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//===-- llvm/Function.h - Class to represent a single function --*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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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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// This file contains the declaration of the Function class, which represents a
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// single function/procedure in LLVM.
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// A function basically consists of a list of basic blocks, a list of arguments,
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// and a symbol table.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_FUNCTION_H
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#define LLVM_IR_FUNCTION_H
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#include "llvm/ADT/iterator_range.h"
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#include "llvm/ADT/Optional.h"
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#include "llvm/IR/Argument.h"
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#include "llvm/IR/Attributes.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/CallingConv.h"
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#include "llvm/IR/GlobalObject.h"
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#include "llvm/IR/OperandTraits.h"
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#include "llvm/Support/Compiler.h"
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template<> struct ilist_traits<Argument>
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: public SymbolTableListTraits<Argument, Function> {
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Argument *createSentinel() const {
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return static_cast<Argument*>(&Sentinel);
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static void destroySentinel(Argument*) {}
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Argument *provideInitialHead() const { return createSentinel(); }
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Argument *ensureHead(Argument*) const { return createSentinel(); }
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static void noteHead(Argument*, Argument*) {}
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static ValueSymbolTable *getSymTab(Function *ItemParent);
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mutable ilist_half_node<Argument> Sentinel;
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class Function : public GlobalObject, public ilist_node<Function> {
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typedef iplist<Argument> ArgumentListType;
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typedef iplist<BasicBlock> BasicBlockListType;
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// BasicBlock iterators...
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typedef BasicBlockListType::iterator iterator;
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typedef BasicBlockListType::const_iterator const_iterator;
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typedef ArgumentListType::iterator arg_iterator;
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typedef ArgumentListType::const_iterator const_arg_iterator;
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// Important things that make up a function!
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BasicBlockListType BasicBlocks; ///< The basic blocks
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mutable ArgumentListType ArgumentList; ///< The formal arguments
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ValueSymbolTable *SymTab; ///< Symbol table of args/instructions
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AttributeSet AttributeSets; ///< Parameter attributes
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* bit 0 : HasLazyArguments
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* bit 1 : HasPrefixData
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* bit 2 : HasPrologueData
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* bit 3-6: CallingConvention
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/// Bits from GlobalObject::GlobalObjectSubclassData.
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/// Whether this function is materializable.
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IsMaterializableBit = 1 << 0,
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HasMetadataHashEntryBit = 1 << 1
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void setGlobalObjectBit(unsigned Mask, bool Value) {
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setGlobalObjectSubClassData((~Mask & getGlobalObjectSubClassData()) |
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friend class SymbolTableListTraits<Function, Module>;
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void setParent(Module *parent);
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/// hasLazyArguments/CheckLazyArguments - The argument list of a function is
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/// built on demand, so that the list isn't allocated until the first client
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/// needs it. The hasLazyArguments predicate returns true if the arg list
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/// hasn't been set up yet.
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bool hasLazyArguments() const {
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return getSubclassDataFromValue() & (1<<0);
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void CheckLazyArguments() const {
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if (hasLazyArguments())
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BuildLazyArguments();
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void BuildLazyArguments() const;
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Function(const Function&) = delete;
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void operator=(const Function&) = delete;
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/// Function ctor - If the (optional) Module argument is specified, the
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/// function is automatically inserted into the end of the function list for
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Function(FunctionType *Ty, LinkageTypes Linkage,
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const Twine &N = "", Module *M = nullptr);
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static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
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const Twine &N = "", Module *M = nullptr) {
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return new(1) Function(Ty, Linkage, N, M);
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~Function() override;
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/// \brief Provide fast operand accessors
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DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
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/// \brief Get the personality function associated with this function.
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bool hasPersonalityFn() const { return getNumOperands() != 0; }
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Constant *getPersonalityFn() const {
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assert(hasPersonalityFn());
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return cast<Constant>(Op<0>());
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void setPersonalityFn(Constant *C);
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Type *getReturnType() const; // Return the type of the ret val
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FunctionType *getFunctionType() const; // Return the FunctionType for me
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/// getContext - Return a reference to the LLVMContext associated with this
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LLVMContext &getContext() const;
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/// isVarArg - Return true if this function takes a variable number of
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bool isVarArg() const;
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bool isMaterializable() const;
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void setIsMaterializable(bool V);
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/// getIntrinsicID - This method returns the ID number of the specified
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/// function, or Intrinsic::not_intrinsic if the function is not an
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/// intrinsic, or if the pointer is null. This value is always defined to be
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/// zero to allow easy checking for whether a function is intrinsic or not.
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/// The particular intrinsic functions which correspond to this value are
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/// defined in llvm/Intrinsics.h.
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Intrinsic::ID getIntrinsicID() const LLVM_READONLY { return IntID; }
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bool isIntrinsic() const { return getName().startswith("llvm."); }
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/// \brief Recalculate the ID for this function if it is an Intrinsic defined
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/// in llvm/Intrinsics.h. Sets the intrinsic ID to Intrinsic::not_intrinsic
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/// if the name of this function does not match an intrinsic in that header.
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/// Note, this method does not need to be called directly, as it is called
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/// from Value::setName() whenever the name of this function changes.
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void recalculateIntrinsicID();
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/// getCallingConv()/setCallingConv(CC) - These method get and set the
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/// calling convention of this function. The enum values for the known
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/// calling conventions are defined in CallingConv.h.
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CallingConv::ID getCallingConv() const {
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return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 3);
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void setCallingConv(CallingConv::ID CC) {
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setValueSubclassData((getSubclassDataFromValue() & 7) |
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(static_cast<unsigned>(CC) << 3));
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/// @brief Return the attribute list for this Function.
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AttributeSet getAttributes() const { return AttributeSets; }
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/// @brief Set the attribute list for this Function.
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void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
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/// @brief Add function attributes to this function.
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void addFnAttr(Attribute::AttrKind N) {
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setAttributes(AttributeSets.addAttribute(getContext(),
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AttributeSet::FunctionIndex, N));
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/// @brief Remove function attributes from this function.
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void removeFnAttr(Attribute::AttrKind N) {
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setAttributes(AttributeSets.removeAttribute(
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getContext(), AttributeSet::FunctionIndex, N));
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/// @brief Add function attributes to this function.
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void addFnAttr(StringRef Kind) {
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AttributeSets.addAttribute(getContext(),
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AttributeSet::FunctionIndex, Kind));
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void addFnAttr(StringRef Kind, StringRef Value) {
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AttributeSets.addAttribute(getContext(),
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AttributeSet::FunctionIndex, Kind, Value));
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/// Set the entry count for this function.
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void setEntryCount(uint64_t Count);
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/// Get the entry count for this function.
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Optional<uint64_t> getEntryCount() const;
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/// @brief Return true if the function has the attribute.
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bool hasFnAttribute(Attribute::AttrKind Kind) const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
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bool hasFnAttribute(StringRef Kind) const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
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/// @brief Return the attribute for the given attribute kind.
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Attribute getFnAttribute(Attribute::AttrKind Kind) const {
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return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
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Attribute getFnAttribute(StringRef Kind) const {
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return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
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/// \brief Return the stack alignment for the function.
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unsigned getFnStackAlignment() const {
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return AttributeSets.getStackAlignment(AttributeSet::FunctionIndex);
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/// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
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/// to use during code generation.
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const char *getGC() const;
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void setGC(const char *Str);
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/// @brief adds the attribute to the list of attributes.
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void addAttribute(unsigned i, Attribute::AttrKind attr);
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/// @brief adds the attributes to the list of attributes.
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void addAttributes(unsigned i, AttributeSet attrs);
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/// @brief removes the attributes from the list of attributes.
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void removeAttributes(unsigned i, AttributeSet attr);
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/// @brief adds the dereferenceable attribute to the list of attributes.
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void addDereferenceableAttr(unsigned i, uint64_t Bytes);
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/// @brief adds the dereferenceable_or_null attribute to the list of
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void addDereferenceableOrNullAttr(unsigned i, uint64_t Bytes);
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/// @brief Extract the alignment for a call or parameter (0=unknown).
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unsigned getParamAlignment(unsigned i) const {
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return AttributeSets.getParamAlignment(i);
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/// @brief Extract the number of dereferenceable bytes for a call or
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/// parameter (0=unknown).
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uint64_t getDereferenceableBytes(unsigned i) const {
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return AttributeSets.getDereferenceableBytes(i);
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/// @brief Extract the number of dereferenceable_or_null bytes for a call or
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/// parameter (0=unknown).
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uint64_t getDereferenceableOrNullBytes(unsigned i) const {
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return AttributeSets.getDereferenceableOrNullBytes(i);
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/// @brief Determine if the function does not access memory.
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bool doesNotAccessMemory() const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::ReadNone);
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void setDoesNotAccessMemory() {
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addFnAttr(Attribute::ReadNone);
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/// @brief Determine if the function does not access or only reads memory.
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bool onlyReadsMemory() const {
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return doesNotAccessMemory() ||
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AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::ReadOnly);
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void setOnlyReadsMemory() {
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addFnAttr(Attribute::ReadOnly);
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/// @brief Determine if the call can access memmory only using pointers based
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/// on its arguments.
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bool onlyAccessesArgMemory() const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::ArgMemOnly);
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void setOnlyAccessesArgMemory() {
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addFnAttr(Attribute::ArgMemOnly);
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/// @brief Determine if the function cannot return.
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bool doesNotReturn() const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::NoReturn);
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void setDoesNotReturn() {
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addFnAttr(Attribute::NoReturn);
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/// @brief Determine if the function cannot unwind.
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bool doesNotThrow() const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::NoUnwind);
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void setDoesNotThrow() {
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addFnAttr(Attribute::NoUnwind);
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/// @brief Determine if the call cannot be duplicated.
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bool cannotDuplicate() const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::NoDuplicate);
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void setCannotDuplicate() {
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addFnAttr(Attribute::NoDuplicate);
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/// @brief Determine if the call is convergent.
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bool isConvergent() const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::Convergent);
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void setConvergent() {
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addFnAttr(Attribute::Convergent);
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/// @brief True if the ABI mandates (or the user requested) that this
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/// function be in a unwind table.
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bool hasUWTable() const {
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return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
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void setHasUWTable() {
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addFnAttr(Attribute::UWTable);
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/// @brief True if this function needs an unwind table.
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bool needsUnwindTableEntry() const {
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return hasUWTable() || !doesNotThrow();
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/// @brief Determine if the function returns a structure through first
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/// pointer argument.
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bool hasStructRetAttr() const {
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return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
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AttributeSets.hasAttribute(2, Attribute::StructRet);
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/// @brief Determine if the parameter does not alias other parameters.
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/// @param n The parameter to check. 1 is the first parameter, 0 is the return
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bool doesNotAlias(unsigned n) const {
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return AttributeSets.hasAttribute(n, Attribute::NoAlias);
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void setDoesNotAlias(unsigned n) {
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addAttribute(n, Attribute::NoAlias);
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/// @brief Determine if the parameter can be captured.
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/// @param n The parameter to check. 1 is the first parameter, 0 is the return
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bool doesNotCapture(unsigned n) const {
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return AttributeSets.hasAttribute(n, Attribute::NoCapture);
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void setDoesNotCapture(unsigned n) {
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addAttribute(n, Attribute::NoCapture);
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bool doesNotAccessMemory(unsigned n) const {
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return AttributeSets.hasAttribute(n, Attribute::ReadNone);
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void setDoesNotAccessMemory(unsigned n) {
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addAttribute(n, Attribute::ReadNone);
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bool onlyReadsMemory(unsigned n) const {
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return doesNotAccessMemory(n) ||
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AttributeSets.hasAttribute(n, Attribute::ReadOnly);
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void setOnlyReadsMemory(unsigned n) {
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addAttribute(n, Attribute::ReadOnly);
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/// copyAttributesFrom - copy all additional attributes (those not needed to
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/// create a Function) from the Function Src to this one.
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void copyAttributesFrom(const GlobalValue *Src) override;
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/// deleteBody - This method deletes the body of the function, and converts
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/// the linkage to external.
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setLinkage(ExternalLinkage);
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/// removeFromParent - This method unlinks 'this' from the containing module,
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/// but does not delete it.
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void removeFromParent() override;
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/// eraseFromParent - This method unlinks 'this' from the containing module
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void eraseFromParent() override;
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/// Get the underlying elements of the Function... the basic block list is
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/// empty for external functions.
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const ArgumentListType &getArgumentList() const {
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CheckLazyArguments();
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ArgumentListType &getArgumentList() {
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CheckLazyArguments();
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static iplist<Argument> Function::*getSublistAccess(Argument*) {
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return &Function::ArgumentList;
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const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
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BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
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static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
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return &Function::BasicBlocks;
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const BasicBlock &getEntryBlock() const { return front(); }
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BasicBlock &getEntryBlock() { return front(); }
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//===--------------------------------------------------------------------===//
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// Symbol Table Accessing functions...
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/// getSymbolTable() - Return the symbol table...
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inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
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inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
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//===--------------------------------------------------------------------===//
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// BasicBlock iterator forwarding functions
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iterator begin() { return BasicBlocks.begin(); }
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const_iterator begin() const { return BasicBlocks.begin(); }
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iterator end () { return BasicBlocks.end(); }
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const_iterator end () const { return BasicBlocks.end(); }
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size_t size() const { return BasicBlocks.size(); }
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bool empty() const { return BasicBlocks.empty(); }
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const BasicBlock &front() const { return BasicBlocks.front(); }
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BasicBlock &front() { return BasicBlocks.front(); }
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const BasicBlock &back() const { return BasicBlocks.back(); }
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BasicBlock &back() { return BasicBlocks.back(); }
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/// @name Function Argument Iteration
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arg_iterator arg_begin() {
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CheckLazyArguments();
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return ArgumentList.begin();
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const_arg_iterator arg_begin() const {
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CheckLazyArguments();
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return ArgumentList.begin();
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arg_iterator arg_end() {
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CheckLazyArguments();
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return ArgumentList.end();
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const_arg_iterator arg_end() const {
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CheckLazyArguments();
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return ArgumentList.end();
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iterator_range<arg_iterator> args() {
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return iterator_range<arg_iterator>(arg_begin(), arg_end());
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iterator_range<const_arg_iterator> args() const {
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return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
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size_t arg_size() const;
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bool arg_empty() const;
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bool hasPrefixData() const {
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return getSubclassDataFromValue() & (1<<1);
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Constant *getPrefixData() const;
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void setPrefixData(Constant *PrefixData);
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bool hasPrologueData() const {
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return getSubclassDataFromValue() & (1<<2);
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Constant *getPrologueData() const;
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void setPrologueData(Constant *PrologueData);
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/// Print the function to an output stream with an optional
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/// AssemblyAnnotationWriter.
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void print(raw_ostream &OS, AssemblyAnnotationWriter *AAW = nullptr) const;
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/// viewCFG - This function is meant for use from the debugger. You can just
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/// say 'call F->viewCFG()' and a ghostview window should pop up from the
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/// program, displaying the CFG of the current function with the code for each
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/// basic block inside. This depends on there being a 'dot' and 'gv' program
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void viewCFG() const;
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/// viewCFGOnly - This function is meant for use from the debugger. It works
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/// just like viewCFG, but it does not include the contents of basic blocks
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/// into the nodes, just the label. If you are only interested in the CFG
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/// this can make the graph smaller.
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void viewCFGOnly() const;
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/// Methods for support type inquiry through isa, cast, and dyn_cast:
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static inline bool classof(const Value *V) {
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return V->getValueID() == Value::FunctionVal;
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/// dropAllReferences() - This method causes all the subinstructions to "let
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/// go" of all references that they are maintaining. This allows one to
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/// 'delete' a whole module at a time, even though there may be circular
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/// references... first all references are dropped, and all use counts go to
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/// zero. Then everything is deleted for real. Note that no operations are
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/// valid on an object that has "dropped all references", except operator
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/// Since no other object in the module can have references into the body of a
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/// function, dropping all references deletes the entire body of the function,
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/// including any contained basic blocks.
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void dropAllReferences();
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/// hasAddressTaken - returns true if there are any uses of this function
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/// other than direct calls or invokes to it, or blockaddress expressions.
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/// Optionally passes back an offending user for diagnostic purposes.
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bool hasAddressTaken(const User** = nullptr) const;
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/// isDefTriviallyDead - Return true if it is trivially safe to remove
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/// this function definition from the module (because it isn't externally
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/// visible, does not have its address taken, and has no callers). To make
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/// this more accurate, call removeDeadConstantUsers first.
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bool isDefTriviallyDead() const;
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/// callsFunctionThatReturnsTwice - Return true if the function has a call to
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/// setjmp or other function that gcc recognizes as "returning twice".
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bool callsFunctionThatReturnsTwice() const;
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/// \brief Check if this has any metadata.
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bool hasMetadata() const { return hasMetadataHashEntry(); }
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/// \brief Get the current metadata attachment, if any.
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/// Returns \c nullptr if such an attachment is missing.
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MDNode *getMetadata(unsigned KindID) const;
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MDNode *getMetadata(StringRef Kind) const;
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/// \brief Set a particular kind of metadata attachment.
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/// Sets the given attachment to \c MD, erasing it if \c MD is \c nullptr or
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/// replacing it if it already exists.
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void setMetadata(unsigned KindID, MDNode *MD);
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void setMetadata(StringRef Kind, MDNode *MD);
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/// \brief Get all current metadata attachments.
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getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const;
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/// \brief Drop metadata not in the given list.
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/// Drop all metadata from \c this not included in \c KnownIDs.
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void dropUnknownMetadata(ArrayRef<unsigned> KnownIDs);
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// Shadow Value::setValueSubclassData with a private forwarding method so that
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// subclasses cannot accidentally use it.
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void setValueSubclassData(unsigned short D) {
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Value::setValueSubclassData(D);
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bool hasMetadataHashEntry() const {
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return getGlobalObjectSubClassData() & HasMetadataHashEntryBit;
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void setHasMetadataHashEntry(bool HasEntry) {
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setGlobalObjectBit(HasMetadataHashEntryBit, HasEntry);
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void clearMetadata();
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inline ValueSymbolTable *
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ilist_traits<BasicBlock>::getSymTab(Function *F) {
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return F ? &F->getValueSymbolTable() : nullptr;
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inline ValueSymbolTable *
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ilist_traits<Argument>::getSymTab(Function *F) {
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return F ? &F->getValueSymbolTable() : nullptr;
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struct OperandTraits<Function> : public OptionalOperandTraits<Function> {};
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DEFINE_TRANSPARENT_OPERAND_ACCESSORS(Function, Value)
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} // End llvm namespace