darling-libobjc2/opts/IMPCacher.cpp
2013-01-10 09:22:25 +00:00

296 lines
11 KiB
C++

#include "llvm/Analysis/Verifier.h"
#include "IMPCacher.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "LLVMCompat.h"
GNUstep::IMPCacher::IMPCacher(LLVMContext &C, Pass *owner) : Context(C),
Owner(owner) {
PtrTy = Type::getInt8PtrTy(Context);
IntTy = (sizeof(int) == 4 ) ? Type::getInt32Ty(C) : Type::getInt64Ty(C);
IdTy = PointerType::getUnqual(PtrTy);
Value *AlreadyCachedFlagValue = MDString::get(C, "IMPCached");
AlreadyCachedFlag = CreateMDNode(C, &AlreadyCachedFlagValue);
IMPCacheFlagKind = Context.getMDKindID("IMPCache");
}
void GNUstep::IMPCacher::CacheLookup(Instruction *lookup, Value *slot, Value
*version, bool isSuperMessage) {
// If this IMP is already cached, don't cache it again.
if (lookup->getMetadata(IMPCacheFlagKind)) { return; }
lookup->setMetadata(IMPCacheFlagKind, AlreadyCachedFlag);
bool isInvoke = false;
BasicBlock *beforeLookupBB = lookup->getParent();
BasicBlock *lookupBB = SplitBlock(beforeLookupBB, lookup, Owner);
BasicBlock *lookupFinishedBB = lookupBB;
BasicBlock *afterLookupBB;
if (InvokeInst *inv = dyn_cast<InvokeInst>(lookup)) {
afterLookupBB = inv->getNormalDest();
lookupFinishedBB =
BasicBlock::Create(Context, "done_lookup", lookupBB->getParent());
CGBuilder B(lookupFinishedBB);
B.CreateBr(afterLookupBB);
inv->setNormalDest(lookupFinishedBB);
isInvoke = true;
} else {
BasicBlock::iterator iter = lookup;
iter++;
afterLookupBB = SplitBlock(iter->getParent(), iter, Owner);
}
removeTerminator(beforeLookupBB);
CGBuilder B = CGBuilder(beforeLookupBB);
// Load the slot and check that neither it nor the version is 0.
Value *versionValue = B.CreateLoad(version);
Value *receiverPtr = lookup->getOperand(0);
Value *receiver = receiverPtr;
if (!isSuperMessage) {
receiver = B.CreateLoad(receiverPtr);
}
// For small objects, we skip the cache entirely.
// FIXME: Class messages are never to small objects...
bool is64Bit = llvm::Module::Pointer64 ==
B.GetInsertBlock()->getParent()->getParent()->getPointerSize();
LLVMType *intPtrTy = is64Bit ? Type::getInt64Ty(Context) :
Type::getInt32Ty(Context);
// Receiver as an integer
Value *receiverSmallObject = B.CreatePtrToInt(receiver, intPtrTy);
// Receiver is a small object...
receiverSmallObject =
B.CreateAnd(receiverSmallObject, is64Bit ? 7 : 1);
// Receiver is not a small object.
receiverSmallObject =
B.CreateICmpNE(receiverSmallObject, Constant::getNullValue(intPtrTy));
// Ideally, we'd call objc_msgSend() here, but for now just skip the cache
// lookup
Value *isCacheEmpty =
B.CreateICmpEQ(versionValue, Constant::getNullValue(IntTy));
Value *receiverNil =
B.CreateICmpEQ(receiver, Constant::getNullValue(receiver->getType()));
isCacheEmpty = B.CreateOr(isCacheEmpty, receiverNil);
isCacheEmpty = B.CreateOr(isCacheEmpty, receiverSmallObject);
BasicBlock *cacheLookupBB = BasicBlock::Create(Context, "cache_check",
lookupBB->getParent());
B.CreateCondBr(isCacheEmpty, lookupBB, cacheLookupBB);
// Check the cache node is current
B.SetInsertPoint(cacheLookupBB);
Value *slotValue = B.CreateLoad(slot, "slot_value");
Value *slotVersion = B.CreateStructGEP(slotValue, 3);
// Note: Volatile load because the slot version might have changed in
// another thread.
slotVersion = B.CreateLoad(slotVersion, true, "slot_version");
Value *slotCachedFor = B.CreateStructGEP(slotValue, 1);
slotCachedFor = B.CreateLoad(slotCachedFor, true, "slot_owner");
Value *cls = B.CreateLoad(B.CreateBitCast(receiver, IdTy));
Value *isVersionCorrect = B.CreateICmpEQ(slotVersion, versionValue);
Value *isOwnerCorrect = B.CreateICmpEQ(slotCachedFor, cls);
Value *isSlotValid = B.CreateAnd(isVersionCorrect, isOwnerCorrect);
// If this slot is still valid, skip the lookup.
B.CreateCondBr(isSlotValid, afterLookupBB, lookupBB);
// Perform the real lookup and cache the result
removeTerminator(lookupFinishedBB);
// Replace the looked up slot with the loaded one
B.SetInsertPoint(afterLookupBB, afterLookupBB->begin());
PHINode *newLookup = IRBuilderCreatePHI(&B, lookup->getType(), 3, "new_lookup");
// Not volatile, so a redundant load elimination pass can do some phi
// magic with this later.
lookup->replaceAllUsesWith(newLookup);
B.SetInsertPoint(lookupFinishedBB);
Value * newReceiver = receiver;
if (!isSuperMessage) {
newReceiver = B.CreateLoad(receiverPtr);
}
BasicBlock *storeCacheBB = BasicBlock::Create(Context, "cache_store",
lookupBB->getParent());
// Don't store the cached lookup if we are doing forwarding tricks.
// Also skip caching small object messages for now
Value *skipCacheWrite =
B.CreateOr(B.CreateICmpNE(receiver, newReceiver), receiverSmallObject);
skipCacheWrite = B.CreateOr(skipCacheWrite, receiverNil);
B.CreateCondBr(skipCacheWrite, afterLookupBB, storeCacheBB);
B.SetInsertPoint(storeCacheBB);
// Store it even if the version is 0, because we always check that the
// version is not 0 at the start and an occasional redundant store is
// probably better than a branch every time.
B.CreateStore(lookup, slot);
B.CreateStore(B.CreateLoad(B.CreateStructGEP(lookup, 3)), version);
cls = B.CreateLoad(B.CreateBitCast(receiver, IdTy));
B.CreateStore(cls, B.CreateStructGEP(lookup, 1));
B.CreateBr(afterLookupBB);
newLookup->addIncoming(lookup, lookupFinishedBB);
newLookup->addIncoming(slotValue, cacheLookupBB);
newLookup->addIncoming(lookup, storeCacheBB);
}
void GNUstep::IMPCacher::SpeculativelyInline(Instruction *call, Function
*function) {
BasicBlock *beforeCallBB = call->getParent();
BasicBlock *callBB = SplitBlock(beforeCallBB, call, Owner);
BasicBlock *inlineBB = BasicBlock::Create(Context, "inline",
callBB->getParent());
BasicBlock::iterator iter = call;
iter++;
BasicBlock *afterCallBB = SplitBlock(iter->getParent(), iter, Owner);
removeTerminator(beforeCallBB);
// Put a branch before the call, testing whether the callee really is the
// function
IRBuilder<> B = IRBuilder<>(beforeCallBB);
Value *callee = isa<CallInst>(call) ? cast<CallInst>(call)->getCalledValue()
: cast<InvokeInst>(call)->getCalledValue();
const FunctionType *FTy = function->getFunctionType();
const FunctionType *calleeTy = cast<FunctionType>(
cast<PointerType>(callee->getType())->getElementType());
if (calleeTy != FTy) {
callee = B.CreateBitCast(callee, function->getType());
}
Value *isInlineValid = B.CreateICmpEQ(callee, function);
B.CreateCondBr(isInlineValid, inlineBB, callBB);
// In the inline BB, add a copy of the call, but this time calling the real
// version.
Instruction *inlineCall = call->clone();
Value *inlineResult= inlineCall;
inlineBB->getInstList().push_back(inlineCall);
B.SetInsertPoint(inlineBB);
if (calleeTy != FTy) {
for (unsigned i=0 ; i<FTy->getNumParams() ; i++) {
LLVMType *callType = calleeTy->getParamType(i);
LLVMType *argType = FTy->getParamType(i);
if (callType != argType) {
inlineCall->setOperand(i, new
BitCastInst(inlineCall->getOperand(i), argType, "", inlineCall));
}
}
if (FTy->getReturnType() != calleeTy->getReturnType()) {
if (FTy->getReturnType() == Type::getVoidTy(Context)) {
inlineResult = Constant::getNullValue(calleeTy->getReturnType());
} else {
inlineResult =
new BitCastInst(inlineCall, calleeTy->getReturnType(), "", inlineBB);
}
}
}
B.CreateBr(afterCallBB);
// Unify the return values
if (call->getType() != Type::getVoidTy(Context)) {
PHINode *phi = CreatePHI(call->getType(), 2, "", afterCallBB->begin());
call->replaceAllUsesWith(phi);
phi->addIncoming(call, callBB);
phi->addIncoming(inlineResult, inlineBB);
}
// Really do the real inlining
InlineFunctionInfo IFI(0, 0);
if (CallInst *c = dyn_cast<CallInst>(inlineCall)) {
c->setCalledFunction(function);
InlineFunction(c, IFI);
} else if (InvokeInst *c = dyn_cast<InvokeInst>(inlineCall)) {
c->setCalledFunction(function);
InlineFunction(c, IFI);
}
}
CallSite GNUstep::IMPCacher::SplitSend(CallSite msgSend)
{
BasicBlock *lookupBB = msgSend->getParent();
Function *F = lookupBB->getParent();
Module *M = F->getParent();
Function *send = M->getFunction("objc_msgSend");
Function *send_stret = M->getFunction("objc_msgSend_stret");
Function *send_fpret = M->getFunction("objc_msgSend_fpret");
Value *self;
Value *cmd;
int selfIndex = 0;
if ((msgSend.getCalledFunction() == send) ||
(msgSend.getCalledFunction() == send_fpret)) {
self = msgSend.getArgument(0);
cmd = msgSend.getArgument(1);
} else if (msgSend.getCalledFunction() == send_stret) {
selfIndex = 1;
self = msgSend.getArgument(1);
cmd = msgSend.getArgument(2);
} else {
abort();
return CallSite();
}
CGBuilder B(&F->getEntryBlock(), F->getEntryBlock().begin());
Value *selfPtr = B.CreateAlloca(self->getType());
B.SetInsertPoint(msgSend.getInstruction());
B.CreateStore(self, selfPtr, true);
LLVMType *impTy = msgSend.getCalledValue()->getType();
LLVMType *slotTy = PointerType::getUnqual(StructType::get(PtrTy, PtrTy, PtrTy,
IntTy, impTy, PtrTy, NULL));
Value *slot;
Constant *lookupFn = M->getOrInsertFunction("objc_msg_lookup_sender",
slotTy, selfPtr->getType(), cmd->getType(), PtrTy, NULL);
if (msgSend.isCall()) {
slot = B.CreateCall3(lookupFn, selfPtr, cmd, Constant::getNullValue(PtrTy));
} else {
InvokeInst *inv = cast<InvokeInst>(msgSend.getInstruction());
BasicBlock *callBB = SplitBlock(lookupBB, msgSend.getInstruction(), Owner);
removeTerminator(lookupBB);
B.SetInsertPoint(lookupBB);
slot = B.CreateInvoke3(lookupFn, callBB, inv->getUnwindDest(), selfPtr, cmd,
Constant::getNullValue(PtrTy));
addPredecssor(inv->getUnwindDest(), msgSend->getParent(), lookupBB);
B.SetInsertPoint(msgSend.getInstruction());
}
Value *imp = B.CreateLoad(B.CreateStructGEP(slot, 4));
msgSend.setArgument(selfIndex, B.CreateLoad(selfPtr, true));
msgSend.setCalledFunction(imp);
return CallSite(slot);
}
// Cleanly removes a terminator instruction.
void GNUstep::removeTerminator(BasicBlock *BB) {
TerminatorInst *BBTerm = BB->getTerminator();
// Remove the BB as a predecessor from all of successors
for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i) {
BBTerm->getSuccessor(i)->removePredecessor(BB);
}
BBTerm->replaceAllUsesWith(UndefValue::get(BBTerm->getType()));
// Remove the terminator instruction itself.
BBTerm->eraseFromParent();
}
void GNUstep::addPredecssor(BasicBlock *block, BasicBlock *oldPredecessor,
BasicBlock *newPredecessor) {
for (BasicBlock::iterator i=block->begin() ; PHINode *phi=dyn_cast<PHINode>(i)
; ++i) {
Value *v = phi->getIncomingValueForBlock(oldPredecessor);
phi->addIncoming(v, newPredecessor);
}
}