path: root/lib/CodeGen/SjLjEHPrepare.cpp

//===- SjLjEHPass.cpp - Eliminate Invoke & Unwind instructions -----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This transformation is designed for use by code generators which use SjLj
// based exception handling.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "sjljehprepare"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include <set>
using namespace llvm;

static cl::opt<bool> DisableOldSjLjEH("disable-old-sjlj-eh", cl::Hidden,
                                      cl::init(true),
    cl::desc("Disable the old SjLj EH preparation pass"));

STATISTIC(NumInvokes, "Number of invokes replaced");
STATISTIC(NumUnwinds, "Number of unwinds replaced");
STATISTIC(NumSpilled, "Number of registers live across unwind edges");

namespace {
  class SjLjEHPass : public FunctionPass {
    const TargetLowering *TLI;
    Type *FunctionContextTy;
    Constant *RegisterFn;
    Constant *UnregisterFn;
    Constant *BuiltinSetjmpFn;
    Constant *FrameAddrFn;
    Constant *StackAddrFn;
    Constant *StackRestoreFn;
    Constant *LSDAAddrFn;
    Value *PersonalityFn;
    Constant *SelectorFn;
    Constant *ExceptionFn;
    Constant *CallSiteFn;
    Constant *DispatchSetupFn;
    Constant *FuncCtxFn;
    Value *CallSite;
    DenseMap<InvokeInst*, BasicBlock*> LPadSuccMap;
  public:
    static char ID; // Pass identification, replacement for typeid
    explicit SjLjEHPass(const TargetLowering *tli = NULL)
      : FunctionPass(ID), TLI(tli) { }
    bool doInitialization(Module &M);
    bool runOnFunction(Function &F);

    virtual void getAnalysisUsage(AnalysisUsage &AU) const {}
    const char *getPassName() const {
      return "SJLJ Exception Handling preparation";
    }

  private:
    bool setupEntryBlockAndCallSites(Function &F);
    Value *setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> LPads);
    void lowerIncomingArguments(Function &F);
    void lowerAcrossUnwindEdges(Function &F, ArrayRef<InvokeInst*> Invokes);

    void insertCallSiteStore(Instruction *I, int Number, Value *CallSite);
    void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite,
                            SwitchInst *CatchSwitch);
    void splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes);
    void splitLandingPad(InvokeInst *II);
    bool insertSjLjEHSupport(Function &F);
  };
} // end anonymous namespace

char SjLjEHPass::ID = 0;

// Public Interface To the SjLjEHPass pass.
FunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) {
  return new SjLjEHPass(TLI);
}
// doInitialization - Set up decalarations and types needed to process
// exceptions.
bool SjLjEHPass::doInitialization(Module &M) {
  // Build the function context structure.
  // builtin_setjmp uses a five word jbuf
  Type *VoidPtrTy = Type::getInt8PtrTy(M.getContext());
  Type *Int32Ty = Type::getInt32Ty(M.getContext());
  FunctionContextTy =
    StructType::get(VoidPtrTy,                        // __prev
                    Int32Ty,                          // call_site
                    ArrayType::get(Int32Ty, 4),       // __data
                    VoidPtrTy,                        // __personality
                    VoidPtrTy,                        // __lsda
                    ArrayType::get(VoidPtrTy, 5),     // __jbuf
                    NULL);
  RegisterFn = M.getOrInsertFunction("_Unwind_SjLj_Register",
                                     Type::getVoidTy(M.getContext()),
                                     PointerType::getUnqual(FunctionContextTy),
                                     (Type *)0);
  UnregisterFn =
    M.getOrInsertFunction(