ready to start register allocation

Reports/5-bonus/report.md

+# Lab5 报告
+
+## 实验任务
+
+基于前4个实验，完成对LightIR的翻译，目标架构为龙芯LA64架构。
+
+## 实验流程
+
+1. 使用栈式内存分配，优先追求功能性
+   
+   这一步主要完成了指令选择，所有变量(local or global)均在栈中储存，参数通过栈传递。常量保存在只读区(模拟gcc)。
+   
+   这里对于phi指令的处理是：将phi指令还原为前驱块的`copy-statement`，需要将其插入在基本块的最后一条指令(跳转指令)之前。
+   
+   这一步可以完成所有测试样例，但是生成的代码效率较差。
+
+2. 活跃变量分析
+   
+   先确定指令的遍历顺序，这里使用常规的BFS遍历，phi指令的处理和上述相同，例如对于`5-while.ll`：
+   
+   ```llvm
+   define i32 @main() {
+   label_entry:
+     br label %label0
+   label0:                                                ; preds = %label_entry, %label5
+     %op1 = phi i32 [ 0, %label_entry ], [ %op6, %label5 ]
+     %op2 = icmp slt i32 %op1, 10
+     %op3 = zext i1 %op2 to i32
+     %op4 = icmp ne i32 %op3, 0
+     br i1 %op4, label %label5, label %label7
+   label5:                                                ; preds = %label0
+     call void @output(i32 %op1)
+     %op6 = add i32 %op1, 1
+     br label %label0
+   label7:                                                ; preds = %label0
+     ret i32 0
+   }
+   ```
+   
+   指令遍历顺序如下，第1条与第9条指令就是phi指令的还原。
+   
+   ```llvm
+   1. op1 = 0
+   2. br label %label0 
+   3. %op2 = icmp slt i32 %op1, 10 
+   4. %op3 = zext i1 %op2 to i32 
+   5. %op4 = icmp ne i32 %op3, 0 
+   6. br i1 %op4, label %label5, label %label7 
+   7. call void @output(i32 %op1) 
+   8. %op6 = add i32 %op1, 1 
+   9. op1 = op6
+   10. br label %label0 
+   11. ret i32 0 
+   ```
+   
+   用编号代替指令，获得每个程序点的IN和OUT：
+   
+   ```llvm
+   1. op1 = 0
+   	in-set: [ ]
+   	out-set: [ op1 ]
+   2. br label %label0 
+   	in-set: [ op1 ]
+   	out-set: [ op1 ]
+   3. %op2 = icmp slt i32 %op1, 10 
+   	in-set: [ op1 ]
+   	out-set: [ op2 op1 ]
+   4. %op3 = zext i1 %op2 to i32 
+   	in-set: [ op2 op1 ]
+   	out-set: [ op3 op1 ]
+   5. %op4 = icmp ne i32 %op3, 0 
+   	in-set: [ op3 op1 ]
+   	out-set: [ op4 op1 ]
+   6. br i1 %op4, label %label5, label %label7 
+   	in-set: [ op4 op1 ]
+   	out-set: [ op1 ]
+   7. call void @output(i32 %op1) 
+   	in-set: [ op1 ]
+   	out-set: [ op1 ]
+   8. %op6 = add i32 %op1, 1 
+   	in-set: [ op1 ]
+   	out-set: [ op6 ]
+   9. op1 = op6
+   	in-set: [ op6 ]
+   	out-set: [ op1 ]
+   10. br label %label0 
+   	in-set: [ op1 ]
+   	out-set: [ op1 ]
+   11. ret i32 0 
+   	in-set: [ ]
+   	out-set: [ ]
+   ```
+   
+   获得活跃区间：编号为i的指令，涉及两个端点：i-1和i，分别对应IN和OUT。由此得到各个变量的活跃区间是：
+   
+   ```llvm
+   op1: <1, 10>
+   op2: <3, 3>
+   op3: <4, 4>
+   op4: <5, 5>
+   op6: <8, 8>
+   ```
+
+3. 寄存器分配
+   
+   使用线性扫描算法实现寄存器分配，参考：
+   
+    - http://web.cs.ucla.edu/~palsberg/course/cs132/linearscan.pdf
+   
+    - [Documentations/5-bonus/寄存器分配.md · master · compiler_staff / 2022fall-Compiler_CMinus · GitLab](https://cscourse.ustc.edu.cn/vdir/Gitlab/compiler_staff/2022fall-compiler_cminus/-/blob/master/Documentations/5-bonus/%E5%AF%84%E5%AD%98%E5%99%A8%E5%88%86%E9%85%8D.md#poletto)
+   
+   

include/codegen/codegen.hpp

@@ -156,7 +156,7 @@ class CodeGen {
     vector<string> output;
 
     // register allocation
-    LiveRangeAnalyzer LRA;
+    LRA::LiveRangeAnalyzer LRA;
 };
 
 #endif

include/codegen/liverange.hpp

@@ -13,52 +13,75 @@
 #include <map>
 #include <set>
 #include <string>
+#include <utility>
+#include <vector>
 
 using std::map;
 using std::pair;
 using std::set;
 using std::string;
+using std::to_string;
 using std::vector;
 
 #define __LRA_PRINT__
 
+namespace LRA {
+
+struct Interval {
+    Interval(int a = 0, int b = 0) : i(a), j(b) {}
+    int i; // 0 means uninitialized
+    int j;
+};
+
+using LiveSet = set<Value *>;
+using PhiMap = map<BasicBlock *, vector<pair<Value *, Value *>>>;
+using LiveInterval = pair<Interval, Value *>;
+
+struct LiveIntervalCMP {
+    bool operator()(LiveInterval const &lhs, LiveInterval const &rhs) const {
+        if (lhs.first.i != rhs.first.i)
+            return lhs.first.i < rhs.first.i;
+        else
+            return lhs.second < rhs.second;
+    }
+};
+
 class LiveRangeAnalyzer {
+  public:
     friend class CodeGen;
-    using LiveSet = set<Value *>;
-    using PhiMap = map<BasicBlock *, vector<pair<Value *, Value *>>>;
 
-  public:
-    struct Interval {
-        Interval(int a, int b) : i(a), j(b) {}
-        Interval() = delete;
-        int i, j;
-    };
     LiveRangeAnalyzer(Module *m_, PhiMap &phi_map_)
         : m(m_), phi_map(phi_map_) {}
     LiveRangeAnalyzer() = delete;
 
     void run();
+    void run(Function *);
     void clear();
     void print(Function *func, bool printSet = true);
-    string print_liveSet(LiveSet &ls) {
+    string print_liveSet(const LiveSet &ls) {
         string s = "[ ";
         for (auto k : ls)
             s += k->get_name() + " ";
         s += "]";
         return s;
     }
+    string print_interval(Interval &i) {
+        return "<" + to_string(i.i) + ", " + to_string(i.j) + ">";
+    }
 
   private:
     Module *m;
     // Function *func;
-    map<Value *, Interval> liverange;
+    int ir_cnt;
     map<int, LiveSet> IN, OUT;
     map<Value *, int> instr_id;
     map<pair<Value *, Value *>, int> cpstmt_id;
     const PhiMap &phi_map;
+    set<LiveInterval, LiveIntervalCMP> liveIntervals;
 
     void make_id(Function *);
-    void run(Function *);
+    void make_interval(Function *);
+
     LiveSet joinFor(BasicBlock *bb);
     void union_ip(LiveSet &dest, LiveSet &src) {
         LiveSet res;
@@ -73,4 +96,5 @@ class LiveRangeAnalyzer {
     // Return: the in-set(will not set IN-map)
     LiveSet transferFunction(Instruction *);
 };
+} // namespace LRA
 #endif

src/cminusfc/cminusfc.cpp

@@ -34,7 +34,7 @@ main(int argc, char **argv) {
     bool gvn = false;
     bool dump_json = false;
     bool emit = false;
-    bool assembly = false;
+    bool assembly = true;
 
     for (int i = 1; i < argc; ++i) {
         if (argv[i] == "-h"s || argv[i] == "--help"s) {
@@ -128,7 +128,7 @@ main(int argc, char **argv) {
         std::ofstream target_file(target_path + ".s");
         target_file << codegen.print();
         target_file.close();
-        return 0;
+        // return 0;
     }
 
     std::ofstream output_stream;

src/codegen/liverange.cpp

@@ -6,15 +6,21 @@
 #include <algorithm>
 #include <iterator>
 
+using std::cout;
+using std::endl;
+using namespace LRA;
+
 void
 LiveRangeAnalyzer::clear() {
+    ir_cnt = 0;
     IN.clear();
     OUT.clear();
-    liverange.clear();
     instr_id.clear();
+    cpstmt_id.clear();
+    liveIntervals.clear();
 }
 
-LiveRangeAnalyzer::LiveSet
+LiveSet
 LiveRangeAnalyzer::joinFor(BasicBlock *bb) {
     LiveSet out;
     for (auto succ : bb->get_succ_basic_blocks()) {
@@ -24,9 +30,9 @@ LiveRangeAnalyzer::joinFor(BasicBlock *bb) {
             ++it;
         assert(it != irs.end() && "need to find first_ir from copy-stmt");
         union_ip(out, IN[instr_id.at(&(*it))]);
-        // std::cout << "# " + it->print() << std::endl;
+        // cout << "# " + it->print() << endl;
     }
-    // std::cout << "\tget out: " << print_liveSet(out) << std::endl;
+    // cout << "\tget out: " << print_liveSet(out) << endl;
     return out;
 }
 
@@ -35,7 +41,6 @@ LiveRangeAnalyzer::make_id(Function *func) {
     // instruction numbering
     // this is also the structure of the IR logically:
     // ignore phi, add copy-statement
-    int ir_cnt = 0;
     for (auto &bb : func->get_basic_blocks()) {
         for (auto &instr : bb.get_instructions()) {
             if (instr.is_phi())
@@ -125,12 +130,37 @@ LiveRangeAnalyzer::run(Function *func) {
             }
         }
     }
+    make_interval(func);
+
 #ifdef __LRA_PRINT__
     print(func);
 #endif
 }
 
-LiveRangeAnalyzer::LiveSet
+void
+LiveRangeAnalyzer::make_interval(Function *) {
+    map<Value *, Interval> liverange;
+    for (int time = 1; time <= ir_cnt; ++time) {
+        for (auto op : IN.at(time)) {
+            auto &interval = liverange[op];
+            if (interval.i == 0) // uninitialized
+                interval.i = time - 1;
+            else
+                interval.j = time - 1;
+        }
+        for (auto op : OUT.at(time)) {
+            auto &interval = liverange[op];
+            if (interval.i == 0) // uninitialized
+                interval.i = time;
+            else
+                interval.j = time;
+        }
+    }
+    for (auto [op, interval] : liverange)
+        liveIntervals.insert({interval, op});
+}
+
+LiveSet
 LiveRangeAnalyzer::transferFunction(Instruction *instr) {
     LiveSet in, out = OUT[instr_id.at(instr)];
     LiveSet use;
@@ -165,6 +195,7 @@ LiveRangeAnalyzer::transferFunction(Instruction *instr) {
 
 void
 LiveRangeAnalyzer::print(Function *func, bool printSet) { // for debug
+    cout << "Function " << func->get_name() << endl;
     for (auto &bb : func->get_basic_blocks()) {
         for (auto &instr : bb.get_instructions()) {
             if (instr.is_phi()) // ignore phi
@@ -175,44 +206,33 @@ LiveRangeAnalyzer::print(Function *func, bool printSet) { // for debug
                 for (auto pr : phi_map.find(&bb)->second) {
                     auto [lv, rv] = pr;
                     auto idx = cpstmt_id.at(pr);
-                    std::cout
-                        << cpstmt_id[pr] << ". " << lv->get_name() << " = "
-                        << (rv->get_name() == "" ? rv->print() : rv->get_name())
-                        << std::endl;
+                    cout << cpstmt_id[pr] << ". " << lv->get_name() << " = "
+                         << (rv->get_name() == "" ? rv->print()
+                                                  : rv->get_name())
+                         << endl;
                     if (not printSet)
                         continue;
                     auto &in = IN.at(idx);
                     auto &out = OUT.at(idx);
-                    std::cout << "\tin-set: " + print_liveSet(in) << "\n";
-                    std::cout << "\tout-set: " + print_liveSet(out) << "\n";
+                    cout << "\tin-set: " + print_liveSet(in) << "\n";
+                    cout << "\tout-set: " + print_liveSet(out) << "\n";
                 }
             }
             // normal ir
-            std::cout << instr_id[&instr] << ". " << instr.print() << " # "
-                      << &instr << std::endl;
+            cout << instr_id[&instr] << ". " << instr.print() << " # " << &instr
+                 << endl;
             if (not printSet)
                 continue;
             auto idx = instr_id.at(&instr);
             auto &in = IN.at(idx);
             auto &out = OUT.at(idx);
-            std::cout << "\tin-set: " + print_liveSet(in) << "\n";
-            std::cout << "\tout-set: " + print_liveSet(out) << "\n";
-        }
-        /* if (phi_map.find(&bb) != phi_map.end()) {
-         *     for (auto pr : phi_map.find(&bb)->second) {
-         *         auto [lv, rv] = pr;
-         *         auto idx = cpstmt_id.at(pr);
-         *         std::cout << cpstmt_id[pr] << ". " << lv->get_name() << " = "
-         *                   << (rv->get_name() == "" ? rv->print()
-         *                                            : rv->get_name())
-         *                   << std::endl;
-         *         if (not printSet)
-         *             continue;
-         *         auto &in = IN.at(idx);
-         *         auto &out = OUT.at(idx);
-         *         std::cout << "\tin-set: " + print_liveSet(in) << "\n";
-         *         std::cout << "\tout-set: " + print_liveSet(out) << "\n";
-         *     }
-         * } */
+            cout << "\tin-set: " + print_liveSet(in) << "\n";
+            cout << "\tout-set: " + print_liveSet(out) << "\n";
+        }
+    }
+
+    if (printSet) {
+        for (auto [interval, op] : liveIntervals)
+            cout << op->get_name() << ": " << print_interval(interval) << endl;
     }
 }

tests/5-bonus/test_time.py

@@ -68,7 +68,7 @@ def eval(console=False, test_dir=testfile_dir, use_clang=False):
         if not use_clang:
             try:
                 # ===可修改===
-                compile_res = subprocess.run([cminus, filepath, '-S', 'a.s'],
+                compile_res = subprocess.run([cminus, '-mem2reg', filepath, '-S',  'a.s'],
                                              stdout=subprocess.PIPE,
                                              stderr=subprocess.PIPE,
                                              timeout=300)