IndirectBrExpandPass.cpp File Reference

Implements an expansion pass to turn indirectbr instructions in the IR into switch instructions. More...

#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Sequence.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"

Include dependency graph for IndirectBrExpandPass.cpp:

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Macros
#define	DEBUG_TYPE   "indirectbr-expand"

Functions
	INITIALIZE_PASS (IndirectBrExpandPass, DEBUG_TYPE, "Expand indirectbr instructions", false, false) FunctionPass *llvm

Detailed Description

Implements an expansion pass to turn indirectbr instructions in the IR into switch instructions.

This works by enumerating the basic blocks in a dense range of integers, replacing each blockaddr constant with the corresponding integer constant, and then building a switch that maps from the integers to the actual blocks. All of the indirectbr instructions in the function are redirected to this common switch.

While this is generically useful if a target is unable to codegen indirectbr natively, it is primarily useful when there is some desire to get the builtin non-jump-table lowering of a switch even when the input source contained an explicit indirect branch construct.

Note that it doesn't make any sense to enable this pass unless a target also disables jump-table lowering of switches. Doing that is likely to pessimize the code.

Definition in file IndirectBrExpandPass.cpp.

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "indirectbr-expand"

Definition at line 48 of file IndirectBrExpandPass.cpp.

Function Documentation

INITIALIZE_PASS()

INITIALIZE_PASS	(	IndirectBrExpandPass	,
		DEBUG_TYPE	,
		"Expand indirectbr instructions"	,
		false	,
		false
	)

Definition at line 69 of file IndirectBrExpandPass.cpp.

References assert(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::BasicBlock::Create(), llvm::PHINode::Create(), llvm::BranchInst::Create(), llvm::SwitchInst::Create(), llvm::CastInst::CreatePointerCast(), llvm::SmallVectorBase::empty(), llvm::Instruction::eraseFromParent(), F(), llvm::find_if(), llvm::ConstantInt::get(), llvm::IntegerType::getBitWidth(), llvm::Module::getDataLayout(), llvm::ConstantExpr::getIntToPtr(), llvm::BasicBlock::getParent(), llvm::GlobalValue::getParent(), llvm::ConstantInt::getType(), llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::SmallVectorTemplateBase< T >::push_back(), runOnFunction(), SI, llvm::SmallVectorBase::size(), and llvm::SystemZISD::TM.