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Add utility function to IRBuilder that takes the difference between two
pointers, taking into account the size of the pointed-to object. Patch by Jeffrey Yasskin! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68768 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -681,6 +681,20 @@ public:
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Name);
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}
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/// CreatePtrDiff - Return the i64 difference between two pointer values,
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/// dividing out the size of the pointed-to objects. This is intended to
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/// implement C-style pointer subtraction.
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Value *CreatePtrDiff(Value *LHS, Value *RHS, const char *Name = "") {
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assert(LHS->getType() == RHS->getType() &&
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"Pointer subtraction operand types must match!");
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const PointerType *ArgType = cast<PointerType>(LHS->getType());
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Value *LHS_int = CreatePtrToInt(LHS, Type::Int64Ty);
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Value *RHS_int = CreatePtrToInt(RHS, Type::Int64Ty);
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Value *Difference = CreateSub(LHS_int, RHS_int);
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return CreateSDiv(Difference,
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ConstantExpr::getSizeOf(ArgType->getElementType()),
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Name);
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}
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};
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}
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