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//===--- SILBasicBlock.h - Basic blocks for SIL -----------------*- C++ -*-===//
// This source file is part of the open source project
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
// See for license information
// See for the list of Swift project authors
// This file defines the high-level BasicBlocks used for Swift SIL code.
#include "swift/Basic/Compiler.h"
#include "swift/Basic/Range.h"
#include "swift/SIL/SILArgumentArrayRef.h"
#include "swift/SIL/SILInstruction.h"
namespace swift {
class SILFunction;
class SILArgument;
class SILPrintContext;
class SILBasicBlock :
public llvm::ilist_node<SILBasicBlock>, public SILAllocated<SILBasicBlock> {
friend class SILSuccessor;
friend class SILFunction;
friend class SILGlobalVariable;
using InstListType = llvm::iplist<SILInstruction>;
/// A backreference to the containing SILFunction.
SILFunction *Parent;
/// PrevList - This is a list of all of the terminator operands that are
/// branching to this block, forming the predecessor list. This is
/// automatically managed by the SILSuccessor class.
SILSuccessor *PredList;
/// This is the list of basic block arguments for this block.
std::vector<SILArgument *> ArgumentList;
/// The ordered set of instructions in the SILBasicBlock.
InstListType InstList;
friend struct llvm::ilist_traits<SILBasicBlock>;
SILBasicBlock() : Parent(nullptr) {}
void operator=(const SILBasicBlock &) = delete;
void operator delete(void *Ptr, size_t) = delete;
SILBasicBlock(SILFunction *F, SILBasicBlock *relativeToBB, bool after);
/// Gets the ID (= index in the function's block list) of the block.
/// Returns -1 if the block is not contained in a function.
/// Warning: This function is slow. Therefore it should only be used for
/// debug output.
int getDebugID() const;
SILFunction *getParent() { return Parent; }
const SILFunction *getParent() const { return Parent; }
SILModule &getModule() const;
/// This method unlinks 'self' from the containing SILFunction and deletes it.
void eraseFromParent();
/// Remove all instructions of a SILGlobalVariable's static initializer block.
void clearStaticInitializerBlock(SILModule &module);
// SILInstruction List Inspection and Manipulation
using iterator = InstListType::iterator;
using const_iterator = InstListType::const_iterator;
using reverse_iterator = InstListType::reverse_iterator;
using const_reverse_iterator = InstListType::const_reverse_iterator;
void insert(iterator InsertPt, SILInstruction *I);
void insert(SILInstruction *InsertPt, SILInstruction *I) {
insert(InsertPt->getIterator(), I);
void push_back(SILInstruction *I);
void push_front(SILInstruction *I);
void remove(SILInstruction *I);
iterator erase(SILInstruction *I);
SILInstruction &back() { return InstList.back(); }
const SILInstruction &back() const {
return const_cast<SILBasicBlock *>(this)->back();
SILInstruction &front() { return InstList.front(); }
const SILInstruction &front() const {
return const_cast<SILBasicBlock *>(this)->front();
/// Transfer the instructions from Other to the end of this block.
void spliceAtEnd(SILBasicBlock *Other) {
InstList.splice(end(), Other->InstList);
void spliceAtBegin(SILBasicBlock *Other) {
InstList.splice(begin(), Other->InstList);
bool empty() const { return InstList.empty(); }
iterator begin() { return InstList.begin(); }
iterator end() { return InstList.end(); }
const_iterator begin() const { return InstList.begin(); }
const_iterator end() const { return InstList.end(); }
reverse_iterator rbegin() { return InstList.rbegin(); }
reverse_iterator rend() { return InstList.rend(); }
const_reverse_iterator rbegin() const { return InstList.rbegin(); }
const_reverse_iterator rend() const { return InstList.rend(); }
TermInst *getTerminator() {
assert(!InstList.empty() && "Can't get successors for malformed block");
return cast<TermInst>(&InstList.back());
const TermInst *getTerminator() const {
return const_cast<SILBasicBlock *>(this)->getTerminator();
/// Splits a basic block into two at the specified instruction.
/// Note that all the instructions BEFORE the specified iterator
/// stay as part of the original basic block. The old basic block is left
/// without a terminator.
SILBasicBlock *split(iterator I);
/// Move the basic block to after the specified basic block in the IR.
/// Assumes that the basic blocks must reside in the same function. In asserts
/// builds, an assert verifies that this is true.
void moveAfter(SILBasicBlock *After);
/// Moves the instruction to the iterator in this basic block.
void moveTo(SILBasicBlock::iterator To, SILInstruction *I);
// SILBasicBlock Argument List Inspection and Manipulation
using arg_iterator = std::vector<SILArgument *>::iterator;
using const_arg_iterator = std::vector<SILArgument *>::const_iterator;
bool args_empty() const { return ArgumentList.empty(); }
size_t args_size() const { return ArgumentList.size(); }
arg_iterator args_begin() { return ArgumentList.begin(); }
arg_iterator args_end() { return ArgumentList.end(); }
const_arg_iterator args_begin() const { return ArgumentList.begin(); }
const_arg_iterator args_end() const { return ArgumentList.end(); }
/// Iterator over the PHI arguments of a basic block.
/// Defines an implicit cast operator on the iterator, so that this iterator
/// can be used in the SSAUpdaterImpl.
template <typename PHIArgT = SILPhiArgument,
typename IteratorT = arg_iterator>
class phi_iterator_impl {
IteratorT It;
explicit phi_iterator_impl(IteratorT A) : It(A) {}
phi_iterator_impl &operator++() { ++It; return *this; }
operator PHIArgT *() { return cast<PHIArgT>(*It); }
bool operator==(const phi_iterator_impl& x) const { return It == x.It; }
bool operator!=(const phi_iterator_impl& x) const { return !operator==(x); }
typedef phi_iterator_impl<> phi_iterator;
typedef phi_iterator_impl<const SILPhiArgument,
inline iterator_range<phi_iterator> phis() {
return make_range(phi_iterator(args_begin()), phi_iterator(args_end()));
inline iterator_range<const_phi_iterator> phis() const {
return make_range(const_phi_iterator(args_begin()),
ArrayRef<SILArgument *> getArguments() const { return ArgumentList; }
/// Returns a transform array ref that performs llvm::cast<NAME>
/// each argument and then returns the downcasted value.
#define ARGUMENT(NAME, PARENT) NAME##ArrayRef get##NAME##s() const;
#include "swift/SIL/SILNodes.def"
unsigned getNumArguments() const { return ArgumentList.size(); }
const SILArgument *getArgument(unsigned i) const { return ArgumentList[i]; }
SILArgument *getArgument(unsigned i) { return ArgumentList[i]; }
void cloneArgumentList(SILBasicBlock *Other);
void moveArgumentList(SILBasicBlock *from);
/// Erase a specific argument from the arg list.
void eraseArgument(int Index);
/// Allocate a new argument of type \p Ty and append it to the argument
/// list. Optionally you can pass in a value decl parameter.
SILFunctionArgument *createFunctionArgument(SILType Ty,
const ValueDecl *D = nullptr,
bool disableEntryBlockVerification = false);
SILFunctionArgument *insertFunctionArgument(unsigned Index, SILType Ty,
ValueOwnershipKind OwnershipKind,
const ValueDecl *D = nullptr) {
arg_iterator Pos = ArgumentList.begin();
std::advance(Pos, Index);
return insertFunctionArgument(Pos, Ty, OwnershipKind, D);
/// Replace the \p{i}th Function arg with a new Function arg with SILType \p
/// Ty and ValueDecl \p D.
SILFunctionArgument *replaceFunctionArgument(unsigned i, SILType Ty,
ValueOwnershipKind Kind,
const ValueDecl *D = nullptr);
/// Replace the \p{i}th BB arg with a new BBArg with SILType \p Ty and
/// ValueDecl \p D.
/// NOTE: This assumes that the current argument in position \p i has had its
/// uses eliminated. To replace/replace all uses with, use
/// replacePhiArgumentAndRAUW.
SILPhiArgument *replacePhiArgument(unsigned i, SILType type,
ValueOwnershipKind kind,
const ValueDecl *decl = nullptr);
/// Replace phi argument \p i and RAUW all uses.
SILPhiArgument *
replacePhiArgumentAndReplaceAllUses(unsigned i, SILType type,
ValueOwnershipKind kind,
const ValueDecl *decl = nullptr);
/// Allocate a new argument of type \p Ty and append it to the argument
/// list. Optionally you can pass in a value decl parameter.
SILPhiArgument *createPhiArgument(SILType Ty, ValueOwnershipKind Kind,
const ValueDecl *D = nullptr);
/// Insert a new SILPhiArgument with type \p Ty and \p Decl at position \p
/// Pos.
SILPhiArgument *insertPhiArgument(arg_iterator Pos, SILType Ty,
ValueOwnershipKind Kind,
const ValueDecl *D = nullptr);
SILPhiArgument *insertPhiArgument(unsigned Index, SILType Ty,
ValueOwnershipKind Kind,
const ValueDecl *D = nullptr) {
arg_iterator Pos = ArgumentList.begin();
std::advance(Pos, Index);
return insertPhiArgument(Pos, Ty, Kind, D);
/// Remove all block arguments.
void dropAllArguments() { ArgumentList.clear(); }
// Successors
using SuccessorListTy = TermInst::SuccessorListTy;
using ConstSuccessorListTy = TermInst::ConstSuccessorListTy;
/// The successors of a SILBasicBlock are defined either explicitly as
/// a single successor as the branch targets of the terminator instruction.
ConstSuccessorListTy getSuccessors() const {
return getTerminator()->getSuccessors();
SuccessorListTy getSuccessors() {
return getTerminator()->getSuccessors();
using const_succ_iterator = TermInst::const_succ_iterator;
using succ_iterator = TermInst::succ_iterator;
bool succ_empty() const { return getTerminator()->succ_empty(); }
succ_iterator succ_begin() { return getTerminator()->succ_begin(); }
succ_iterator succ_end() { return getTerminator()->succ_end(); }
const_succ_iterator succ_begin() const {
return getTerminator()->succ_begin();
const_succ_iterator succ_end() const { return getTerminator()->succ_end(); }
using succblock_iterator = TermInst::succblock_iterator;
using const_succblock_iterator = TermInst::const_succblock_iterator;
succblock_iterator succblock_begin() {
return getTerminator()->succblock_begin();
succblock_iterator succblock_end() {
return getTerminator()->succblock_end();
const_succblock_iterator succblock_begin() const {
return getTerminator()->succblock_begin();
const_succblock_iterator succblock_end() const {
return getTerminator()->succblock_end();
SILBasicBlock *getSingleSuccessorBlock() {
return getTerminator()->getSingleSuccessorBlock();
const SILBasicBlock *getSingleSuccessorBlock() const {
return getTerminator()->getSingleSuccessorBlock();
/// Returns true if \p BB is a successor of this block.
bool isSuccessorBlock(SILBasicBlock *Block) const {
return getTerminator()->isSuccessorBlock(Block);
using SuccessorBlockListTy = TermInst::SuccessorBlockListTy;
using ConstSuccessorBlockListTy = TermInst::ConstSuccessorBlockListTy;
/// Return the range of SILBasicBlocks that are successors of this block.
SuccessorBlockListTy getSuccessorBlocks() {
return getTerminator()->getSuccessorBlocks();
/// Return the range of SILBasicBlocks that are successors of this block.
ConstSuccessorBlockListTy getSuccessorBlocks() const {
return getTerminator()->getSuccessorBlocks();
// Predecessors
using pred_iterator = SILSuccessor::pred_iterator;
bool pred_empty() const { return PredList == nullptr; }
pred_iterator pred_begin() const { return pred_iterator(PredList); }
pred_iterator pred_end() const { return pred_iterator(); }
iterator_range<pred_iterator> getPredecessorBlocks() const {
return {pred_begin(), pred_end()};
bool isPredecessorBlock(SILBasicBlock *BB) const {
return any_of(
[&BB](const SILBasicBlock *PredBB) -> bool { return BB == PredBB; });
SILBasicBlock *getSinglePredecessorBlock() {
if (pred_empty() || std::next(pred_begin()) != pred_end())
return nullptr;
return *pred_begin();
const SILBasicBlock *getSinglePredecessorBlock() const {
return const_cast<SILBasicBlock *>(this)->getSinglePredecessorBlock();
// Utility
/// Returns true if this BB is the entry BB of its parent.
bool isEntry() const;
/// Returns true if this block ends in an unreachable or an apply of a
/// no-return apply or builtin.
bool isNoReturn() const;
/// Returns true if this block only contains a branch instruction.
bool isTrampoline() const;
/// Returns true if it is legal to hoist instructions into this block.
/// Used by llvm::LoopInfo.
bool isLegalToHoistInto() const;
/// Returns the debug scope of the first non-meta instructions in the
/// basic block. SILBuilderWithScope uses this to correctly set up
/// the debug scope for newly created instructions.
const SILDebugScope *getScopeOfFirstNonMetaInstruction();
// Debugging
/// Pretty-print the SILBasicBlock.
void dump() const;
/// Pretty-print the SILBasicBlock with the designated stream.
void print(llvm::raw_ostream &OS) const;
/// Pretty-print the SILBasicBlock with the designated context.
void print(SILPrintContext &Ctx) const;
void printAsOperand(raw_ostream &OS, bool PrintType = true);
/// getSublistAccess() - returns pointer to member of instruction list
static InstListType SILBasicBlock::*getSublistAccess() {
return &SILBasicBlock::InstList;
/// Drops all uses that belong to this basic block.
void dropAllReferences() {
for (SILInstruction &I : *this)
void eraseInstructions();
friend class SILArgument;
/// BBArgument's ctor adds it to the argument list of this block.
void insertArgument(arg_iterator Iter, SILArgument *Arg) {
ArgumentList.insert(Iter, Arg);
/// Insert a new SILFunctionArgument with type \p Ty and \p Decl at position
/// \p Pos.
SILFunctionArgument *insertFunctionArgument(arg_iterator Pos, SILType Ty,
ValueOwnershipKind OwnershipKind,
const ValueDecl *D = nullptr);
inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
const SILBasicBlock &BB) {
return OS;
} // end swift namespace
namespace llvm {
// ilist_traits for SILBasicBlock
template <>
struct ilist_traits<::swift::SILBasicBlock>
: ilist_node_traits<::swift::SILBasicBlock> {
using SelfTy = ilist_traits<::swift::SILBasicBlock>;
using SILBasicBlock = ::swift::SILBasicBlock;
using SILFunction = ::swift::SILFunction;
using FunctionPtrTy = ::swift::NullablePtr<SILFunction>;
friend class ::swift::SILFunction;
SILFunction *Parent;
using block_iterator = simple_ilist<SILBasicBlock>::iterator;
static void deleteNode(SILBasicBlock *BB) { BB->~SILBasicBlock(); }
void transferNodesFromList(ilist_traits<SILBasicBlock> &SrcTraits,
block_iterator First, block_iterator Last);
static void createNode(const SILBasicBlock &);
} // end llvm namespace