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] Look for an llvm.eh.exception call in the given block.
static EHExceptionInst *findExceptionInBlock(BasicBlock *bb) {
  for (BasicBlock::iterator i = bb->begin(), e = bb->end(); i != e; i++) {
    EHExceptionInst *exn = dyn_cast<EHExceptionInst>(i);
    if (exn) return exn;
  }

  return 0;
}

/// [LIBUNWIND] Look for the 'best' llvm.eh.selector instruction for
/// the given llvm.eh.exception call.
static EHSelectorInst *findSelectorForException(EHExceptionInst *exn) {
  BasicBlock *exnBlock = exn->getParent();

  EHSelectorInst *outOfBlockSelector = 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 same block as the
    // excepton call.
    if (sel->getParent() == exnBlock) return sel;

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

  return outOfBlockSelector;
}

/// [LIBUNWIND] Find the (possibly absent) call to @llvm.eh.selector
/// in the given landing pad.  In principle, llvm.eh.exception is
/// required to be in the landing pad; in practice, SplitCriticalEdge
/// can break that invariant, and then inlining can break it further.
/// There's a real need for a reliable solution here, but until that
/// happens, we have some fragile workarounds here.
static EHSelectorInst *findSelectorForLandingPad(BasicBlock *lpad) {
  // Look for an exception call in the actual landing pad.
  EHExceptionInst *exn = findExceptionInBlock(lpad);
  if (exn) return findSelectorForException(exn);

  // Okay, if that failed, look for one in an obvious successor.  If
  // we find one, we'll fix the IR by moving things back to the
  // landing pad.

  bool dominates = true; // does the lpad dominate the exn call
  BasicBlock *nonDominated = 0; // if not, the first non-dominated block
  BasicBlock *lastDominated = 0; // and the block which branched to it

  BasicBlock