1 files changed, 208 insertions, 0 deletions
diff --git a/examples/BFtoLLVM/BFtoLLVM.cpp b/examples/BFtoLLVM/BFtoLLVM.cpp
new file mode 100644
index 0000000000..b870676fb8
--- /dev/null
+++ b/examples/BFtoLLVM/BFtoLLVM.cpp
@@ -0,0 +1,208 @@
+//===-- BFtoLLVM.cpp - BF language Front End for LLVM ---------------------===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This is a simple front end for the BF language.  It is compatible with the
+// language as described in "The BrainF*** Language Specification (01 January
+// 2002)", which is available from http://esoteric.sange.fi/ENSI . It does not
+// implement the optional keyword # ("Output partial tape state").
+//
+//===----------------------------------------------------------------------===//
+
+#include <iostream>
+#include <vector>
+#include <fstream>
+#include <cerrno>
+#include <cstring>
+#include <string>
+#include <cstdio>
+#include <cassert>
+
+void emitDeclarations(std::ofstream &dest) {
+  dest << "; This assembly code brought to you by BFtoLLVM\n"
+       << "\nimplementation\n"
+       << "\n; Declarations\n"
+       << "\ndeclare int %getchar()\n"
+       << "declare int %putchar(int)\n"
+       << "declare void %llvm.memset(sbyte*, ubyte, uint, uint)\n"
+       << "\n";
+}
+
+void emitMainFunctionProlog(std::ofstream &dest) {
+  dest << "\n; Main function\n"
+       << "int %main(int %argc, sbyte** %argv) {\n"
+       << "\nentry:\n"
+       << "%arr = alloca sbyte, uint 30000\n"
+       << "call void (sbyte*, ubyte, uint, uint)* %llvm.memset(sbyte* %arr, ubyte 0, uint 30000, uint 1)\n"
+       << "%ptrbox = alloca sbyte*\n"
+       << "store sbyte* %arr, sbyte **%ptrbox\n"
+       << "\n";
+}
+
+void emitMainFunctionEpilog(std::ofstream &dest) {
+  dest << "ret int 0\n"
+       << "}\n";
+}
+
+std::string gensym (const std::string varName, bool percent = true) {
+  char buf[80];
+  static unsigned int SymbolCounter = 0;
+  sprintf (buf, "%s%s%u", percent ? "%" : "", varName.c_str(), SymbolCounter++);
+  return std::string (buf);
+}
+
+void emitArith (std::string op, char delta, std::ofstream &dest) {
+  std::string ptr = gensym (op + "ptr"),
+	      val = gensym (op + "val"),
+	      result = gensym (op + "result");
+  dest << ptr << " = load sbyte** %ptrbox\n" 
+       << val << " = load sbyte* " << ptr << "\n"
+       << result << " = add sbyte " << val << ", " << (int)delta << "\n"
+       << "store sbyte " << result << ", sbyte* " << ptr << "\n";
+}
+
+// + becomes ++*p; and - becomes --*p;
+void emitPlus  (std::ofstream &dest, int ct) { emitArith ("plus",  +ct, dest); }
+void emitMinus (std::ofstream &dest, int ct) { emitArith ("minus", -ct, dest); }
+
+void emitLoadAndCast (std::string ptr, std::string val, std::string cast,
+                      std::string type, std::ofstream &dest) {
+  dest << ptr << " = load sbyte** %ptrbox\n"
+       << val << " = load sbyte* " << ptr << "\n"
+       << cast << " = cast sbyte " << val << " to " << type << "\n";
+}
+
+// , becomes *p = getchar();
+void emitComma(std::ofstream &dest, int ct) {
+  assert (ct == 1);
+  std::string ptr = gensym("commaptr"), read = gensym("commaread"),
+              cast = gensym("commacast");
+  dest << ptr << " = load sbyte** %ptrbox\n"
+       << read << " = call int %getchar()\n"
+       << cast << " = cast int " << read << " to sbyte\n"
+       << "store sbyte " << cast << ", sbyte* " << ptr << "\n";
+}
+
+// . becomes putchar(*p);
+void emitDot(std::ofstream &dest, int ct) {
+  assert (ct == 1);
+  std::string ptr = gensym("dotptr"), val = gensym("dotval"),
+              cast = gensym("dotcast");
+  emitLoadAndCast (ptr, val, cast, "int", dest);
+  dest << "call int %putchar(int " << cast << ")\n";
+}
+
+void emitPointerArith(std::string opname, int delta, std::ofstream &dest) {
+  std::string ptr = gensym(opname + "ptr"), result = gensym(opname + "result");
+  dest << ptr << " = load sbyte** %ptrbox\n"
+       << result << " = getelementptr sbyte* " << ptr << ", int " << delta
+       << "\n"
+       << "store sbyte* " << result << ", sbyte** %ptrbox\n";
+}
+
+// < becomes --p; and > becomes ++p;
+void emitLT(std::ofstream &dest, int ct) { emitPointerArith ("lt", -ct, dest); }
+void emitGT(std::ofstream &dest, int ct) { emitPointerArith ("gt", +ct, dest); }
+
+static std::vector<std::string> whileStack;
+
+// [ becomes while (*p) {
+void emitLeftBracket(std::ofstream &dest, int ct) {
+  assert (ct == 1);
+  std::string whileName = gensym ("While", false);
+  whileStack.push_back (whileName);
+  dest << "br label %testFor" << whileName << "\n"
+       << "\ninside" << whileName << ":\n";
+}
+
+// ] becomes }
+void emitRightBracket(std::ofstream &dest, int ct) {
+  assert (ct == 1);
+  std::string whileName = whileStack.back (),
+              ptr = gensym("bracketptr"),
+              val = gensym("bracketval"),
+              cast = gensym("bracketcast");
+  whileStack.pop_back ();
+  dest << "br label %testFor" << whileName << "\n"
+       << "\ntestFor" << whileName << ":\n";
+  emitLoadAndCast (ptr, val, cast, "bool", dest);
+  dest << "br bool " << cast << ", label %inside" << whileName << ", "
+       << "label %after" << whileName << "\n"
+       << "\nafter" << whileName << ":\n";
+}
+
+typedef void (*FuncTy)(std::ofstream &, int);
+static FuncTy table[256];
+static bool multi[256];
+
+void consume (int ch, int repeatCount, std::ofstream &dest) {
+  FuncTy func = table[ch];
+  if (!func)
+    return;
+  else if (multi[ch])
+    func (dest, repeatCount);
+  else
+    for (int i = 0; i < repeatCount; ++i)
+      func (dest, 1);
+}
+
+void initializeTable() {
+  memset (table, 0, 256);
+  memset (multi, 0, 256);
+  table[(int)'+'] = emitPlus;          multi[(int)'+'] = true;
+  table[(int)'-'] = emitMinus;         multi[(int)'-'] = true;
+  table[(int)','] = emitComma;         multi[(int)','] = false;
+  table[(int)'.'] = emitDot;           multi[(int)'.'] = false;
+  table[(int)'<'] = emitLT;            multi[(int)'<'] = true;
+  table[(int)'>'] = emitGT;            multi[(int)'>'] = true;
+  table[(int)'['] = emitLeftBracket;   multi[(int)'['] = false;
+  table[(int)']'] = emitRightBracket;  multi[(int)']'] = false;
+}
+
+int main (int argc, char **argv) {
+  if (argc != 3) {
+    std::cerr << "usage: " << argv[0] << " input-source output-llvm\n";
+    return 1;
+  }
+
+  char *sourceFileName = argv[1];
+  char *destFileName = argv[2];
+  
+  std::ifstream src (sourceFileName);
+  if (!src.good()) {
+    std::cerr << sourceFileName << ": " << strerror(errno) << "\n";
+    return 1;
+  }
+
+  std::ofstream dest (destFileName);
+  if (!dest.good()) {
+    std::cerr << destFileName << ": " << strerror(errno) << "\n";
+    return 1;
+  }
+  
+  emitDeclarations(dest);
+  emitMainFunctionProlog(dest);
+
+  initializeTable();
+  char ch, lastCh;
+  src >> lastCh;
+  int repeatCount = 1;
+  for (src >> ch; !src.eof (); src >> ch, ++repeatCount)
+    if (ch != lastCh) {
+      consume (lastCh, repeatCount, dest);
+      lastCh = ch;
+      repeatCount = 0;
+    }
+  consume (lastCh, repeatCount, dest);
+  
+  emitMainFunctionEpilog(dest);
+
+  src.close();
+  dest.close();
+  return 0;
+}