104#define DEBUG_TYPE "global-merge"
109 cl::desc(
"Enable the global merge pass"),
114 cl::desc(
"Set maximum offset for global merge pass"),
123 cl::desc(
"Improve global merge pass to ignore globals only used alone"),
128 cl::desc(
"Enable global merge pass on constants"),
135 cl::desc(
"Enable global merge pass on external linkage"));
141class GlobalMergeImpl {
144 bool IsMachO =
false;
148 bool isConst,
unsigned AddrSpace)
const;
154 unsigned AddrSpace)
const;
160 return MustKeepGlobalVariables.count(GV);
165 void setMustKeepGlobalVariables(
Module &M);
175 :
TM(
TM), Opt(Opt) {}
191 explicit GlobalMerge(
const TargetMachine *TM,
unsigned MaximalOffset,
192 bool OnlyOptimizeForSize,
bool MergeExternalGlobals)
201 GlobalMergeImpl
P(TM, Opt);
217 GlobalMergeImpl
P(
TM, Options);
218 bool Changed =
P.run(M);
227char GlobalMerge::ID = 0;
233 unsigned AddrSpace)
const {
234 auto &
DL = M.getDataLayout();
247 return doMerge(Globals, AllGlobals, M, isConst, AddrSpace);
269 struct UsedGlobalSet {
271 unsigned UsageCount = 1;
273 UsedGlobalSet(
size_t Size) : Globals(
Size) {}
277 std::vector<UsedGlobalSet> UsedGlobalSets;
280 auto CreateGlobalSet = [&]() -> UsedGlobalSet & {
281 UsedGlobalSets.emplace_back(Globals.size());
282 return UsedGlobalSets.
back();
286 CreateGlobalSet().UsageCount = 0;
307 std::vector<size_t> EncounteredUGS;
309 for (
size_t GI = 0, GE = Globals.size(); GI != GE; ++GI) {
314 EncounteredUGS.assign(UsedGlobalSets.size(), 0);
318 size_t CurGVOnlySetIdx = 0;
321 for (
auto &U : GV->
uses()) {
325 if (
ConstantExpr *CE = dyn_cast<ConstantExpr>(
U.getUser())) {
328 UI = &*
CE->use_begin();
330 }
else if (isa<Instruction>(
U.getUser())) {
339 for (; UI != UE; UI = UI->getNext()) {
344 Function *ParentFn =
I->getParent()->getParent();
350 size_t UGSIdx = GlobalUsesByFunction[ParentFn];
356 if (!CurGVOnlySetIdx) {
357 CurGVOnlySetIdx = UsedGlobalSets.size();
358 CreateGlobalSet().Globals.set(GI);
360 ++UsedGlobalSets[CurGVOnlySetIdx].UsageCount;
363 GlobalUsesByFunction[ParentFn] = CurGVOnlySetIdx;
368 if (UsedGlobalSets[UGSIdx].Globals.test(GI)) {
369 ++UsedGlobalSets[UGSIdx].UsageCount;
374 --UsedGlobalSets[UGSIdx].UsageCount;
378 if (
size_t ExpandedIdx = EncounteredUGS[UGSIdx]) {
379 ++UsedGlobalSets[ExpandedIdx].UsageCount;
380 GlobalUsesByFunction[ParentFn] = ExpandedIdx;
386 GlobalUsesByFunction[ParentFn] = EncounteredUGS[UGSIdx] =
387 UsedGlobalSets.size();
389 UsedGlobalSet &NewUGS = CreateGlobalSet();
390 NewUGS.Globals.set(GI);
391 NewUGS.Globals |= UsedGlobalSets[UGSIdx].Globals;
403 [](
const UsedGlobalSet &UGS1,
const UsedGlobalSet &UGS2) {
404 return UGS1.Globals.count() * UGS1.UsageCount <
405 UGS2.Globals.count() * UGS2.UsageCount;
413 for (
const UsedGlobalSet &UGS :
llvm::reverse(UsedGlobalSets)) {
414 if (UGS.UsageCount == 0)
416 if (UGS.Globals.count() > 1)
417 AllGlobals |= UGS.Globals;
419 return doMerge(Globals, AllGlobals, M, isConst, AddrSpace);
429 bool Changed =
false;
431 for (
const UsedGlobalSet &UGS :
llvm::reverse(UsedGlobalSets)) {
432 if (UGS.UsageCount == 0)
434 if (PickedGlobals.anyCommon(UGS.Globals))
436 PickedGlobals |= UGS.Globals;
440 if (UGS.Globals.count() < 2)
442 Changed |= doMerge(Globals, UGS.Globals, M, isConst, AddrSpace);
450 bool isConst,
unsigned AddrSpace)
const {
455 auto &
DL =
M.getDataLayout();
460 bool Changed =
false;
465 std::vector<Type*> Tys;
466 std::vector<Constant*> Inits;
467 std::vector<unsigned> StructIdxs;
469 bool HasExternal =
false;
474 Type *Ty = Globals[
j]->getValueType();
477 Align Alignment =
DL.getPreferredAlign(Globals[j]);
480 MergedSize +=
DL.getTypeAllocSize(Ty);
490 Inits.push_back(Globals[j]->getInitializer());
491 StructIdxs.push_back(CurIdx++);
493 MaxAlign = std::max(MaxAlign, Alignment);
495 if (Globals[j]->hasExternalLinkage() && !HasExternal) {
497 FirstExternalName = Globals[
j]->getName();
502 if (Tys.size() < 2) {
523 (IsMachO && HasExternal)
524 ?
"_MergedGlobals_" + FirstExternalName
528 M, MergedTy, isConst, MergedLinkage, MergedInit, MergedName,
nullptr,
531 MergedGV->setAlignment(MaxAlign);
532 MergedGV->setSection(Globals[i]->
getSection());
535 for (ssize_t k = i, idx = 0;
k !=
j;
k = GlobalSet.
find_next(k), ++idx) {
540 Globals[
k]->getDLLStorageClass();
544 MergedGV->copyMetadata(Globals[k],
549 ConstantInt::get(
Int32Ty, StructIdxs[idx]),
553 Globals[
k]->replaceAllUsesWith(
GEP);
554 Globals[
k]->eraseFromParent();
588 MustKeepGlobalVariables.insert(
G);
591void GlobalMergeImpl::setMustKeepGlobalVariables(
Module &M) {
604 dyn_cast<GlobalVariable>(
U->stripPointerCasts()))
605 MustKeepGlobalVariables.insert(GV);
606 else if (
const ConstantArray *CA = dyn_cast<ConstantArray>(
U->stripPointerCasts())) {
607 for (
const Use &Elt : CA->operands()) {
609 dyn_cast<GlobalVariable>(Elt->stripPointerCasts()))
610 MustKeepGlobalVariables.insert(GV);
618bool GlobalMergeImpl::run(
Module &M) {
624 auto &
DL =
M.getDataLayout();
626 Globals, ConstGlobals, BSSGlobals;
627 bool Changed =
false;
628 setMustKeepGlobalVariables(M);
631 dbgs() <<
"Number of GV that must be kept: " <<
632 MustKeepGlobalVariables.size() <<
"\n";
634 dbgs() <<
"Kept: " << *KeptGV <<
"\n";
637 for (
auto &GV :
M.globals()) {
643 if (
TM && !
TM->shouldAssumeDSOLocal(&GV))
651 assert(PT &&
"Global variable is not a pointer!");
661 if (isMustKeepGlobalVariable(&GV))
684 for (
auto &
P : Globals)
685 if (
P.second.size() > 1)
686 Changed |= doMerge(
P.second, M,
false,
P.first.first);
688 for (
auto &
P : BSSGlobals)
689 if (
P.second.size() > 1)
690 Changed |= doMerge(
P.second, M,
false,
P.first.first);
693 for (
auto &
P : ConstGlobals)
694 if (
P.second.size() > 1)
695 Changed |= doMerge(
P.second, M,
true,
P.first.first);
701 bool OnlyOptimizeForSize,
702 bool MergeExternalByDefault) {
705 return new GlobalMerge(
TM,
Offset, OnlyOptimizeForSize, MergeExternal);
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
This file implements the BitVector class.
This file contains the declarations for the subclasses of Constant, which represent the different fla...
Returns the sub type a function will return at a given Idx Should correspond to the result type of an ExtractValue instruction executed with just that one unsigned Idx
This file defines the DenseMap class.
static cl::opt< bool > GlobalMergeIgnoreSingleUse("global-merge-ignore-single-use", cl::Hidden, cl::desc("Improve global merge pass to ignore globals only used alone"), cl::init(true))
static cl::opt< bool > GlobalMergeGroupByUse("global-merge-group-by-use", cl::Hidden, cl::desc("Improve global merge pass to look at uses"), cl::init(true))
static cl::opt< bool > EnableGlobalMergeOnConst("global-merge-on-const", cl::Hidden, cl::desc("Enable global merge pass on constants"), cl::init(false))
static cl::opt< unsigned > GlobalMergeMaxOffset("global-merge-max-offset", cl::Hidden, cl::desc("Set maximum offset for global merge pass"), cl::init(0))
static cl::opt< bool > EnableGlobalMerge("enable-global-merge", cl::Hidden, cl::desc("Enable the global merge pass"), cl::init(true))
static cl::opt< cl::boolOrDefault > EnableGlobalMergeOnExternal("global-merge-on-external", cl::Hidden, cl::desc("Enable global merge pass on external linkage"))
Module.h This file contains the declarations for the Module class.
const char LLVMTargetMachineRef TM
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
static StringRef getName(Value *V)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This file implements a set that has insertion order iteration characteristics.
This file defines the SmallVector class.
This file defines the 'Statistic' class, which is designed to be an easy way to expose various metric...
#define STATISTIC(VARNAME, DESC)
This defines the Use class.
A container for analyses that lazily runs them and caches their results.
Represent the analysis usage information of a pass.
void setPreservesCFG()
This function should be called by the pass, iff they do not:
static ArrayType * get(Type *ElementType, uint64_t NumElements)
This static method is the primary way to construct an ArrayType.
LLVM Basic Block Representation.
int find_first() const
find_first - Returns the index of the first set bit, -1 if none of the bits are set.
bool back() const
Return the last element in the vector.
int find_next(unsigned Prev) const
find_next - Returns the index of the next set bit following the "Prev" bit.
Represents analyses that only rely on functions' control flow.
static ConstantAggregateZero * get(Type *Ty)
ConstantArray - Constant Array Declarations.
A constant value that is initialized with an expression using other constant values.
static Constant * getInBoundsGetElementPtr(Type *Ty, Constant *C, ArrayRef< Constant * > IdxList)
Create an "inbounds" getelementptr.
static Constant * get(StructType *T, ArrayRef< Constant * > V)
This is an important base class in LLVM.
FunctionPass class - This class is used to implement most global optimizations.
virtual bool runOnFunction(Function &F)=0
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass.
bool hasMinSize() const
Optimize this function for minimum size (-Oz).
static GlobalAlias * create(Type *Ty, unsigned AddressSpace, LinkageTypes Linkage, const Twine &Name, Constant *Aliasee, Module *Parent)
If a parent module is specified, the alias is automatically inserted into the end of the specified mo...
PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM)
StringRef getSection() const
Get the custom section of this global if it has one.
bool hasExternalLinkage() const
bool isThreadLocal() const
If the value is "Thread Local", its value isn't shared by the threads.
bool isDeclaration() const
Return true if the primary definition of this global value is outside of the current translation unit...
void setDLLStorageClass(DLLStorageClassTypes C)
DLLStorageClassTypes
Storage classes of global values for PE targets.
bool hasInternalLinkage() const
PointerType * getType() const
Global values are always pointers.
VisibilityTypes
An enumeration for the kinds of visibility of global values.
void setVisibility(VisibilityTypes V)
LinkageTypes
An enumeration for the kinds of linkage for global values.
@ PrivateLinkage
Like Internal, but omit from symbol table.
@ InternalLinkage
Rename collisions when linking (static functions).
@ ExternalLinkage
Externally visible function.
Type * getValueType() const
const Constant * getInitializer() const
getInitializer - Return the initializer for this global variable.
bool hasInitializer() const
Definitions have initializers, declarations don't.
bool hasImplicitSection() const
Check if section name is present.
bool isConstant() const
If the value is a global constant, its value is immutable throughout the runtime execution of the pro...
bool isEHPad() const
Return true if the instruction is a variety of EH-block.
void push_back(MachineInstr *MI)
A Module instance is used to store all the information related to an LLVM module.
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
Pass interface - Implemented by all 'passes'.
virtual void getAnalysisUsage(AnalysisUsage &) const
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
virtual bool doInitialization(Module &)
doInitialization - Virtual method overridden by subclasses to do any necessary initialization before ...
virtual StringRef getPassName() const
getPassName - Return a nice clean name for a pass.
A set of analyses that are preserved following a run of a transformation pass.
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
void preserveSet()
Mark an analysis set as preserved.
A SetVector that performs no allocations if smaller than a certain size.
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
StringRef - Represent a constant reference to a string, i.e.
bool starts_with(StringRef Prefix) const
Check if this string starts with the given Prefix.
Used to lazily calculate structure layout information for a target machine, based on the DataLayout s...
TypeSize getElementOffset(unsigned Idx) const
Class to represent struct types.
static StructType * get(LLVMContext &Context, ArrayRef< Type * > Elements, bool isPacked=false)
This static method is the primary way to create a literal StructType.
static SectionKind getKindForGlobal(const GlobalObject *GO, const TargetMachine &TM)
Classify the specified global variable into a set of target independent categories embodied in Sectio...
Primary interface to the complete machine description for the target machine.
Triple - Helper class for working with autoconf configuration names.
bool isOSBinFormatMachO() const
Tests whether the environment is MachO.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
The instances of the Type class are immutable: once they are created, they are never changed.
static IntegerType * getInt8Ty(LLVMContext &C)
static IntegerType * getInt32Ty(LLVMContext &C)
A Use represents the edge between a Value definition and its users.
Value * getOperand(unsigned i) const
unsigned getNumOperands() const
const Value * stripPointerCasts() const
Strip off pointer casts, all-zero GEPs and address space casts.
iterator_range< use_iterator > uses()
StringRef getName() const
Return a constant reference to the value's name.
unsigned ID
LLVM IR allows to use arbitrary numbers as calling convention identifiers.
@ CE
Windows NT (Windows on ARM)
initializer< Ty > init(const Ty &Val)
PointerTypeMap run(const Module &M)
Compute the PointerTypeMap for the module M.
Linkage
Describes symbol linkage. This can be used to resolve definition clashes.
Expected< const typename ELFT::Shdr * > getSection(typename ELFT::ShdrRange Sections, uint32_t Index)
This is an optimization pass for GlobalISel generic memory operations.
void stable_sort(R &&Range)
void initializeGlobalMergePass(PassRegistry &)
auto reverse(ContainerTy &&C)
Pass * createGlobalMergePass(const TargetMachine *TM, unsigned MaximalOffset, bool OnlyOptimizeForSize=false, bool MergeExternalByDefault=false)
GlobalMerge - This pass merges internal (by default) globals into structs to enable reuse of a base p...
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
uint64_t alignTo(uint64_t Size, Align A)
Returns a multiple of A needed to store Size bytes.
GlobalVariable * collectUsedGlobalVariables(const Module &M, SmallVectorImpl< GlobalValue * > &Vec, bool CompilerUsed)
Given "llvm.used" or "llvm.compiler.used" as a global name, collect the initializer elements of that ...
This struct is a compact representation of a valid (non-zero power of two) alignment.
bool SizeOnly
Whether we should try to optimize for size only.
bool MergeExternal
Whether we should merge global variables that have external linkage.