llvm-6502/lib/Transforms/Utils/InlineFunction.cpp
2011-07-18 04:54:35 +00:00

1183 lines
46 KiB
C++

//===- 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);
// 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, 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) {
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();
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.
Type *Tys[3] = {VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context)};
Function *MemCpyFn = Intrinsic::getDeclaration(Caller->getParent(),
Intrinsic::memcpy,
Tys);
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);
// 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) {
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.
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;
}