SPIR-V: WIP shader compiler / optimizations / alpha test implementation

src/xenia/gpu/spirv/passes/control_flow_analysis_pass.cpp

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+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2016 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include "xenia/gpu/spirv/passes/control_flow_analysis_pass.h"
+
+namespace xe {
+namespace gpu {
+namespace spirv {
+
+ControlFlowAnalysisPass::ControlFlowAnalysisPass() {}
+
+bool ControlFlowAnalysisPass::Run(spv::Module* module) {
+  for (auto function : module->getFunctions()) {
+    // For each OpBranchConditional, see if we can find a point where control
+    // flow converges and then append an OpSelectionMerge.
+    // Potential problems: while loops constructed from branch instructions
+  }
+
+  return true;
+}
+
+}  // namespace spirv
+}  // namespace gpu
+}  // namespace xe

src/xenia/gpu/spirv/passes/control_flow_analysis_pass.h

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+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2016 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_GPU_SPIRV_PASSES_CONTROL_FLOW_ANALYSIS_PASS_H_
+#define XENIA_GPU_SPIRV_PASSES_CONTROL_FLOW_ANALYSIS_PASS_H_
+
+#include "xenia/gpu/spirv/compiler_pass.h"
+
+namespace xe {
+namespace gpu {
+namespace spirv {
+
+// Control-flow analysis pass. Runs through control-flow and adds merge opcodes
+// where necessary.
+class ControlFlowAnalysisPass : public CompilerPass {
+ public:
+  ControlFlowAnalysisPass();
+
+  bool Run(spv::Module* module) override;
+
+ private:
+};
+
+}  // namespace spirv
+}  // namespace gpu
+}  // namespace xe
+
+#endif  // XENIA_GPU_SPIRV_PASSES_CONTROL_FLOW_ANALYSIS_PASS_H_

src/xenia/gpu/spirv/passes/control_flow_simplification_pass.cc

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+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2016 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include "xenia/gpu/spirv/passes/control_flow_simplification_pass.h"
+
+namespace xe {
+namespace gpu {
+namespace spirv {
+
+ControlFlowSimplificationPass::ControlFlowSimplificationPass() {}
+
+bool ControlFlowSimplificationPass::Run(spv::Module* module) {
+  for (auto function : module->getFunctions()) {
+    // Walk through the blocks in the function and merge any blocks which are
+    // unconditionally dominated.
+    for (auto it = function->getBlocks().end() - 1;
+         it != function->getBlocks().begin() - 1;) {
+      auto block = *it;
+      if (!block->isUnreachable() && block->getPredecessors().size() == 1) {
+        auto prev_block = block->getPredecessors()[0];
+        auto last_instr =
+            prev_block->getInstruction(prev_block->getInstructionCount() - 1);
+        if (last_instr->getOpCode() == spv::Op::OpBranch) {
+          if (prev_block->getSuccessors().size() == 1 &&
+              prev_block->getSuccessors()[0] == block) {
+            // We're dominated by this block. Merge into it.
+            prev_block->merge(block);
+            block->setUnreachable();
+          }
+        }
+      }
+
+      --it;
+    }
+  }
+
+  return true;
+}
+
+}  // namespace spirv
+}  // namespace gpu
+}  // namespace xe

src/xenia/gpu/spirv/passes/control_flow_simplification_pass.h

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+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2016 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_GPU_SPIRV_PASSES_CONTROL_FLOW_SIMPLIFICATION_PASS_H_
+#define XENIA_GPU_SPIRV_PASSES_CONTROL_FLOW_SIMPLIFICATION_PASS_H_
+
+#include "xenia/gpu/spirv/compiler_pass.h"
+
+namespace xe {
+namespace gpu {
+namespace spirv {
+
+// Control-flow simplification pass. Combines adjacent blocks and marks
+// any unreachable blocks.
+class ControlFlowSimplificationPass : public CompilerPass {
+ public:
+  ControlFlowSimplificationPass();
+
+  bool Run(spv::Module* module) override;
+
+ private:
+};
+
+}  // namespace spirv
+}  // namespace gpu
+}  // namespace xe
+
+#endif  // XENIA_GPU_SPIRV_PASSES_CONTROL_FLOW_SIMPLIFICATION_PASS_H_