feat: plan for register allocation + temp fix for 'E' not being printed

TODO.md

@@ -0,0 +1,20 @@
+
+0. Define how many physical regs are available, which are caller-saved and callee-saved
+1. Implement if-else and while statements
+2. Find out what use[B] and def[B] are for each block
+3. Define successors and predecessors of each block and make them accessible
+4. Compute liveIn[B] and liveOut[B] for each block
+  
+  Classic equations:
+
+  liveIn[B] = use[B] ∪ (liveOut[B] - def[B])
+
+  liveOut[B] = ⋃ liveIn[S] for S in succ[B]
+5. Linear scan register allocation
+
+
+- Instruction numbering + per-instruction liveness
+- Live intervals
+- Linear scan allocator with ~6 fake regs
+- Spill to stack slots
+- Add “CALL clobbers regs” rule

include/codegen/fasm_stack.hpp

@@ -8,6 +8,7 @@ class StackFasmX86_64Generator : public CodeGenerator
 {
 public:
     ~StackFasmX86_64Generator() override = default;
+
 private:
     StringView GetTempAddr(IR::Value reg)
     {
@@ -21,19 +22,22 @@ private:
         case IR::IRSlot::Type::REGISTRY:
         {
             StringBuilder sb;
-            sb.AppendFormat("r%d", slot.GetSlot() + 10); // for r10, r11, r12 etc.
+            sb.AppendFormat("r%d", slot.GetSlot() + 12); // for r10, r11, r12 etc.
             return sb.view();
-        } break;
+        }
+        break;
         case IR::IRSlot::Type::STACK:
         {
             StringBuilder sb;
             sb.AppendFormat("[rbp-%d]", slot.GetSlot()); // for r10, r11, r12 etc.
             return sb.view();
-        } break;
+        }
+        break;
         default:
             assert(0 && "TODO: either unreachable or handle properly");
         }
     }
+
 private:
     void GenerateOp(const IR::Op *op)
     {
@@ -135,7 +139,9 @@ private:
             appendf("mov %s, rax\n", GetSlotAddr(result_slot).c_str());
         }
         break;
-        default: appendf("; NOT HANDLED\n; %s\n", op->Format(0).c_str()); break;
+        default:
+            appendf("; NOT HANDLED\n; %s\n", op->Format(0).c_str());
+            break;
         }
     }
 
@@ -147,10 +153,13 @@ private:
         m_output->VAppendFormat(fmt, args);
         va_end(args);
     }
+
 public:
     StringView GetOutput() { return m_output->view(); }
+
 private:
     StringBuilder *m_output = nullptr;
+
 public:
     void Generate(const char *filename, View<IR::Op *> ops) override
     {
@@ -164,6 +173,7 @@ public:
             GenerateOp(op);
         }
     }
+
 public:
     // StackAllocator* m_stack = nullptr;
     // TODO: handle sub-blocks

src/main.cpp

@@ -1,5 +1,7 @@
 #include <iostream>
 #include <fstream>
+#include <cstdio>
+#include <cstdlib>
 #include <print>
 #include "parser/lexer.hpp"
 #include "parser/ast.hpp"
@@ -9,7 +11,8 @@
 
 void dump_tokens(const char *filename, Lexer *lexer)
 {
-    while (lexer->NextToken()) {
+    while (lexer->NextToken())
+    {
         std::print("{}:{}:{}: ", filename, lexer->token().line_number, lexer->token().offset_start);
         if (lexer->token().token == TokenType::Id)
             std::println("id = {}", lexer->token().string);
@@ -23,15 +26,19 @@ void dump_tokens(const char* filename, Lexer* lexer)
 int main(int argc, char **argv)
 {
     char *filename;
-    if (argc > 1) {
+    if (argc > 1)
+    {
         filename = (++argv)[0];
-    } else {
+    }
+    else
+    {
         fprintf(stderr, "ERROR: Input file is required.\n");
         return 1;
     }
 
     std::ifstream f(filename);
-    if (!f.is_open()) {
+    if (!f.is_open())
+    {
         fprintf(stderr, "ERROR: Failed to open input file: %s\n", filename);
         return 1;
     }
@@ -55,11 +62,20 @@ int main(int argc, char** argv)
         printf("%s\n", ops.data[i]->Format(0).c_str());
     }
 
-    // StackFasmX86_64Generator gen;
+    StackFasmX86_64Generator gen;
 
-    // gen.Generate(filename, ops);
+    gen.Generate(filename, ops);
 
-    // printf("%s\n", gen.GetOutput().c_str());
+    StringView output = gen.GetOutput();
+
+    FILE *file = fopen("out.asm", "w");
+
+    fwrite(output.c_str(), output.size - 1, sizeof(char), file);
+
+    fclose(file);
+
+    system("fasm out.asm");
+    system("gcc -o out out.o");
 
     return 0;
 }