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//===- InlineFunction.cpp - Code to perform function inlining -------------===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file implements inlining of a function into a call site, resolving
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// parameters and the return value as appropriate.
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Module.h"
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#include "llvm/Instructions.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Intrinsics.h"
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#include "llvm/Attributes.h"
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/Analysis/DebugInfo.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Support/CallSite.h"
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bool llvm::InlineFunction(CallInst *CI, CallGraph *CG, const TargetData *TD,
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SmallVectorImpl<AllocaInst*> *StaticAllocas) {
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return InlineFunction(CallSite(CI), CG, TD, StaticAllocas);
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bool llvm::InlineFunction(InvokeInst *II, CallGraph *CG, const TargetData *TD,
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SmallVectorImpl<AllocaInst*> *StaticAllocas) {
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return InlineFunction(CallSite(II), CG, TD, StaticAllocas);
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/// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into
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/// an invoke, we have to turn all of the calls that can throw into
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/// invokes. This function analyze BB to see if there are any calls, and if so,
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/// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI
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/// nodes in that block with the values specified in InvokeDestPHIValues.
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static void HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
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BasicBlock *InvokeDest,
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const SmallVectorImpl<Value*> &InvokeDestPHIValues) {
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for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
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Instruction *I = BBI++;
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// We only need to check for function calls: inlined invoke
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// instructions require no special handling.
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CallInst *CI = dyn_cast<CallInst>(I);
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if (CI == 0) continue;
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// If this call cannot unwind, don't convert it to an invoke.
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if (CI->doesNotThrow())
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// Convert this function call into an invoke instruction.
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// First, split the basic block.
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BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
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// Next, create the new invoke instruction, inserting it at the end
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// of the old basic block.
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SmallVector<Value*, 8> InvokeArgs(CI->op_begin()+1, CI->op_end());
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InvokeInst::Create(CI->getCalledValue(), Split, InvokeDest,
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InvokeArgs.begin(), InvokeArgs.end(),
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CI->getName(), BB->getTerminator());
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II->setCallingConv(CI->getCallingConv());
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II->setAttributes(CI->getAttributes());
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// Make sure that anything using the call now uses the invoke! This also
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// updates the CallGraph if present.
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CI->replaceAllUsesWith(II);
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// Delete the unconditional branch inserted by splitBasicBlock
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BB->getInstList().pop_back();
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Split->getInstList().pop_front(); // Delete the original call
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// Update any PHI nodes in the exceptional block to indicate that
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// there is now a new entry in them.
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for (BasicBlock::iterator I = InvokeDest->begin();
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isa<PHINode>(I); ++I, ++i)
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cast<PHINode>(I)->addIncoming(InvokeDestPHIValues[i], BB);
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// This basic block is now complete, the caller will continue scanning the
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/// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls
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/// in the body of the inlined function into invokes and turn unwind
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/// instructions into branches to the invoke unwind dest.
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/// II is the invoke instruction being inlined. FirstNewBlock is the first
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/// block of the inlined code (the last block is the end of the function),
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/// and InlineCodeInfo is information about the code that got inlined.
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static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock,
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ClonedCodeInfo &InlinedCodeInfo) {
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BasicBlock *InvokeDest = II->getUnwindDest();
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SmallVector<Value*, 8> InvokeDestPHIValues;
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// If there are PHI nodes in the unwind destination block, we need to
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// keep track of which values came into them from this invoke, then remove
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// the entry for this block.
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BasicBlock *InvokeBlock = II->getParent();
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for (BasicBlock::iterator I = InvokeDest->begin(); isa<PHINode>(I); ++I) {
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PHINode *PN = cast<PHINode>(I);
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// Save the value to use for this edge.
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InvokeDestPHIValues.push_back(PN->getIncomingValueForBlock(InvokeBlock));
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Function *Caller = FirstNewBlock->getParent();
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// The inlined code is currently at the end of the function, scan from the
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// start of the inlined code to its end, checking for stuff we need to
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// rewrite. If the code doesn't have calls or unwinds, we know there is
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// nothing to rewrite.
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if (!InlinedCodeInfo.ContainsCalls && !InlinedCodeInfo.ContainsUnwinds) {
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// Now that everything is happy, we have one final detail. The PHI nodes in
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// the exception destination block still have entries due to the original
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// invoke instruction. Eliminate these entries (which might even delete the
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InvokeDest->removePredecessor(II->getParent());
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for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){
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if (InlinedCodeInfo.ContainsCalls)
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HandleCallsInBlockInlinedThroughInvoke(BB, InvokeDest,
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InvokeDestPHIValues);
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if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
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// An UnwindInst requires special handling when it gets inlined into an
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// invoke site. Once this happens, we know that the unwind would cause
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// a control transfer to the invoke exception destination, so we can
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// transform it into a direct branch to the exception destination.
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BranchInst::Create(InvokeDest, UI);
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// Delete the unwind instruction!
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UI->eraseFromParent();
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// Update any PHI nodes in the exceptional block to indicate that
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// there is now a new entry in them.
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for (BasicBlock::iterator I = InvokeDest->begin();
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isa<PHINode>(I); ++I, ++i) {
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PHINode *PN = cast<PHINode>(I);
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PN->addIncoming(InvokeDestPHIValues[i], BB);
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// Now that everything is happy, we have one final detail. The PHI nodes in
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// the exception destination block still have entries due to the original
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// invoke instruction. Eliminate these entries (which might even delete the
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InvokeDest->removePredecessor(II->getParent());
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/// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee
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/// into the caller, update the specified callgraph to reflect the changes we
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/// made. Note that it's possible that not all code was copied over, so only
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/// some edges of the callgraph may remain.
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static void UpdateCallGraphAfterInlining(CallSite CS,
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Function::iterator FirstNewBlock,
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DenseMap<const Value*, Value*> &ValueMap,
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const Function *Caller = CS.getInstruction()->getParent()->getParent();
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const Function *Callee = CS.getCalledFunction();
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CallGraphNode *CalleeNode = CG[Callee];
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CallGraphNode *CallerNode = CG[Caller];
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// Since we inlined some uninlined call sites in the callee into the caller,
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// add edges from the caller to all of the callees of the callee.
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CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end();
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// Consider the case where CalleeNode == CallerNode.
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CallGraphNode::CalledFunctionsVector CallCache;
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if (CalleeNode == CallerNode) {
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CallCache.assign(I, E);
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I = CallCache.begin();
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for (; I != E; ++I) {
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const Value *OrigCall = I->first;
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DenseMap<const Value*, Value*>::iterator VMI = ValueMap.find(OrigCall);
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// Only copy the edge if the call was inlined!
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if (VMI == ValueMap.end() || VMI->second == 0)
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// If the call was inlined, but then constant folded, there is no edge to
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// add. Check for this case.
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if (Instruction *NewCall = dyn_cast<Instruction>(VMI->second))
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CallerNode->addCalledFunction(CallSite::get(NewCall), I->second);
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// Update the call graph by deleting the edge from Callee to Caller. We must
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// do this after the loop above in case Caller and Callee are the same.
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CallerNode->removeCallEdgeFor(CS);
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// InlineFunction - This function inlines the called function into the basic
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// block of the caller. This returns false if it is not possible to inline this
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// call. The program is still in a well defined state if this occurs though.
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// Note that this only does one level of inlining. For example, if the
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// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
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// exists in the instruction stream. Similiarly this will inline a recursive
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// function by one level.
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bool llvm::InlineFunction(CallSite CS, CallGraph *CG, const TargetData *TD,
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SmallVectorImpl<AllocaInst*> *StaticAllocas) {
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Instruction *TheCall = CS.getInstruction();
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LLVMContext &Context = TheCall->getContext();
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assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
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"Instruction not in function!");
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const Function *CalledFunc = CS.getCalledFunction();
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if (CalledFunc == 0 || // Can't inline external function or indirect
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CalledFunc->isDeclaration() || // call, or call to a vararg function!
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CalledFunc->getFunctionType()->isVarArg()) return false;
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// If the call to the callee is not a tail call, we must clear the 'tail'
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// flags on any calls that we inline.
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bool MustClearTailCallFlags =
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!(isa<CallInst>(TheCall) && cast<CallInst>(TheCall)->isTailCall());
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// If the call to the callee cannot throw, set the 'nounwind' flag on any
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// calls that we inline.
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bool MarkNoUnwind = CS.doesNotThrow();
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BasicBlock *OrigBB = TheCall->getParent();
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Function *Caller = OrigBB->getParent();
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// GC poses two hazards to inlining, which only occur when the callee has GC:
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// 1. If the caller has no GC, then the callee's GC must be propagated to the
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// 2. If the caller has a differing GC, it is invalid to inline.
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if (CalledFunc->hasGC()) {
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if (!Caller->hasGC())
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Caller->setGC(CalledFunc->getGC());
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else if (CalledFunc->getGC() != Caller->getGC())
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// Get an iterator to the last basic block in the function, which will have
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// the new function inlined after it.
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Function::iterator LastBlock = &Caller->back();
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// Make sure to capture all of the return instructions from the cloned
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SmallVector<ReturnInst*, 8> Returns;
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ClonedCodeInfo InlinedFunctionInfo;
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Function::iterator FirstNewBlock;
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{ // Scope to destroy ValueMap after cloning.
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DenseMap<const Value*, Value*> ValueMap;
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assert(CalledFunc->arg_size() == CS.arg_size() &&
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"No varargs calls can be inlined!");
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// Calculate the vector of arguments to pass into the function cloner, which
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// matches up the formal to the actual argument values.
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CallSite::arg_iterator AI = CS.arg_begin();
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for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
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E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) {
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Value *ActualArg = *AI;
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// When byval arguments actually inlined, we need to make the copy implied
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// by them explicit. However, we don't do this if the callee is readonly
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// or readnone, because the copy would be unneeded: the callee doesn't
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// modify the struct.
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if (CalledFunc->paramHasAttr(ArgNo+1, Attribute::ByVal) &&
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!CalledFunc->onlyReadsMemory()) {
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const Type *AggTy = cast<PointerType>(I->getType())->getElementType();
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const Type *VoidPtrTy =
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Type::getInt8PtrTy(Context);
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// Create the alloca. If we have TargetData, use nice alignment.
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if (TD) Align = TD->getPrefTypeAlignment(AggTy);
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Value *NewAlloca = new AllocaInst(AggTy, 0, Align,
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&*Caller->begin()->begin());
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const Type *Tys[] = { Type::getInt64Ty(Context) };
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Function *MemCpyFn = Intrinsic::getDeclaration(Caller->getParent(),
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Value *DestCast = new BitCastInst(NewAlloca, VoidPtrTy, "tmp", TheCall);
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Value *SrcCast = new BitCastInst(*AI, VoidPtrTy, "tmp", TheCall);
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Size = ConstantExpr::getSizeOf(AggTy);
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Size = ConstantInt::get(Type::getInt64Ty(Context),
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TD->getTypeStoreSize(AggTy));
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// Always generate a memcpy of alignment 1 here because we don't know
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// the alignment of the src pointer. Other optimizations can infer
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Value *CallArgs[] = {
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DestCast, SrcCast, Size,
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ConstantInt::get(Type::getInt32Ty(Context), 1)
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CallInst *TheMemCpy =
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CallInst::Create(MemCpyFn, CallArgs, CallArgs+4, "", TheCall);
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// If we have a call graph, update it.
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CallGraphNode *MemCpyCGN = CG->getOrInsertFunction(MemCpyFn);
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CallGraphNode *CallerNode = (*CG)[Caller];
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CallerNode->addCalledFunction(TheMemCpy, MemCpyCGN);
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// Uses of the argument in the function should use our new alloca
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ActualArg = NewAlloca;
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ValueMap[I] = ActualArg;
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// We want the inliner to prune the code as it copies. We would LOVE to
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// have no dead or constant instructions leftover after inlining occurs
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// (which can happen, e.g., because an argument was constant), but we'll be
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// happy with whatever the cloner can do.
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CloneAndPruneFunctionInto(Caller, CalledFunc, ValueMap, Returns, ".i",
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&InlinedFunctionInfo, TD, TheCall);
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// Remember the first block that is newly cloned over.
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FirstNewBlock = LastBlock; ++FirstNewBlock;
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// Update the callgraph if requested.
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UpdateCallGraphAfterInlining(CS, FirstNewBlock, ValueMap, *CG);
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// If there are any alloca instructions in the block that used to be the entry
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// block for the callee, move them to the entry block of the caller. First
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// calculate which instruction they should be inserted before. We insert the
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// instructions at the end of the current alloca list.
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BasicBlock::iterator InsertPoint = Caller->begin()->begin();
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for (BasicBlock::iterator I = FirstNewBlock->begin(),
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E = FirstNewBlock->end(); I != E; ) {
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AllocaInst *AI = dyn_cast<AllocaInst>(I++);
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if (AI == 0) continue;
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// If the alloca is now dead, remove it. This often occurs due to code
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if (AI->use_empty()) {
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AI->eraseFromParent();
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if (!isa<Constant>(AI->getArraySize()))
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// Keep track of the static allocas that we inline into the caller if the
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// StaticAllocas pointer is non-null.
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if (StaticAllocas) StaticAllocas->push_back(AI);
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// Scan for the block of allocas that we can move over, and move them
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while (isa<AllocaInst>(I) &&
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isa<Constant>(cast<AllocaInst>(I)->getArraySize())) {
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if (StaticAllocas) StaticAllocas->push_back(cast<AllocaInst>(I));
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// Transfer all of the allocas over in a block. Using splice means
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// that the instructions aren't removed from the symbol table, then
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Caller->getEntryBlock().getInstList().splice(InsertPoint,
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FirstNewBlock->getInstList(),
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// If the inlined code contained dynamic alloca instructions, wrap the inlined
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// code with llvm.stacksave/llvm.stackrestore intrinsics.
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if (InlinedFunctionInfo.ContainsDynamicAllocas) {
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Module *M = Caller->getParent();
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// Get the two intrinsics we care about.
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Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave);
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Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore);
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// If we are preserving the callgraph, add edges to the stacksave/restore
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// functions for the calls we insert.
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CallGraphNode *StackSaveCGN = 0, *StackRestoreCGN = 0, *CallerNode = 0;
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StackSaveCGN = CG->getOrInsertFunction(StackSave);
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StackRestoreCGN = CG->getOrInsertFunction(StackRestore);
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CallerNode = (*CG)[Caller];
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// Insert the llvm.stacksave.
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CallInst *SavedPtr = CallInst::Create(StackSave, "savedstack",
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FirstNewBlock->begin());
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if (CG) CallerNode->addCalledFunction(SavedPtr, StackSaveCGN);
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// Insert a call to llvm.stackrestore before any return instructions in the
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for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
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CallInst *CI = CallInst::Create(StackRestore, SavedPtr, "", Returns[i]);
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if (CG) CallerNode->addCalledFunction(CI, StackRestoreCGN);
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// Count the number of StackRestore calls we insert.
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unsigned NumStackRestores = Returns.size();
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// If we are inlining an invoke instruction, insert restores before each
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// unwind. These unwinds will be rewritten into branches later.
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if (InlinedFunctionInfo.ContainsUnwinds && isa<InvokeInst>(TheCall)) {
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for (Function::iterator BB = FirstNewBlock, E = Caller->end();
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if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
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CallInst *CI = CallInst::Create(StackRestore, SavedPtr, "", UI);
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if (CG) CallerNode->addCalledFunction(CI, StackRestoreCGN);
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// If we are inlining tail call instruction through a call site that isn't
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// marked 'tail', we must remove the tail marker for any calls in the inlined
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// code. Also, calls inlined through a 'nounwind' call site should be marked
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if (InlinedFunctionInfo.ContainsCalls &&
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(MustClearTailCallFlags || MarkNoUnwind)) {
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for (Function::iterator BB = FirstNewBlock, E = Caller->end();
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
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if (CallInst *CI = dyn_cast<CallInst>(I)) {
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if (MustClearTailCallFlags)
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CI->setTailCall(false);
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CI->setDoesNotThrow();
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// If we are inlining through a 'nounwind' call site then any inlined 'unwind'
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// instructions are unreachable.
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if (InlinedFunctionInfo.ContainsUnwinds && MarkNoUnwind)
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for (Function::iterator BB = FirstNewBlock, E = Caller->end();
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TerminatorInst *Term = BB->getTerminator();
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if (isa<UnwindInst>(Term)) {
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new UnreachableInst(Context, Term);
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BB->getInstList().erase(Term);
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// If we are inlining for an invoke instruction, we must make sure to rewrite
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// any inlined 'unwind' instructions into branches to the invoke exception
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// destination, and call instructions into invoke instructions.
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if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
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HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo);
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// If we cloned in _exactly one_ basic block, and if that block ends in a
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// return instruction, we splice the body of the inlined callee directly into
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// the calling basic block.
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if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) {
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// Move all of the instructions right before the call.
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OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(),
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FirstNewBlock->begin(), FirstNewBlock->end());
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// Remove the cloned basic block.
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Caller->getBasicBlockList().pop_back();
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// If the call site was an invoke instruction, add a branch to the normal
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if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
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BranchInst::Create(II->getNormalDest(), TheCall);
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// If the return instruction returned a value, replace uses of the call with
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// uses of the returned value.
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if (!TheCall->use_empty()) {
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ReturnInst *R = Returns[0];
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if (TheCall == R->getReturnValue())
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TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
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TheCall->replaceAllUsesWith(R->getReturnValue());
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// Since we are now done with the Call/Invoke, we can delete it.
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TheCall->eraseFromParent();
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// Since we are now done with the return instruction, delete it also.
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Returns[0]->eraseFromParent();
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// We are now done with the inlining.
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// Otherwise, we have the normal case, of more than one block to inline or
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// multiple return sites.
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// We want to clone the entire callee function into the hole between the
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// "starter" and "ender" blocks. How we accomplish this depends on whether
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// this is an invoke instruction or a call instruction.
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BasicBlock *AfterCallBB;
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if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
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// Add an unconditional branch to make this look like the CallInst case...
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BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall);
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// Split the basic block. This guarantees that no PHI nodes will have to be
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// updated due to new incoming edges, and make the invoke case more
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// symmetric to the call case.
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AfterCallBB = OrigBB->splitBasicBlock(NewBr,
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CalledFunc->getName()+".exit");
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} else { // It's a call
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// If this is a call instruction, we need to split the basic block that
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// the call lives in.
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AfterCallBB = OrigBB->splitBasicBlock(TheCall,
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CalledFunc->getName()+".exit");
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// Change the branch that used to go to AfterCallBB to branch to the first
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// basic block of the inlined function.
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TerminatorInst *Br = OrigBB->getTerminator();
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assert(Br && Br->getOpcode() == Instruction::Br &&
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"splitBasicBlock broken!");
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Br->setOperand(0, FirstNewBlock);
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// Now that the function is correct, make it a little bit nicer. In
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// particular, move the basic blocks inserted from the end of the function
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// into the space made by splitting the source basic block.
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Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(),
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FirstNewBlock, Caller->end());
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// Handle all of the return instructions that we just cloned in, and eliminate
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// any users of the original call/invoke instruction.
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const Type *RTy = CalledFunc->getReturnType();
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if (Returns.size() > 1) {
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// The PHI node should go at the front of the new basic block to merge all
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// possible incoming values.
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if (!TheCall->use_empty()) {
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PHI = PHINode::Create(RTy, TheCall->getName(),
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AfterCallBB->begin());
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// Anything that used the result of the function call should now use the
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// PHI node as their operand.
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TheCall->replaceAllUsesWith(PHI);
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// Loop over all of the return instructions adding entries to the PHI node
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for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
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ReturnInst *RI = Returns[i];
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assert(RI->getReturnValue()->getType() == PHI->getType() &&
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"Ret value not consistent in function!");
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PHI->addIncoming(RI->getReturnValue(), RI->getParent());
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// Now that we inserted the PHI, check to see if it has a single value
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// (e.g. all the entries are the same or undef). If so, remove the PHI so
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// it doesn't block other optimizations.
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if (Value *V = PHI->hasConstantValue()) {
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PHI->replaceAllUsesWith(V);
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PHI->eraseFromParent();
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// Add a branch to the merge points and remove return instructions.
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for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
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ReturnInst *RI = Returns[i];
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BranchInst::Create(AfterCallBB, RI);
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RI->eraseFromParent();
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} else if (!Returns.empty()) {
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// Otherwise, if there is exactly one return value, just replace anything
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// using the return value of the call with the computed value.
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if (!TheCall->use_empty()) {
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if (TheCall == Returns[0]->getReturnValue())
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TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
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TheCall->replaceAllUsesWith(Returns[0]->getReturnValue());
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// Splice the code from the return block into the block that it will return
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// to, which contains the code that was after the call.
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BasicBlock *ReturnBB = Returns[0]->getParent();
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AfterCallBB->getInstList().splice(AfterCallBB->begin(),
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ReturnBB->getInstList());
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// Update PHI nodes that use the ReturnBB to use the AfterCallBB.
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ReturnBB->replaceAllUsesWith(AfterCallBB);
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// Delete the return instruction now and empty ReturnBB now.
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Returns[0]->eraseFromParent();
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ReturnBB->eraseFromParent();
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} else if (!TheCall->use_empty()) {
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// No returns, but something is using the return value of the call. Just
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TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
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// Since we are now done with the Call/Invoke, we can delete it.
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TheCall->eraseFromParent();
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// We should always be able to fold the entry block of the function into the
626
// single predecessor of the block...
627
assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!");
628
BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0);
630
// Splice the code entry block into calling block, right before the
631
// unconditional branch.
632
OrigBB->getInstList().splice(Br, CalleeEntry->getInstList());
633
CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes
635
// Remove the unconditional branch.
636
OrigBB->getInstList().erase(Br);
638
// Now we can remove the CalleeEntry block, which is now empty.
639
Caller->getBasicBlockList().erase(CalleeEntry);
added
removed
libclamav/c++/llvm/lib/Transforms/Utils/InlineFunction.cpp
