LLVM 19.0.0git
Macros | Functions | Variables
LoopRotationUtils.cpp File Reference
#include "llvm/Transforms/Utils/LoopRotationUtils.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemorySSA.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include "llvm/Transforms/Utils/ValueMapper.h"

Go to the source code of this file.

Macros

#define DEBUG_TYPE   "loop-rotate"
 

Functions

 STATISTIC (NumNotRotatedDueToHeaderSize, "Number of loops not rotated due to the header size")
 
 STATISTIC (NumInstrsHoisted, "Number of instructions hoisted into loop preheader")
 
 STATISTIC (NumInstrsDuplicated, "Number of instructions cloned into loop preheader")
 
 STATISTIC (NumRotated, "Number of loops rotated")
 
static void InsertNewValueIntoMap (ValueToValueMapTy &VM, Value *K, Value *V)
 Insert (K, V) pair into the ValueToValueMap, and verify the key did not previously exist in the map, and the value was inserted.
 
static void RewriteUsesOfClonedInstructions (BasicBlock *OrigHeader, BasicBlock *OrigPreheader, ValueToValueMapTy &ValueMap, ScalarEvolution *SE, SmallVectorImpl< PHINode * > *InsertedPHIs)
 RewriteUsesOfClonedInstructions - We just cloned the instructions from the old header into the preheader.
 
static bool profitableToRotateLoopExitingLatch (Loop *L)
 
static bool canRotateDeoptimizingLatchExit (Loop *L)
 
static void updateBranchWeights (BranchInst &PreHeaderBI, BranchInst &LoopBI, bool HasConditionalPreHeader, bool SuccsSwapped)
 
static bool shouldSpeculateInstrs (BasicBlock::iterator Begin, BasicBlock::iterator End, Loop *L)
 Determine whether the instructions in this range may be safely and cheaply speculated.
 

Variables

static cl::opt< boolMultiRotate ("loop-rotate-multi", cl::init(false), cl::Hidden, cl::desc("Allow loop rotation multiple times in order to reach " "a better latch exit"))
 
static constexpr uint32_t ZeroTripCountWeights [] = {1, 127}
 

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE   "loop-rotate"

Definition at line 40 of file LoopRotationUtils.cpp.

Function Documentation

◆ canRotateDeoptimizingLatchExit()

static bool canRotateDeoptimizingLatchExit ( Loop L)
static

◆ InsertNewValueIntoMap()

static void InsertNewValueIntoMap ( ValueToValueMapTy VM,
Value K,
Value V 
)
static

Insert (K, V) pair into the ValueToValueMap, and verify the key did not previously exist in the map, and the value was inserted.

Definition at line 92 of file LoopRotationUtils.cpp.

References assert(), and llvm::ValueMap< KeyT, ValueT, Config >::insert().

◆ profitableToRotateLoopExitingLatch()

static bool profitableToRotateLoopExitingLatch ( Loop L)
static

◆ RewriteUsesOfClonedInstructions()

static void RewriteUsesOfClonedInstructions ( BasicBlock OrigHeader,
BasicBlock OrigPreheader,
ValueToValueMapTy ValueMap,
ScalarEvolution SE,
SmallVectorImpl< PHINode * > *  InsertedPHIs 
)
static

RewriteUsesOfClonedInstructions - We just cloned the instructions from the old header into the preheader.

If there were uses of the values produced by these instruction that were outside of the loop, we have to insert PHI nodes to merge the two values. Do this now.

Definition at line 101 of file LoopRotationUtils.cpp.

References llvm::BasicBlock::begin(), E, llvm::BasicBlock::end(), llvm::findDbgValues(), llvm::ScalarEvolution::forgetValue(), llvm::UndefValue::get(), llvm::BasicBlock::getMarker(), llvm::Value::getName(), llvm::DPMarker::getParent(), llvm::Instruction::getParent(), llvm::Value::getType(), I, llvm::ValueMap< KeyT, ValueT, Config >::lookup(), llvm::make_early_inc_range(), SSA, llvm::Value::use_empty(), and llvm::Value::uses().

◆ shouldSpeculateInstrs()

static bool shouldSpeculateInstrs ( BasicBlock::iterator  Begin,
BasicBlock::iterator  End,
Loop L 
)
static

Determine whether the instructions in this range may be safely and cheaply speculated.

This is not an important enough situation to develop complex heuristics. We handle a single arithmetic instruction along with any type conversions.

Definition at line 929 of file LoopRotationUtils.cpp.

References End, I, llvm::isSafeToSpeculativelyExecute(), and llvm::Value::users().

◆ STATISTIC() [1/4]

STATISTIC ( NumInstrsDuplicated  ,
"Number of instructions cloned into loop preheader"   
)

◆ STATISTIC() [2/4]

STATISTIC ( NumInstrsHoisted  ,
"Number of instructions hoisted into loop preheader"   
)

◆ STATISTIC() [3/4]

STATISTIC ( NumNotRotatedDueToHeaderSize  ,
"Number of loops not rotated due to the header size"   
)

◆ STATISTIC() [4/4]

STATISTIC ( NumRotated  ,
"Number of loops rotated"   
)

◆ updateBranchWeights()

static void updateBranchWeights ( BranchInst PreHeaderBI,
BranchInst LoopBI,
bool  HasConditionalPreHeader,
bool  SuccsSwapped 
)
static

Variable Documentation

◆ MultiRotate

cl::opt< bool > MultiRotate("loop-rotate-multi", cl::init(false), cl::Hidden, cl::desc("Allow loop rotation multiple times in order to reach " "a better latch exit")) ( "loop-rotate-multi"  ,
cl::init(false)  ,
cl::Hidden  ,
cl::desc("Allow loop rotation multiple times in order to reach " "a better latch exit")   
)
static

◆ ZeroTripCountWeights

constexpr uint32_t ZeroTripCountWeights[] = {1, 127}
staticconstexpr

Definition at line 56 of file LoopRotationUtils.cpp.

Referenced by updateBranchWeights().