1 files changed, 193 insertions, 0 deletions
diff --git a/src/glsl/nir/nir_from_ssa.c b/src/glsl/nir/nir_from_ssa.c
new file mode 100644
index 00000000000..abfee3577a0
--- /dev/null
+++ b/src/glsl/nir/nir_from_ssa.c
@@ -0,0 +1,193 @@
+/*
+ * Copyright © 2014 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.
+ *
+ * Authors:
+ *    Jason Ekstrand ([email protected])
+ *
+ */
+
+#include "nir.h"
+
+/*
+ * Implements a quick-and-dirty out-of-ssa pass.
+ */
+
+struct from_ssa_state {
+   void *mem_ctx;
+   void *dead_ctx;
+   struct hash_table *ssa_table;
+   nir_function_impl *current_impl;
+};
+
+static bool
+rewrite_ssa_src(nir_src *src, void *void_state)
+{
+   struct from_ssa_state *state = void_state;
+
+   if (src->is_ssa) {
+      struct hash_entry *entry =
+         _mesa_hash_table_search(state->ssa_table, src->ssa);
+      assert(entry);
+      memset(src, 0, sizeof *src);
+      src->reg.reg = (nir_register *)entry->data;
+   }
+
+   return true;
+}
+
+static nir_register *
+reg_create_from_def(nir_ssa_def *def, struct from_ssa_state *state)
+{
+   nir_register *reg = nir_local_reg_create(state->current_impl);
+   reg->name = def->name;
+   reg->num_components = def->num_components;
+   reg->num_array_elems = 0;
+
+   /* Might as well steal the use-def information from SSA */
+   _mesa_set_destroy(reg->uses, NULL);
+   reg->uses = def->uses;
+   _mesa_set_destroy(reg->if_uses, NULL);
+   reg->if_uses = def->if_uses;
+   _mesa_set_add(reg->defs, _mesa_hash_pointer(def->parent_instr),
+                 def->parent_instr);
+
+   /* Add the new register to the table and rewrite the destination */
+   _mesa_hash_table_insert(state->ssa_table, def, reg);
+
+   return reg;
+}
+
+static bool
+rewrite_ssa_dest(nir_dest *dest, void *void_state)
+{
+   struct from_ssa_state *state = void_state;
+
+   if (dest->is_ssa) {
+      nir_register *reg = reg_create_from_def(&dest->ssa, state);
+      memset(dest, 0, sizeof *dest);
+      dest->reg.reg = reg;
+   }
+
+   return true;
+}
+
+static bool
+convert_from_ssa_block(nir_block *block, void *void_state)
+{
+   struct from_ssa_state *state = void_state;
+
+   nir_foreach_instr_safe(block, instr) {
+      if (instr->type == nir_instr_type_ssa_undef) {
+         nir_ssa_undef_instr *undef = nir_instr_as_ssa_undef(instr);
+         reg_create_from_def(&undef->def, state);
+         exec_node_remove(&instr->node);
+         ralloc_steal(state->dead_ctx, instr);
+      } else {
+         nir_foreach_src(instr, rewrite_ssa_src, state);
+         nir_foreach_dest(instr, rewrite_ssa_dest, state);
+      }
+   }
+
+   if (block->cf_node.node.next != NULL && /* check that we aren't the end node */
+       !nir_cf_node_is_last(&block->cf_node) &&
+       nir_cf_node_next(&block->cf_node)->type == nir_cf_node_if) {
+      nir_if *if_stmt = nir_cf_node_as_if(nir_cf_node_next(&block->cf_node));
+      rewrite_ssa_src(&if_stmt->condition, state);
+   }
+
+   return true;
+}
+
+static bool
+remove_phi_nodes(nir_block *block, void *void_state)
+{
+   struct from_ssa_state *state = void_state;
+
+   nir_foreach_instr_safe(block, instr) {
+      /* Phi nodes only ever come at the start of a block */
+      if (instr->type != nir_instr_type_phi)
+         break;
+
+      nir_foreach_dest(instr, rewrite_ssa_dest, state);
+
+      nir_phi_instr *phi = nir_instr_as_phi(instr);
+      foreach_list_typed(nir_phi_src, src, node, &phi->srcs) {
+         assert(src->src.is_ssa);
+         struct hash_entry *entry =
+            _mesa_hash_table_search(state->ssa_table, src->src.ssa);
+         nir_alu_instr *mov = nir_alu_instr_create(state->mem_ctx, nir_op_imov);
+         mov->dest.dest = nir_dest_copy(phi->dest, state->mem_ctx);
+         if (entry) {
+            nir_register *reg = (nir_register *)entry->data;
+            mov->src[0].src.reg.reg = reg;
+            mov->dest.write_mask = (1 << reg->num_components) - 1;
+         } else {
+            mov->src[0].src = nir_src_copy(src->src, state->mem_ctx);
+            mov->dest.write_mask = (1 << src->src.ssa->num_components) - 1;
+         }
+
+         nir_instr *block_end = nir_block_last_instr(src->pred);
+         if (block_end && block_end->type == nir_instr_type_jump) {
+            /* If the last instruction in the block is a jump, we want to
+             * place the moves after the jump.  Otherwise, we want to place
+             * them at the very end.
+             */
+            exec_node_insert_node_before(&block_end->node, &mov->instr.node);
+         } else {
+            exec_list_push_tail(&src->pred->instr_list, &mov->instr.node);
+         }
+      }
+
+      exec_node_remove(&instr->node);
+      ralloc_steal(state->dead_ctx, instr);
+   }
+
+   return true;
+}
+
+static void
+nir_convert_from_ssa_impl(nir_function_impl *impl)
+{
+   struct from_ssa_state state;
+
+   state.mem_ctx = ralloc_parent(impl);
+   state.dead_ctx = ralloc_context(NULL);
+   state.current_impl = impl;
+   state.ssa_table = _mesa_hash_table_create(NULL, _mesa_hash_pointer,
+                                             _mesa_key_pointer_equal);
+
+   nir_foreach_block(impl, remove_phi_nodes, &state);
+   nir_foreach_block(impl, convert_from_ssa_block, &state);
+
+   /* Clean up dead instructions and the hash table */
+   ralloc_free(state.dead_ctx);
+   _mesa_hash_table_destroy(state.ssa_table, NULL);
+}
+
+void
+nir_convert_from_ssa(nir_shader *shader)
+{
+   nir_foreach_overload(shader, overload) {
+      if (overload->impl)
+         nir_convert_from_ssa_impl(overload->impl);
+   }
+}