#include "llvm/Function.h"
#include "llvm/InlineAsm.h"
#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/LLVMContext.h"
#include "llvm/Pass.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/Utils/AddrModeMatcher.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallSet.h"
+#include "llvm/Assembly/Writer.h"
#include "llvm/Support/CallSite.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
using namespace llvm;
using namespace llvm::PatternMatch;
+static cl::opt<bool> FactorCommonPreds("split-critical-paths-tweak",
+ cl::init(false), cl::Hidden);
+
namespace {
class VISIBILITY_HIDDEN CodeGenPrepare : public FunctionPass {
/// TLI - Keep a pointer of a TargetLowering to consult for determining
/// transformation profitability.
const TargetLowering *TLI;
+
+ /// BackEdges - Keep a set of all the loop back edges.
+ ///
+ SmallSet<std::pair<const BasicBlock*, const BasicBlock*>, 8> BackEdges;
public:
static char ID; // Pass identification, replacement for typeid
explicit CodeGenPrepare(const TargetLowering *tli = 0)
bool OptimizeInlineAsmInst(Instruction *I, CallSite CS,
DenseMap<Value*,Value*> &SunkAddrs);
bool OptimizeExtUses(Instruction *I);
+ void findLoopBackEdges(const Function &F);
};
}
return new CodeGenPrepare(TLI);
}
+/// findLoopBackEdges - Do a DFS walk to find loop back edges.
+///
+void CodeGenPrepare::findLoopBackEdges(const Function &F) {
+ SmallVector<std::pair<const BasicBlock*,const BasicBlock*>, 32> Edges;
+ FindFunctionBackedges(F, Edges);
+
+ BackEdges.insert(Edges.begin(), Edges.end());
+}
+
bool CodeGenPrepare::runOnFunction(Function &F) {
bool EverMadeChange = false;
// unconditional branch.
EverMadeChange |= EliminateMostlyEmptyBlocks(F);
+ // Now find loop back edges.
+ findLoopBackEdges(F);
+
bool MadeChange = true;
while (MadeChange) {
MadeChange = false;
return EverMadeChange;
}
-/// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes
-/// and an unconditional branch. Passes before isel (e.g. LSR/loopsimplify)
-/// often split edges in ways that are non-optimal for isel. Start by
-/// eliminating these blocks so we can split them the way we want them.
+/// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes,
+/// debug info directives, and an unconditional branch. Passes before isel
+/// (e.g. LSR/loopsimplify) often split edges in ways that are non-optimal for
+/// isel. Start by eliminating these blocks so we can split them the way we
+/// want them.
bool CodeGenPrepare::EliminateMostlyEmptyBlocks(Function &F) {
bool MadeChange = false;
// Note that this intentionally skips the entry block.
if (!BI || !BI->isUnconditional())
continue;
- // If the instruction before the branch isn't a phi node, then other stuff
- // is happening here.
+ // If the instruction before the branch (skipping debug info) isn't a phi
+ // node, then other stuff is happening here.
BasicBlock::iterator BBI = BI;
if (BBI != BB->begin()) {
--BBI;
- if (!isa<PHINode>(BBI)) continue;
+ while (isa<DbgInfoIntrinsic>(BBI)) {
+ if (BBI == BB->begin())
+ break;
+ --BBI;
+ }
+ if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
+ continue;
}
// Do not break infinite loops.
// If the destination block has a single pred, then this is a trivial edge,
// just collapse it.
- if (DestBB->getSinglePredecessor()) {
- // If DestBB has single-entry PHI nodes, fold them.
- while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
- Value *NewVal = PN->getIncomingValue(0);
- // Replace self referencing PHI with undef, it must be dead.
- if (NewVal == PN) NewVal = UndefValue::get(PN->getType());
- PN->replaceAllUsesWith(NewVal);
- PN->eraseFromParent();
+ if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
+ if (SinglePred != DestBB) {
+ // Remember if SinglePred was the entry block of the function. If so, we
+ // will need to move BB back to the entry position.
+ bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
+ MergeBasicBlockIntoOnlyPred(DestBB);
+
+ if (isEntry && BB != &BB->getParent()->getEntryBlock())
+ BB->moveBefore(&BB->getParent()->getEntryBlock());
+
+ DOUT << "AFTER:\n" << *DestBB << "\n\n\n";
+ return;
}
-
- // Splice all the PHI nodes from BB over to DestBB.
- DestBB->getInstList().splice(DestBB->begin(), BB->getInstList(),
- BB->begin(), BI);
-
- // Anything that branched to BB now branches to DestBB.
- BB->replaceAllUsesWith(DestBB);
-
- // Nuke BB.
- BB->eraseFromParent();
-
- DOUT << "AFTER:\n" << *DestBB << "\n\n\n";
- return;
}
// Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
/// phi nodes (otherwise critical edges are ok). If there is already another
/// predecessor of the succ that is empty (and thus has no phi nodes), use it
/// instead of introducing a new block.
-static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
+static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum,
+ SmallSet<std::pair<const BasicBlock*,
+ const BasicBlock*>, 8> &BackEdges,
+ Pass *P) {
BasicBlock *TIBB = TI->getParent();
BasicBlock *Dest = TI->getSuccessor(SuccNum);
assert(isa<PHINode>(Dest->begin()) &&
"This should only be called if Dest has a PHI!");
+ // Do not split edges to EH landing pads.
+ if (InvokeInst *Invoke = dyn_cast<InvokeInst>(TI)) {
+ if (Invoke->getSuccessor(1) == Dest)
+ return;
+ }
+
// As a hack, never split backedges of loops. Even though the copy for any
// PHIs inserted on the backedge would be dead for exits from the loop, we
// assume that the cost of *splitting* the backedge would be too high.
- if (Dest == TIBB)
+ if (BackEdges.count(std::make_pair(TIBB, Dest)))
return;
- /// TIPHIValues - This array is lazily computed to determine the values of
- /// PHIs in Dest that TI would provide.
- SmallVector<Value*, 32> TIPHIValues;
+ if (!FactorCommonPreds) {
+ /// TIPHIValues - This array is lazily computed to determine the values of
+ /// PHIs in Dest that TI would provide.
+ SmallVector<Value*, 32> TIPHIValues;
+
+ // Check to see if Dest has any blocks that can be used as a split edge for
+ // this terminator.
+ for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) {
+ BasicBlock *Pred = *PI;
+ // To be usable, the pred has to end with an uncond branch to the dest.
+ BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator());
+ if (!PredBr || !PredBr->isUnconditional())
+ continue;
+ // Must be empty other than the branch and debug info.
+ BasicBlock::iterator I = Pred->begin();
+ while (isa<DbgInfoIntrinsic>(I))
+ I++;
+ if (dyn_cast<Instruction>(I) != PredBr)
+ continue;
+ // Cannot be the entry block; its label does not get emitted.
+ if (Pred == &(Dest->getParent()->getEntryBlock()))
+ continue;
- // Check to see if Dest has any blocks that can be used as a split edge for
- // this terminator.
- for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) {
- BasicBlock *Pred = *PI;
- // To be usable, the pred has to end with an uncond branch to the dest.
- BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator());
- if (!PredBr || !PredBr->isUnconditional() ||
- // Must be empty other than the branch.
- &Pred->front() != PredBr ||
- // Cannot be the entry block; its label does not get emitted.
- Pred == &(Dest->getParent()->getEntryBlock()))
- continue;
+ // Finally, since we know that Dest has phi nodes in it, we have to make
+ // sure that jumping to Pred will have the same effect as going to Dest in
+ // terms of PHI values.
+ PHINode *PN;
+ unsigned PHINo = 0;
+ bool FoundMatch = true;
+ for (BasicBlock::iterator I = Dest->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) {
+ if (PHINo == TIPHIValues.size())
+ TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB));
+
+ // If the PHI entry doesn't work, we can't use this pred.
+ if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) {
+ FoundMatch = false;
+ break;
+ }
+ }
- // Finally, since we know that Dest has phi nodes in it, we have to make
- // sure that jumping to Pred will have the same affect as going to Dest in
- // terms of PHI values.
- PHINode *PN;
- unsigned PHINo = 0;
- bool FoundMatch = true;
- for (BasicBlock::iterator I = Dest->begin();
- (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) {
- if (PHINo == TIPHIValues.size())
- TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB));
-
- // If the PHI entry doesn't work, we can't use this pred.
- if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) {
- FoundMatch = false;
- break;
+ // If we found a workable predecessor, change TI to branch to Succ.
+ if (FoundMatch) {
+ Dest->removePredecessor(TIBB);
+ TI->setSuccessor(SuccNum, Pred);
+ return;
}
}
- // If we found a workable predecessor, change TI to branch to Succ.
- if (FoundMatch) {
- Dest->removePredecessor(TIBB);
- TI->setSuccessor(SuccNum, Pred);
- return;
+ SplitCriticalEdge(TI, SuccNum, P, true);
+ return;
+ }
+
+ PHINode *PN;
+ SmallVector<Value*, 8> TIPHIValues;
+ for (BasicBlock::iterator I = Dest->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I)
+ TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB));
+
+ SmallVector<BasicBlock*, 8> IdenticalPreds;
+ for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) {
+ BasicBlock *Pred = *PI;
+ if (BackEdges.count(std::make_pair(Pred, Dest)))
+ continue;
+ if (PI == TIBB)
+ IdenticalPreds.push_back(Pred);
+ else {
+ bool Identical = true;
+ unsigned PHINo = 0;
+ for (BasicBlock::iterator I = Dest->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo)
+ if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) {
+ Identical = false;
+ break;
+ }
+ if (Identical)
+ IdenticalPreds.push_back(Pred);
}
}
- SplitCriticalEdge(TI, SuccNum, P, true);
+ assert(!IdenticalPreds.empty());
+ SplitBlockPredecessors(Dest, &IdenticalPreds[0], IdenticalPreds.size(),
+ ".critedge", P);
}
+
/// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
-/// copy (e.g. it's casting from one pointer type to another, int->uint, or
-/// int->sbyte on PPC), sink it into user blocks to reduce the number of virtual
+/// copy (e.g. it's casting from one pointer type to another, i32->i8 on PPC),
+/// sink it into user blocks to reduce the number of virtual
/// registers that must be created and coalesced.
///
/// Return true if any changes are made.
// appropriate predecessor block.
BasicBlock *UserBB = User->getParent();
if (PHINode *PN = dyn_cast<PHINode>(User)) {
- unsigned OpVal = UI.getOperandNo()/2;
- UserBB = PN->getIncomingBlock(OpVal);
+ UserBB = PN->getIncomingBlock(UI);
}
// Preincrement use iterator so we don't invalidate it.
return MadeChange;
}
-/// EraseDeadInstructions - Erase any dead instructions, recursively.
-static void EraseDeadInstructions(Value *V) {
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I || !I->use_empty()) return;
-
- SmallPtrSet<Instruction*, 16> Insts;
- Insts.insert(I);
-
- while (!Insts.empty()) {
- I = *Insts.begin();
- Insts.erase(I);
- if (isInstructionTriviallyDead(I)) {
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i)))
- Insts.insert(U);
- I->eraseFromParent();
- }
- }
-}
-
-//===----------------------------------------------------------------------===//
-// Addressing Mode Analysis and Optimization
-//===----------------------------------------------------------------------===//
-
-namespace {
- /// ExtAddrMode - This is an extended version of TargetLowering::AddrMode
- /// which holds actual Value*'s for register values.
- struct ExtAddrMode : public TargetLowering::AddrMode {
- Value *BaseReg;
- Value *ScaledReg;
- ExtAddrMode() : BaseReg(0), ScaledReg(0) {}
- void print(OStream &OS) const;
- void dump() const {
- print(cerr);
- cerr << '\n';
- }
- };
-} // end anonymous namespace
-
-static inline OStream &operator<<(OStream &OS, const ExtAddrMode &AM) {
- AM.print(OS);
- return OS;
-}
-
-void ExtAddrMode::print(OStream &OS) const {
- bool NeedPlus = false;
- OS << "[";
- if (BaseGV)
- OS << (NeedPlus ? " + " : "")
- << "GV:%" << BaseGV->getName(), NeedPlus = true;
-
- if (BaseOffs)
- OS << (NeedPlus ? " + " : "") << BaseOffs, NeedPlus = true;
-
- if (BaseReg)
- OS << (NeedPlus ? " + " : "")
- << "Base:%" << BaseReg->getName(), NeedPlus = true;
- if (Scale)
- OS << (NeedPlus ? " + " : "")
- << Scale << "*%" << ScaledReg->getName(), NeedPlus = true;
-
- OS << ']';
-}
-
-namespace {
-/// AddressingModeMatcher - This class exposes a single public method, which is
-/// used to construct a "maximal munch" of the addressing mode for the target
-/// specified by TLI for an access to "V" with an access type of AccessTy. This
-/// returns the addressing mode that is actually matched by value, but also
-/// returns the list of instructions involved in that addressing computation in
-/// AddrModeInsts.
-class AddressingModeMatcher {
- SmallVectorImpl<Instruction*> &AddrModeInsts;
- const TargetLowering &TLI;
-
- /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
- /// the memory instruction that we're computing this address for.
- const Type *AccessTy;
- Instruction *MemoryInst;
-
- /// AddrMode - This is the addressing mode that we're building up. This is
- /// part of the return value of this addressing mode matching stuff.
- ExtAddrMode &AddrMode;
-
- /// IgnoreProfitability - This is set to true when we should not do
- /// profitability checks. When true, IsProfitableToFoldIntoAddressingMode
- /// always returns true.
- bool IgnoreProfitability;
-
- AddressingModeMatcher(SmallVectorImpl<Instruction*> &AMI,
- const TargetLowering &T, const Type *AT,
- Instruction *MI, ExtAddrMode &AM)
- : AddrModeInsts(AMI), TLI(T), AccessTy(AT), MemoryInst(MI), AddrMode(AM) {
- IgnoreProfitability = false;
- }
-public:
-
- /// Match - Find the maximal addressing mode that a load/store of V can fold,
- /// give an access type of AccessTy. This returns a list of involved
- /// instructions in AddrModeInsts.
- static ExtAddrMode Match(Value *V, const Type *AccessTy,
- Instruction *MemoryInst,
- SmallVectorImpl<Instruction*> &AddrModeInsts,
- const TargetLowering &TLI) {
- ExtAddrMode Result;
-
- bool Success =
- AddressingModeMatcher(AddrModeInsts, TLI, AccessTy,
- MemoryInst, Result).MatchAddr(V, 0);
- Success = Success; assert(Success && "Couldn't select *anything*?");
- return Result;
- }
-private:
- bool MatchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
- bool MatchAddr(Value *V, unsigned Depth);
- bool MatchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth);
- bool IsProfitableToFoldIntoAddressingMode(Instruction *I,
- ExtAddrMode &AMBefore,
- ExtAddrMode &AMAfter);
- bool ValueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
-};
-} // end anonymous namespace
-
-/// MatchScaledValue - Try adding ScaleReg*Scale to the current addressing mode.
-/// Return true and update AddrMode if this addr mode is legal for the target,
-/// false if not.
-bool AddressingModeMatcher::MatchScaledValue(Value *ScaleReg, int64_t Scale,
- unsigned Depth) {
- // If Scale is 1, then this is the same as adding ScaleReg to the addressing
- // mode. Just process that directly.
- if (Scale == 1)
- return MatchAddr(ScaleReg, Depth);
-
- // If the scale is 0, it takes nothing to add this.
- if (Scale == 0)
- return true;
-
- // If we already have a scale of this value, we can add to it, otherwise, we
- // need an available scale field.
- if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
- return false;
-
- ExtAddrMode TestAddrMode = AddrMode;
-
- // Add scale to turn X*4+X*3 -> X*7. This could also do things like
- // [A+B + A*7] -> [B+A*8].
- TestAddrMode.Scale += Scale;
- TestAddrMode.ScaledReg = ScaleReg;
-
- // If the new address isn't legal, bail out.
- if (!TLI.isLegalAddressingMode(TestAddrMode, AccessTy))
- return false;
-
- // It was legal, so commit it.
- AddrMode = TestAddrMode;
-
- // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
- // to see if ScaleReg is actually X+C. If so, we can turn this into adding
- // X*Scale + C*Scale to addr mode.
- ConstantInt *CI; Value *AddLHS;
- if (match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
- TestAddrMode.ScaledReg = AddLHS;
- TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
-
- // If this addressing mode is legal, commit it and remember that we folded
- // this instruction.
- if (TLI.isLegalAddressingMode(TestAddrMode, AccessTy)) {
- AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
- AddrMode = TestAddrMode;
- return true;
- }
- }
-
- // Otherwise, not (x+c)*scale, just return what we have.
- return true;
-}
-
-/// MightBeFoldableInst - This is a little filter, which returns true if an
-/// addressing computation involving I might be folded into a load/store
-/// accessing it. This doesn't need to be perfect, but needs to accept at least
-/// the set of instructions that MatchOperationAddr can.
-static bool MightBeFoldableInst(Instruction *I) {
- switch (I->getOpcode()) {
- case Instruction::BitCast:
- // Don't touch identity bitcasts.
- if (I->getType() == I->getOperand(0)->getType())
- return false;
- return isa<PointerType>(I->getType()) || isa<IntegerType>(I->getType());
- case Instruction::PtrToInt:
- // PtrToInt is always a noop, as we know that the int type is pointer sized.
- return true;
- case Instruction::IntToPtr:
- // We know the input is intptr_t, so this is foldable.
- return true;
- case Instruction::Add:
- return true;
- case Instruction::Mul:
- case Instruction::Shl:
- // Can only handle X*C and X << C.
- return isa<ConstantInt>(I->getOperand(1));
- case Instruction::GetElementPtr:
- return true;
- default:
- return false;
- }
-}
-
-
-/// MatchOperationAddr - Given an instruction or constant expr, see if we can
-/// fold the operation into the addressing mode. If so, update the addressing
-/// mode and return true, otherwise return false without modifying AddrMode.
-bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
- unsigned Depth) {
- // Avoid exponential behavior on extremely deep expression trees.
- if (Depth >= 5) return false;
-
- switch (Opcode) {
- case Instruction::PtrToInt:
- // PtrToInt is always a noop, as we know that the int type is pointer sized.
- return MatchAddr(AddrInst->getOperand(0), Depth);
- case Instruction::IntToPtr:
- // This inttoptr is a no-op if the integer type is pointer sized.
- if (TLI.getValueType(AddrInst->getOperand(0)->getType()) ==
- TLI.getPointerTy())
- return MatchAddr(AddrInst->getOperand(0), Depth);
- return false;
- case Instruction::BitCast:
- // BitCast is always a noop, and we can handle it as long as it is
- // int->int or pointer->pointer (we don't want int<->fp or something).
- if ((isa<PointerType>(AddrInst->getOperand(0)->getType()) ||
- isa<IntegerType>(AddrInst->getOperand(0)->getType())) &&
- // Don't touch identity bitcasts. These were probably put here by LSR,
- // and we don't want to mess around with them. Assume it knows what it
- // is doing.
- AddrInst->getOperand(0)->getType() != AddrInst->getType())
- return MatchAddr(AddrInst->getOperand(0), Depth);
- return false;
- case Instruction::Add: {
- // Check to see if we can merge in the RHS then the LHS. If so, we win.
- ExtAddrMode BackupAddrMode = AddrMode;
- unsigned OldSize = AddrModeInsts.size();
- if (MatchAddr(AddrInst->getOperand(1), Depth+1) &&
- MatchAddr(AddrInst->getOperand(0), Depth+1))
- return true;
-
- // Restore the old addr mode info.
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
-
- // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
- if (MatchAddr(AddrInst->getOperand(0), Depth+1) &&
- MatchAddr(AddrInst->getOperand(1), Depth+1))
- return true;
-
- // Otherwise we definitely can't merge the ADD in.
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
- break;
- }
- //case Instruction::Or:
- // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
- //break;
- case Instruction::Mul:
- case Instruction::Shl: {
- // Can only handle X*C and X << C.
- ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
- if (!RHS) return false;
- int64_t Scale = RHS->getSExtValue();
- if (Opcode == Instruction::Shl)
- Scale = 1 << Scale;
-
- return MatchScaledValue(AddrInst->getOperand(0), Scale, Depth);
- }
- case Instruction::GetElementPtr: {
- // Scan the GEP. We check it if it contains constant offsets and at most
- // one variable offset.
- int VariableOperand = -1;
- unsigned VariableScale = 0;
-
- int64_t ConstantOffset = 0;
- const TargetData *TD = TLI.getTargetData();
- gep_type_iterator GTI = gep_type_begin(AddrInst);
- for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- const StructLayout *SL = TD->getStructLayout(STy);
- unsigned Idx =
- cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
- ConstantOffset += SL->getElementOffset(Idx);
- } else {
- uint64_t TypeSize = TD->getABITypeSize(GTI.getIndexedType());
- if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
- ConstantOffset += CI->getSExtValue()*TypeSize;
- } else if (TypeSize) { // Scales of zero don't do anything.
- // We only allow one variable index at the moment.
- if (VariableOperand != -1)
- return false;
-
- // Remember the variable index.
- VariableOperand = i;
- VariableScale = TypeSize;
- }
- }
- }
-
- // A common case is for the GEP to only do a constant offset. In this case,
- // just add it to the disp field and check validity.
- if (VariableOperand == -1) {
- AddrMode.BaseOffs += ConstantOffset;
- if (ConstantOffset == 0 || TLI.isLegalAddressingMode(AddrMode, AccessTy)){
- // Check to see if we can fold the base pointer in too.
- if (MatchAddr(AddrInst->getOperand(0), Depth+1))
- return true;
- }
- AddrMode.BaseOffs -= ConstantOffset;
- return false;
- }
-
- // Save the valid addressing mode in case we can't match.
- ExtAddrMode BackupAddrMode = AddrMode;
-
- // Check that this has no base reg yet. If so, we won't have a place to
- // put the base of the GEP (assuming it is not a null ptr).
- bool SetBaseReg = true;
- if (isa<ConstantPointerNull>(AddrInst->getOperand(0)))
- SetBaseReg = false; // null pointer base doesn't need representation.
- else if (AddrMode.HasBaseReg)
- return false; // Base register already specified, can't match GEP.
- else {
- // Otherwise, we'll use the GEP base as the BaseReg.
- AddrMode.HasBaseReg = true;
- AddrMode.BaseReg = AddrInst->getOperand(0);
- }
-
- // See if the scale and offset amount is valid for this target.
- AddrMode.BaseOffs += ConstantOffset;
-
- if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
- Depth)) {
- AddrMode = BackupAddrMode;
- return false;
- }
-
- // If we have a null as the base of the GEP, folding in the constant offset
- // plus variable scale is all we can do.
- if (!SetBaseReg) return true;
-
- // If this match succeeded, we know that we can form an address with the
- // GepBase as the basereg. Match the base pointer of the GEP more
- // aggressively by zeroing out BaseReg and rematching. If the base is
- // (for example) another GEP, this allows merging in that other GEP into
- // the addressing mode we're forming.
- AddrMode.HasBaseReg = false;
- AddrMode.BaseReg = 0;
- bool Success = MatchAddr(AddrInst->getOperand(0), Depth+1);
- assert(Success && "MatchAddr should be able to fill in BaseReg!");
- Success=Success;
- return true;
- }
- }
- return false;
-}
-
-/// MatchAddr - If we can, try to add the value of 'Addr' into the current
-/// addressing mode. If Addr can't be added to AddrMode this returns false and
-/// leaves AddrMode unmodified. This assumes that Addr is either a pointer type
-/// or intptr_t for the target.
-///
-bool AddressingModeMatcher::MatchAddr(Value *Addr, unsigned Depth) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
- // Fold in immediates if legal for the target.
- AddrMode.BaseOffs += CI->getSExtValue();
- if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
- return true;
- AddrMode.BaseOffs -= CI->getSExtValue();
- } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
- // If this is a global variable, try to fold it into the addressing mode.
- if (AddrMode.BaseGV == 0) {
- AddrMode.BaseGV = GV;
- if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
- return true;
- AddrMode.BaseGV = 0;
- }
- } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
- ExtAddrMode BackupAddrMode = AddrMode;
- unsigned OldSize = AddrModeInsts.size();
-
- // Check to see if it is possible to fold this operation.
- if (MatchOperationAddr(I, I->getOpcode(), Depth)) {
- // Okay, it's possible to fold this. Check to see if it is actually
- // *profitable* to do so. We use a simple cost model to avoid increasing
- // register pressure too much.
- if (I->hasOneUse() ||
- IsProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
- AddrModeInsts.push_back(I);
- return true;
- }
-
- // It isn't profitable to do this, roll back.
- //cerr << "NOT FOLDING: " << *I;
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
- }
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
- if (MatchOperationAddr(CE, CE->getOpcode(), Depth))
- return true;
- } else if (isa<ConstantPointerNull>(Addr)) {
- // Null pointer gets folded without affecting the addressing mode.
- return true;
- }
-
- // Worse case, the target should support [reg] addressing modes. :)
- if (!AddrMode.HasBaseReg) {
- AddrMode.HasBaseReg = true;
- AddrMode.BaseReg = Addr;
- // Still check for legality in case the target supports [imm] but not [i+r].
- if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
- return true;
- AddrMode.HasBaseReg = false;
- AddrMode.BaseReg = 0;
- }
-
- // If the base register is already taken, see if we can do [r+r].
- if (AddrMode.Scale == 0) {
- AddrMode.Scale = 1;
- AddrMode.ScaledReg = Addr;
- if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
- return true;
- AddrMode.Scale = 0;
- AddrMode.ScaledReg = 0;
- }
- // Couldn't match.
- return false;
-}
-
-/// FindAllMemoryUses - Recursively walk all the uses of I until we find a
-/// memory use. If we find an obviously non-foldable instruction, return true.
-/// Add the ultimately found memory instructions to MemoryUses.
-static bool FindAllMemoryUses(Instruction *I,
- SmallVectorImpl<std::pair<Instruction*,unsigned> > &MemoryUses,
- SmallPtrSet<Instruction*, 16> &ConsideredInsts) {
- // If we already considered this instruction, we're done.
- if (!ConsideredInsts.insert(I))
- return false;
-
- // If this is an obviously unfoldable instruction, bail out.
- if (!MightBeFoldableInst(I))
- return true;
-
- // Loop over all the uses, recursively processing them.
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI) {
- if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
- MemoryUses.push_back(std::make_pair(LI, UI.getOperandNo()));
- continue;
- }
-
- if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
- if (UI.getOperandNo() == 0) return true; // Storing addr, not into addr.
- MemoryUses.push_back(std::make_pair(SI, UI.getOperandNo()));
- continue;
- }
-
- if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
- InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
- if (IA == 0) return true;
-
-
- // FIXME: HANDLE MEM OPS
- //MemoryUses.push_back(std::make_pair(CI, UI.getOperandNo()));
- return true;
- }
-
- if (FindAllMemoryUses(cast<Instruction>(*UI), MemoryUses, ConsideredInsts))
- return true;
- }
-
- return false;
-}
-
-
-/// ValueAlreadyLiveAtInst - Retrn true if Val is already known to be live at
-/// the use site that we're folding it into. If so, there is no cost to
-/// include it in the addressing mode. KnownLive1 and KnownLive2 are two values
-/// that we know are live at the instruction already.
-bool AddressingModeMatcher::ValueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
- Value *KnownLive2) {
- // If Val is either of the known-live values, we know it is live!
- if (Val == 0 || Val == KnownLive1 || Val == KnownLive2)
- return true;
-
- // All values other than instructions and arguments (e.g. constants) are live.
- if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
-
- // If Val is a constant sized alloca in the entry block, it is live, this is
- // true because it is just a reference to the stack/frame pointer, which is
- // live for the whole function.
- if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
- if (AI->isStaticAlloca())
- return true;
-
- // Check to see if this value is already used in the memory instruction's
- // block. If so, it's already live into the block at the very least, so we
- // can reasonably fold it.
- BasicBlock *MemBB = MemoryInst->getParent();
- for (Value::use_iterator UI = Val->use_begin(), E = Val->use_end();
- UI != E; ++UI)
- // We know that uses of arguments and instructions have to be instructions.
- if (cast<Instruction>(*UI)->getParent() == MemBB)
- return true;
-
- return false;
-}
-
-
-
-#include "llvm/Support/CommandLine.h"
-cl::opt<bool> ENABLECRAZYHACK("enable-smarter-addr-folding", cl::Hidden);
-
-
-/// IsProfitableToFoldIntoAddressingMode - It is possible for the addressing
-/// mode of the machine to fold the specified instruction into a load or store
-/// that ultimately uses it. However, the specified instruction has multiple
-/// uses. Given this, it may actually increase register pressure to fold it
-/// into the load. For example, consider this code:
-///
-/// X = ...
-/// Y = X+1
-/// use(Y) -> nonload/store
-/// Z = Y+1
-/// load Z
-///
-/// In this case, Y has multiple uses, and can be folded into the load of Z
-/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
-/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
-/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
-/// number of computations either.
-///
-/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
-/// X was live across 'load Z' for other reasons, we actually *would* want to
-/// fold the addressing mode in the Z case. This would make Y die earlier.
-bool AddressingModeMatcher::
-IsProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
- ExtAddrMode &AMAfter) {
- if (IgnoreProfitability || !ENABLECRAZYHACK) return true;
-
- // AMBefore is the addressing mode before this instruction was folded into it,
- // and AMAfter is the addressing mode after the instruction was folded. Get
- // the set of registers referenced by AMAfter and subtract out those
- // referenced by AMBefore: this is the set of values which folding in this
- // address extends the lifetime of.
- //
- // Note that there are only two potential values being referenced here,
- // BaseReg and ScaleReg (global addresses are always available, as are any
- // folded immediates).
- Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
-
- // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
- // lifetime wasn't extended by adding this instruction.
- if (ValueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
- BaseReg = 0;
- if (ValueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
- ScaledReg = 0;
-
- // If folding this instruction (and it's subexprs) didn't extend any live
- // ranges, we're ok with it.
- if (BaseReg == 0 && ScaledReg == 0)
- return true;
-
- // If all uses of this instruction are ultimately load/store/inlineasm's,
- // check to see if their addressing modes will include this instruction. If
- // so, we can fold it into all uses, so it doesn't matter if it has multiple
- // uses.
- SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
- SmallPtrSet<Instruction*, 16> ConsideredInsts;
- if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts))
- return false; // Has a non-memory, non-foldable use!
-
- // Now that we know that all uses of this instruction are part of a chain of
- // computation involving only operations that could theoretically be folded
- // into a memory use, loop over each of these uses and see if they could
- // *actually* fold the instruction.
- SmallVector<Instruction*, 32> MatchedAddrModeInsts;
- for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
- Instruction *User = MemoryUses[i].first;
- unsigned OpNo = MemoryUses[i].second;
-
- // Get the access type of this use. If the use isn't a pointer, we don't
- // know what it accesses.
- Value *Address = User->getOperand(OpNo);
- if (!isa<PointerType>(Address->getType()))
- return false;
- const Type *AddressAccessTy =
- cast<PointerType>(Address->getType())->getElementType();
-
- // Do a match against the root of this address, ignoring profitability. This
- // will tell us if the addressing mode for the memory operation will
- // *actually* cover the shared instruction.
- ExtAddrMode Result;
- AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, AddressAccessTy,
- MemoryInst, Result);
- Matcher.IgnoreProfitability = true;
- bool Success = Matcher.MatchAddr(Address, 0);
- Success = Success; assert(Success && "Couldn't select *anything*?");
-
- // If the match didn't cover I, then it won't be shared by it.
- if (std::find(MatchedAddrModeInsts.begin(), MatchedAddrModeInsts.end(),
- I) == MatchedAddrModeInsts.end())
- return false;
-
- MatchedAddrModeInsts.clear();
- }
-
- return true;
-}
-
-
//===----------------------------------------------------------------------===//
// Memory Optimization
//===----------------------------------------------------------------------===//
// computation.
Value *&SunkAddr = SunkAddrs[Addr];
if (SunkAddr) {
- DEBUG(cerr << "CGP: Reusing nonlocal addrmode: " << AddrMode << "\n");
+ DEBUG(cerr << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "
+ << *MemoryInst);
if (SunkAddr->getType() != Addr->getType())
SunkAddr = new BitCastInst(SunkAddr, Addr->getType(), "tmp", InsertPt);
} else {
- DEBUG(cerr << "CGP: SINKING nonlocal addrmode: " << AddrMode << "\n");
+ DEBUG(cerr << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "
+ << *MemoryInst);
const Type *IntPtrTy = TLI->getTargetData()->getIntPtrType();
Value *Result = 0;
V = new SExtInst(V, IntPtrTy, "sunkaddr", InsertPt);
}
if (AddrMode.Scale != 1)
- V = BinaryOperator::CreateMul(V, ConstantInt::get(IntPtrTy,
- AddrMode.Scale),
+ V = BinaryOperator::CreateMul(V, Context->getConstantInt(IntPtrTy,
+ AddrMode.Scale),
"sunkaddr", InsertPt);
Result = V;
}
// Add in the base register.
if (AddrMode.BaseReg) {
Value *V = AddrMode.BaseReg;
- if (V->getType() != IntPtrTy)
+ if (isa<PointerType>(V->getType()))
V = new PtrToIntInst(V, IntPtrTy, "sunkaddr", InsertPt);
+ if (V->getType() != IntPtrTy)
+ V = CastInst::CreateIntegerCast(V, IntPtrTy, /*isSigned=*/true,
+ "sunkaddr", InsertPt);
if (Result)
Result = BinaryOperator::CreateAdd(Result, V, "sunkaddr", InsertPt);
else
// Add in the Base Offset if present.
if (AddrMode.BaseOffs) {
- Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
+ Value *V = Context->getConstantInt(IntPtrTy, AddrMode.BaseOffs);
if (Result)
Result = BinaryOperator::CreateAdd(Result, V, "sunkaddr", InsertPt);
else
}
if (Result == 0)
- SunkAddr = Constant::getNullValue(Addr->getType());
+ SunkAddr = Context->getNullValue(Addr->getType());
else
SunkAddr = new IntToPtrInst(Result, Addr->getType(), "sunkaddr",InsertPt);
}
MemoryInst->replaceUsesOfWith(Addr, SunkAddr);
if (Addr->use_empty())
- EraseDeadInstructions(Addr);
+ RecursivelyDeleteTriviallyDeadInstructions(Addr);
return true;
}
bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) {
bool MadeChange = false;
- // Split all critical edges where the dest block has a PHI and where the phi
- // has shared immediate operands.
+ // Split all critical edges where the dest block has a PHI.
TerminatorInst *BBTI = BB.getTerminator();
if (BBTI->getNumSuccessors() > 1) {
- for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i)
- if (isa<PHINode>(BBTI->getSuccessor(i)->begin()) &&
- isCriticalEdge(BBTI, i, true))
- SplitEdgeNicely(BBTI, i, this);
+ for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i) {
+ BasicBlock *SuccBB = BBTI->getSuccessor(i);
+ if (isa<PHINode>(SuccBB->begin()) && isCriticalEdge(BBTI, i, true))
+ SplitEdgeNicely(BBTI, i, BackEdges, this);
+ }
}
-
// Keep track of non-local addresses that have been sunk into this block.
// This allows us to avoid inserting duplicate code for blocks with multiple
// load/stores of the same address.
if (TLI && isa<InlineAsm>(CI->getCalledValue()))
if (const TargetAsmInfo *TAI =
TLI->getTargetMachine().getTargetAsmInfo()) {
- if (TAI->ExpandInlineAsm(CI))
+ if (TAI->ExpandInlineAsm(CI)) {
BBI = BB.begin();
- else
+ // Avoid processing instructions out of order, which could cause
+ // reuse before a value is defined.
+ SunkAddrs.clear();
+ } else
// Sink address computing for memory operands into the block.
MadeChange |= OptimizeInlineAsmInst(I, &(*CI), SunkAddrs);
}