| //===- 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 *exnBlock = lpad; |
| |
| // We need to protect against lpads that lead into infinite loops. |
| SmallPtrSet<BasicBlock*,4> visited; |
| visited.insert(exnBlock); |
| |
| do { |
| // We're not going to apply this hack to anything more complicated |
| // than a series of unconditional branches, so if the block |
| // doesn't terminate in an unconditional branch, just fail. More |
| // complicated cases can arise when, say, sinking a call into a |
| // split unwind edge and then inlining it; but that can do almost |
| // *anything* to the CFG, including leaving the selector |
| // completely unreachable. The only way to fix that properly is |
| // to (1) prohibit transforms which move the exception or selector |
| // values away from the landing pad, e.g. by producing them with |
| // instructions that are pinned to an edge like a phi, or |
| // producing them with not-really-instructions, and (2) making |
| // transforms which split edges deal with that. |
| BranchInst *branch = dyn_cast<BranchInst>(&exnBlock->back()); |
| if (!branch || branch->isConditional()) return 0; |
| |
| BasicBlock *successor = branch->getSuccessor(0); |
| |
| // Fail if we found an infinite loop. |
| if (!visited.insert(successor)) return 0; |
| |
| // If the successor isn't dominated by exnBlock: |
| if (!successor->getSinglePredecessor()) { |
| // We don't want to have to deal with threading the exception |
| // through multiple levels of phi, so give up if we've already |
| // followed a non-dominating edge. |
| if (!dominates) return 0; |
| |
| // Otherwise, remember this as a non-dominating edge. |
| dominates = false; |
| nonDominated = successor; |
| lastDominated = exnBlock; |
| } |
| |
| exnBlock = successor; |
| |
| // Can we stop here? |
| exn = findExceptionInBlock(exnBlock); |
| } while (!exn); |
| |
| // Look for a selector call for the exception we found. |
| EHSelectorInst *selector = findSelectorForException(exn); |
| if (!selector) return 0; |
| |
| // The easy case is when the landing pad still dominates the |
| // exception call, in which case we can just move both calls back to |
| // the landing pad. |
| if (dominates) { |
| selector->moveBefore(lpad->getFirstNonPHI()); |
| exn->moveBefore(selector); |
| return selector; |
| } |
| |
| // Otherwise, we have to split at the first non-dominating block. |
| // The CFG looks basically like this: |
| // lpad: |
| // phis_0 |
| // insnsAndBranches_1 |
| // br label %nonDominated |
| // nonDominated: |
| // phis_2 |
| // insns_3 |
| // %exn = call i8* @llvm.eh.exception() |
| // insnsAndBranches_4 |
| // %selector = call @llvm.eh.selector(i8* %exn, ... |
| // We need to turn this into: |
| // lpad: |
| // phis_0 |
| // %exn0 = call i8* @llvm.eh.exception() |
| // %selector0 = call @llvm.eh.selector(i8* %exn0, ... |
| // insnsAndBranches_1 |
| // br label %split // from lastDominated |
| // nonDominated: |
| // phis_2 (without edge from lastDominated) |
| // %exn1 = call i8* @llvm.eh.exception() |
| // %selector1 = call i8* @llvm.eh.selector(i8* %exn1, ... |
| // br label %split |
| // split: |
| // phis_2 (edge from lastDominated, edge from split) |
| // %exn = phi ... |
| // %selector = phi ... |
| // insns_3 |
| // insnsAndBranches_4 |
| |
| assert(nonDominated); |
| assert(lastDominated); |
| |
| // First, make clones of the intrinsics to go in lpad. |
| EHExceptionInst *lpadExn = cast<EHExceptionInst>(exn->clone()); |
| EHSelectorInst *lpadSelector = cast<EHSelectorInst>(selector->clone()); |
| lpadSelector->setArgOperand(0, lpadExn); |
| lpadSelector->insertBefore(lpad->getFirstNonPHI()); |
| lpadExn->insertBefore(lpadSelector); |
| |
| // Split the non-dominated block. |
| BasicBlock *split = |
| nonDominated->splitBasicBlock(nonDominated->getFirstNonPHI(), |
| nonDominated->getName() + ".lpad-fix"); |
| |
| // Redirect the last dominated branch there. |
| cast<BranchInst>(lastDominated->back()).setSuccessor(0, split); |
| |
| // Move the existing intrinsics to the end of the old block. |
| selector->moveBefore(&nonDominated->back()); |
| exn->moveBefore(selector); |
| |
| Instruction *splitIP = &split->front(); |
| |
| // For all the phis in nonDominated, make a new phi in split to join |
| // that phi with the edge from lastDominated. |
| for (BasicBlock::iterator |
| i = nonDominated->begin(), e = nonDominated->end(); i != e; ++i) { |
| PHINode *phi = dyn_cast<PHINode>(i); |
| if (!phi) break; |
| |
| PHINode *splitPhi = PHINode::Create(phi->getType(), 2, phi->getName(), |
| splitIP); |
| phi->replaceAllUsesWith(splitPhi); |
| splitPhi->addIncoming(phi, nonDominated); |
| splitPhi->addIncoming(phi->removeIncomingValue(lastDominated), |
| lastDominated); |
| } |
| |
| // Make new phis for the exception and selector. |
| PHINode *exnPhi = PHINode::Create(exn->getType(), 2, "", splitIP); |
| exn->replaceAllUsesWith(exnPhi); |
| selector->setArgOperand(0, exn); // except for this use |
| exnPhi->addIncoming(exn, nonDominated); |
| exnPhi->addIncoming(lpadExn, lastDominated); |
| |
| PHINode *selectorPhi = PHINode::Create(selector->getType(), 2, "", splitIP); |
| selector->replaceAllUsesWith(selectorPhi); |
| selectorPhi->addIncoming(selector, nonDominated); |
| selectorPhi->addIncoming(lpadSelector, lastDominated); |
| |
| return lpadSelector; |
| } |
| |
| 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 != e; ++i, ++I) { |
| PHINode *phi = cast<PHINode>(I); |
| phi->addIncoming(UnwindDestPHIValues[i], src); |
| } |
| } |
| }; |
| } |
| |
| /// Get or create a target for the branch out of rewritten calls to |
| /// llvm.eh.resume. |
| BasicBlock *InvokeInliningInfo::getInnerUnwindDest() { |
| if (InnerUnwindDest) return InnerUnwindDest; |
| |
| // Find and hoist the llvm.eh.exception and llvm.eh.selector calls |
| // in the outer landing pad to immediately following the phis. |
| EHSelectorInst *selector = getOuterSelector(); |
| if (!selector) return 0; |
| |
| // The call to llvm.eh.exception *must* be in the landing pad. |
| Instruction *exn = cast<Instruction>(selector->getArgOperand(0)); |
| assert(exn->getParent() == OuterUnwindDest); |
| |
| // TODO: recognize when we've already done this, so that we don't |
| // get a linear number of these when inlining calls into lots of |
| // invokes with the same landing pad. |
| |
| // Do the hoisting. |
| Instruction *splitPoint = exn->getParent()->getFirstNonPHI(); |
| assert(splitPoint != selector && "selector-on-exception dominance broken!"); |
| if (splitPoint == exn) { |
| selector->removeFromParent(); |
| selector->insertAfter(exn); |
| splitPoint = selector->getNextNode(); |
| } else { |
| exn->moveBefore(splitPoint); |
| selector->moveBefore(splitPoint); |
| } |
| |
| // Split the landing pad. |
| InnerUnwindDest = OuterUnwindDest->splitBasicBlock(splitPoint, |
| OuterUnwindDest->getName() + ".body"); |
| |
| // The number of incoming edges we expect to the inner landing pad. |
| const unsigned phiCapacity = 2; |
| |
| // Create corresponding new phis for all the phis in the outer landing pad. |
| BasicBlock::iterator insertPoint = InnerUnwindDest->begin(); |
| BasicBlock::iterator I = OuterUnwindDest->begin(); |
| for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) { |
| PHINode *outerPhi = cast<PHINode>(I); |
| PHINode *innerPhi = PHINode::Create(outerPhi->getType(), phiCapacity, |
| outerPhi->getName() + ".lpad-body", |
| insertPoint); |
| outerPhi->replaceAllUsesWith(innerPhi); |
| innerPhi->addIncoming(outerPhi, OuterUnwindDest); |
| } |
| |
| // Create a phi for the exception value... |
| InnerExceptionPHI = PHINode::Create(exn->getType(), phiCapacity, |
| "exn.lpad-body", insertPoint); |
| exn->replaceAllUsesWith(InnerExceptionPHI); |
| selector->setArgOperand(0, exn); // restore this use |
| InnerExceptionPHI->addIncoming(exn, OuterUnwindDest); |
| |
| // ...and the selector. |
| InnerSelectorPHI = PHINode::Create(selector->getType(), phiCapacity, |
| "selector.lpad-body", insertPoint); |
| selector->replaceAllUsesWith(InnerSelectorPHI); |
| InnerSelectorPHI->addIncoming(selector, OuterUnwindDest); |
| |
| // All done. |
| return InnerUnwindDest; |
| } |
| |
| /// [LIBUNWIND] Try to forward the given call, which logically occurs |
| /// at the end of the given block, as a branch to the inner unwind |
| /// block. Returns true if the call was forwarded. |
| bool InvokeInliningInfo::forwardEHResume(CallInst *call, BasicBlock *src) { |
| // First, check whether this is a call to the intrinsic. |
| Function *fn = dyn_cast<Function>(call->getCalledValue()); |
| if (!fn || fn->getName() != "llvm.eh.resume") |
| return false; |
| |
| // At this point, we need to return true on all paths, because |
| // otherwise we'll construct an invoke of the intrinsic, which is |
| // not well-formed. |
| |
| // Try to find or make an inner unwind dest, which will fail if we |
| // can't find a selector call for the outer unwind dest. |
| BasicBlock *dest = getInnerUnwindDest(); |
| bool hasSelector = (dest != 0); |
| |
| // If we failed, just use the outer unwind dest, dropping the |
| // exception and selector on the floor. |
| if (!hasSelector) |
| dest = OuterUnwindDest; |
| |
| // Make a branch. |
| BranchInst::Create(dest, src); |
| |
| // Update the phis in the destination. They were inserted in an |
| // order which makes this work. |
| addIncomingPHIValuesForInto(src, dest); |
| |
| if (hasSelector) { |
| InnerExceptionPHI->addIncoming(call->getArgOperand(0), src); |
| InnerSelectorPHI->addIncoming(call->getArgOperand(1), src); |
| } |
| |
| return true; |
| } |
| |
| /// [LIBUNWIND] Check whether this selector is "only cleanups": |
| /// call i32 @llvm.eh.selector(blah, blah, i32 0) |
| static bool isCleanupOnlySelector(EHSelectorInst *selector) { |
| if (selector->getNumArgOperands() != 3) return false; |
| ConstantInt *val = dyn_cast<ConstantInt>(selector->getArgOperand(2)); |
| return (val && val->isZero()); |
| } |
| |
| /// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into |
| /// an invoke, we have to turn all of the calls that can throw into |
| /// invokes. This function analyze BB to see if there are any calls, and if so, |
| /// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI |
| /// nodes in that block with the values specified in InvokeDestPHIValues. |
| /// |
| /// Returns true to indicate that the next block should be skipped. |
| static bool HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB, |
| InvokeInliningInfo &Invoke) { |
| for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) { |
| Instruction *I = BBI++; |
| |
| // We only need to check for function calls: inlined invoke |
| // instructions require no special handling. |
| CallInst *CI = dyn_cast<CallInst>(I); |
| if (CI == 0) continue; |
| |
| // LIBUNWIND: merge selector instructions. |
| if (EHSelectorInst *Inner = dyn_cast<EHSelectorInst>(CI)) { |
| EHSelectorInst *Outer = Invoke.getOuterSelector(); |
| if (!Outer) continue; |
| |
| bool innerIsOnlyCleanup = isCleanupOnlySelector(Inner); |
| bool outerIsOnlyCleanup = isCleanupOnlySelector(Outer); |
| |
| // If both selectors contain only cleanups, we don't need to do |
| // anything. TODO: this is really just a very specific instance |
| // of a much more general optimization. |
| if (innerIsOnlyCleanup && outerIsOnlyCleanup) continue; |
| |
| // Otherwise, we just append the outer selector to the inner selector. |
| SmallVector<Value*, 16> NewSelector; |
| for (unsigned i = 0, e = Inner->getNumArgOperands(); i != e; ++i) |
| NewSelector.push_back(Inner->getArgOperand(i)); |
| for (unsigned i = 2, e = Outer->getNumArgOperands(); i != e; ++i) |
| NewSelector.push_back(Outer->getArgOperand(i)); |
| |
| CallInst *NewInner = |
| IRBuilder<>(Inner).CreateCall(Inner->getCalledValue(), |
| NewSelector.begin(), |
| NewSelector.end()); |
| // No need to copy attributes, calling convention, etc. |
| NewInner->takeName(Inner); |
| Inner->replaceAllUsesWith(NewInner); |
| Inner->eraseFromParent(); |
| continue; |
| } |
| |
| // If this call cannot unwind, don't convert it to an invoke. |
| if (CI->doesNotThrow()) |
| continue; |
| |
| // Convert this function call into an invoke instruction. |
| // First, split the basic block. |
| BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc"); |
| |
| // Delete the unconditional branch inserted by splitBasicBlock |
| BB->getInstList().pop_back(); |
| |
| // LIBUNWIND: If this is a call to @llvm.eh.resume, just branch |
| // directly to the new landing pad. |
| if (Invoke.forwardEHResume(CI, BB)) { |
| // TODO: 'Split' is now unreachable; clean it up. |
| |
| // We want to leave the original call intact so that the call |
| // graph and other structures won't get misled. We also have to |
| // avoid processing the next block, or we'll iterate here forever. |
| return true; |
| } |
| |
| // Otherwise, create the new invoke instruction. |
| ImmutableCallSite CS(CI); |
| SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end()); |
| InvokeInst *II = |
| InvokeInst::Create(CI->getCalledValue(), Split, |
| Invoke.getOuterUnwindDest(), |
| InvokeArgs.begin(), InvokeArgs.end(), |
| CI->getName(), BB); |
| II->setCallingConv(CI->getCallingConv()); |
| II->setAttributes(CI->getAttributes()); |
| |
| // Make sure that anything using the call now uses the invoke! This also |
| // updates the CallGraph if present, because it uses a WeakVH. |
| CI->replaceAllUsesWith(II); |
| |
| Split->getInstList().pop_front(); // Delete the original call |
| |
| // Update any PHI nodes in the exceptional block to indicate that |
| // there is now a new entry in them. |
| Invoke.addIncomingPHIValuesFor(BB); |
| return false; |
| } |
| |
| return false; |
| } |
| |
| |
| /// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls |
| /// in the body of the inlined function into invokes and turn unwind |
| /// instructions into branches to the invoke unwind dest. |
| /// |
| /// II is the invoke instruction being inlined. FirstNewBlock is the first |
| /// block of the inlined code (the last block is the end of the function), |
| /// and InlineCodeInfo is information about the code that got inlined. |
| static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock, |
| ClonedCodeInfo &InlinedCodeInfo) { |
| BasicBlock *InvokeDest = II->getUnwindDest(); |
| |
| Function *Caller = FirstNewBlock->getParent(); |
| |
| // The inlined code is currently at the end of the function, scan from the |
| // start of the inlined code to its end, checking for stuff we need to |
| // rewrite. If the code doesn't have calls or unwinds, we know there is |
| // nothing to rewrite. |
| if (!InlinedCodeInfo.ContainsCalls && !InlinedCodeInfo.ContainsUnwinds) { |
| // Now that everything is happy, we have one final detail. The PHI nodes in |
| // the exception destination block still have entries due to the original |
| // invoke instruction. Eliminate these entries (which might even delete the |
| // PHI node) now. |
| InvokeDest->removePredecessor(II->getParent()); |
| return; |
| } |
| |
| InvokeInliningInfo Invoke(II); |
| |
| for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){ |
| if (InlinedCodeInfo.ContainsCalls) |
| if (HandleCallsInBlockInlinedThroughInvoke(BB, Invoke)) { |
| // Honor a request to skip the next block. We don't need to |
| // consider UnwindInsts in this case either. |
| ++BB; |
| continue; |
| } |
| |
| if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { |
| // An UnwindInst requires special handling when it gets inlined into an |
| // invoke site. Once this happens, we know that the unwind would cause |
| // a control transfer to the invoke exception destination, so we can |
| // transform it into a direct branch to the exception destination. |
| BranchInst::Create(InvokeDest, UI); |
| |
| // Delete the unwind instruction! |
| UI->eraseFromParent(); |
| |
| // Update any PHI nodes in the exceptional block to indicate that |
| // there is now a new entry in them. |
| Invoke.addIncomingPHIValuesFor(BB); |
| } |
| } |
| |
| // Now that everything is happy, we have one final detail. The PHI nodes in |
| // the exception destination block still have entries due to the original |
| // invoke instruction. Eliminate these entries (which might even delete the |
| // PHI node) now. |
| InvokeDest->removePredecessor(II->getParent()); |
| } |
| |
| /// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee |
| /// into the caller, update the specified callgraph to reflect the changes we |
| /// made. Note that it's possible that not all code was copied over, so only |
| /// some edges of the callgraph may remain. |
| static void UpdateCallGraphAfterInlining(CallSite CS, |
| Function::iterator FirstNewBlock, |
| ValueToValueMapTy &VMap, |
| InlineFunctionInfo &IFI) { |
| CallGraph &CG = *IFI.CG; |
| const Function *Caller = CS.getInstruction()->getParent()->getParent(); |
| const Function *Callee = CS.getCalledFunction(); |
| CallGraphNode *CalleeNode = CG[Callee]; |
| CallGraphNode *CallerNode = CG[Caller]; |
| |
| // Since we inlined some uninlined call sites in the callee into the caller, |
| // add edges from the caller to all of the callees of the callee. |
| CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end(); |
| |
| // Consider the case where CalleeNode == CallerNode. |
| CallGraphNode::CalledFunctionsVector CallCache; |
| if (CalleeNode == CallerNode) { |
| CallCache.assign(I, E); |
| I = CallCache.begin(); |
| E = CallCache.end(); |
| } |
| |
| for (; I != E; ++I) { |
| const Value *OrigCall = I->first; |
| |
| ValueToValueMapTy::iterator VMI = VMap.find(OrigCall); |
| // Only copy the edge if the call was inlined! |
| if (VMI == VMap.end() || VMI->second == 0) |
| continue; |
| |
| // If the call was inlined, but then constant folded, there is no edge to |
| // add. Check for this case. |
| Instruction *NewCall = dyn_cast<Instruction>(VMI->second); |
| if (NewCall == 0) continue; |
| |
| // Remember that this call site got inlined for the client of |
| // InlineFunction. |
| IFI.InlinedCalls.push_back(NewCall); |
| |
| // It's possible that inlining the callsite will cause it to go from an |
| // indirect to a direct call by resolving a function pointer. If this |
| // happens, set the callee of the new call site to a more precise |
| // destination. This can also happen if the call graph node of the caller |
| // was just unnecessarily imprecise. |
| if (I->second->getFunction() == 0) |
| if (Function *F = CallSite(NewCall).getCalledFunction()) { |
| // Indirect call site resolved to direct call. |
| CallerNode->addCalledFunction(CallSite(NewCall), CG[F]); |
| |
| continue; |
| } |
| |
| CallerNode->addCalledFunction(CallSite(NewCall), I->second); |
| } |
| |
| // Update the call graph by deleting the edge from Callee to Caller. We must |
| // do this after the loop above in case Caller and Callee are the same. |
| CallerNode->removeCallEdgeFor(CS); |
| } |
| |
| /// HandleByValArgument - When inlining a call site that has a byval argument, |
| /// we have to make the implicit memcpy explicit by adding it. |
| static Value *HandleByValArgument(Value *Arg, Instruction *TheCall, |
| const Function *CalledFunc, |
| InlineFunctionInfo &IFI, |
| unsigned ByValAlignment) { |
| const Type *AggTy = cast<PointerType>(Arg->getType())->getElementType(); |
| |
| // If the called function is readonly, then it could not mutate the caller's |
| // copy of the byval'd memory. In this case, it is safe to elide the copy and |
| // temporary. |
| if (CalledFunc->onlyReadsMemory()) { |
| // If the byval argument has a specified alignment that is greater than the |
| // passed in pointer, then we either have to round up the input pointer or |
| // give up on this transformation. |
| if (ByValAlignment <= 1) // 0 = unspecified, 1 = no particular alignment. |
| return Arg; |
| |
| // If the pointer is already known to be sufficiently aligned, or if we can |
| // round it up to a larger alignment, then we don't need a temporary. |
| if (getOrEnforceKnownAlignment(Arg, ByValAlignment, |
| IFI.TD) >= ByValAlignment) |
| return Arg; |
| |
| // Otherwise, we have to make a memcpy to get a safe alignment. This is bad |
| // for code quality, but rarely happens and is required for correctness. |
| } |
| |
| LLVMContext &Context = Arg->getContext(); |
| |
| const Type *VoidPtrTy = Type::getInt8PtrTy(Context); |
| |
| // Create the alloca. If we have TargetData, use nice alignment. |
| unsigned Align = 1; |
| if (IFI.TD) |
| Align = IFI.TD->getPrefTypeAlignment(AggTy); |
| |
| // If the byval had an alignment specified, we *must* use at least that |
| // alignment, as it is required by the byval argument (and uses of the |
| // pointer inside the callee). |
| Align = std::max(Align, ByValAlignment); |
| |
| Function *Caller = TheCall->getParent()->getParent(); |
| |
| Value *NewAlloca = new AllocaInst(AggTy, 0, Align, Arg->getName(), |
| &*Caller->begin()->begin()); |
| // Emit a memcpy. |
| const Type *Tys[3] = {VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context)}; |
| Function *MemCpyFn = Intrinsic::getDeclaration(Caller->getParent(), |
| Intrinsic::memcpy, |
| Tys, 3); |
| Value *DestCast = new BitCastInst(NewAlloca, VoidPtrTy, "tmp", TheCall); |
| Value *SrcCast = new BitCastInst(Arg, VoidPtrTy, "tmp", TheCall); |
| |
| Value *Size; |
| if (IFI.TD == 0) |
| Size = ConstantExpr::getSizeOf(AggTy); |
| else |
| Size = ConstantInt::get(Type::getInt64Ty(Context), |
| IFI.TD->getTypeStoreSize(AggTy)); |
| |
| // Always generate a memcpy of alignment 1 here because we don't know |
| // the alignment of the src pointer. Other optimizations can infer |
| // better alignment. |
| Value *CallArgs[] = { |
| DestCast, SrcCast, Size, |
| ConstantInt::get(Type::getInt32Ty(Context), 1), |
| ConstantInt::getFalse(Context) // isVolatile |
| }; |
| IRBuilder<>(TheCall).CreateCall(MemCpyFn, CallArgs, CallArgs+5); |
| |
| // Uses of the argument in the function should use our new alloca |
| // instead. |
| return NewAlloca; |
| } |
| |
| // isUsedByLifetimeMarker - Check whether this Value is used by a lifetime |
| // intrinsic. |
| static bool isUsedByLifetimeMarker(Value *V) { |
| for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE; |
| ++UI) { |
| if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI)) { |
| switch (II->getIntrinsicID()) { |
| default: break; |
| case Intrinsic::lifetime_start: |
| case Intrinsic::lifetime_end: |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| // hasLifetimeMarkers - Check whether the given alloca already has |
| // lifetime.start or lifetime.end intrinsics. |
| static bool hasLifetimeMarkers(AllocaInst *AI) { |
| const Type *Int8PtrTy = Type::getInt8PtrTy(AI->getType()->getContext()); |
| if (AI->getType() == Int8PtrTy) |
| return isUsedByLifetimeMarker(AI); |
| |
| // Do a scan to find all the casts to i8*. |
| for (Value::use_iterator I = AI->use_begin(), E = AI->use_end(); I != E; |
| ++I) { |
| if (I->getType() != Int8PtrTy) continue; |
| if (I->stripPointerCasts() != AI) continue; |
| if (isUsedByLifetimeMarker(*I)) |
| return true; |
| } |
| return false; |
| } |
| |
| /// updateInlinedAtInfo - Helper function used by fixupLineNumbers to recursively |
| /// update InlinedAtEntry of a DebugLoc. |
| static DebugLoc updateInlinedAtInfo(const DebugLoc &DL, |
| const DebugLoc &InlinedAtDL, |
| LLVMContext &Ctx) { |
| if (MDNode *IA = DL.getInlinedAt(Ctx)) { |
| DebugLoc NewInlinedAtDL |
| = updateInlinedAtInfo(DebugLoc::getFromDILocation(IA), InlinedAtDL, Ctx); |
| return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx), |
| NewInlinedAtDL.getAsMDNode(Ctx)); |
| } |
| |
| return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx), |
| InlinedAtDL.getAsMDNode(Ctx)); |
| } |
| |
| |
| /// fixupLineNumbers - Update inlined instructions' line numbers to |
| /// to encode location where these instructions are inlined. |
| static void fixupLineNumbers(Function *Fn, Function::iterator FI, |
| Instruction *TheCall) { |
| DebugLoc TheCallDL = TheCall->getDebugLoc(); |
| if (TheCallDL.isUnknown()) |
| return; |
| |
| for (; FI != Fn->end(); ++FI) { |
| for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); |
| BI != BE; ++BI) { |
| DebugLoc DL = BI->getDebugLoc(); |
| if (!DL.isUnknown()) |
| BI->setDebugLoc(updateInlinedAtInfo(DL, TheCallDL, BI->getContext())); |
| } |
| } |
| } |
| |
| // InlineFunction - This function inlines the called function into the basic |
| // block of the caller. This returns false if it is not possible to inline this |
| // call. The program is still in a well defined state if this occurs though. |
| // |
| // Note that this only does one level of inlining. For example, if the |
| // instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now |
| // exists in the instruction stream. Similarly this will inline a recursive |
| // function by one level. |
| // |
| bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI) { |
| Instruction *TheCall = CS.getInstruction(); |
| LLVMContext &Context = TheCall->getContext(); |
| assert(TheCall->getParent() && TheCall->getParent()->getParent() && |
| "Instruction not in function!"); |
| |
| // If IFI has any state in it, zap it before we fill it in. |
| IFI.reset(); |
| |
| const Function *CalledFunc = CS.getCalledFunction(); |
| if (CalledFunc == 0 || // Can't inline external function or indirect |
| CalledFunc->isDeclaration() || // call, or call to a vararg function! |
| CalledFunc->getFunctionType()->isVarArg()) return false; |
| |
| // If the call to the callee is not a tail call, we must clear the 'tail' |
| // flags on any calls that we inline. |
| bool MustClearTailCallFlags = |
| !(isa<CallInst>(TheCall) && cast<CallInst>(TheCall)->isTailCall()); |
| |
| // If the call to the callee cannot throw, set the 'nounwind' flag on any |
| // calls that we inline. |
| bool MarkNoUnwind = CS.doesNotThrow(); |
| |
| BasicBlock *OrigBB = TheCall->getParent(); |
| Function *Caller = OrigBB->getParent(); |
| |
| // GC poses two hazards to inlining, which only occur when the callee has GC: |
| // 1. If the caller has no GC, then the callee's GC must be propagated to the |
| // caller. |
| // 2. If the caller has a differing GC, it is invalid to inline. |
| if (CalledFunc->hasGC()) { |
| if (!Caller->hasGC()) |
| Caller->setGC(CalledFunc->getGC()); |
| else if (CalledFunc->getGC() != Caller->getGC()) |
| return false; |
| } |
| |
| // Get an iterator to the last basic block in the function, which will have |
| // the new function inlined after it. |
| // |
| Function::iterator LastBlock = &Caller->back(); |
| |
| // Make sure to capture all of the return instructions from the cloned |
| // function. |
| SmallVector<ReturnInst*, 8> Returns; |
| ClonedCodeInfo InlinedFunctionInfo; |
| Function::iterator FirstNewBlock; |
| |
| { // Scope to destroy VMap after cloning. |
| ValueToValueMapTy VMap; |
| |
| assert(CalledFunc->arg_size() == CS.arg_size() && |
| "No varargs calls can be inlined!"); |
| |
| // Calculate the vector of arguments to pass into the function cloner, which |
| // matches up the formal to the actual argument values. |
| CallSite::arg_iterator AI = CS.arg_begin(); |
| unsigned ArgNo = 0; |
| for (Function::const_arg_iterator I = CalledFunc->arg_begin(), |
| E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) { |
| Value *ActualArg = *AI; |
| |
| // When byval arguments actually inlined, we need to make the copy implied |
| // by them explicit. However, we don't do this if the callee is readonly |
| // or readnone, because the copy would be unneeded: the callee doesn't |
| // modify the struct. |
| if (CalledFunc->paramHasAttr(ArgNo+1, Attribute::ByVal)) { |
| ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI, |
| CalledFunc->getParamAlignment(ArgNo+1)); |
| |
| // Calls that we inline may use the new alloca, so we need to clear |
| // their 'tail' flags if HandleByValArgument introduced a new alloca and |
| // the callee has calls. |
| MustClearTailCallFlags |= ActualArg != *AI; |
| } |
| |
| VMap[I] = ActualArg; |
| } |
| |
| // We want the inliner to prune the code as it copies. We would LOVE to |
| // have no dead or constant instructions leftover after inlining occurs |
| // (which can happen, e.g., because an argument was constant), but we'll be |
| // happy with whatever the cloner can do. |
| CloneAndPruneFunctionInto(Caller, CalledFunc, VMap, |
| /*ModuleLevelChanges=*/false, Returns, ".i", |
| &InlinedFunctionInfo, IFI.TD, TheCall); |
| |
| // Remember the first block that is newly cloned over. |
| FirstNewBlock = LastBlock; ++FirstNewBlock; |
| |
| // Update the callgraph if requested. |
| if (IFI.CG) |
| UpdateCallGraphAfterInlining(CS, FirstNewBlock, VMap, IFI); |
| |
| // Update inlined instructions' line number information. |
| fixupLineNumbers(Caller, FirstNewBlock, TheCall); |
| } |
| |
| // If there are any alloca instructions in the block that used to be the entry |
| // block for the callee, move them to the entry block of the caller. First |
| // calculate which instruction they should be inserted before. We insert the |
| // instructions at the end of the current alloca list. |
| // |
| { |
| BasicBlock::iterator InsertPoint = Caller->begin()->begin(); |
| for (BasicBlock::iterator I = FirstNewBlock->begin(), |
| E = FirstNewBlock->end(); I != E; ) { |
| AllocaInst *AI = dyn_cast<AllocaInst>(I++); |
| if (AI == 0) continue; |
| |
| // If the alloca is now dead, remove it. This often occurs due to code |
| // specialization. |
| if (AI->use_empty()) { |
| AI->eraseFromParent(); |
| continue; |
| } |
| |
| if (!isa<Constant>(AI->getArraySize())) |
| continue; |
| |
| // Keep track of the static allocas that we inline into the caller. |
| IFI.StaticAllocas.push_back(AI); |
| |
| // Scan for the block of allocas that we can move over, and move them |
| // all at once. |
| while (isa<AllocaInst>(I) && |
| isa<Constant>(cast<AllocaInst>(I)->getArraySize())) { |
| IFI.StaticAllocas.push_back(cast<AllocaInst>(I)); |
| ++I; |
| } |
| |
| // Transfer all of the allocas over in a block. Using splice means |
| // that the instructions aren't removed from the symbol table, then |
| // reinserted. |
| Caller->getEntryBlock().getInstList().splice(InsertPoint, |
| FirstNewBlock->getInstList(), |
| AI, I); |
| } |
| } |
| |
| // Leave lifetime markers for the static alloca's, scoping them to the |
| // function we just inlined. |
| if (!IFI.StaticAllocas.empty()) { |
| IRBuilder<> builder(FirstNewBlock->begin()); |
| for (unsigned ai = 0, ae = IFI.StaticAllocas.size(); ai != ae; ++ai) { |
| AllocaInst *AI = IFI.StaticAllocas[ai]; |
| |
| // If the alloca is already scoped to something smaller than the whole |
| // function then there's no need to add redundant, less accurate markers. |
| if (hasLifetimeMarkers(AI)) |
| continue; |
| |
| builder.CreateLifetimeStart(AI); |
| for (unsigned ri = 0, re = Returns.size(); ri != re; ++ri) { |
| IRBuilder<> builder(Returns[ri]); |
| builder.CreateLifetimeEnd(AI); |
| } |
| } |
| } |
| |
| // If the inlined code contained dynamic alloca instructions, wrap the inlined |
| // code with llvm.stacksave/llvm.stackrestore intrinsics. |
| if (InlinedFunctionInfo.ContainsDynamicAllocas) { |
| Module *M = Caller->getParent(); |
| // Get the two intrinsics we care about. |
| Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave); |
| Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore); |
| |
| // Insert the llvm.stacksave. |
| CallInst *SavedPtr = IRBuilder<>(FirstNewBlock, FirstNewBlock->begin()) |
| .CreateCall(StackSave, "savedstack"); |
| |
| // Insert a call to llvm.stackrestore before any return instructions in the |
| // inlined function. |
| for (unsigned i = 0, e = Returns.size(); i != e; ++i) { |
| IRBuilder<>(Returns[i]).CreateCall(StackRestore, SavedPtr); |
| } |
| |
| // Count the number of StackRestore calls we insert. |
| unsigned NumStackRestores = Returns.size(); |
| |
| // If we are inlining an invoke instruction, insert restores before each |
| // unwind. These unwinds will be rewritten into branches later. |
| if (InlinedFunctionInfo.ContainsUnwinds && isa<InvokeInst>(TheCall)) { |
| for (Function::iterator BB = FirstNewBlock, E = Caller->end(); |
| BB != E; ++BB) |
| if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { |
| IRBuilder<>(UI).CreateCall(StackRestore, SavedPtr); |
| ++NumStackRestores; |
| } |
| } |
| } |
| |
| // If we are inlining tail call instruction through a call site that isn't |
| // marked 'tail', we must remove the tail marker for any calls in the inlined |
| // code. Also, calls inlined through a 'nounwind' call site should be marked |
| // 'nounwind'. |
| if (InlinedFunctionInfo.ContainsCalls && |
| (MustClearTailCallFlags || MarkNoUnwind)) { |
| for (Function::iterator BB = FirstNewBlock, E = Caller->end(); |
| BB != E; ++BB) |
| for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) |
| if (CallInst *CI = dyn_cast<CallInst>(I)) { |
| if (MustClearTailCallFlags) |
| CI->setTailCall(false); |
| if (MarkNoUnwind) |
| CI->setDoesNotThrow(); |
| } |
| } |
| |
| // If we are inlining through a 'nounwind' call site then any inlined 'unwind' |
| // instructions are unreachable. |
| if (InlinedFunctionInfo.ContainsUnwinds && MarkNoUnwind) |
| for (Function::iterator BB = FirstNewBlock, E = Caller->end(); |
| BB != E; ++BB) { |
| TerminatorInst *Term = BB->getTerminator(); |
| if (isa<UnwindInst>(Term)) { |
| new UnreachableInst(Context, Term); |
| BB->getInstList().erase(Term); |
| } |
| } |
| |
| // If we are inlining for an invoke instruction, we must make sure to rewrite |
| // any inlined 'unwind' instructions into branches to the invoke exception |
| // destination, and call instructions into invoke instructions. |
| if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) |
| HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo); |
| |
| // If we cloned in _exactly one_ basic block, and if that block ends in a |
| // return instruction, we splice the body of the inlined callee directly into |
| // the calling basic block. |
| if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) { |
| // Move all of the instructions right before the call. |
| OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(), |
| FirstNewBlock->begin(), FirstNewBlock->end()); |
| // Remove the cloned basic block. |
| Caller->getBasicBlockList().pop_back(); |
| |
| // If the call site was an invoke instruction, add a branch to the normal |
| // destination. |
| if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) |
| BranchInst::Create(II->getNormalDest(), TheCall); |
| |
| // If the return instruction returned a value, replace uses of the call with |
| // uses of the returned value. |
| if (!TheCall->use_empty()) { |
| ReturnInst *R = Returns[0]; |
| if (TheCall == R->getReturnValue()) |
| TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); |
| else |
| TheCall->replaceAllUsesWith(R->getReturnValue()); |
| } |
| // Since we are now done with the Call/Invoke, we can delete it. |
| TheCall->eraseFromParent(); |
| |
| // Since we are now done with the return instruction, delete it also. |
| Returns[0]->eraseFromParent(); |
| |
| // We are now done with the inlining. |
| return true; |
| } |
| |
| // Otherwise, we have the normal case, of more than one block to inline or |
| // multiple return sites. |
| |
| // We want to clone the entire callee function into the hole between the |
| // "starter" and "ender" blocks. How we accomplish this depends on whether |
| // this is an invoke instruction or a call instruction. |
| BasicBlock *AfterCallBB; |
| if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) { |
| |
| // Add an unconditional branch to make this look like the CallInst case... |
| BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall); |
| |
| // Split the basic block. This guarantees that no PHI nodes will have to be |
| // updated due to new incoming edges, and make the invoke case more |
| // symmetric to the call case. |
| AfterCallBB = OrigBB->splitBasicBlock(NewBr, |
| CalledFunc->getName()+".exit"); |
| |
| } else { // It's a call |
| // If this is a call instruction, we need to split the basic block that |
| // the call lives in. |
| // |
| AfterCallBB = OrigBB->splitBasicBlock(TheCall, |
| CalledFunc->getName()+".exit"); |
| } |
| |
| // Change the branch that used to go to AfterCallBB to branch to the first |
| // basic block of the inlined function. |
| // |
| TerminatorInst *Br = OrigBB->getTerminator(); |
| assert(Br && Br->getOpcode() == Instruction::Br && |
| "splitBasicBlock broken!"); |
| Br->setOperand(0, FirstNewBlock); |
| |
| |
| // Now that the function is correct, make it a little bit nicer. In |
| // particular, move the basic blocks inserted from the end of the function |
| // into the space made by splitting the source basic block. |
| Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(), |
| FirstNewBlock, Caller->end()); |
| |
| // Handle all of the return instructions that we just cloned in, and eliminate |
| // any users of the original call/invoke instruction. |
| const Type *RTy = CalledFunc->getReturnType(); |
| |
| PHINode *PHI = 0; |
| if (Returns.size() > 1) { |
| // The PHI node should go at the front of the new basic block to merge all |
| // possible incoming values. |
| if (!TheCall->use_empty()) { |
| PHI = PHINode::Create(RTy, Returns.size(), TheCall->getName(), |
| AfterCallBB->begin()); |
| // Anything that used the result of the function call should now use the |
| // PHI node as their operand. |
| TheCall->replaceAllUsesWith(PHI); |
| } |
| |
| // Loop over all of the return instructions adding entries to the PHI node |
| // as appropriate. |
| if (PHI) { |
| for (unsigned i = 0, e = Returns.size(); i != e; ++i) { |
| ReturnInst *RI = Returns[i]; |
| assert(RI->getReturnValue()->getType() == PHI->getType() && |
| "Ret value not consistent in function!"); |
| PHI->addIncoming(RI->getReturnValue(), RI->getParent()); |
| } |
| } |
| |
| |
| // Add a branch to the merge points and remove return instructions. |
| for (unsigned i = 0, e = Returns.size(); i != e; ++i) { |
| ReturnInst *RI = Returns[i]; |
| BranchInst::Create(AfterCallBB, RI); |
| RI->eraseFromParent(); |
| } |
| } else if (!Returns.empty()) { |
| // Otherwise, if there is exactly one return value, just replace anything |
| // using the return value of the call with the computed value. |
| if (!TheCall->use_empty()) { |
| if (TheCall == Returns[0]->getReturnValue()) |
| TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); |
| else |
| TheCall->replaceAllUsesWith(Returns[0]->getReturnValue()); |
| } |
| |
| // Update PHI nodes that use the ReturnBB to use the AfterCallBB. |
| BasicBlock *ReturnBB = Returns[0]->getParent(); |
| ReturnBB->replaceAllUsesWith(AfterCallBB); |
| |
| // Splice the code from the return block into the block that it will return |
| // to, which contains the code that was after the call. |
| AfterCallBB->getInstList().splice(AfterCallBB->begin(), |
| ReturnBB->getInstList()); |
| |
| // Delete the return instruction now and empty ReturnBB now. |
| Returns[0]->eraseFromParent(); |
| ReturnBB->eraseFromParent(); |
| } else if (!TheCall->use_empty()) { |
| // No returns, but something is using the return value of the call. Just |
| // nuke the result. |
| TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); |
| } |
| |
| // Since we are now done with the Call/Invoke, we can delete it. |
| TheCall->eraseFromParent(); |
| |
| // We should always be able to fold the entry block of the function into the |
| // single predecessor of the block... |
| assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!"); |
| BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0); |
| |
| // Splice the code entry block into calling block, right before the |
| // unconditional branch. |
| CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes |
| OrigBB->getInstList().splice(Br, CalleeEntry->getInstList()); |
| |
| // Remove the unconditional branch. |
| OrigBB->getInstList().erase(Br); |
| |
| // Now we can remove the CalleeEntry block, which is now empty. |
| Caller->getBasicBlockList().erase(CalleeEntry); |
| |
| // If we inserted a phi node, check to see if it has a single value (e.g. all |
| // the entries are the same or undef). If so, remove the PHI so it doesn't |
| // block other optimizations. |
| if (PHI) |
| if (Value *V = SimplifyInstruction(PHI, IFI.TD)) { |
| PHI->replaceAllUsesWith(V); |
| PHI->eraseFromParent(); |
| } |
| |
| return true; |
| } |