From aa7906815724171e3f81d71fb9b12fd13b845311 Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed.bougacha@gmail.com>
Date: Fri, 24 May 2013 01:07:04 +0000
Subject: MC: Disassembled CFG reconstruction.

This patch builds on some existing code to do CFG reconstruction from
a disassembled binary:
- MCModule represents the binary, and has a list of MCAtoms.
- MCAtom represents either disassembled instructions (MCTextAtom), or
  contiguous data (MCDataAtom), and covers a specific range of addresses.
- MCBasicBlock and MCFunction form the reconstructed CFG. An MCBB is
  backed by an MCTextAtom, and has the usual successors/predecessors.
- MCObjectDisassembler creates a module from an ObjectFile using a
  disassembler. It first builds an atom for each section. It can also
  construct the CFG, and this splits the text atoms into basic blocks.

MCModule and MCAtom were only sketched out; MCFunction and MCBB were
implemented under the experimental "-cfg" llvm-objdump -macho option.
This cleans them up for further use; llvm-objdump -d -cfg now generates
graphviz files for each function found in the binary.

In the future, MCObjectDisassembler may be the right place to do
"intelligent" disassembly: for example, handling constant islands is just
a matter of splitting the atom, using information that may be available
in the ObjectFile. Also, better initial atom formation than just using
sections is possible using symbols (and things like Mach-O's
function_starts load command).

This brings two minor regressions in llvm-objdump -macho -cfg:
- The printing of a relocation's referenced symbol.
- An annotation on loop BBs, i.e., which are their own successor.

Relocation printing is replaced by the MCSymbolizer; the basic CFG
annotation will be superseded by more related functionality.

llvm-svn: 182628
---
 llvm/lib/MC/MCFunction.cpp | 55 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 llvm/lib/MC/MCFunction.cpp

(limited to 'llvm/lib/MC/MCFunction.cpp')

diff --git a/llvm/lib/MC/MCFunction.cpp b/llvm/lib/MC/MCFunction.cpp
new file mode 100644
index 00000000000..2665d3e167b
--- /dev/null
+++ b/llvm/lib/MC/MCFunction.cpp
@@ -0,0 +1,55 @@
+//===-- lib/MC/MCFunction.cpp -----------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCFunction.h"
+#include "llvm/MC/MCAtom.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+
+using namespace llvm;
+
+// MCFunction
+
+MCFunction::MCFunction(StringRef Name)
+  : Name(Name)
+{}
+
+MCFunction::~MCFunction() {
+  for (iterator I = begin(), E = end(); I != E; ++I)
+    delete *I;
+}
+
+MCBasicBlock &MCFunction::createBlock(const MCTextAtom &TA) {
+  Blocks.push_back(new MCBasicBlock(TA, this));
+  return *Blocks.back();
+}
+
+// MCBasicBlock
+
+MCBasicBlock::MCBasicBlock(const MCTextAtom &Insts, MCFunction *Parent)
+  : Insts(&Insts), Parent(Parent)
+{}
+
+void MCBasicBlock::addSuccessor(const MCBasicBlock *MCBB) {
+  Successors.push_back(MCBB);
+}
+
+bool MCBasicBlock::isSuccessor(const MCBasicBlock *MCBB) const {
+  return std::find(Successors.begin(), Successors.end(),
+                   MCBB) != Successors.end();
+}
+
+void MCBasicBlock::addPredecessor(const MCBasicBlock *MCBB) {
+  Predecessors.push_back(MCBB);
+}
+
+bool MCBasicBlock::isPredecessor(const MCBasicBlock *MCBB) const {
+  return std::find(Predecessors.begin(), Predecessors.end(),
+                   MCBB) != Predecessors.end();
+}
-- 
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