrinsic_instr *instr = nir_instr_as_intrinsic(instr_); if (instr->intrinsic == nir_intrinsic_discard_if) { b->cursor = nir_before_instr(&instr->instr); nir_if *if_stmt = nir_push_if(b, nir_ssa_for_src(b, instr->src[0], 1)); nir_discard(b); nir_pop_if(b, if_stmt); nir_instr_remove(&instr->instr); return true; } else if (instr->intrinsic == nir_intrinsic_terminate_if || instr->intrinsic == nir_intrinsic_demote_if) { unreachable("todo: handle terminates and demotes for Vulkan"); } /* a shader like this (shaders@glsl-fs-discard-04): uniform int j, k; void main() { for (int i = 0; i < j; i++) { if (i > k) continue; discard; } gl_FragColor = vec4(0.0, 1.0, 0.0, 0.0); } will generate nir like: loop { //snip if ssa_11 { block block_5: / preds: block_4 / vec1 32 ssa_17 = iadd ssa_50, ssa_31 / succs: block_7 / } else { block block_6: / preds: block_4 / intrinsic discard () () <-- not last instruction vec1 32 ssa_23 = iadd ssa_50, ssa_31 <-- dead code loop itr increment / succs: block_7 / } //snip } which means that we can't assert like this: assert(instr->intrinsic != nir_intrinsic_discard || nir_block_last_instr(instr->instr.block) == &instr->instr); and it's unnecessary anyway since later optimizations will dce the instructions following the discard */ return false; } bool nir_lower_discard_if(nir_shader *shader) { return nir_shader_instructions_pass(shader, lower_discard_if_instr, nir_metadata_none, NULL); }