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			347 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			347 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| //===-- FunctionLoweringInfo.cpp ------------------------------------------===//
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| //
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| //                     The LLVM Compiler Infrastructure
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| //
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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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| //===----------------------------------------------------------------------===//
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| //
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| // This implements routines for translating functions from LLVM IR into
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| // Machine IR.
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| //
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| //===----------------------------------------------------------------------===//
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| 
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| #define DEBUG_TYPE "function-lowering-info"
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| #include "llvm/CodeGen/FunctionLoweringInfo.h"
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| #include "llvm/DerivedTypes.h"
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| #include "llvm/Function.h"
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| #include "llvm/Instructions.h"
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| #include "llvm/IntrinsicInst.h"
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| #include "llvm/LLVMContext.h"
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| #include "llvm/Module.h"
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| #include "llvm/Analysis/DebugInfo.h"
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| #include "llvm/CodeGen/Analysis.h"
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| #include "llvm/CodeGen/MachineFunction.h"
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| #include "llvm/CodeGen/MachineFrameInfo.h"
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| #include "llvm/CodeGen/MachineInstrBuilder.h"
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| #include "llvm/CodeGen/MachineModuleInfo.h"
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| #include "llvm/CodeGen/MachineRegisterInfo.h"
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| #include "llvm/Target/TargetRegisterInfo.h"
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| #include "llvm/Target/TargetData.h"
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| #include "llvm/Target/TargetFrameInfo.h"
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| #include "llvm/Target/TargetInstrInfo.h"
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| #include "llvm/Target/TargetLowering.h"
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| #include "llvm/Target/TargetOptions.h"
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| #include "llvm/Support/Debug.h"
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| #include "llvm/Support/ErrorHandling.h"
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| #include "llvm/Support/MathExtras.h"
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| #include <algorithm>
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| using namespace llvm;
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| 
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| /// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by
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| /// PHI nodes or outside of the basic block that defines it, or used by a
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| /// switch or atomic instruction, which may expand to multiple basic blocks.
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| static bool isUsedOutsideOfDefiningBlock(const Instruction *I) {
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|   if (I->use_empty()) return false;
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|   if (isa<PHINode>(I)) return true;
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|   const BasicBlock *BB = I->getParent();
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|   for (Value::const_use_iterator UI = I->use_begin(), E = I->use_end();
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|         UI != E; ++UI) {
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|     const User *U = *UI;
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|     if (cast<Instruction>(U)->getParent() != BB || isa<PHINode>(U))
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|       return true;
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|   }
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|   return false;
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| }
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| 
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| /// isOnlyUsedInEntryBlock - If the specified argument is only used in the
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| /// entry block, return true.  This includes arguments used by switches, since
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| /// the switch may expand into multiple basic blocks.
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| static bool isOnlyUsedInEntryBlock(const Argument *A, bool EnableFastISel) {
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|   // With FastISel active, we may be splitting blocks, so force creation
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|   // of virtual registers for all non-dead arguments.
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|   if (EnableFastISel)
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|     return A->use_empty();
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| 
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|   const BasicBlock *Entry = A->getParent()->begin();
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|   for (Value::const_use_iterator UI = A->use_begin(), E = A->use_end();
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|        UI != E; ++UI) {
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|     const User *U = *UI;
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|     if (cast<Instruction>(U)->getParent() != Entry || isa<SwitchInst>(U))
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|       return false;  // Use not in entry block.
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|   }
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|   return true;
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| }
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| 
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| FunctionLoweringInfo::FunctionLoweringInfo(const TargetLowering &tli)
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|   : TLI(tli) {
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| }
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| 
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| void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
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|   Fn = &fn;
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|   MF = &mf;
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|   RegInfo = &MF->getRegInfo();
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| 
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|   // Check whether the function can return without sret-demotion.
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|   SmallVector<ISD::OutputArg, 4> Outs;
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|   GetReturnInfo(Fn->getReturnType(),
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|                 Fn->getAttributes().getRetAttributes(), Outs, TLI);
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|   CanLowerReturn = TLI.CanLowerReturn(Fn->getCallingConv(), Fn->isVarArg(),
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|                                       Outs, Fn->getContext());
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| 
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|   // Create a vreg for each argument register that is not dead and is used
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|   // outside of the entry block for the function.
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|   for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
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|        AI != E; ++AI)
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|     if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
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|       InitializeRegForValue(AI);
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| 
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|   // Initialize the mapping of values to registers.  This is only set up for
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|   // instruction values that are used outside of the block that defines
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|   // them.
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|   Function::const_iterator BB = Fn->begin(), EB = Fn->end();
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|   for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
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|     if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
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|       if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
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|         const Type *Ty = AI->getAllocatedType();
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|         uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
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|         unsigned Align =
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|           std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
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|                    AI->getAlignment());
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| 
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|         TySize *= CUI->getZExtValue();   // Get total allocated size.
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|         if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
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| 
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|         // The object may need to be placed onto the stack near the stack
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|         // protector if one exists. Determine here if this object is a suitable
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|         // candidate. I.e., it would trigger the creation of a stack protector.
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|         bool MayNeedSP =
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|           (AI->isArrayAllocation() ||
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|            (TySize > 8 && isa<ArrayType>(Ty) &&
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|             cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
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|         StaticAllocaMap[AI] =
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|           MF->getFrameInfo()->CreateStackObject(TySize, Align, false, MayNeedSP);
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|       }
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| 
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|   for (; BB != EB; ++BB)
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|     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
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|       // Mark values used outside their block as exported, by allocating
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|       // a virtual register for them.
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|       if (isUsedOutsideOfDefiningBlock(I))
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|         if (!isa<AllocaInst>(I) ||
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|             !StaticAllocaMap.count(cast<AllocaInst>(I)))
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|           InitializeRegForValue(I);
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| 
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|       // Collect llvm.dbg.declare information. This is done now instead of
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|       // during the initial isel pass through the IR so that it is done
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|       // in a predictable order.
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|       if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
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|         MachineModuleInfo &MMI = MF->getMMI();
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|         if (MMI.hasDebugInfo() &&
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|             DIVariable(DI->getVariable()).Verify() &&
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|             !DI->getDebugLoc().isUnknown()) {
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|           // Don't handle byval struct arguments or VLAs, for example.
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|           // Non-byval arguments are handled here (they refer to the stack
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|           // temporary alloca at this point).
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|           const Value *Address = DI->getAddress();
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|           if (Address) {
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|             if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
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|               Address = BCI->getOperand(0);
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|             if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
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|               DenseMap<const AllocaInst *, int>::iterator SI =
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|                 StaticAllocaMap.find(AI);
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|               if (SI != StaticAllocaMap.end()) { // Check for VLAs.
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|                 int FI = SI->second;
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|                 MMI.setVariableDbgInfo(DI->getVariable(),
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|                                        FI, DI->getDebugLoc());
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|               }
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|             }
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|           }
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|         }
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|       }
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|     }
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| 
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|   // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
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|   // also creates the initial PHI MachineInstrs, though none of the input
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|   // operands are populated.
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|   for (BB = Fn->begin(); BB != EB; ++BB) {
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|     MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
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|     MBBMap[BB] = MBB;
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|     MF->push_back(MBB);
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| 
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|     // Transfer the address-taken flag. This is necessary because there could
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|     // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
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|     // the first one should be marked.
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|     if (BB->hasAddressTaken())
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|       MBB->setHasAddressTaken();
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| 
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|     // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
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|     // appropriate.
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|     for (BasicBlock::const_iterator I = BB->begin();
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|          const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
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|       if (PN->use_empty()) continue;
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| 
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|       DebugLoc DL = PN->getDebugLoc();
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|       unsigned PHIReg = ValueMap[PN];
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|       assert(PHIReg && "PHI node does not have an assigned virtual register!");
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| 
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|       SmallVector<EVT, 4> ValueVTs;
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|       ComputeValueVTs(TLI, PN->getType(), ValueVTs);
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|       for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
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|         EVT VT = ValueVTs[vti];
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|         unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
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|         const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
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|         for (unsigned i = 0; i != NumRegisters; ++i)
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|           BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
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|         PHIReg += NumRegisters;
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|       }
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|     }
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|   }
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| 
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|   // Mark landing pad blocks.
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|   for (BB = Fn->begin(); BB != EB; ++BB)
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|     if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
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|       MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
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| }
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| 
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| /// clear - Clear out all the function-specific state. This returns this
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| /// FunctionLoweringInfo to an empty state, ready to be used for a
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| /// different function.
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| void FunctionLoweringInfo::clear() {
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|   assert(CatchInfoFound.size() == CatchInfoLost.size() &&
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|          "Not all catch info was assigned to a landing pad!");
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| 
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|   MBBMap.clear();
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|   ValueMap.clear();
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|   StaticAllocaMap.clear();
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| #ifndef NDEBUG
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|   CatchInfoLost.clear();
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|   CatchInfoFound.clear();
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| #endif
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|   LiveOutRegInfo.clear();
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|   ArgDbgValues.clear();
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|   ByValArgFrameIndexMap.clear();
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|   RegFixups.clear();
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| }
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| 
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| /// CreateReg - Allocate a single virtual register for the given type.
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| unsigned FunctionLoweringInfo::CreateReg(EVT VT) {
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|   return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
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| }
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| 
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| /// CreateRegs - Allocate the appropriate number of virtual registers of
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| /// the correctly promoted or expanded types.  Assign these registers
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| /// consecutive vreg numbers and return the first assigned number.
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| ///
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| /// In the case that the given value has struct or array type, this function
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| /// will assign registers for each member or element.
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| ///
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| unsigned FunctionLoweringInfo::CreateRegs(const Type *Ty) {
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|   SmallVector<EVT, 4> ValueVTs;
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|   ComputeValueVTs(TLI, Ty, ValueVTs);
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| 
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|   unsigned FirstReg = 0;
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|   for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
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|     EVT ValueVT = ValueVTs[Value];
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|     EVT RegisterVT = TLI.getRegisterType(Ty->getContext(), ValueVT);
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| 
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|     unsigned NumRegs = TLI.getNumRegisters(Ty->getContext(), ValueVT);
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|     for (unsigned i = 0; i != NumRegs; ++i) {
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|       unsigned R = CreateReg(RegisterVT);
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|       if (!FirstReg) FirstReg = R;
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|     }
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|   }
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|   return FirstReg;
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| }
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| 
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| /// setByValArgumentFrameIndex - Record frame index for the byval
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| /// argument. This overrides previous frame index entry for this argument,
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| /// if any.
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| void FunctionLoweringInfo::setByValArgumentFrameIndex(const Argument *A, 
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|                                                       int FI) {
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|   assert (A->hasByValAttr() && "Argument does not have byval attribute!");
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|   ByValArgFrameIndexMap[A] = FI;
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| }
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|   
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| /// getByValArgumentFrameIndex - Get frame index for the byval argument.
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| /// If the argument does not have any assigned frame index then 0 is
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| /// returned.
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| int FunctionLoweringInfo::getByValArgumentFrameIndex(const Argument *A) {
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|   assert (A->hasByValAttr() && "Argument does not have byval attribute!");
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|   DenseMap<const Argument *, int>::iterator I = 
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|     ByValArgFrameIndexMap.find(A);
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|   if (I != ByValArgFrameIndexMap.end())
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|     return I->second;
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|   DEBUG(dbgs() << "Argument does not have assigned frame index!");
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|   return 0;
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| }
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| 
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| /// AddCatchInfo - Extract the personality and type infos from an eh.selector
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| /// call, and add them to the specified machine basic block.
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| void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
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|                         MachineBasicBlock *MBB) {
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|   // Inform the MachineModuleInfo of the personality for this landing pad.
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|   const ConstantExpr *CE = cast<ConstantExpr>(I.getArgOperand(1));
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|   assert(CE->getOpcode() == Instruction::BitCast &&
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|          isa<Function>(CE->getOperand(0)) &&
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|          "Personality should be a function");
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|   MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
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| 
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|   // Gather all the type infos for this landing pad and pass them along to
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|   // MachineModuleInfo.
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|   std::vector<const GlobalVariable *> TyInfo;
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|   unsigned N = I.getNumArgOperands();
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| 
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|   for (unsigned i = N - 1; i > 1; --i) {
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|     if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getArgOperand(i))) {
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|       unsigned FilterLength = CI->getZExtValue();
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|       unsigned FirstCatch = i + FilterLength + !FilterLength;
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|       assert(FirstCatch <= N && "Invalid filter length");
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| 
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|       if (FirstCatch < N) {
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|         TyInfo.reserve(N - FirstCatch);
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|         for (unsigned j = FirstCatch; j < N; ++j)
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|           TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
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|         MMI->addCatchTypeInfo(MBB, TyInfo);
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|         TyInfo.clear();
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|       }
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| 
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|       if (!FilterLength) {
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|         // Cleanup.
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|         MMI->addCleanup(MBB);
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|       } else {
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|         // Filter.
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|         TyInfo.reserve(FilterLength - 1);
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|         for (unsigned j = i + 1; j < FirstCatch; ++j)
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|           TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
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|         MMI->addFilterTypeInfo(MBB, TyInfo);
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|         TyInfo.clear();
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|       }
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| 
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|       N = i;
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|     }
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|   }
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| 
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|   if (N > 2) {
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|     TyInfo.reserve(N - 2);
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|     for (unsigned j = 2; j < N; ++j)
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|       TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
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|     MMI->addCatchTypeInfo(MBB, TyInfo);
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|   }
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| }
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| 
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| void llvm::CopyCatchInfo(const BasicBlock *SrcBB, const BasicBlock *DestBB,
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|                          MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
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|   for (BasicBlock::const_iterator I = SrcBB->begin(), E = --SrcBB->end();
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|        I != E; ++I)
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|     if (const EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
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|       // Apply the catch info to DestBB.
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|       AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
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| #ifndef NDEBUG
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|       if (!FLI.MBBMap[SrcBB]->isLandingPad())
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|         FLI.CatchInfoFound.insert(EHSel);
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| #endif
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|     }
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| }
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