diff --git a/src/freedreno/ir3/ir3.c b/src/freedreno/ir3/ir3.c index 1491429c14a..48f9f38cca4 100644 --- a/src/freedreno/ir3/ir3.c +++ b/src/freedreno/ir3/ir3.c @@ -393,6 +393,22 @@ ir3_block_remove_predecessor(struct ir3_block *block, struct ir3_block *pred) } } +void +ir3_block_remove_physical_predecessor(struct ir3_block *block, struct ir3_block *pred) +{ + for (unsigned i = 0; i < block->physical_predecessors_count; i++) { + if (block->physical_predecessors[i] == pred) { + if (i < block->predecessors_count - 1) { + block->physical_predecessors[i] = + block->physical_predecessors[block->predecessors_count - 1]; + } + + block->physical_predecessors_count--; + return; + } + } +} + unsigned ir3_block_get_pred_index(struct ir3_block *block, struct ir3_block *pred) { diff --git a/src/freedreno/ir3/ir3.h b/src/freedreno/ir3/ir3.h index 723eb6567ed..e0dd870971d 100644 --- a/src/freedreno/ir3/ir3.h +++ b/src/freedreno/ir3/ir3.h @@ -615,6 +615,8 @@ void ir3_block_add_physical_predecessor(struct ir3_block *block, struct ir3_block *pred); void ir3_block_remove_predecessor(struct ir3_block *block, struct ir3_block *pred); +void ir3_block_remove_physical_predecessor(struct ir3_block *block, + struct ir3_block *pred); unsigned ir3_block_get_pred_index(struct ir3_block *block, struct ir3_block *pred); @@ -1593,6 +1595,9 @@ unsigned ir3_delay_calc_exact(struct ir3_block *block, struct ir3_instruction *instr, bool mergedregs); void ir3_remove_nops(struct ir3 *ir); +/* unreachable block elimination: */ +bool ir3_remove_unreachable(struct ir3 *ir); + /* dead code elimination: */ struct ir3_shader_variant; bool ir3_dce(struct ir3 *ir, struct ir3_shader_variant *so); diff --git a/src/freedreno/ir3/ir3_compiler_nir.c b/src/freedreno/ir3/ir3_compiler_nir.c index b634eb50e96..16be6e1f810 100644 --- a/src/freedreno/ir3/ir3_compiler_nir.c +++ b/src/freedreno/ir3/ir3_compiler_nir.c @@ -4135,6 +4135,8 @@ ir3_compile_shader_nir(struct ir3_compiler *compiler, ir3_debug_print(ir, "AFTER: nir->ir3"); ir3_validate(ir); + IR3_PASS(ir, ir3_remove_unreachable); + IR3_PASS(ir, ir3_array_to_ssa); do { diff --git a/src/freedreno/ir3/ir3_remove_unreachable.c b/src/freedreno/ir3/ir3_remove_unreachable.c new file mode 100644 index 00000000000..c598d9f2e59 --- /dev/null +++ b/src/freedreno/ir3/ir3_remove_unreachable.c @@ -0,0 +1,122 @@ +/* + * Copyright (C) 2021 Valve 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. + */ + +#include "ir3.h" + +/* Sometimes we can get unreachable blocks from NIR. In particular this happens + * for blocks after an if where both sides end in a break/continue. These blocks + * are then reachable only via the physical CFG. This pass deletes these blocks + * and reroutes the physical edge past it. + */ + +static void +delete_block(struct ir3 *ir, struct ir3_block *block) +{ + struct ir3_instruction *end = NULL; + foreach_instr (instr, &block->instr_list) { + if (instr->opc == OPC_END) { + end = instr; + break; + } + } + + /* The end block can be legitimately unreachable if the shader only exits via + * discarding. ir3_legalize will then insert a branch to the end. Keep the + * block around but delete all the other instructions and make the end not + * take any sources, so that we don't have any dangling references to other + * unreachable blocks. + */ + if (end) { + foreach_instr_safe (instr, &block->instr_list) { + if (instr != end) + list_delinit(&instr->node); + } + end->srcs_count = 0; + return; + } + + for (unsigned i = 0; i < 2; i++) { + struct ir3_block *succ = block->successors[i]; + if (!succ) + continue; + + unsigned pred_idx = ir3_block_get_pred_index(succ, block); + + /* If this isn't the last predecessor, we swap it with the last before + * removing it. + */ + bool swap_pred = pred_idx != succ->predecessors_count - 1; + + foreach_instr (phi, &succ->instr_list) { + if (phi->opc != OPC_META_PHI) + break; + + if (swap_pred) + phi->srcs[pred_idx] = phi->srcs[phi->srcs_count - 1]; + phi->srcs_count--; + } + if (swap_pred) { + succ->predecessors[pred_idx] = + succ->predecessors[succ->predecessors_count - 1]; + } + succ->predecessors_count--; + } + + for (unsigned i = 0; i < 2; i++) { + struct ir3_block *succ = block->physical_successors[i]; + if (!succ) + continue; + + ir3_block_remove_physical_predecessor(succ, block); + } + + if (block->physical_predecessors_count != 0) { + /* There should be only one physical predecessor, for the fallthrough + * edge. + */ + assert(block->physical_predecessors_count == 1); + struct ir3_block *pred = block->physical_predecessors[0]; + assert(block->node.next != &ir->block_list); + struct ir3_block *next = LIST_ENTRY(struct ir3_block, block->node.next, node); + if (pred->physical_successors[1] == block) + pred->physical_successors[1] = next; + else + pred->physical_successors[0] = next; + ir3_block_add_physical_predecessor(next, pred); + } +} + +bool +ir3_remove_unreachable(struct ir3 *ir) +{ + bool progress = false; + foreach_block_safe (block, &ir->block_list) { + if (block != ir3_start_block(ir) && block->predecessors_count == 0) { + delete_block(ir, block); + list_del(&block->node); + progress = true; + } + } + + return progress; +} diff --git a/src/freedreno/ir3/meson.build b/src/freedreno/ir3/meson.build index 1bf9847ad95..40bdb26194d 100644 --- a/src/freedreno/ir3/meson.build +++ b/src/freedreno/ir3/meson.build @@ -105,6 +105,7 @@ libfreedreno_ir3_files = files( 'ir3_ra.c', 'ir3_ra.h', 'ir3_ra_validate.c', + 'ir3_remove_unreachable.c', 'ir3_sched.c', 'ir3_shader.c', 'ir3_shader.h',