[Decompiler] WIP Conversion to SSA and variable naming (#195)

* begin ssa algorithm

* ssa based splitting appears to work

* add merge pass

* finish basic implementation

* better output

* bug fix

decompiler/IR2/Env.cpp

@@ -1,11 +1,10 @@
 #include <stdexcept>
+#include <unordered_set>
 #include "Env.h"
 
 namespace decompiler {
-std::string Env::get_variable_name(Register reg, int atomic_idx) const {
-  (void)reg;
-  (void)atomic_idx;
-  throw std::runtime_error("Env::get_variable_name not yet implemented.");
+std::string Env::get_variable_name(Register reg, int atomic_idx, VariableMode mode) const {
+  return m_var_names.lookup(reg, atomic_idx, mode).name();
 }
 
 /*!
@@ -17,4 +16,63 @@ void Env::set_types(const std::vector<TypeState>& block_init_types,
   m_op_end_types = op_end_types;
   m_has_types = true;
 }
+
+std::string Env::print_local_var_types() const {
+  assert(has_local_vars());
+  std::vector<std::string> entries;
+  std::unordered_map<Register, std::unordered_set<int>, Register::hash> printed;
+
+  for (auto& reg_info : m_var_names.read_vars) {
+    auto& reg_printed = printed[reg_info.first];
+    for (int var_id = 0; var_id < int(reg_info.second.size()); var_id++) {
+      auto& info = reg_info.second.at(var_id);
+      if (info.initialized) {
+        reg_printed.insert(var_id);
+        entries.push_back(fmt::format("{}: {}", info.name(), info.type.typespec().print()));
+      }
+    }
+  }
+
+  for (auto& reg_info : m_var_names.write_vars) {
+    auto& reg_printed = printed[reg_info.first];
+    for (int var_id = 0; var_id < int(reg_info.second.size()); var_id++) {
+      auto& info = reg_info.second.at(var_id);
+      if (info.initialized) {
+        if (reg_printed.find(var_id) == reg_printed.end()) {
+          entries.push_back(fmt::format("{}: {}", info.name(), info.type.typespec().print()));
+        }
+      }
+    }
+  }
+
+  int max_len = 0;
+  for (auto& entry : entries) {
+    if (int(entry.length()) > max_len) {
+      max_len = entry.length();
+    }
+  }
+
+  constexpr int row_len = 100;
+  int per_row = std::max(1, row_len / max_len);
+  int entry_len = 100 / per_row;
+
+  std::string result;
+
+  for (int entry_id = 0; entry_id < int(entries.size()); entry_id++) {
+    if ((entry_id % per_row) == 0) {
+      // onto a new line!
+      if (entry_id != 0) {
+        result += '\n';
+      }
+      result += ";; ";
+    }
+    result += ' ';
+    result += entries.at(entry_id);
+    result += std::string(std::max(0, entry_len - int(entries.at(entry_id).length())), ' ');
+  }
+
+  result += '\n';
+
+  return result;
+}
 }  // namespace decompiler