From a3b4cb34589e2f1a6898e88c8d9686cc3e133de3 Mon Sep 17 00:00:00 2001 From: Jason Ekstrand Date: Fri, 19 Oct 2018 21:42:22 -0500 Subject: [PATCH] nir/opt_if: Rework condition propagation Instead of doing our own constant folding, we just emit instructions and let constant folding happen. This is substantially simpler and lets us use the nir_imm_bool helper instead of dealing with the const_value's ourselves. Reviewed-by: Ian Romanick Reviewed-by: Timothy Arceri --- src/compiler/nir/nir_opt_if.c | 91 ++++++++++++----------------------- 1 file changed, 30 insertions(+), 61 deletions(-) diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c index fb161f1c4fd..72a7285c1ea 100644 --- a/src/compiler/nir/nir_opt_if.c +++ b/src/compiler/nir/nir_opt_if.c @@ -376,31 +376,15 @@ opt_if_loop_terminator(nir_if *nif) return true; } -static void -replace_if_condition_use_with_const(nir_builder *b, nir_src *use, - nir_const_value nir_boolean, - bool if_condition) -{ - /* Create const */ - nir_ssa_def *const_def = nir_build_imm(b, 1, 32, nir_boolean); - - /* Rewrite use to use const */ - nir_src new_src = nir_src_for_ssa(const_def); - if (if_condition) - nir_if_rewrite_condition(use->parent_if, new_src); - else - nir_instr_rewrite_src(use->parent_instr, use, new_src); -} - static bool -evaluate_if_condition(nir_if *nif, nir_cursor cursor, uint32_t *value) +evaluate_if_condition(nir_if *nif, nir_cursor cursor, bool *value) { nir_block *use_block = nir_cursor_current_block(cursor); if (nir_block_dominates(nir_if_first_then_block(nif), use_block)) { - *value = NIR_TRUE; + *value = true; return true; } else if (nir_block_dominates(nir_if_first_else_block(nif), use_block)) { - *value = NIR_FALSE; + *value = false; return true; } else { return false; @@ -459,52 +443,31 @@ propagate_condition_eval(nir_builder *b, nir_if *nif, nir_src *use_src, nir_src *alu_use, nir_alu_instr *alu, bool is_if_condition) { - bool progress = false; + bool bool_value; + if (!evaluate_if_condition(nif, b->cursor, &bool_value)) + return false; - nir_const_value bool_value; b->cursor = nir_before_src(alu_use, is_if_condition); - if (nir_op_infos[alu->op].num_inputs == 1) { - assert(alu->op == nir_op_inot || alu->op == nir_op_b2i); - - if (evaluate_if_condition(nif, b->cursor, &bool_value.u32[0])) { - assert(nir_src_bit_size(alu->src[0].src) == 32); - - nir_const_value result = - nir_eval_const_opcode(alu->op, 1, 32, &bool_value); - replace_if_condition_use_with_const(b, alu_use, result, - is_if_condition); - progress = true; + nir_ssa_def *def[2] = { }; + for (unsigned i = 0; i < nir_op_infos[alu->op].num_inputs; i++) { + if (alu->src[i].src.ssa == use_src->ssa) { + def[i] = nir_imm_bool(b, bool_value); + } else { + def[i] = alu->src[i].src.ssa; } - } else { - assert(alu->op == nir_op_ior || alu->op == nir_op_iand); - - if (evaluate_if_condition(nif, b->cursor, &bool_value.u32[0])) { - nir_ssa_def *def[2]; - for (unsigned i = 0; i < 2; i++) { - if (alu->src[i].src.ssa == use_src->ssa) { - def[i] = nir_build_imm(b, 1, 32, bool_value); - } else { - def[i] = alu->src[i].src.ssa; - } - } - - nir_ssa_def *nalu = - nir_build_alu(b, alu->op, def[0], def[1], NULL, NULL); - - /* Rewrite use to use new alu instruction */ - nir_src new_src = nir_src_for_ssa(nalu); + } + nir_ssa_def *nalu = nir_build_alu(b, alu->op, def[0], def[1], NULL, NULL); - if (is_if_condition) - nir_if_rewrite_condition(alu_use->parent_if, new_src); - else - nir_instr_rewrite_src(alu_use->parent_instr, alu_use, new_src); + /* Rewrite use to use new alu instruction */ + nir_src new_src = nir_src_for_ssa(nalu); - progress = true; - } - } + if (is_if_condition) + nir_if_rewrite_condition(alu_use->parent_if, new_src); + else + nir_instr_rewrite_src(alu_use->parent_instr, alu_use, new_src); - return progress; + return true; } static bool @@ -526,11 +489,17 @@ evaluate_condition_use(nir_builder *b, nir_if *nif, nir_src *use_src, { bool progress = false; - nir_const_value value; b->cursor = nir_before_src(use_src, is_if_condition); - if (evaluate_if_condition(nif, b->cursor, &value.u32[0])) { - replace_if_condition_use_with_const(b, use_src, value, is_if_condition); + bool bool_value; + if (evaluate_if_condition(nif, b->cursor, &bool_value)) { + /* Rewrite use to use const */ + nir_src imm_src = nir_src_for_ssa(nir_imm_bool(b, bool_value)); + if (is_if_condition) + nir_if_rewrite_condition(use_src->parent_if, imm_src); + else + nir_instr_rewrite_src(use_src->parent_instr, use_src, imm_src); + progress = true; } -- 2.30.2