path: root/lib/Transforms/Utils/InlineFunction.cpp

//===- InlineFunction.cpp - Code to perform function inlining -------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements inlining of a function into a call site, resolving
// parameters and the return value as appropriate.
//
// The code in this file for handling inlines through invoke
// instructions preserves semantics only under some assumptions about
// the behavior of unwinders which correspond to gcc-style libUnwind
// exception personality functions.  Eventually the IR will be
// improved to make this unnecessary, but until then, this code is
// marked [LIBUNWIND].
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Intrinsics.h"
#include "llvm/Attributes.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Analysis/DebugInfo.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/IRBuilder.h"
using namespace llvm;

bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI) {
  return InlineFunction(CallSite(CI), IFI);
}
bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI) {
  return InlineFunction(CallSite(II), IFI);
}

/// [LIBUNWIND] Find the (possibly absent) call to @llvm.eh.selector in
/// the given landing pad.
static EHSelectorInst *findSelectorForLandingPad(BasicBlock *lpad) {
  // The llvm.eh.exception call is required to be in the landing pad.
  for (BasicBlock::iterator i = lpad->begin(), e = lpad->end(); i != e; i++) {
    EHExceptionInst *exn = dyn_cast<EHExceptionInst>(i);
    if (!exn) continue;

    EHSelectorInst *selector = 0;
    for (Instruction::use_iterator
           ui = exn->use_begin(), ue = exn->use_end(); ui != ue; ++ui) {
      EHSelectorInst *sel = dyn_cast<EHSelectorInst>(*ui);
      if (!sel) continue;

      // Immediately accept an eh.selector in the landing pad.
      if (sel->getParent() == lpad) return sel;

      // Otherwise, use the first selector we see.
      if (!selector) selector = sel;
    }

    return selector;
  }

  return 0;
}

namespace {
  /// A class for recording information about inlining through an invoke.
  class InvokeInliningInfo {
    BasicBlock *OuterUnwindDest;
    EHSelectorInst *OuterSelector;
    BasicBlock *InnerUnwindDest;
    PHINode *InnerExceptionPHI;
    PHINode *InnerSelectorPHI;
    SmallVector<Value*, 8> UnwindDestPHIValues;

  public:
    InvokeInliningInfo(InvokeInst *II) :
      OuterUnwindDest(II->getUnwindDest()), OuterSelector(0),
      InnerUnwindDest(0), InnerExceptionPHI(0), InnerSelectorPHI(0) {

      // If there are PHI nodes in the unwind destination block, we
      // need to keep track of which values came into them from the
      // invoke before removing the edge from this block.
      llvm::BasicBlock *invokeBB = II->getParent();
      for (BasicBlock::iterator I = OuterUnwindDest->begin();
             isa<PHINode>(I); ++I) {
        // Save the value to use for this edge.
        PHINode *phi = cast<PHINode>(I);
        UnwindDestPHIValues.push_back(phi->getIncomingValueForBlock(invokeBB));
      }
    }

    /// The outer unwind destination is the target of unwind edges
    /// introduced for calls within the inlined function.
    BasicBlock *getOuterUnwindDest() const {
      return OuterUnwindDest;
    }

    EHSelectorInst *getOuterSelector() {
      if (!OuterSelector)
        OuterSelector = findSelectorForLandingPad(OuterUnwindDest);
      return OuterSelector;
    }

    BasicBlock *getInnerUnwindDest();

    bool forwardEHResume(CallInst *call, BasicBlock *src);

    /// Add incoming-PHI values to the unwind destination block for
    /// the given basic block, using the values for the original
    /// invoke's source block.
    void addIncomingPHIValuesFor(BasicBlock *BB) const {
      addIncomingPHIValuesForInto(BB, OuterUnwindDest);
    }

    void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const {
      BasicBlock::iterator I = dest->begin();
      for (unsigned i = 0, e = UnwindDestPHIValues.size(); i