1 files changed, 102 insertions, 0 deletions
diff --git a/src/amd/compiler/aco_dead_code_analysis.cpp b/src/amd/compiler/aco_dead_code_analysis.cpp
new file mode 100644
index 00000000000..f56718f0479
--- /dev/null
+++ b/src/amd/compiler/aco_dead_code_analysis.cpp
@@ -0,0 +1,102 @@
+/*
+ * Copyright © 2019 Valve 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 "aco_ir.h"
+
+#include <algorithm>
+
+/*
+ * Implements an analysis pass to determine the number of uses
+ * for each SSA-definition.
+ */
+
+namespace aco {
+namespace {
+
+struct dce_ctx {
+   int current_block;
+   std::vector<uint16_t> uses;
+   std::vector<std::vector<bool>> live;
+
+   dce_ctx(Program* program) : current_block(program->blocks.size() - 1), uses(program->peekAllocationId())
+   {
+      live.reserve(program->blocks.size());
+      for (Block& block : program->blocks)
+         live.emplace_back(block.instructions.size());
+   }
+};
+
+void process_block(dce_ctx& ctx, Block& block)
+{
+   std::vector<bool>& live = ctx.live[block.index];
+   assert(live.size() == block.instructions.size());
+   bool process_predecessors = false;
+   for (int idx = block.instructions.size() - 1; idx >= 0; idx--) {
+      if (live[idx])
+         continue;
+
+      aco_ptr<Instruction>& instr = block.instructions[idx];
+      const bool is_live = instr->definitions.empty() ||
+                           std::any_of(instr->definitions.begin(), instr->definitions.end(),
+                              [&ctx] (const Definition& def) { return !def.isTemp() || ctx.uses[def.tempId()];});
+
+      if (is_live) {
+         for (const Operand& op : instr->operands) {
+            if (op.isTemp()) {
+               if (ctx.uses[op.tempId()] == 0)
+                  process_predecessors = true;
+               ctx.uses[op.tempId()]++;
+            }
+         }
+         live[idx] = true;
+      }
+   }
+
+   if (process_predecessors) {
+      for (unsigned pred_idx : block.linear_preds)
+         ctx.current_block = std::max(ctx.current_block, (int) pred_idx);
+   }
+}
+
+} /* end namespace */
+
+std::vector<uint16_t> dead_code_analysis(Program *program) {
+
+   dce_ctx ctx(program);
+
+   while (ctx.current_block >= 0) {
+      unsigned next_block = ctx.current_block--;
+      process_block(ctx, program->blocks[next_block]);
+   }
+
+   /* add one use to exec to prevent startpgm from being removed */
+   aco_ptr<Instruction>& startpgm = program->blocks[0].instructions[0];
+   assert(startpgm->opcode == aco_opcode::p_startpgm);
+   ctx.uses[startpgm->definitions.back().tempId()]++;
+
+   return ctx.uses;
+}
+
+}
+