diff options
| -rw-r--r-- | src/glsl/Makefile.sources | 1 | ||||
| -rw-r--r-- | src/glsl/nir/nir.h | 2 | ||||
| -rw-r--r-- | src/glsl/nir/nir_opt_remove_phis.c | 109 |
3 files changed, 112 insertions, 0 deletions
diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources index bf6b70bab2a..a580b6e908b 100644 --- a/src/glsl/Makefile.sources +++ b/src/glsl/Makefile.sources @@ -45,6 +45,7 @@ NIR_FILES = \ nir/nir_opt_dce.c \ nir/nir_opt_global_to_local.c \ nir/nir_opt_peephole_select.c \ + nir/nir_opt_remove_phis.c \ nir/nir_print.c \ nir/nir_remove_dead_variables.c \ nir/nir_search.c \ diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h index 866ac5d4751..4cb2e9274ca 100644 --- a/src/glsl/nir/nir.h +++ b/src/glsl/nir/nir.h @@ -1561,6 +1561,8 @@ bool nir_opt_dce(nir_shader *shader); bool nir_opt_peephole_select(nir_shader *shader); bool nir_opt_peephole_ffma(nir_shader *shader); +bool nir_opt_remove_phis(nir_shader *shader); + #ifdef __cplusplus } /* extern "C" */ #endif diff --git a/src/glsl/nir/nir_opt_remove_phis.c b/src/glsl/nir/nir_opt_remove_phis.c new file mode 100644 index 00000000000..7896584b4e4 --- /dev/null +++ b/src/glsl/nir/nir_opt_remove_phis.c @@ -0,0 +1,109 @@ +/* + * Copyright © 2015 Connor Abbott + * + * 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: + * Connor Abbott ([email protected]) + * + */ + +#include "nir.h" + +/* + * This is a pass for removing phi nodes that look like: + * a = phi(b, b, b, ...) + * + * Note that we can't ignore undef sources here, or else we may create a + * situation where the definition of b isn't dominated by its uses. We're + * allowed to do this since the definition of b must dominate all of the + * phi node's predecessors, which means it must dominate the phi node as well + * as all of the phi node's uses. In essence, the phi node acts as a copy + * instruction. b can't be another phi node in the same block, since the only + * time when phi nodes can source other phi nodes defined in the same block is + * at the loop header, and in that case one of the sources of the phi has to + * be from before the loop and that source can't be b. + */ + +static bool +remove_phis_block(nir_block *block, void *state) +{ + bool *progress = state; + + void *mem_ctx = ralloc_parent(block); + + nir_foreach_instr_safe(block, instr) { + if (instr->type != nir_instr_type_phi) + break; + + nir_phi_instr *phi = nir_instr_as_phi(instr); + + nir_ssa_def *def = NULL; + bool srcs_same = true; + + nir_foreach_phi_src(phi, src) { + assert(src->src.is_ssa); + + if (def == NULL) { + def = src->src.ssa; + } else { + if (src->src.ssa != def) { + srcs_same = false; + break; + } + } + } + + if (!srcs_same) + continue; + + assert(phi->dest.is_ssa); + nir_ssa_def_rewrite_uses(&phi->dest.ssa, nir_src_for_ssa(def), + mem_ctx); + nir_instr_remove(instr); + + *progress = true; + } + + return true; +} + +static bool +remove_phis_impl(nir_function_impl *impl) +{ + bool progress = false; + + nir_foreach_block(impl, remove_phis_block, &progress); + + return progress; +} + +bool +nir_opt_remove_phis(nir_shader *shader) +{ + bool progress = false; + + nir_foreach_overload(shader, overload) + if (overload->impl) + progress = remove_phis_impl(overload->impl) || progress; + + return progress; +} + |