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-rw-r--r--src/compiler/Makefile.sources1
-rw-r--r--src/compiler/nir/nir.h2
-rw-r--r--src/compiler/nir/nir_to_lcssa.c203
3 files changed, 206 insertions, 0 deletions
diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index edc70f7c4c2..f551449ed1c 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -256,6 +256,7 @@ NIR_FILES = \
nir/nir_split_var_copies.c \
nir/nir_sweep.c \
nir/nir_to_ssa.c \
+ nir/nir_to_lcssa.c \
nir/nir_validate.c \
nir/nir_vla.h \
nir/nir_worklist.c \
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index c7da1e779db..21769463e7f 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2526,6 +2526,8 @@ void nir_convert_to_ssa(nir_shader *shader);
bool nir_repair_ssa_impl(nir_function_impl *impl);
bool nir_repair_ssa(nir_shader *shader);
+void nir_convert_loop_to_lcssa(nir_loop *loop);
+
/* 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_to_lcssa.c b/src/compiler/nir/nir_to_lcssa.c
new file mode 100644
index 00000000000..9b3539193ea
--- /dev/null
+++ b/src/compiler/nir/nir_to_lcssa.c
@@ -0,0 +1,203 @@
+/*
+ * Copyright © 2015 Thomas Helland
+ *
+ * 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.
+ */
+
+/*
+ * This pass converts the ssa-graph into "Loop Closed SSA form". This is
+ * done by placing phi nodes at the exits of the loop for all values
+ * that are used outside the loop. The result is it transforms:
+ *
+ * loop { -> loop {
+ * ssa2 = .... -> ssa2 = ...
+ * if (cond) -> if (cond)
+ * break; -> break;
+ * ssa3 = ssa2 * ssa4 -> ssa3 = ssa2 * ssa4
+ * } -> }
+ * ssa6 = ssa2 + 4 -> ssa5 = phi(ssa2)
+ * ssa6 = ssa5 + 4
+ */
+
+#include "nir.h"
+
+typedef struct {
+ /* The nir_shader we are transforming */
+ nir_shader *shader;
+
+ /* The loop we store information for */
+ nir_loop *loop;
+
+} lcssa_state;
+
+static bool
+is_if_use_inside_loop(nir_src *use, nir_loop* loop)
+{
+ nir_block *block_before_loop =
+ nir_cf_node_as_block(nir_cf_node_prev(&loop->cf_node));
+ nir_block *block_after_loop =
+ nir_cf_node_as_block(nir_cf_node_next(&loop->cf_node));
+
+ nir_block *prev_block =
+ nir_cf_node_as_block(nir_cf_node_prev(&use->parent_if->cf_node));
+ if (prev_block->index <= block_before_loop->index ||
+ prev_block->index >= block_after_loop->index) {
+ return false;
+ }
+
+ return true;
+}
+
+static bool
+is_use_inside_loop(nir_src *use, nir_loop* loop)
+{
+ nir_block *block_before_loop =
+ nir_cf_node_as_block(nir_cf_node_prev(&loop->cf_node));
+ nir_block *block_after_loop =
+ nir_cf_node_as_block(nir_cf_node_next(&loop->cf_node));
+
+ if (use->parent_instr->block->index <= block_before_loop->index ||
+ use->parent_instr->block->index >= block_after_loop->index) {
+ return false;
+ }
+
+ return true;
+}
+
+static bool
+convert_loop_exit_for_ssa(nir_ssa_def *def, void *void_state)
+{
+ lcssa_state *state = void_state;
+ bool all_uses_inside_loop = true;
+
+ nir_block *block_after_loop =
+ nir_cf_node_as_block(nir_cf_node_next(&state->loop->cf_node));
+
+ nir_foreach_use(use, def) {
+ if (use->parent_instr->type == nir_instr_type_phi &&
+ use->parent_instr->block == block_after_loop) {
+ continue;
+ }
+
+ if (!is_use_inside_loop(use, state->loop)) {
+ all_uses_inside_loop = false;
+ }
+ }
+
+ nir_foreach_if_use(use, def) {
+ if (!is_if_use_inside_loop(use, state->loop)) {
+ all_uses_inside_loop = false;
+ }
+ }
+
+ /* There where no sources that had defs outside the loop */
+ if (all_uses_inside_loop)
+ return true;
+
+ /* Initialize a phi-instruction */
+ nir_phi_instr *phi = nir_phi_instr_create(state->shader);
+ nir_ssa_dest_init(&phi->instr, &phi->dest,
+ def->num_components, def->bit_size, "LCSSA-phi");
+
+ /* Create a phi node with as many sources pointing to the same ssa_def as
+ * the block has predecessors.
+ */
+ struct set_entry *entry;
+ set_foreach(block_after_loop->predecessors, entry) {
+ nir_phi_src *phi_src = ralloc(phi, nir_phi_src);
+ phi_src->src = nir_src_for_ssa(def);
+ phi_src->pred = (nir_block *) entry->key;
+
+ exec_list_push_tail(&phi->srcs, &phi_src->node);
+ }
+
+ nir_instr_insert_before_block(block_after_loop, &phi->instr);
+
+ /* Run through all uses and rewrite those outside the loop to point to
+ * the phi instead of pointing to the ssa-def.
+ */
+ nir_foreach_use_safe(use, def) {
+ if (use->parent_instr->type == nir_instr_type_phi &&
+ block_after_loop == use->parent_instr->block) {
+ continue;
+ }
+
+ if (!is_use_inside_loop(use, state->loop)) {
+ nir_instr_rewrite_src(use->parent_instr, use,
+ nir_src_for_ssa(&phi->dest.ssa));
+ }
+ }
+
+ nir_foreach_if_use_safe(use, def) {
+ if (!is_if_use_inside_loop(use, state->loop)) {
+ nir_if_rewrite_condition(use->parent_if,
+ nir_src_for_ssa(&phi->dest.ssa));
+ }
+ }
+
+ return true;
+}
+
+static void
+convert_to_lcssa(nir_cf_node *cf_node, lcssa_state *state)
+{
+ switch (cf_node->type) {
+ case nir_cf_node_block:
+ nir_foreach_instr(instr, nir_cf_node_as_block(cf_node))
+ nir_foreach_ssa_def(instr, convert_loop_exit_for_ssa, state);
+ return;
+ case nir_cf_node_if: {
+ nir_if *if_stmt = nir_cf_node_as_if(cf_node);
+ foreach_list_typed(nir_cf_node, nested_node, node, &if_stmt->then_list)
+ convert_to_lcssa(nested_node, state);
+ foreach_list_typed(nir_cf_node, nested_node, node, &if_stmt->else_list)
+ convert_to_lcssa(nested_node, state);
+ return;
+ }
+ case nir_cf_node_loop: {
+ nir_loop *parent_loop = state->loop;
+ state->loop = nir_cf_node_as_loop(cf_node);
+
+ foreach_list_typed(nir_cf_node, nested_node, node, &state->loop->body)
+ convert_to_lcssa(nested_node, state);
+
+ state->loop = parent_loop;
+ return;
+ }
+ default:
+ unreachable("unknown cf node type");
+ }
+}
+
+void
+nir_convert_loop_to_lcssa(nir_loop *loop) {
+ nir_function_impl *impl = nir_cf_node_get_function(&loop->cf_node);
+
+ nir_metadata_require(impl, nir_metadata_block_index);
+
+ lcssa_state *state = rzalloc(NULL, lcssa_state);
+ state->loop = loop;
+ state->shader = impl->function->shader;
+
+ foreach_list_typed(nir_cf_node, node, node, &state->loop->body)
+ convert_to_lcssa(node, state);
+
+ ralloc_free(state);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-13 18:56:30 +0000