[Mesa-dev] [PATCH 13/21] nir: Add a pass to repair SSA form
Jason Ekstrand
jason at jlekstrand.net
Sun Feb 14 02:14:30 UTC 2016
---
src/compiler/Makefile.sources | 1 +
src/compiler/nir/Makefile.sources | 1 +
src/compiler/nir/nir.h | 3 +
src/compiler/nir/nir_repair_ssa.c | 157 ++++++++++++++++++++++++++++++++++++++
4 files changed, 162 insertions(+)
create mode 100644 src/compiler/nir/nir_repair_ssa.c
diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index 4a1b120..b594c8e 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -216,6 +216,7 @@ NIR_FILES = \
nir/nir_phi_builder.c \
nir/nir_phi_builder.h \
nir/nir_print.c \
+ nir/nir_repair_ssa.c \
nir/nir_remove_dead_variables.c \
nir/nir_search.c \
nir/nir_search.h \
diff --git a/src/compiler/nir/Makefile.sources b/src/compiler/nir/Makefile.sources
index 7269f9f..a7188bf 100644
--- a/src/compiler/nir/Makefile.sources
+++ b/src/compiler/nir/Makefile.sources
@@ -60,6 +60,7 @@ NIR_FILES = \
nir_phi_builder.c \
nir_phi_builder.h \
nir_print.c \
+ nir_repair_ssa.c \
nir_remove_dead_variables.c \
nir_search.c \
nir_search.h \
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index ae57e5f..4c6c22f 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2165,6 +2165,9 @@ bool nir_ssa_defs_interfere(nir_ssa_def *a, nir_ssa_def *b);
void nir_convert_to_ssa_impl(nir_function_impl *impl);
void nir_convert_to_ssa(nir_shader *shader);
+bool nir_repair_ssa_impl(nir_function_impl *impl);
+bool nir_repair_ssa(nir_shader *shader);
+
/* If phi_webs_only is true, only convert SSA values involved in phi nodes to
* registers. If false, convert all values (even those not involved in a phi
* node) to registers.
diff --git a/src/compiler/nir/nir_repair_ssa.c b/src/compiler/nir/nir_repair_ssa.c
new file mode 100644
index 0000000..3ab4f0f
--- /dev/null
+++ b/src/compiler/nir/nir_repair_ssa.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright © 2016 Intel 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 "nir.h"
+#include "nir_phi_builder.h"
+
+struct repair_ssa_state {
+ nir_function_impl *impl;
+
+ BITSET_WORD *def_set;
+ struct nir_phi_builder *phi_builder;
+
+ bool progress;
+};
+
+/* Get ready to build a phi and return the builder */
+static struct nir_phi_builder *
+prep_build_phi(struct repair_ssa_state *state)
+{
+ const unsigned num_words = BITSET_WORDS(state->impl->num_blocks);
+
+ /* We create the phi builder on-demand. */
+ if (state->phi_builder == NULL) {
+ state->phi_builder = nir_phi_builder_create(state->impl);
+ state->def_set = ralloc_array(NULL, BITSET_WORD, num_words);
+ }
+
+ /* We're going to build a phi. That's progress. */
+ state->progress = true;
+
+ /* Set the defs set to empty */
+ memset(state->def_set, 0, num_words * sizeof(*state->def_set));
+
+ return state->phi_builder;
+}
+
+static nir_block *
+get_src_block(nir_src *src)
+{
+ if (src->parent_instr->type == nir_instr_type_phi) {
+ return exec_node_data(nir_phi_src, src, src)->pred;
+ } else {
+ return src->parent_instr->block;
+ }
+}
+
+static bool
+repair_ssa_def(nir_ssa_def *def, void *void_state)
+{
+ struct repair_ssa_state *state = void_state;
+
+ bool is_valid = true;
+ nir_foreach_use(def, src) {
+ if (!nir_block_dominates(def->parent_instr->block, get_src_block(src))) {
+ is_valid = false;
+ break;
+ }
+ }
+
+ if (is_valid)
+ return true;
+
+ struct nir_phi_builder *pb = prep_build_phi(state);
+
+ BITSET_SET(state->def_set, def->parent_instr->block->index);
+
+ struct nir_phi_builder_value *val =
+ nir_phi_builder_add_value(pb, def->num_components, state->def_set);
+
+ nir_phi_builder_value_set_block_def(val, def->parent_instr->block, def);
+
+ nir_foreach_use_safe(def, src) {
+ nir_block *src_block = get_src_block(src);
+ if (!nir_block_dominates(def->parent_instr->block, src_block)) {
+ nir_instr_rewrite_src(src->parent_instr, src, nir_src_for_ssa(
+ nir_phi_builder_value_get_block_def(val, src_block)));
+ }
+ }
+
+ return true;
+}
+
+static bool
+repair_ssa_block(nir_block *block, void *state)
+{
+ nir_foreach_instr_safe(block, instr) {
+ nir_foreach_ssa_def(instr, repair_ssa_def, state);
+ }
+
+ return true;
+}
+
+bool
+nir_repair_ssa_impl(nir_function_impl *impl)
+{
+ struct repair_ssa_state state;
+
+ state.impl = impl;
+ state.phi_builder = NULL;
+ state.progress = false;
+
+ nir_metadata_require(impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+
+ nir_foreach_block(impl, repair_ssa_block, &state);
+
+ if (state.progress)
+ nir_metadata_preserve(impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+
+ if (state.phi_builder) {
+ nir_phi_builder_finish(state.phi_builder);
+ ralloc_free(state.def_set);
+ }
+
+ return state.progress;
+}
+
+/** This pass can be used to repair SSA form in a shader.
+ *
+ * Sometimes a transformation (such as return lowering) will have to make
+ * changes to a shader which, while still correct, break some of NIR's SSA
+ * invariants. This pass will insert ssa_undefs and phi nodes as needed to
+ * get the shader back into SSA that the validator will like.
+ */
+bool
+nir_repair_ssa(nir_shader *shader)
+{
+ bool progress = false;
+
+ nir_foreach_function(shader, function) {
+ if (function->impl)
+ progress = nir_repair_ssa_impl(function->impl) || progress;
+ }
+
+ return progress;
+}
--
2.5.0.400.gff86faf
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