llvm/lib/CodeGen/MachineCFGPrinter.cpp

   1 //===- MachineCFGPrinter.cpp - DOT Printer for Machine Functions ----------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines the `-dot-machine-cfg` analysis pass, which emits
  11 // Machine Function in DOT format in file titled `<prefix>.<function-name>.dot.
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/CodeGen/MachineCFGPrinter.h"
  15 #include "llvm/CodeGen/MachineBasicBlock.h"
  16 #include "llvm/CodeGen/MachineFunctionPass.h"
  17 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  18 #include "llvm/InitializePasses.h"
  19 #include "llvm/Pass.h"
  20 #include "llvm/PassRegistry.h"
  21 #include "llvm/Support/GraphWriter.h"
  22
  23 using namespace llvm;
  24
  25 #define DEBUG_TYPE "dot-machine-cfg"
  26
  27 static cl::opt<std::string>
  28     MCFGFuncName("mcfg-func-name", cl::Hidden,
  29                  cl::desc("The name of a function (or its substring)"
  30                           " whose CFG is viewed/printed."));
  31
  32 static cl::opt<std::string> MCFGDotFilenamePrefix(
  33     "mcfg-dot-filename-prefix", cl::Hidden,
  34     cl::desc("The prefix used for the Machine CFG dot file names."));
  35
  36 static cl::opt<bool>
  37     CFGOnly("dot-mcfg-only", cl::init(false), cl::Hidden,
  38             cl::desc("Print only the CFG without blocks body"));
  39
  40 static void writeMCFGToDotFile(MachineFunction &MF) {
  41   std::string Filename =
  42       (MCFGDotFilenamePrefix + "." + MF.getName() + ".dot").str();
  43   errs() << "Writing '" << Filename << "'...";
  44
  45   std::error_code EC;
  46   raw_fd_ostream File(Filename, EC, sys::fs::OF_Text);
  47
  48   DOTMachineFuncInfo MCFGInfo(&MF);
  49
  50   if (!EC)
  51     WriteGraph(File, &MCFGInfo, CFGOnly);
  52   else
  53     errs() << "  error opening file for writing!";
  54   errs() << '\n';
  55 }
  56
  57 namespace {
  58
  59 class MachineCFGPrinter : public MachineFunctionPass {
  60 public:
  61   static char ID;
  62
  63   MachineCFGPrinter();
  64
  65   bool runOnMachineFunction(MachineFunction &MF) override;
  66
  67   void getAnalysisUsage(AnalysisUsage &AU) const override {
  68     AU.setPreservesCFG();
  69     MachineFunctionPass::getAnalysisUsage(AU);
  70   }
  71 };
  72
  73 } // namespace
  74
  75 char MachineCFGPrinter::ID = 0;
  76
  77 char &llvm::MachineCFGPrinterID = MachineCFGPrinter::ID;
  78
  79 INITIALIZE_PASS(MachineCFGPrinter, DEBUG_TYPE, "Machine CFG Printer Pass",
  80                 false, true)
  81
  82 /// Default construct and initialize the pass.
  83 MachineCFGPrinter::MachineCFGPrinter() : MachineFunctionPass(ID) {
  84   initializeMachineCFGPrinterPass(*PassRegistry::getPassRegistry());
  85 }
  86
  87 bool MachineCFGPrinter::runOnMachineFunction(MachineFunction &MF) {
  88   if (!MCFGFuncName.empty() && !MF.getName().contains(MCFGFuncName))
  89     return false;
  90   errs() << "Writing Machine CFG for function ";
  91   errs().write_escaped(MF.getName()) << '\n';
  92
  93   writeMCFGToDotFile(MF);
  94   return false;
  95 }