| //===- InlineFunction.cpp - Code to perform function inlining -------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and 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. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Transforms/Utils/Cloning.h" |
| #include "llvm/Constants.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Module.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Intrinsics.h" |
| #include "llvm/Analysis/CallGraph.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/Support/CallSite.h" |
| using namespace llvm; |
| |
| bool llvm::InlineFunction(CallInst *CI, CallGraph *CG, const TargetData *TD) { |
| return InlineFunction(CallSite(CI), CG, TD); |
| } |
| bool llvm::InlineFunction(InvokeInst *II, CallGraph *CG, const TargetData *TD) { |
| return InlineFunction(CallSite(II), CG, TD); |
| } |
| |
| /// 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 begin 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(); |
| std::vector<Value*> InvokeDestPHIValues; |
| |
| // If there are PHI nodes in the unwind destination block, we need to |
| // keep track of which values came into them from this invoke, then remove |
| // the entry for this block. |
| BasicBlock *InvokeBlock = II->getParent(); |
| for (BasicBlock::iterator I = InvokeDest->begin(); isa<PHINode>(I); ++I) { |
| PHINode *PN = cast<PHINode>(I); |
| // Save the value to use for this edge. |
| InvokeDestPHIValues.push_back(PN->getIncomingValueForBlock(InvokeBlock)); |
| } |
| |
| 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 (InlinedCodeInfo.ContainsCalls || InlinedCodeInfo.ContainsUnwinds) { |
| for (Function::iterator BB = FirstNewBlock, E = Caller->end(); |
| BB != E; ++BB) { |
| if (InlinedCodeInfo.ContainsCalls) { |
| 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. |
| if (!isa<CallInst>(I)) continue; |
| CallInst *CI = cast<CallInst>(I); |
| |
| // If this call cannot unwind or is an inline asm, don't |
| // convert it to an invoke. |
| if (CI->isNoUnwind() || isa<InlineAsm>(CI->getCalledValue())) |
| continue; |
| |
| // Convert this function call into an invoke instruction. |
| // First, split the basic block. |
| BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc"); |
| |
| // Next, create the new invoke instruction, inserting it at the end |
| // of the old basic block. |
| SmallVector<Value*, 8> InvokeArgs(CI->op_begin()+1, CI->op_end()); |
| InvokeInst *II = |
| new InvokeInst(CI->getCalledValue(), Split, InvokeDest, |
| InvokeArgs.begin(), InvokeArgs.end(), |
| CI->getName(), BB->getTerminator()); |
| II->setCallingConv(CI->getCallingConv()); |
| II->setParamAttrs(CI->getParamAttrs()); |
| |
| // Make sure that anything using the call now uses the invoke! |
| CI->replaceAllUsesWith(II); |
| |
| // Delete the unconditional branch inserted by splitBasicBlock |
| BB->getInstList().pop_back(); |
| 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. |
| unsigned i = 0; |
| for (BasicBlock::iterator I = InvokeDest->begin(); |
| isa<PHINode>(I); ++I, ++i) { |
| PHINode *PN = cast<PHINode>(I); |
| PN->addIncoming(InvokeDestPHIValues[i], BB); |
| } |
| |
| // This basic block is now complete, start scanning the next one. |
| break; |
| } |
| } |
| |
| 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. |
| new BranchInst(InvokeDest, UI); |
| |
| // Delete the unwind instruction! |
| UI->getParent()->getInstList().pop_back(); |
| |
| // Update any PHI nodes in the exceptional block to indicate that |
| // there is now a new entry in them. |
| unsigned i = 0; |
| for (BasicBlock::iterator I = InvokeDest->begin(); |
| isa<PHINode>(I); ++I, ++i) { |
| PHINode *PN = cast<PHINode>(I); |
| PN->addIncoming(InvokeDestPHIValues[i], 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 will be remain. |
| static void UpdateCallGraphAfterInlining(const Function *Caller, |
| const Function *Callee, |
| Function::iterator FirstNewBlock, |
| DenseMap<const Value*, Value*> &ValueMap, |
| CallGraph &CG) { |
| // Update the call graph by deleting the edge from Callee to Caller |
| CallGraphNode *CalleeNode = CG[Callee]; |
| CallGraphNode *CallerNode = CG[Caller]; |
| CallerNode->removeCallEdgeTo(CalleeNode); |
| |
| // 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. |
| for (CallGraphNode::iterator I = CalleeNode->begin(), |
| E = CalleeNode->end(); I != E; ++I) { |
| const Instruction *OrigCall = I->first.getInstruction(); |
| |
| DenseMap<const Value*, Value*>::iterator VMI = ValueMap.find(OrigCall); |
| // Only copy the edge if the call was inlined! |
| if (VMI != ValueMap.end() && VMI->second) { |
| // If the call was inlined, but then constant folded, there is no edge to |
| // add. Check for this case. |
| if (Instruction *NewCall = dyn_cast<Instruction>(VMI->second)) |
| CallerNode->addCalledFunction(CallSite::get(NewCall), I->second); |
| } |
| } |
| } |
| |
| |
| // 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. Similiarly this will inline a recursive |
| // function by one level. |
| // |
| bool llvm::InlineFunction(CallSite CS, CallGraph *CG, const TargetData *TD) { |
| Instruction *TheCall = CS.getInstruction(); |
| assert(TheCall->getParent() && TheCall->getParent()->getParent() && |
| "Instruction not in function!"); |
| |
| 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 a non-tail call, we must clear the 'tail' |
| // flags on any calls that we inline. |
| bool MustClearTailCallFlags = |
| isa<CallInst>(TheCall) && !cast<CallInst>(TheCall)->isTailCall(); |
| |
| BasicBlock *OrigBB = TheCall->getParent(); |
| Function *Caller = OrigBB->getParent(); |
| |
| // 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. |
| std::vector<ReturnInst*> Returns; |
| ClonedCodeInfo InlinedFunctionInfo; |
| Function::iterator FirstNewBlock; |
| |
| { // Scope to destroy ValueMap after cloning. |
| DenseMap<const Value*, Value*> ValueMap; |
| |
| // Calculate the vector of arguments to pass into the function cloner, which |
| // matches up the formal to the actual argument values. |
| assert(std::distance(CalledFunc->arg_begin(), CalledFunc->arg_end()) == |
| std::distance(CS.arg_begin(), CS.arg_end()) && |
| "No varargs calls can be inlined!"); |
| CallSite::arg_iterator AI = CS.arg_begin(); |
| for (Function::const_arg_iterator I = CalledFunc->arg_begin(), |
| E = CalledFunc->arg_end(); I != E; ++I, ++AI) |
| ValueMap[I] = *AI; |
| |
| // 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, ValueMap, Returns, ".i", |
| &InlinedFunctionInfo, TD); |
| |
| // Remember the first block that is newly cloned over. |
| FirstNewBlock = LastBlock; ++FirstNewBlock; |
| |
| // Update the callgraph if requested. |
| if (CG) |
| UpdateCallGraphAfterInlining(Caller, CalledFunc, FirstNewBlock, ValueMap, |
| *CG); |
| } |
| |
| // 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; ) |
| if (AllocaInst *AI = dyn_cast<AllocaInst>(I++)) { |
| // 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())) { |
| // 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())) |
| ++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); |
| } |
| } |
| } |
| |
| // 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(); |
| const Type *BytePtr = PointerType::get(Type::Int8Ty); |
| // Get the two intrinsics we care about. |
| Constant *StackSave, *StackRestore; |
| StackSave = M->getOrInsertFunction("llvm.stacksave", BytePtr, NULL); |
| StackRestore = M->getOrInsertFunction("llvm.stackrestore", Type::VoidTy, |
| BytePtr, NULL); |
| |
| // If we are preserving the callgraph, add edges to the stacksave/restore |
| // functions for the calls we insert. |
| CallGraphNode *StackSaveCGN = 0, *StackRestoreCGN = 0, *CallerNode = 0; |
| if (CG) { |
| // We know that StackSave/StackRestore are Function*'s, because they are |
| // intrinsics which must have the right types. |
| StackSaveCGN = CG->getOrInsertFunction(cast<Function>(StackSave)); |
| StackRestoreCGN = CG->getOrInsertFunction(cast<Function>(StackRestore)); |
| CallerNode = (*CG)[Caller]; |
| } |
| |
| // Insert the llvm.stacksave. |
| CallInst *SavedPtr = new CallInst(StackSave, "savedstack", |
| FirstNewBlock->begin()); |
| if (CG) CallerNode->addCalledFunction(SavedPtr, StackSaveCGN); |
| |
| // Insert a call to llvm.stackrestore before any return instructions in the |
| // inlined function. |
| for (unsigned i = 0, e = Returns.size(); i != e; ++i) { |
| CallInst *CI = new CallInst(StackRestore, SavedPtr, "", Returns[i]); |
| if (CG) CallerNode->addCalledFunction(CI, StackRestoreCGN); |
| } |
| |
| // 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())) { |
| new CallInst(StackRestore, SavedPtr, "", UI); |
| ++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. |
| if (MustClearTailCallFlags && InlinedFunctionInfo.ContainsCalls) { |
| 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)) |
| CI->setTailCall(false); |
| } |
| |
| // 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)) |
| new BranchInst(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()) |
| TheCall->replaceAllUsesWith(Returns[0]->getReturnValue()); |
| |
| // Since we are now done with the Call/Invoke, we can delete it. |
| TheCall->getParent()->getInstList().erase(TheCall); |
| |
| // Since we are now done with the return instruction, delete it also. |
| Returns[0]->getParent()->getInstList().erase(Returns[0]); |
| |
| // 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 = new BranchInst(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. |
| if (Returns.size() > 1) { |
| // The PHI node should go at the front of the new basic block to merge all |
| // possible incoming values. |
| // |
| PHINode *PHI = 0; |
| if (!TheCall->use_empty()) { |
| PHI = new PHINode(CalledFunc->getReturnType(), |
| 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, turning them into unconditional |
| // branches to the merge point now, and adding entries to the PHI node as |
| // appropriate. |
| for (unsigned i = 0, e = Returns.size(); i != e; ++i) { |
| ReturnInst *RI = Returns[i]; |
| |
| if (PHI) { |
| assert(RI->getReturnValue() && "Ret should have value!"); |
| assert(RI->getReturnValue()->getType() == PHI->getType() && |
| "Ret value not consistent in function!"); |
| PHI->addIncoming(RI->getReturnValue(), RI->getParent()); |
| } |
| |
| // Add a branch to the merge point where the PHI node lives if it exists. |
| new BranchInst(AfterCallBB, RI); |
| |
| // Delete the return instruction now |
| RI->getParent()->getInstList().erase(RI); |
| } |
| |
| } 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()) |
| TheCall->replaceAllUsesWith(Returns[0]->getReturnValue()); |
| |
| // Splice the code from the return block into the block that it will return |
| // to, which contains the code that was after the call. |
| BasicBlock *ReturnBB = Returns[0]->getParent(); |
| AfterCallBB->getInstList().splice(AfterCallBB->begin(), |
| ReturnBB->getInstList()); |
| |
| // Update PHI nodes that use the ReturnBB to use the AfterCallBB. |
| ReturnBB->replaceAllUsesWith(AfterCallBB); |
| |
| // 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. |
| OrigBB->getInstList().splice(Br, CalleeEntry->getInstList()); |
| CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes |
| |
| // Remove the unconditional branch. |
| OrigBB->getInstList().erase(Br); |
| |
| // Now we can remove the CalleeEntry block, which is now empty. |
| Caller->getBasicBlockList().erase(CalleeEntry); |
| |
| return true; |
| } |