write phi elimination

include/IR/IR_basic.h

@@ -89,17 +89,9 @@ class BRAction : public JMPActionItem {
   }
 };
 class UNConditionJMPAction : public JMPActionItem {
-  friend class IRBuilder;
+ public:
-  friend class FunctionDefItem;
-  friend void GenerateNaiveASM(std::ostream &os, std::shared_ptr<ModuleItem> prog);
-  friend void NaiveBackend::GenerateASM(std::shared_ptr<ActionItem> act, std::vector<std::string> &code_lines,
-                                        NaiveBackend::FuncLayout &layout,
-                                        const std::unordered_map<std::string, IRClassInfo> &low_level_class_info,
-                                        bool process_phi);
-  friend class CFGType BuildCFGForFunction(const std::shared_ptr<class FunctionDefItem> &func);
   std::string label_full;
 
- public:
   UNConditionJMPAction() = default;
   void RecursivePrint(std::ostream &os) const { os << "br label %" << label_full << "\n"; }
 };
@@ -492,10 +484,7 @@ class ConstStrItem : public LLVMIRItemBase {
   }
 };
 class ModuleItem : public LLVMIRItemBase {
-  friend class IRBuilder;
+ public:
-  friend std::shared_ptr<ModuleItem> BuildIR(std::shared_ptr<Program_ASTNode> src);
-  friend void GenerateNaiveASM(std::ostream &os, std::shared_ptr<ModuleItem> prog);
-  friend std::shared_ptr<ModuleItem> Mem2Reg(std::shared_ptr<ModuleItem> src);
   std::vector<std::shared_ptr<ConstStrItem>> const_strs;
   std::vector<std::shared_ptr<FunctionDeclareItem>> function_declares;
   std::vector<std::shared_ptr<TypeDefItem>> type_defs;
@@ -503,7 +492,6 @@ class ModuleItem : public LLVMIRItemBase {
   std::vector<std::shared_ptr<FunctionDefItem>> function_defs;
   std::unordered_map<std::string, IRClassInfo> low_level_class_info;
 
- public:
   ModuleItem() = default;
   void RecursivePrint(std::ostream &os) const {
     for (auto &item : const_strs) {

include/opt/cfg.h

@@ -8,8 +8,10 @@
 using CFGNodeCollection = std::list<class CFGNodeType *>;
 class CFGNodeType {
  public:
+  // successors, predecessors, corresponding_block is provided by BuildCFGForFunction
   std::vector<CFGNodeType *> successors, predecessors;
   BlockItem *corresponding_block;
+  // the following fields are provided by user
   CFGNodeCollection dom;
   bool visited;
   CFGNodeType *idom;

include/opt/opt.h

@@ -1,2 +1,3 @@
-#include "mem2reg.h"
 #include "cfg.h"
+#include "mem2reg.h"
+#include "regalloc.h"

include/opt/phieliminate.h

@@ -0,0 +1,18 @@
+#pragma once
+#include "IR/IR_basic.h"
+#include "cfg.h"
+
+namespace opt {
+class MoveInstruct : public ActionItem {
+ public:
+  std::string src_full;
+  std::string dest_full;
+  MoveInstruct() = default;
+  void RecursivePrint(std::ostream &os) const {
+    throw std::runtime_error("Move instruction is not an actual LLVM IR instruction");
+  }
+};
+}  // namespace opt
+
+
+std::shared_ptr<ModuleItem> PhiEliminate(std::shared_ptr<ModuleItem> src);

include/opt/regalloc.h

@@ -0,0 +1,2 @@
+#pragma once
+#include "phieliminate.h"

src/main.cpp

@@ -46,7 +46,8 @@ int main(int argc, char **argv) {
       GenerateNaiveASM(fout, IR);
     } else {
       auto IR_with_out_allocas = Mem2Reg(IR);
-      IR_with_out_allocas->RecursivePrint(fout);
+      // IR_with_out_allocas->RecursivePrint(fout);
+      auto IR_with_out_phis = PhiEliminate(IR_with_out_allocas);
     }
   } catch (const SemanticError &err) {
     std::cout << err.what() << std::endl;

src/opt/phieliminate.cpp

@@ -0,0 +1,72 @@
+#include "phieliminate.h"
+#include <stdexcept>
+#include "IR/IR_basic.h"
+
+using namespace opt;
+
+void ConductPhiEliminateForFunction([[maybe_unused]] std::shared_ptr<FunctionDefItem> func, CFGType &cfg) {
+  size_t new_block_cnt = 0;
+  for (auto cur_node : cfg.nodes) {
+    auto cur_block = cur_node->corresponding_block;
+    if (cur_block->actions.size() > 0) {
+      if (auto phi_act = std::dynamic_pointer_cast<PhiItem>(cur_block->actions[0])) {
+        // simple phi action caused by and, or and ternary operator, no need to insert extra blocks, just remove it and
+        // add phi values to the corresponding blocks
+        cur_block->actions.erase(cur_block->actions.begin());
+        for (auto [src_val, src_label] : phi_act->values) {
+          auto src_block = cfg.label_to_block[src_label];
+          auto new_move = std::make_shared<MoveInstruct>();
+          new_move->src_full = src_val;
+          new_move->dest_full = phi_act->result_full;
+          src_block->actions.push_back(new_move);
+        }
+      }
+    }
+    for (auto [_, phi_act] : cur_block->phi_map) {
+      for (auto [src_val, src_label] : phi_act->values) {
+        auto src_block = cfg.label_to_block[src_label];
+        auto src_node = cfg.block_to_node[src_block];
+        if (src_node->successors.size() > 1 && cur_node->predecessors.size() > 1) {
+          // it is a critical edge, need to insert a new block
+          auto new_block = std::make_shared<BlockItem>();
+          new_block->label_full = cur_block->label_full + ".phieliminate." + std::to_string(new_block_cnt++);
+          new_block->exit_action = std::make_shared<UNConditionJMPAction>();
+          std::dynamic_pointer_cast<UNConditionJMPAction>(new_block->exit_action)->label_full = cur_block->label_full;
+          auto src_block_exit_action = std::dynamic_pointer_cast<BRAction>(src_block->exit_action);
+          if (!src_block_exit_action) {
+            throw std::runtime_error(
+                "something strange happened: src block of a critical edge does not have a BRAction");
+          }
+          if (src_block_exit_action->true_label_full == cur_block->label_full) {
+            src_block_exit_action->true_label_full = new_block->label_full;
+          } else if (src_block_exit_action->false_label_full == cur_block->label_full) {
+            src_block_exit_action->false_label_full = new_block->label_full;
+          } else {
+            throw std::runtime_error(
+                "something strange happened: src block of a critical edge cannot find the corresponding label");
+          }
+          auto new_move = std::make_shared<MoveInstruct>();
+          new_move->src_full = src_val;
+          new_move->dest_full = phi_act->result_full;
+          new_block->actions.push_back(new_move);
+        } else {
+          auto new_move = std::make_shared<MoveInstruct>();
+          new_move->src_full = src_val;
+          new_move->dest_full = phi_act->result_full;
+          cur_block->actions.push_back(new_move);
+        }
+      }
+    }
+    cur_block->phi_map.clear();
+  }
+}
+
+std::shared_ptr<ModuleItem> PhiEliminate(std::shared_ptr<ModuleItem> src) {
+  auto res = src;
+  for (auto &func : res->function_defs) {
+    // func = std::make_shared<FunctionDefItem>(*func);
+    auto cfg = BuildCFGForFunction(func);
+    ConductPhiEliminateForFunction(func, cfg);
+  }
+  return res;
+}

src/opt/regalloc.cpp

@@ -0,0 +1 @@
+#include "regalloc.h"