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//===-- llvm/Function.h - Class to represent a single function --*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file contains the declaration of the Function class, which represents a
// single function/procedure in LLVM.
// A function basically consists of a list of basic blocks, a list of arguments,
// and a symbol table.
#include "llvm/ADT/iterator_range.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/GlobalObject.h"
#include "llvm/Support/Compiler.h"
namespace llvm {
class FunctionType;
class LLVMContext;
// Traits for intrusive list of basic blocks...
template<> struct ilist_traits<BasicBlock>
: public SymbolTableListTraits<BasicBlock, Function> {
// createSentinel is used to get hold of the node that marks the end of the
// list... (same trick used here as in ilist_traits<Instruction>)
BasicBlock *createSentinel() const {
return static_cast<BasicBlock*>(&Sentinel);
static void destroySentinel(BasicBlock*) {}
BasicBlock *provideInitialHead() const { return createSentinel(); }
BasicBlock *ensureHead(BasicBlock*) const { return createSentinel(); }
static void noteHead(BasicBlock*, BasicBlock*) {}
static ValueSymbolTable *getSymTab(Function *ItemParent);
mutable ilist_half_node<BasicBlock> Sentinel;
template<> struct ilist_traits<Argument>
: public SymbolTableListTraits<Argument, Function> {
Argument *createSentinel() const {
return static_cast<Argument*>(&Sentinel);
static void destroySentinel(Argument*) {}
Argument *provideInitialHead() const { return createSentinel(); }
Argument *ensureHead(Argument*) const { return createSentinel(); }
static void noteHead(Argument*, Argument*) {}
static ValueSymbolTable *getSymTab(Function *ItemParent);
mutable ilist_half_node<Argument> Sentinel;
class Function : public GlobalObject, public ilist_node<Function> {
typedef iplist<Argument> ArgumentListType;
typedef iplist<BasicBlock> BasicBlockListType;
// BasicBlock iterators...
typedef BasicBlockListType::iterator iterator;
typedef BasicBlockListType::const_iterator const_iterator;
typedef ArgumentListType::iterator arg_iterator;
typedef ArgumentListType::const_iterator const_arg_iterator;
// Important things that make up a function!
BasicBlockListType BasicBlocks; ///< The basic blocks
mutable ArgumentListType ArgumentList; ///< The formal arguments
ValueSymbolTable *SymTab; ///< Symbol table of args/instructions
AttributeSet AttributeSets; ///< Parameter attributes
// HasLazyArguments is stored in Value::SubclassData.
/*bool HasLazyArguments;*/
// The Calling Convention is stored in Value::SubclassData.
/*CallingConv::ID CallingConvention;*/
friend class SymbolTableListTraits<Function, Module>;
void setParent(Module *parent);
/// hasLazyArguments/CheckLazyArguments - The argument list of a function is
/// built on demand, so that the list isn't allocated until the first client
/// needs it. The hasLazyArguments predicate returns true if the arg list
/// hasn't been set up yet.
bool hasLazyArguments() const {
return getSubclassDataFromValue() & 1;
void CheckLazyArguments() const {
if (hasLazyArguments())
void BuildLazyArguments() const;
Function(const Function&) LLVM_DELETED_FUNCTION;
void operator=(const Function&) LLVM_DELETED_FUNCTION;
/// Do the actual lookup of an intrinsic ID when the query could not be
/// answered from the cache.
unsigned lookupIntrinsicID() const LLVM_READONLY;
/// Function ctor - If the (optional) Module argument is specified, the
/// function is automatically inserted into the end of the function list for
/// the module.
Function(FunctionType *Ty, LinkageTypes Linkage,
const Twine &N = "", Module *M = nullptr);
static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
const Twine &N = "", Module *M = nullptr) {
return new(0) Function(Ty, Linkage, N, M);
Type *getReturnType() const; // Return the type of the ret val
FunctionType *getFunctionType() const; // Return the FunctionType for me
/// getContext - Return a pointer to the LLVMContext associated with this
/// function, or NULL if this function is not bound to a context yet.
LLVMContext &getContext() const;
/// isVarArg - Return true if this function takes a variable number of
/// arguments.
bool isVarArg() const;
/// getIntrinsicID - This method returns the ID number of the specified
/// function, or Intrinsic::not_intrinsic if the function is not an
/// intrinsic, or if the pointer is null. This value is always defined to be
/// zero to allow easy checking for whether a function is intrinsic or not.
/// The particular intrinsic functions which correspond to this value are
/// defined in llvm/Intrinsics.h. Results are cached in the LLVM context,
/// subsequent requests for the same ID return results much faster from the
/// cache.
unsigned getIntrinsicID() const LLVM_READONLY;
bool isIntrinsic() const { return getName().startswith("llvm."); }
/// getCallingConv()/setCallingConv(CC) - These method get and set the
/// calling convention of this function. The enum values for the known
/// calling conventions are defined in CallingConv.h.
CallingConv::ID getCallingConv() const {
return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 2);
void setCallingConv(CallingConv::ID CC) {
setValueSubclassData((getSubclassDataFromValue() & 3) |
(static_cast<unsigned>(CC) << 2));
/// @brief Return the attribute list for this Function.
AttributeSet getAttributes() const { return AttributeSets; }
/// @brief Set the attribute list for this Function.
void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
/// @brief Add function attributes to this function.
void addFnAttr(Attribute::AttrKind N) {
AttributeSet::FunctionIndex, N));
/// @brief Remove function attributes from this function.
void removeFnAttr(Attribute::AttrKind N) {
getContext(), AttributeSet::FunctionIndex, N));
/// @brief Add function attributes to this function.
void addFnAttr(StringRef Kind) {
AttributeSet::FunctionIndex, Kind));
void addFnAttr(StringRef Kind, StringRef Value) {
AttributeSet::FunctionIndex, Kind, Value));
/// @brief Return true if the function has the attribute.
bool hasFnAttribute(Attribute::AttrKind Kind) const {
return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
bool hasFnAttribute(StringRef Kind) const {
return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
/// @brief Return the attribute for the given attribute kind.
Attribute getFnAttribute(Attribute::AttrKind Kind) const {
return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
Attribute getFnAttribute(StringRef Kind) const {
return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
/// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
/// to use during code generation.
bool hasGC() const;
const char *getGC() const;
void setGC(const char *Str);
void clearGC();
/// @brief adds the attribute to the list of attributes.
void addAttribute(unsigned i, Attribute::AttrKind attr);
/// @brief adds the attributes to the list of attributes.
void addAttributes(unsigned i, AttributeSet attrs);
/// @brief removes the attributes from the list of attributes.
void removeAttributes(unsigned i, AttributeSet attr);
/// @brief Extract the alignment for a call or parameter (0=unknown).
unsigned getParamAlignment(unsigned i) const {
return AttributeSets.getParamAlignment(i);
/// @brief Extract the number of dereferenceable bytes for a call or
/// parameter (0=unknown).
uint64_t getDereferenceableBytes(unsigned i) const {
return AttributeSets.getDereferenceableBytes(i);
/// @brief Determine if the function does not access memory.
bool doesNotAccessMemory() const {
return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
void setDoesNotAccessMemory() {
/// @brief Determine if the function does not access or only reads memory.
bool onlyReadsMemory() const {
return doesNotAccessMemory() ||
void setOnlyReadsMemory() {
/// @brief Determine if the function cannot return.
bool doesNotReturn() const {
return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
void setDoesNotReturn() {
/// @brief Determine if the function cannot unwind.
bool doesNotThrow() const {
return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
void setDoesNotThrow() {
/// @brief Determine if the call cannot be duplicated.
bool cannotDuplicate() const {
return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
void setCannotDuplicate() {
/// @brief True if the ABI mandates (or the user requested) that this
/// function be in a unwind table.
bool hasUWTable() const {
return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
void setHasUWTable() {
/// @brief True if this function needs an unwind table.
bool needsUnwindTableEntry() const {
return hasUWTable() || !doesNotThrow();
/// @brief Determine if the function returns a structure through first
/// pointer argument.
bool hasStructRetAttr() const {
return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
AttributeSets.hasAttribute(2, Attribute::StructRet);
/// @brief Determine if the parameter does not alias other parameters.
/// @param n The parameter to check. 1 is the first parameter, 0 is the return
bool doesNotAlias(unsigned n) const {
return AttributeSets.hasAttribute(n, Attribute::NoAlias);
void setDoesNotAlias(unsigned n) {
addAttribute(n, Attribute::NoAlias);
/// @brief Determine if the parameter can be captured.
/// @param n The parameter to check. 1 is the first parameter, 0 is the return
bool doesNotCapture(unsigned n) const {
return AttributeSets.hasAttribute(n, Attribute::NoCapture);
void setDoesNotCapture(unsigned n) {
addAttribute(n, Attribute::NoCapture);
bool doesNotAccessMemory(unsigned n) const {
return AttributeSets.hasAttribute(n, Attribute::ReadNone);
void setDoesNotAccessMemory(unsigned n) {
addAttribute(n, Attribute::ReadNone);
bool onlyReadsMemory(unsigned n) const {
return doesNotAccessMemory(n) ||
AttributeSets.hasAttribute(n, Attribute::ReadOnly);
void setOnlyReadsMemory(unsigned n) {
addAttribute(n, Attribute::ReadOnly);
/// copyAttributesFrom - copy all additional attributes (those not needed to
/// create a Function) from the Function Src to this one.
void copyAttributesFrom(const GlobalValue *Src) override;
/// deleteBody - This method deletes the body of the function, and converts
/// the linkage to external.
void deleteBody() {
/// removeFromParent - This method unlinks 'this' from the containing module,
/// but does not delete it.
void removeFromParent() override;
/// eraseFromParent - This method unlinks 'this' from the containing module
/// and deletes it.
void eraseFromParent() override;
/// Get the underlying elements of the Function... the basic block list is
/// empty for external functions.
const ArgumentListType &getArgumentList() const {
return ArgumentList;
ArgumentListType &getArgumentList() {
return ArgumentList;
static iplist<Argument> Function::*getSublistAccess(Argument*) {
return &Function::ArgumentList;
const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
return &Function::BasicBlocks;
const BasicBlock &getEntryBlock() const { return front(); }
BasicBlock &getEntryBlock() { return front(); }
// Symbol Table Accessing functions...
/// getSymbolTable() - Return the symbol table...
inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
// BasicBlock iterator forwarding functions
iterator begin() { return BasicBlocks.begin(); }
const_iterator begin() const { return BasicBlocks.begin(); }
iterator end () { return BasicBlocks.end(); }
const_iterator end () const { return BasicBlocks.end(); }
size_t size() const { return BasicBlocks.size(); }
bool empty() const { return BasicBlocks.empty(); }
const BasicBlock &front() const { return BasicBlocks.front(); }
BasicBlock &front() { return BasicBlocks.front(); }
const BasicBlock &back() const { return BasicBlocks.back(); }
BasicBlock &back() { return BasicBlocks.back(); }
/// @name Function Argument Iteration
/// @{
arg_iterator arg_begin() {
return ArgumentList.begin();
const_arg_iterator arg_begin() const {
return ArgumentList.begin();
arg_iterator arg_end() {
return ArgumentList.end();
const_arg_iterator arg_end() const {
return ArgumentList.end();
iterator_range<arg_iterator> args() {
return iterator_range<arg_iterator>(arg_begin(), arg_end());
iterator_range<const_arg_iterator> args() const {
return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
/// @}
size_t arg_size() const;
bool arg_empty() const;
bool hasPrefixData() const {
return getSubclassDataFromValue() & 2;
Constant *getPrefixData() const;
void setPrefixData(Constant *PrefixData);
/// viewCFG - This function is meant for use from the debugger. You can just
/// say 'call F->viewCFG()' and a ghostview window should pop up from the
/// program, displaying the CFG of the current function with the code for each
/// basic block inside. This depends on there being a 'dot' and 'gv' program
/// in your path.
void viewCFG() const;
/// viewCFGOnly - This function is meant for use from the debugger. It works
/// just like viewCFG, but it does not include the contents of basic blocks
/// into the nodes, just the label. If you are only interested in the CFG
/// this can make the graph smaller.
void viewCFGOnly() const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const Value *V) {
return V->getValueID() == Value::FunctionVal;
/// dropAllReferences() - This method causes all the subinstructions to "let
/// go" of all references that they are maintaining. This allows one to
/// 'delete' a whole module at a time, even though there may be circular
/// references... first all references are dropped, and all use counts go to
/// zero. Then everything is deleted for real. Note that no operations are
/// valid on an object that has "dropped all references", except operator
/// delete.
/// Since no other object in the module can have references into the body of a
/// function, dropping all references deletes the entire body of the function,
/// including any contained basic blocks.
void dropAllReferences();
/// hasAddressTaken - returns true if there are any uses of this function
/// other than direct calls or invokes to it, or blockaddress expressions.
/// Optionally passes back an offending user for diagnostic purposes.
bool hasAddressTaken(const User** = nullptr) const;
/// isDefTriviallyDead - Return true if it is trivially safe to remove
/// this function definition from the module (because it isn't externally
/// visible, does not have its address taken, and has no callers). To make
/// this more accurate, call removeDeadConstantUsers first.
bool isDefTriviallyDead() const;
/// callsFunctionThatReturnsTwice - Return true if the function has a call to
/// setjmp or other function that gcc recognizes as "returning twice".
bool callsFunctionThatReturnsTwice() const;
// Shadow Value::setValueSubclassData with a private forwarding method so that
// subclasses cannot accidentally use it.
void setValueSubclassData(unsigned short D) {
inline ValueSymbolTable *
ilist_traits<BasicBlock>::getSymTab(Function *F) {
return F ? &F->getValueSymbolTable() : nullptr;
inline ValueSymbolTable *
ilist_traits<Argument>::getSymTab(Function *F) {
return F ? &F->getValueSymbolTable() : nullptr;
} // End llvm namespace