LLVM 17.0.0git
Classes | Macros | Functions | Variables
BasicAliasAnalysis.cpp File Reference
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/SaveAndRestore.h"
#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <optional>
#include <utility>
Include dependency graph for BasicAliasAnalysis.cpp:

Go to the source code of this file.

Classes

struct  llvm::BasicAAResult::DecomposedGEP
 

Macros

#define DEBUG_TYPE   "basicaa"
 

Functions

 STATISTIC (SearchLimitReached, "Number of times the limit to " "decompose GEPs is reached")
 SearchLimitReached / SearchTimes shows how often the limit of to decompose GEPs is reached.
 
 STATISTIC (SearchTimes, "Number of times a GEP is decomposed")
 
static uint64_t getObjectSize (const Value *V, const DataLayout &DL, const TargetLibraryInfo &TLI, bool NullIsValidLoc, bool RoundToAlign=false)
 Returns the size of the object specified by V or UnknownSize if unknown.
 
static bool isObjectSmallerThan (const Value *V, uint64_t Size, const DataLayout &DL, const TargetLibraryInfo &TLI, bool NullIsValidLoc)
 Returns true if we can prove that the object specified by V is smaller than Size.
 
static uint64_t getMinimalExtentFrom (const Value &V, const LocationSize &LocSize, const DataLayout &DL, bool NullIsValidLoc)
 Return the minimal extent from V to the end of the underlying object, assuming the result is used in an aliasing query.
 
static bool isObjectSize (const Value *V, uint64_t Size, const DataLayout &DL, const TargetLibraryInfo &TLI, bool NullIsValidLoc)
 Returns true if we can prove that the object specified by V has size Size.
 
static LinearExpression GetLinearExpression (const CastedValue &Val, const DataLayout &DL, unsigned Depth, AssumptionCache *AC, DominatorTree *DT)
 Analyzes the specified value as a linear expression: "A*V + B", where A and B are constant integers.
 
static APInt adjustToIndexSize (const APInt &Offset, unsigned IndexSize)
 To ensure a pointer offset fits in an integer of size IndexSize (in bits) when that size is smaller than the maximum index size.
 
static bool isIntrinsicCall (const CallBase *Call, Intrinsic::ID IID)
 
static const FunctiongetParent (const Value *V)
 
static bool notDifferentParent (const Value *O1, const Value *O2)
 
static bool isBaseOfObject (const Value *V)
 Return true if we know V to the base address of the corresponding memory object.
 
static AliasResult MergeAliasResults (AliasResult A, AliasResult B)
 
 INITIALIZE_PASS_BEGIN (BasicAAWrapperPass, "basic-aa", "Basic Alias Analysis (stateless AA impl)", true, true) INITIALIZE_PASS_END(BasicAAWrapperPass
 
basic Basic Alias Analysis (stateless AA impl)"
 

Variables

static cl::opt< boolEnableRecPhiAnalysis ("basic-aa-recphi", cl::Hidden, cl::init(true))
 Enable analysis of recursive PHI nodes.
 
static cl::opt< boolEnableSeparateStorageAnalysis ("basic-aa-separate-storage", cl::Hidden, cl::init(false))
 
static const unsigned MaxLookupSearchDepth = 6
 
basic aa
 
basic Basic Alias true
 

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE   "basicaa"

Definition at line 63 of file BasicAliasAnalysis.cpp.

Function Documentation

◆ adjustToIndexSize()

static APInt adjustToIndexSize ( const APInt Offset,
unsigned  IndexSize 
)
static

To ensure a pointer offset fits in an integer of size IndexSize (in bits) when that size is smaller than the maximum index size.

This is an issue, for example, in particular for 32b pointers with negative indices that rely on two's complement wrap-arounds for precise alias information where the maximum index size is 64b.

Definition at line 445 of file BasicAliasAnalysis.cpp.

References assert(), and llvm::Offset.

◆ Analysis()

basic Basic Alias Analysis ( stateless AA  impl)

◆ GetLinearExpression()

static LinearExpression GetLinearExpression ( const CastedValue &  Val,
const DataLayout DL,
unsigned  Depth,
AssumptionCache AC,
DominatorTree DT 
)
static

Analyzes the specified value as a linear expression: "A*V + B", where A and B are constant integers.

Definition at line 345 of file BasicAliasAnalysis.cpp.

References llvm::Depth, DL, E, GetLinearExpression(), llvm::MaskedValueIsZero(), and RHS.

Referenced by GetLinearExpression().

◆ getMinimalExtentFrom()

static uint64_t getMinimalExtentFrom ( const Value V,
const LocationSize LocSize,
const DataLayout DL,
bool  NullIsValidLoc 
)
static

Return the minimal extent from V to the end of the underlying object, assuming the result is used in an aliasing query.

E.g., we do use the query location size and the fact that null pointers cannot alias here.

Definition at line 163 of file BasicAliasAnalysis.cpp.

References DL, llvm::Value::getPointerDereferenceableBytes(), llvm::LocationSize::getValue(), and llvm::LocationSize::isPrecise().

◆ getObjectSize()

static uint64_t getObjectSize ( const Value V,
const DataLayout DL,
const TargetLibraryInfo TLI,
bool  NullIsValidLoc,
bool  RoundToAlign = false 
)
static

Returns the size of the object specified by V or UnknownSize if unknown.

Definition at line 104 of file BasicAliasAnalysis.cpp.

References DL, llvm::getObjectSize(), llvm::ObjectSizeOpts::NullIsUnknownSize, llvm::ObjectSizeOpts::RoundToAlign, Size, and llvm::MemoryLocation::UnknownSize.

◆ getParent()

static const Function * getParent ( const Value V)
static

◆ INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN ( BasicAAWrapperPass  ,
"basic-aa"  ,
"Basic Alias Analysis (stateless AA impl)"  ,
true  ,
true   
)

◆ isBaseOfObject()

static bool isBaseOfObject ( const Value V)
static

Return true if we know V to the base address of the corresponding memory object.

This implies that any address less than V must be out of bounds for the underlying object. Note that just being isIdentifiedObject() is not enough - For example, a negative offset from a noalias argument or call can be inbounds w.r.t the actual underlying object.

Definition at line 1001 of file BasicAliasAnalysis.cpp.

◆ isIntrinsicCall()

static bool isIntrinsicCall ( const CallBase Call,
Intrinsic::ID  IID 
)
static

◆ isObjectSize()

static bool isObjectSize ( const Value V,
uint64_t  Size,
const DataLayout DL,
const TargetLibraryInfo TLI,
bool  NullIsValidLoc 
)
static

Returns true if we can prove that the object specified by V has size Size.

Definition at line 183 of file BasicAliasAnalysis.cpp.

References DL, llvm::getObjectSize(), Size, and llvm::MemoryLocation::UnknownSize.

◆ isObjectSmallerThan()

static bool isObjectSmallerThan ( const Value V,
uint64_t  Size,
const DataLayout DL,
const TargetLibraryInfo TLI,
bool  NullIsValidLoc 
)
static

Returns true if we can prove that the object specified by V is smaller than Size.

Definition at line 119 of file BasicAliasAnalysis.cpp.

References DL, llvm::getObjectSize(), llvm::isIdentifiedObject(), Size, and llvm::MemoryLocation::UnknownSize.

◆ MergeAliasResults()

static AliasResult MergeAliasResults ( AliasResult  A,
AliasResult  B 
)
static

◆ notDifferentParent()

static bool notDifferentParent ( const Value O1,
const Value O2 
)
static

◆ STATISTIC() [1/2]

STATISTIC ( SearchLimitReached  ,
"Number of times the limit to " "decompose GEPs is reached"   
)

SearchLimitReached / SearchTimes shows how often the limit of to decompose GEPs is reached.

It will affect the precision of basic alias analysis.

◆ STATISTIC() [2/2]

STATISTIC ( SearchTimes  ,
"Number of times a GEP is decomposed"   
)

Variable Documentation

◆ aa

basic aa

Definition at line 1803 of file BasicAliasAnalysis.cpp.

◆ EnableRecPhiAnalysis

cl::opt< bool > EnableRecPhiAnalysis("basic-aa-recphi", cl::Hidden, cl::init(true)) ( "basic-aa-recphi"  ,
cl::Hidden  ,
cl::init(true  
)
static

Enable analysis of recursive PHI nodes.

◆ EnableSeparateStorageAnalysis

cl::opt< bool > EnableSeparateStorageAnalysis("basic-aa-separate-storage", cl::Hidden, cl::init(false)) ( "basic-aa-separate-storage"  ,
cl::Hidden  ,
cl::init(false)   
)
static

◆ MaxLookupSearchDepth

const unsigned MaxLookupSearchDepth = 6
static

Definition at line 83 of file BasicAliasAnalysis.cpp.

◆ true

print machine Print Machine Uniformity Info true