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Differential D112965 Diff 383907 llvm/lib/Transforms/IPO/GlobalDCE.cpp

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llvm/lib/Transforms/IPO/GlobalDCE.cpp

Show First 20 Lines • Show All 153 Lines • ▼ Show 20 Lines if (Comdat *C = GV.getComdat()) {
for (auto &&CM : make_range(ComdatMembers.equal_range(C))) { for (auto &&CM : make_range(ComdatMembers.equal_range(C))) {
MarkLive(*CM.second, Updates); // Recursion depth is only two because only MarkLive(*CM.second, Updates); // Recursion depth is only two because only
// globals in the same comdat are visited. // globals in the same comdat are visited.
} }
} }
} }
/// Recursively iterate over the (sub-)constants in the vtable and look for /// Recursively iterate over the (sub-)constants in the vtable and look for
/// vptrs, if their offset is within [RangeStart..RangeEnd), add them to VFuncs. /// vptrs, if their offset is within ranges in List, add them to VFuncs.
static void FindVirtualFunctionsInVTable(Module &M, Constant *C, static void FindVirtualFunctionsInVTable(Module &M, Constant *C,
uint64_t RangeStart, uint64_t RangeEnd, GlobalObject::VCallVisibilityList List,
SmallPtrSet<GlobalValue *, 8> *VFuncs, SmallPtrSet<GlobalValue *, 8> *VFuncs,
uint64_t BaseOffset = 0) { uint64_t BaseOffset = 0) {
if (auto *GV = dyn_cast<GlobalValue>(C)) { if (auto *GV = dyn_cast<GlobalValue>(C)) {
if (auto *F = dyn_cast<Function>(GV)) if (auto *F = dyn_cast<Function>(GV))
if (RangeStart <= BaseOffset && BaseOffset < RangeEnd) for (auto Entry : List)
if (Entry.RangeStart <= BaseOffset && BaseOffset < Entry.RangeEnd)
VFuncs->insert(F); VFuncs->insert(F);
// Do not recurse outside of the current global. // Do not recurse outside of the current global.
return; return;
} }
if (auto *S = dyn_cast<ConstantStruct>(C)) { if (auto *S = dyn_cast<ConstantStruct>(C)) {
StructType *STy = dyn_cast<StructType>(S->getType()); StructType *STy = dyn_cast<StructType>(S->getType());
const StructLayout *SL = M.getDataLayout().getStructLayout(STy); const StructLayout *SL = M.getDataLayout().getStructLayout(STy);
for (auto EI : llvm::enumerate(STy->elements())) { for (auto EI : llvm::enumerate(STy->elements())) {
auto Offset = SL->getElementOffset(EI.index()); auto Offset = SL->getElementOffset(EI.index());
unsigned Op = SL->getElementContainingOffset(Offset); unsigned Op = SL->getElementContainingOffset(Offset);
FindVirtualFunctionsInVTable(M, cast<Constant>(S->getOperand(Op)), FindVirtualFunctionsInVTable(M, cast<Constant>(S->getOperand(Op)), List,
RangeStart, RangeEnd, VFuncs, VFuncs, BaseOffset + Offset);
BaseOffset + Offset);
} }
} else if (auto *A = dyn_cast<ConstantArray>(C)) { } else if (auto *A = dyn_cast<ConstantArray>(C)) {
ArrayType *ATy = A->getType(); ArrayType *ATy = A->getType();
auto EltSize = M.getDataLayout().getTypeAllocSize(ATy->getElementType()); auto EltSize = M.getDataLayout().getTypeAllocSize(ATy->getElementType());
for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) { for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
FindVirtualFunctionsInVTable(M, cast<Constant>(A->getOperand(i)), FindVirtualFunctionsInVTable(M, cast<Constant>(A->getOperand(i)), List,
RangeStart, RangeEnd, VFuncs, VFuncs, BaseOffset + EltSize * i);
BaseOffset + EltSize * i);
} }
} else { } else {
for (auto &Op : C->operands()) { for (auto &Op : C->operands()) {
FindVirtualFunctionsInVTable(M, cast<Constant>(Op), RangeStart, RangeEnd, FindVirtualFunctionsInVTable(M, cast<Constant>(Op), List, VFuncs,
VFuncs, BaseOffset); BaseOffset);
} }
} }
} }
void GlobalDCEPass::ScanVTables(Module &M) { void GlobalDCEPass::ScanVTables(Module &M) {
SmallVector<MDNode *, 2> Types; SmallVector<MDNode *, 2> Types;
LLVM_DEBUG(dbgs() << "Building type info -> vtable map\n"); LLVM_DEBUG(dbgs() << "Building type info -> vtable map\n");
Show All 22 Lines for (MDNode *Type : Types) {
TypeIdMap[TypeID].insert(std::make_pair(&GV, Offset)); TypeIdMap[TypeID].insert(std::make_pair(&GV, Offset));
} }
// If the type corresponding to the vtable is private to this translation // If the type corresponding to the vtable is private to this translation
// unit, we know that we can see all virtual functions which might use it, // unit, we know that we can see all virtual functions which might use it,
// so VFE is safe. // so VFE is safe.
if (auto GO = dyn_cast<GlobalObject>(&GV)) { if (auto GO = dyn_cast<GlobalObject>(&GV)) {
GlobalObject::VCallVisibility TypeVis = GO->getVCallVisibility(); GlobalObject::VCallVisibilityList List = GO->getVCallVisibility();
// FIXME: For now, find the maximum visibility from all !vcall_visibility
// attachments, and conservatively treat all ranges with that visibility.
GlobalObject::VCallVisibility TypeVis =
GlobalObject::VCallVisibilityTranslationUnit;
for (auto Entry : List) {
TypeVis = std::min(TypeVis, Entry.Visibility);
}
if (List.empty())
TypeVis = GlobalObject::VCallVisibilityPublic;
if (TypeVis == GlobalObject::VCallVisibilityTranslationUnit || if (TypeVis == GlobalObject::VCallVisibilityTranslationUnit ||
(LTOPostLink && (LTOPostLink &&
TypeVis == GlobalObject::VCallVisibilityLinkageUnit)) { TypeVis == GlobalObject::VCallVisibilityLinkageUnit)) {
LLVM_DEBUG(dbgs() << GV.getName() << " is safe for VFE\n"); LLVM_DEBUG(dbgs() << GV.getName() << " is safe for VFE\n");
// Find and record all the vfunctions that are within the offset range // Find and record all the vfunctions that are within the offset ranges
// specified in the !vcall_visibility attribute. // specified in the !vcall_visibility attributes.
auto Range = GO->getVTableOffsetRange();
SmallPtrSet<GlobalValue *, 8> VFuncs; SmallPtrSet<GlobalValue *, 8> VFuncs;
FindVirtualFunctionsInVTable(M, GV.getInitializer(), std::get<0>(Range), FindVirtualFunctionsInVTable(M, GV.getInitializer(), List, &VFuncs);
std::get<1>(Range), &VFuncs);
VFESafeVTablesAndFns[&GV] = VFuncs; VFESafeVTablesAndFns[&GV] = VFuncs;
} }
} }
} }
} }
void GlobalDCEPass::ScanVTableLoad(Function *Caller, Metadata *TypeId, void GlobalDCEPass::ScanVTableLoad(Function *Caller, Metadata *TypeId,
uint64_t CallOffset) { uint64_t CallOffset) {
▲ Show 20 Lines • Show All 263 Lines • Show Last 20 Lines