Sketch out an CFG reconstruction mode for llvm-objdump.

- Not great yet, but it's a start.
- Requires an object file with a symbol table. (I really want to fix this, but it'll need a whole new algorithm)
- ELF and COFF won't work at the moment due to libObject shortcomings.

To try it out run
$ llvm-objdump -d --cfg foo.o

This will create a graphviz file for every symbol in the object file's text section containing a CFG.

llvm-svn: 135608

1 files changed, 88 insertions, 0 deletions

diff --git a/llvm/tools/llvm-objdump/MCFunction.h b/llvm/tools/llvm-objdump/MCFunction.h
new file mode 100644
index 00000000000..60f64292092
--- /dev/null
+++ b/llvm/tools/llvm-objdump/MCFunction.h
@@ -0,0 +1,88 @@
+//===-- MCFunction.h ------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the data structures to hold a CFG reconstructed from
+// machine code.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/MC/MCInst.h"
+#include <map>
+
+namespace llvm {
+
+class MCDisassembler;
+class MCInstrInfo;
+class MemoryObject;
+class raw_ostream;
+
+/// MCDecodedInst - Small container to hold an MCInst and associated info like
+/// address and size.
+struct MCDecodedInst {
+  uint64_t Address;
+  uint64_t Size;
+  MCInst Inst;
+
+  MCDecodedInst(uint64_t Address, uint64_t Size, MCInst Inst)
+    : Address(Address), Size(Size), Inst(Inst) {}
+};
+
+/// MCBasicBlock - Consists of multiple MCDecodedInsts and a list of successing
+/// MCBasicBlocks.
+class MCBasicBlock {
+  SmallVector<MCDecodedInst, 8> Insts;
+  typedef SmallPtrSet<MCBasicBlock*, 8> SetTy;
+  SetTy Succs;
+public:
+  ArrayRef<MCDecodedInst> getInsts() const { return Insts; }
+
+  typedef SetTy::const_iterator succ_iterator;
+  succ_iterator succ_begin() const { return Succs.begin(); }
+  succ_iterator succ_end() const { return Succs.end(); }
+
+  void addInst(const MCDecodedInst &Inst) { Insts.push_back(Inst); }
+  void addSucc(MCBasicBlock *BB) { Succs.insert(BB); }
+};
+
+/// MCFunction - Represents a named function in machine code, containing
+/// multiple MCBasicBlocks.
+class MCFunction {
+  const StringRef Name;
+  // Keep BBs sorted by address.
+  typedef std::map<uint64_t, MCBasicBlock> MapTy;
+  MapTy Blocks;
+public:
+  MCFunction(StringRef Name) : Name(Name) {}
+
+  // Create an MCFunction from a region of binary machine code.
+  static MCFunction
+  createFunctionFromMC(StringRef Name, const MCDisassembler *DisAsm,
+                       const MemoryObject &Region, uint64_t Start, uint64_t End,
+                       const MCInstrInfo *InstrInfo, raw_ostream &DebugOut);
+
+  typedef MapTy::iterator iterator;
+  iterator begin() { return Blocks.begin(); }
+  iterator end() { return Blocks.end(); }
+
+  StringRef getName() const { return Name; }
+
+  MCBasicBlock &addBlock(uint64_t Address, const MCBasicBlock &BB) {
+    assert(!Blocks.count(Address) && "Already a BB at address.");
+    return Blocks[Address] = BB;
+  }
+
+  MCBasicBlock &getBlockAtAddress(uint64_t Address) {
+    assert(Blocks.count(Address) && "No BB at address.");
+    return Blocks[Address];
+  }
+};
+
+}