WholeProgramDevirt.cpp File Reference

#include "llvm/Transforms/IPO/WholeProgramDevirt.h"
#include "IPOOptions.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/Analysis/ModuleSummaryAnalysis.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Analysis/TypeMetadataUtils.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/ModuleSummaryIndexYAML.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/DebugCounter.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/GlobPattern.h"
#include "llvm/Support/TimeProfiler.h"
#include "llvm/TargetParser/Triple.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/FunctionAttrs.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/CallPromotionUtils.h"
#include "llvm/Transforms/Utils/Evaluator.h"
#include <algorithm>
#include <cmath>
#include <cstddef>
#include <map>
#include <set>
#include <string>

Go to the source code of this file.

Classes
struct	llvm::DenseMapInfo< VTableSlot >
struct	llvm::DenseMapInfo< VTableSlotSummary >

Namespaces
namespace	llvm
	This is an optimization pass for GlobalISel generic memory operations.

Macros
#define	DEBUG_TYPE   "wholeprogramdevirt"

Functions
	STATISTIC (NumDevirtTargets, "Number of whole program devirtualization targets")
	STATISTIC (NumSingleImpl, "Number of single implementation devirtualizations")
	STATISTIC (NumBranchFunnel, "Number of branch funnels")
	STATISTIC (NumUniformRetVal, "Number of uniform return value optimizations")
	STATISTIC (NumUniqueRetVal, "Number of unique return value optimizations")
	STATISTIC (NumVirtConstProp1Bit, "Number of 1 bit virtual constant propagations")
	STATISTIC (NumVirtConstProp, "Number of virtual constant propagations")
	DEBUG_COUNTER (CallsToDevirt, "calls-to-devirt", "Controls how many calls should be devirtualized.")
static bool	mustBeUnreachableFunction (ValueInfo TheFnVI)
static bool	typeIDVisibleToRegularObj (StringRef TypeID, function_ref< bool(StringRef)> IsVisibleToRegularObj)
static bool	skipUpdateDueToValidation (GlobalVariable &GV, function_ref< bool(StringRef)> IsVisibleToRegularObj)
static Error	checkCombinedSummaryForTesting (const IPOOptions &Opts, ModuleSummaryIndex *Summary)
static bool	addCalls (VTableSlotInfo &SlotInfo, const ValueInfo &Callee)
static void	findAssumesThroughMergesForTypeTest (SmallVectorImpl< CallInst * > &Assumes, CallInst &TypeTest, SmallPtrSetImpl< Value * > &VisitedMerges)
	Find assumes whose conditions depend on this type test through phi or select nodes.

Variables
static cl::opt< bool >	llvm::PrintSummaryDevirt ("wholeprogramdevirt-print-index-based", cl::Hidden, cl::desc("Print index-based devirtualization messages"))
static cl::opt< bool >	llvm::WholeProgramVisibility ("whole-program-visibility", cl::Hidden, cl::desc("Enable whole program visibility"))
	Provide a way to force enable whole program visibility in tests.
static cl::opt< bool >	llvm::DisableWholeProgramVisibility ("disable-whole-program-visibility", cl::Hidden, cl::desc("Disable whole program visibility (overrides enabling options)"))
	Provide a way to force disable whole program for debugging or workarounds, when enabled via the linker.
static cl::list< std::string >	llvm::SkipFunctionNames ("wholeprogramdevirt-skip", cl::desc("Prevent function(s) from being devirtualized"), cl::Hidden, cl::CommaSeparated)
	Provide way to prevent certain function from being devirtualized.
static cl::opt< bool >	WholeProgramDevirtKeepUnreachableFunction ("wholeprogramdevirt-keep-unreachable-function", cl::desc("Regard unreachable functions as possible devirtualize targets."), cl::Hidden, cl::init(true))
	With Clang, a pure virtual class's deleting destructor is emitted as a llvm.trap intrinsic followed by an unreachable IR instruction.

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "wholeprogramdevirt"

Definition at line 126 of file WholeProgramDevirt.cpp.

Function Documentation

addCalls()

bool addCalls ( VTableSlotInfo & SlotInfo, const ValueInfo & Callee )

static

Definition at line 1270 of file WholeProgramDevirt.cpp.

References llvm::CalleeInfo::Hot, and P.

checkCombinedSummaryForTesting()

Error checkCombinedSummaryForTesting ( const IPOOptions & Opts, ModuleSummaryIndex * Summary )

static

Definition at line 954 of file WholeProgramDevirt.cpp.

References llvm::createStringError(), llvm::ModuleSummaryIndex::getRegularLTOModuleName(), llvm::Import, and llvm::invalid_argument.

DEBUG_COUNTER()

DEBUG_COUNTER	(	CallsToDevirt	,
		"calls-to-devirt"	,
		"Controls how many calls should be devirtualized."	)

findAssumesThroughMergesForTypeTest()

void findAssumesThroughMergesForTypeTest ( SmallVectorImpl< CallInst * > & Assumes, CallInst & TypeTest, SmallPtrSetImpl< Value * > & VisitedMerges )

static

Find assumes whose conditions depend on this type test through phi or select nodes.

SimplifyCFG can produce these patterns by merging type test + assume sequences from different predecessors.

Definition at line 2052 of file WholeProgramDevirt.cpp.

References assert(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), llvm::SmallPtrSetImpl< PtrType >::contains(), llvm::dyn_cast(), llvm::SmallVectorTemplateCommon< T, typename >::empty(), llvm::SmallVectorTemplateCommon< T, typename >::end(), llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::isa(), Merge, llvm::SmallVectorImpl< T >::pop_back_val(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), Select, llvm::Instruction::users(), and V.

mustBeUnreachableFunction()

bool mustBeUnreachableFunction ( ValueInfo TheFnVI )

static

Definition at line 364 of file WholeProgramDevirt.cpp.

References llvm::dyn_cast(), llvm::ValueInfo::getSummaryList(), and WholeProgramDevirtKeepUnreachableFunction.

skipUpdateDueToValidation()

bool skipUpdateDueToValidation ( GlobalVariable & GV, function_ref< bool(StringRef)> IsVisibleToRegularObj )

static

Definition at line 800 of file WholeProgramDevirt.cpp.

References llvm::dyn_cast(), llvm::GlobalObject::getMetadata(), and typeIDVisibleToRegularObj().

Referenced by llvm::updateVCallVisibilityInModule().

STATISTIC() [1/7]

STATISTIC	(	NumBranchFunnel	,
		"Number of branch funnels"	)

STATISTIC() [2/7]

STATISTIC	(	NumDevirtTargets	,
		"Number of whole program devirtualization targets"	)

STATISTIC() [3/7]

STATISTIC	(	NumSingleImpl	,
		"Number of single implementation devirtualizations"	)

STATISTIC() [4/7]

STATISTIC	(	NumUniformRetVal	,
		"Number of uniform return value optimizations"	)

STATISTIC() [5/7]

STATISTIC	(	NumUniqueRetVal	,
		"Number of unique return value optimizations"	)

STATISTIC() [6/7]

STATISTIC	(	NumVirtConstProp	,
		"Number of virtual constant propagations"	)

STATISTIC() [7/7]

STATISTIC	(	NumVirtConstProp1Bit	,
		"Number of 1 bit virtual constant propagations"	)

typeIDVisibleToRegularObj()

bool typeIDVisibleToRegularObj ( StringRef TypeID, function_ref< bool(StringRef)> IsVisibleToRegularObj )

static

Definition at line 776 of file WholeProgramDevirt.cpp.

Referenced by llvm::getVisibleToRegularObjVtableGUIDs(), and skipUpdateDueToValidation().

Variable Documentation

WholeProgramDevirtKeepUnreachableFunction

cl::opt< bool > WholeProgramDevirtKeepUnreachableFunction("wholeprogramdevirt-keep-unreachable-function", cl::desc("Regard unreachable functions as possible devirtualize targets."), cl::Hidden, cl::init(true)) ( "wholeprogramdevirt-keep-unreachable-function" , cl::desc("Regard unreachable functions as possible devirtualize targets.") , cl::Hidden , cl::init(true)  )

static

With Clang, a pure virtual class's deleting destructor is emitted as a llvm.trap intrinsic followed by an unreachable IR instruction.

In the context of whole program devirtualization, the deleting destructor of a pure virtual class won't be invoked by the source code so safe to skip as a devirtualize target.

However, not all unreachable functions are safe to skip. In some cases, the program intends to run such functions and terminate, for instance, a unit test may run a death test. A non-test program might (or allowed to) invoke such functions to report failures (whether/when it's a good practice or not is a different topic).

This option is enabled to keep an unreachable function as a possible devirtualize target to conservatively keep the program behavior.

TODO: Make a pure virtual class's deleting destructor precisely identifiable in Clang's codegen for more devirtualization in LLVM.

Referenced by mustBeUnreachableFunction().