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	types and can have arbitrary 32- and 64-bit integer types indexing into sequential types. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12653 91177308-0d34-0410-b5e6-96231b3b80d8
		
			
				
	
	
		
			106 lines
		
	
	
		
			4.2 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			106 lines
		
	
	
		
			4.2 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| //===- TransformInternals.cpp - Implement shared functions for transforms -===//
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| // 
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| //                     The LLVM Compiler Infrastructure
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| //
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| // This file was developed by the LLVM research group and is distributed under
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| // the University of Illinois Open Source License. See LICENSE.TXT for details.
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| // 
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| //===----------------------------------------------------------------------===//
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| //
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| //  This file defines shared functions used by the different components of the
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| //  Transforms library.
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| //
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| //===----------------------------------------------------------------------===//
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| 
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| #include "TransformInternals.h"
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| #include "llvm/Type.h"
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| #include "llvm/Analysis/Expressions.h"
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| #include "llvm/Function.h"
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| #include "llvm/iOther.h"
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| using namespace llvm;
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| 
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| static const Type *getStructOffsetStep(const StructType *STy, uint64_t &Offset,
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|                                        std::vector<Value*> &Indices,
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|                                        const TargetData &TD) {
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|   assert(Offset < TD.getTypeSize(STy) && "Offset not in composite!");
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|   const StructLayout *SL = TD.getStructLayout(STy);
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| 
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|   // This loop terminates always on a 0 <= i < MemberOffsets.size()
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|   unsigned i;
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|   for (i = 0; i < SL->MemberOffsets.size()-1; ++i)
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|     if (Offset >= SL->MemberOffsets[i] && Offset < SL->MemberOffsets[i+1])
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|       break;
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|   
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|   assert(Offset >= SL->MemberOffsets[i] &&
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|          (i == SL->MemberOffsets.size()-1 || Offset < SL->MemberOffsets[i+1]));
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|   
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|   // Make sure to save the current index...
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|   Indices.push_back(ConstantUInt::get(Type::UIntTy, i));
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|   Offset = SL->MemberOffsets[i];
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|   return STy->getContainedType(i);
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| }
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| 
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| 
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| // getStructOffsetType - Return a vector of offsets that are to be used to index
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| // into the specified struct type to get as close as possible to index as we
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| // can.  Note that it is possible that we cannot get exactly to Offset, in which
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| // case we update offset to be the offset we actually obtained.  The resultant
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| // leaf type is returned.
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| //
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| // If StopEarly is set to true (the default), the first object with the
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| // specified type is returned, even if it is a struct type itself.  In this
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| // case, this routine will not drill down to the leaf type.  Set StopEarly to
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| // false if you want a leaf
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| //
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| const Type *llvm::getStructOffsetType(const Type *Ty, unsigned &Offset,
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|                                       std::vector<Value*> &Indices,
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|                                       const TargetData &TD, bool StopEarly) {
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|   if (Offset == 0 && StopEarly && !Indices.empty())
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|     return Ty;    // Return the leaf type
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| 
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|   uint64_t ThisOffset;
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|   const Type *NextType;
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|   if (const StructType *STy = dyn_cast<StructType>(Ty)) {
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|     if (STy->getNumElements()) {
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|       Offset = 0;
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|       return STy;
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|     }
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| 
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|     ThisOffset = Offset;
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|     NextType = getStructOffsetStep(STy, ThisOffset, Indices, TD);
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|   } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
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|     assert(Offset == 0 || Offset < TD.getTypeSize(ATy) &&
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|            "Offset not in composite!");
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| 
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|     NextType = ATy->getElementType();
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|     unsigned ChildSize = TD.getTypeSize(NextType);
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|     if (ConstantSInt::isValueValidForType(Type::IntTy, Offset/ChildSize))
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|       Indices.push_back(ConstantSInt::get(Type::IntTy, Offset/ChildSize));
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|     else
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|       Indices.push_back(ConstantSInt::get(Type::LongTy, Offset/ChildSize));
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|     ThisOffset = (Offset/ChildSize)*ChildSize;
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|   } else {
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|     Offset = 0;   // Return the offset that we were able to achieve
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|     return Ty;    // Return the leaf type
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|   }
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| 
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|   unsigned SubOffs = Offset - ThisOffset;
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|   const Type *LeafTy = getStructOffsetType(NextType, SubOffs,
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|                                            Indices, TD, StopEarly);
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|   Offset = ThisOffset + SubOffs;
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|   return LeafTy;
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| }
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| 
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| // ConvertibleToGEP - This function returns true if the specified value V is
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| // a valid index into a pointer of type Ty.  If it is valid, Idx is filled in
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| // with the values that would be appropriate to make this a getelementptr
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| // instruction.  The type returned is the root type that the GEP would point to
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| //
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| const Type *llvm::ConvertibleToGEP(const Type *Ty, Value *OffsetVal,
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|                                    std::vector<Value*> &Indices,
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|                                    const TargetData &TD,
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|                                    BasicBlock::iterator *BI) {
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|   return 0;
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| }
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| 
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