LoopSimplifyCFG.cpp File Reference

#include "llvm/Transforms/Scalar/LoopSimplifyCFG.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/DependenceAnalysis.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopIterator.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/MemorySSA.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/LoopPassManager.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#include <optional>

Include dependency graph for LoopSimplifyCFG.cpp:

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "loop-simplifycfg"

Functions
	STATISTIC (NumTerminatorsFolded, "Number of terminators folded to unconditional branches")
	STATISTIC (NumLoopBlocksDeleted, "Number of loop blocks deleted")
	STATISTIC (NumLoopExitsDeleted, "Number of loop exiting edges deleted")
static BasicBlock *	getOnlyLiveSuccessor (BasicBlock *BB)
	If BB is a switch or a conditional branch, but only one of its successors can be reached from this block in runtime, return this successor.
static void	removeBlockFromLoops (BasicBlock *BB, Loop *FirstLoop, Loop *LastLoop=nullptr)
	Removes BB from all loops from [FirstLoop, LastLoop) in parent chain.
static Loop *	getInnermostLoopFor (SmallPtrSetImpl< BasicBlock * > &BBs, Loop &L, LoopInfo &LI)
	Find innermost loop that contains at least one block from BBs and contains the header of loop L.
static bool	constantFoldTerminators (Loop &L, DominatorTree &DT, LoopInfo &LI, ScalarEvolution &SE, MemorySSAUpdater *MSSAU, bool &IsLoopDeleted)
	Turn branches and switches with known constant conditions into unconditional branches.
static bool	mergeBlocksIntoPredecessors (Loop &L, DominatorTree &DT, LoopInfo &LI, MemorySSAUpdater *MSSAU, ScalarEvolution &SE)
static bool	simplifyLoopCFG (Loop &L, DominatorTree &DT, LoopInfo &LI, ScalarEvolution &SE, MemorySSAUpdater *MSSAU, bool &IsLoopDeleted)
	INITIALIZE_PASS_BEGIN (LoopSimplifyCFGLegacyPass, "loop-simplifycfg", "Simplify loop CFG", false, false) INITIALIZE_PASS_END(LoopSimplifyCFGLegacyPass

Variables
static cl::opt< bool >	EnableTermFolding ("enable-loop-simplifycfg-term-folding", cl::init(true))
loop	simplifycfg
loop Simplify loop	CFG
loop Simplify loop	false

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "loop-simplifycfg"

Definition at line 38 of file LoopSimplifyCFG.cpp.

Function Documentation

constantFoldTerminators()

static bool constantFoldTerminators ( Loop &  L, DominatorTree &  DT, LoopInfo &  LI, ScalarEvolution &  SE, MemorySSAUpdater *  MSSAU, bool &  IsLoopDeleted  )

static

Turn branches and switches with known constant conditions into unconditional branches.

Definition at line 645 of file LoopSimplifyCFG.cpp.

References EnableTermFolding.

Referenced by simplifyLoopCFG().

getInnermostLoopFor()

static Loop * getInnermostLoopFor ( SmallPtrSetImpl< BasicBlock * > &  BBs, Loop &  L, LoopInfo &  LI  )

static

Find innermost loop that contains at least one block from BBs and contains the header of loop L.

Definition at line 92 of file LoopSimplifyCFG.cpp.

References llvm::LoopBase< BlockT, LoopT >::contains(), llvm::LoopBase< BlockT, LoopT >::getLoopDepth(), llvm::LoopInfoBase< BlockT, LoopT >::getLoopFor(), and llvm::LoopBase< BlockT, LoopT >::getParentLoop().

getOnlyLiveSuccessor()

static BasicBlock * getOnlyLiveSuccessor ( BasicBlock *  BB )

static

If BB is a switch or a conditional branch, but only one of its successors can be reached from this block in runtime, return this successor.

Otherwise, return nullptr.

Definition at line 53 of file LoopSimplifyCFG.cpp.

References Cond, llvm::Instruction::getSuccessor(), llvm::BasicBlock::getTerminator(), and SI.

INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN	(	LoopSimplifyCFGLegacyPass	,
		"loop-simplifycfg"	,
		"Simplify loop CFG"	,
		false	,
		false
	)

mergeBlocksIntoPredecessors()

static bool mergeBlocksIntoPredecessors ( Loop &  L, DominatorTree &  DT, LoopInfo &  LI, MemorySSAUpdater *  MSSAU, ScalarEvolution &  SE  )

static

Definition at line 663 of file LoopSimplifyCFG.cpp.

References llvm::ScalarEvolution::forgetBlockAndLoopDispositions(), llvm::LoopInfoBase< BlockT, LoopT >::getLoopFor(), llvm::MemorySSAUpdater::getMemorySSA(), llvm::BasicBlock::getSinglePredecessor(), llvm::BasicBlock::getSingleSuccessor(), llvm::MergeBlockIntoPredecessor(), llvm::MemorySSA::verifyMemorySSA(), and llvm::VerifyMemorySSA.

Referenced by simplifyLoopCFG().

removeBlockFromLoops()

static void removeBlockFromLoops ( BasicBlock *  BB, Loop *  FirstLoop, Loop *  LastLoop = nullptr  )

static

Removes BB from all loops from [FirstLoop, LastLoop) in parent chain.

Definition at line 80 of file LoopSimplifyCFG.cpp.

References assert(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::LoopBase< BlockT, LoopT >::getHeader(), and llvm::LoopBase< BlockT, LoopT >::getParentLoop().

simplifyLoopCFG()

static bool simplifyLoopCFG ( Loop &  L, DominatorTree &  DT, LoopInfo &  LI, ScalarEvolution &  SE, MemorySSAUpdater *  MSSAU, bool &  IsLoopDeleted  )

static

Definition at line 698 of file LoopSimplifyCFG.cpp.

References constantFoldTerminators(), llvm::ScalarEvolution::forgetTopmostLoop(), and mergeBlocksIntoPredecessors().

Referenced by llvm::LoopSimplifyCFGPass::run().

STATISTIC() [1/3]

STATISTIC	(	NumLoopBlocksDeleted	,
		"Number of loop blocks deleted"
	)

STATISTIC() [2/3]

STATISTIC	(	NumLoopExitsDeleted	,
		"Number of loop exiting edges deleted"
	)

STATISTIC() [3/3]

STATISTIC	(	NumTerminatorsFolded	,
		"Number of terminators folded to unconditional branches"
	)

Variable Documentation

CFG

loop Simplify loop CFG

Definition at line 781 of file LoopSimplifyCFG.cpp.

EnableTermFolding

cl::opt< bool > EnableTermFolding("enable-loop-simplifycfg-term-folding", cl::init(true)) ( "enable-loop-simplifycfg-term-folding"  , cl::init(true)    )

static

Referenced by constantFoldTerminators().

false

loop Simplify loop false

Definition at line 781 of file LoopSimplifyCFG.cpp.

simplifycfg

loop simplifycfg

Definition at line 780 of file LoopSimplifyCFG.cpp.