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LowerTypeTests: Set small code model on imported globals. #141324

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merged 4 commits into from
May 27, 2025
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LowerTypeTests: Set small code model on imported globals. #141324

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d069e16
[𝘀𝗽𝗿] changes to main this commit is based on
pcc May 24, 2025
59b2602
[𝘀𝗽𝗿] initial version
pcc May 24, 2025
3be3252
[𝘀𝗽𝗿] changes introduced through rebase
pcc May 27, 2025
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7 changes: 3 additions & 4 deletions llvm/include/llvm/IR/Module.h
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Expand Up @@ -471,15 +471,14 @@ class LLVM_ABI Module {

/// Look up the specified global in the module symbol table.
/// If it does not exist, invoke a callback to create a declaration of the
/// global and return it. The global is constantexpr casted to the expected
/// type if necessary.
Constant *
/// global and return it.
GlobalVariable *
getOrInsertGlobal(StringRef Name, Type *Ty,
function_ref<GlobalVariable *()> CreateGlobalCallback);

/// Look up the specified global in the module symbol table. If required, this
/// overload constructs the global variable using its constructor's defaults.
Constant *getOrInsertGlobal(StringRef Name, Type *Ty);
GlobalVariable *getOrInsertGlobal(StringRef Name, Type *Ty);

/// @}
/// @name Global Alias Accessors
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6 changes: 2 additions & 4 deletions llvm/lib/CodeGen/LowerEmuTLS.cpp
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Expand Up @@ -140,8 +140,7 @@ bool addEmuTlsVar(Module &M, const GlobalVariable *GV) {
PointerType *InitPtrType = PointerType::getUnqual(C);
Type *ElementTypes[4] = {WordType, WordType, VoidPtrType, InitPtrType};
StructType *EmuTlsVarType = StructType::create(ElementTypes);
EmuTlsVar = cast<GlobalVariable>(
M.getOrInsertGlobal(EmuTlsVarName, EmuTlsVarType));
EmuTlsVar = M.getOrInsertGlobal(EmuTlsVarName, EmuTlsVarType);
copyLinkageVisibility(M, GV, EmuTlsVar);

// Define "__emutls_t.*" and "__emutls_v.*" only if GV is defined.
Expand All @@ -155,8 +154,7 @@ bool addEmuTlsVar(Module &M, const GlobalVariable *GV) {
GlobalVariable *EmuTlsTmplVar = nullptr;
if (InitValue) {
std::string EmuTlsTmplName = ("__emutls_t." + GV->getName()).str();
EmuTlsTmplVar = dyn_cast_or_null<GlobalVariable>(
M.getOrInsertGlobal(EmuTlsTmplName, GVType));
EmuTlsTmplVar = M.getOrInsertGlobal(EmuTlsTmplName, GVType);
assert(EmuTlsTmplVar && "Failed to create emualted TLS initializer");
EmuTlsTmplVar->setConstant(true);
EmuTlsTmplVar->setInitializer(const_cast<Constant*>(InitValue));
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7 changes: 3 additions & 4 deletions llvm/lib/CodeGen/TargetLoweringBase.cpp
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Expand Up @@ -1975,10 +1975,9 @@ Value *TargetLoweringBase::getIRStackGuard(IRBuilderBase &IRB) const {
if (getTargetMachine().getTargetTriple().isOSOpenBSD()) {
Module &M = *IRB.GetInsertBlock()->getParent()->getParent();
PointerType *PtrTy = PointerType::getUnqual(M.getContext());
Constant *C = M.getOrInsertGlobal("__guard_local", PtrTy);
if (GlobalVariable *G = dyn_cast_or_null<GlobalVariable>(C))
G->setVisibility(GlobalValue::HiddenVisibility);
return C;
GlobalVariable *G = M.getOrInsertGlobal("__guard_local", PtrTy);
G->setVisibility(GlobalValue::HiddenVisibility);
return G;
}
return nullptr;
}
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3 changes: 1 addition & 2 deletions llvm/lib/CodeGen/WasmEHPrepare.cpp
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Expand Up @@ -247,8 +247,7 @@ bool WasmEHPrepareImpl::prepareEHPads(Function &F) {
// we depend on CoalesceFeaturesAndStripAtomics to downgrade it to
// non-thread-local ones, in which case we don't allow this object to be
// linked with other objects using shared memory.
LPadContextGV = cast<GlobalVariable>(
M.getOrInsertGlobal("__wasm_lpad_context", LPadContextTy));
LPadContextGV = M.getOrInsertGlobal("__wasm_lpad_context", LPadContextTy);
LPadContextGV->setThreadLocalMode(GlobalValue::GeneralDynamicTLSModel);

LPadIndexField = LPadContextGV;
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11 changes: 4 additions & 7 deletions llvm/lib/IR/Module.cpp
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Expand Up @@ -250,12 +250,9 @@ GlobalVariable *Module::getGlobalVariable(StringRef Name,
}

/// getOrInsertGlobal - Look up the specified global in the module symbol table.
/// 1. If it does not exist, add a declaration of the global and return it.
/// 2. Else, the global exists but has the wrong type: return the function
/// with a constantexpr cast to the right type.
/// 3. Finally, if the existing global is the correct declaration, return the
/// existing global.
Constant *Module::getOrInsertGlobal(
/// If it does not exist, add a declaration of the global and return it.
/// Otherwise, return the existing global.
GlobalVariable *Module::getOrInsertGlobal(
StringRef Name, Type *Ty,
function_ref<GlobalVariable *()> CreateGlobalCallback) {
// See if we have a definition for the specified global already.
Expand All @@ -269,7 +266,7 @@ Constant *Module::getOrInsertGlobal(
}

// Overload to construct a global variable using its constructor's defaults.
Constant *Module::getOrInsertGlobal(StringRef Name, Type *Ty) {
GlobalVariable *Module::getOrInsertGlobal(StringRef Name, Type *Ty) {
return getOrInsertGlobal(Name, Ty, [&] {
return new GlobalVariable(*this, Ty, false, GlobalVariable::ExternalLinkage,
nullptr, Name);
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19 changes: 12 additions & 7 deletions llvm/lib/Transforms/IPO/LowerTypeTests.cpp
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Expand Up @@ -983,11 +983,10 @@ LowerTypeTestsModule::importTypeId(StringRef TypeId) {
auto ImportGlobal = [&](StringRef Name) {
// Give the global a type of length 0 so that it is not assumed not to alias
// with any other global.
Constant *C = M.getOrInsertGlobal(("__typeid_" + TypeId + "_" + Name).str(),
Int8Arr0Ty);
if (auto *GV = dyn_cast<GlobalVariable>(C))
GV->setVisibility(GlobalValue::HiddenVisibility);
return C;
GlobalVariable *GV = M.getOrInsertGlobal(
("__typeid_" + TypeId + "_" + Name).str(), Int8Arr0Ty);
GV->setVisibility(GlobalValue::HiddenVisibility);
return GV;
};

auto ImportConstant = [&](StringRef Name, uint64_t Const, unsigned AbsWidth,
Expand Down Expand Up @@ -1020,8 +1019,14 @@ LowerTypeTestsModule::importTypeId(StringRef TypeId) {
return C;
};

if (TIL.TheKind != TypeTestResolution::Unsat)
TIL.OffsetedGlobal = ImportGlobal("global_addr");
if (TIL.TheKind != TypeTestResolution::Unsat) {
auto *GV = ImportGlobal("global_addr");
// This is either a vtable (in .data.rel.ro) or a jump table (in .text).
// Either way it's expected to be in the low 2 GiB, so set the small code
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preferably there would be some reference why we would expect that

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Added comment with an explanation.

// model.
GV->setCodeModel(CodeModel::Small);
TIL.OffsetedGlobal = GV;
}

if (TIL.TheKind == TypeTestResolution::ByteArray ||
TIL.TheKind == TypeTestResolution::Inline ||
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8 changes: 3 additions & 5 deletions llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
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Expand Up @@ -1689,12 +1689,10 @@ void DevirtModule::exportConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,

Constant *DevirtModule::importGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
StringRef Name) {
Constant *C =
GlobalVariable *GV =
M.getOrInsertGlobal(getGlobalName(Slot, Args, Name), Int8Arr0Ty);
auto *GV = dyn_cast<GlobalVariable>(C);
if (GV)
GV->setVisibility(GlobalValue::HiddenVisibility);
return C;
GV->setVisibility(GlobalValue::HiddenVisibility);
return GV;
}

Constant *DevirtModule::importConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
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10 changes: 4 additions & 6 deletions llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
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Expand Up @@ -1506,12 +1506,10 @@ bool DataFlowSanitizer::runImpl(

auto GetOrInsertGlobal = [this, &Changed](StringRef Name,
Type *Ty) -> Constant * {
Constant *C = Mod->getOrInsertGlobal(Name, Ty);
if (GlobalVariable *G = dyn_cast<GlobalVariable>(C)) {
Changed |= G->getThreadLocalMode() != GlobalVariable::InitialExecTLSModel;
G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel);
}
return C;
GlobalVariable *G = Mod->getOrInsertGlobal(Name, Ty);
Changed |= G->getThreadLocalMode() != GlobalVariable::InitialExecTLSModel;
G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel);
return G;
};

// These globals must be kept in sync with the ones in dfsan.cpp.
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3 changes: 1 addition & 2 deletions llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
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Expand Up @@ -692,15 +692,14 @@ void HWAddressSanitizer::initializeModule() {
}

if (!TargetTriple.isAndroid()) {
Constant *C = M.getOrInsertGlobal("__hwasan_tls", IntptrTy, [&] {
ThreadPtrGlobal = M.getOrInsertGlobal("__hwasan_tls", IntptrTy, [&] {
auto *GV = new GlobalVariable(M, IntptrTy, /*isConstant=*/false,
GlobalValue::ExternalLinkage, nullptr,
"__hwasan_tls", nullptr,
GlobalVariable::InitialExecTLSModel);
appendToCompilerUsed(M, GV);
return GV;
});
ThreadPtrGlobal = cast<GlobalVariable>(C);
}
}

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4 changes: 2 additions & 2 deletions llvm/lib/Transforms/Instrumentation/NumericalStabilitySanitizer.cpp
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Expand Up @@ -642,11 +642,11 @@ NumericalStabilitySanitizerPass::run(Module &M, ModuleAnalysisManager &MAM) {
}

static GlobalValue *createThreadLocalGV(const char *Name, Module &M, Type *Ty) {
return dyn_cast<GlobalValue>(M.getOrInsertGlobal(Name, Ty, [&M, Ty, Name] {
return M.getOrInsertGlobal(Name, Ty, [&M, Ty, Name] {
return new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
nullptr, Name, nullptr,
GlobalVariable::InitialExecTLSModel);
}));
});
}

NumericalStabilitySanitizer::NumericalStabilitySanitizer(Module &M)
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6 changes: 2 additions & 4 deletions llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
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Expand Up @@ -486,10 +486,8 @@ bool ModuleSanitizerCoverage::instrumentModule() {
SanCovTraceSwitchFunction =
M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, PtrTy);

Constant *SanCovLowestStackConstant =
M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
if (!SanCovLowestStack || SanCovLowestStack->getValueType() != IntptrTy) {
SanCovLowestStack = M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
if (SanCovLowestStack->getValueType() != IntptrTy) {
C->emitError(StringRef("'") + SanCovLowestStackName +
"' should not be declared by the user");
return true;
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14 changes: 7 additions & 7 deletions llvm/test/Transforms/LowerTypeTests/import.ll
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Expand Up @@ -6,29 +6,29 @@ target datalayout = "e-p:64:64"

declare i1 @llvm.type.test(ptr %ptr, metadata %bitset) nounwind readnone

; CHECK-DAG: @__typeid_single_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_inline6_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_single_global_addr = external hidden global [0 x i8], code_model "small"
; CHECK-DAG: @__typeid_inline6_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_inline6_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_inline6_size_m1 = external hidden global [0 x i8], !absolute_symbol !1
; X86-DAG: @__typeid_inline6_inline_bits = external hidden global [0 x i8], !absolute_symbol !2
; CHECK-DAG: @__typeid_inline5_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_inline5_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_inline5_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_inline5_size_m1 = external hidden global [0 x i8], !absolute_symbol !3
; X86-DAG: @__typeid_inline5_inline_bits = external hidden global [0 x i8], !absolute_symbol !4
; CHECK-DAG: @__typeid_bytearray32_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_bytearray32_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_bytearray32_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_bytearray32_size_m1 = external hidden global [0 x i8], !absolute_symbol !4
; CHECK-DAG: @__typeid_bytearray32_byte_array = external hidden global [0 x i8]
; X86-DAG: @__typeid_bytearray32_bit_mask = external hidden global [0 x i8], !absolute_symbol !0
; CHECK-DAG: @__typeid_bytearray7_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_bytearray7_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_bytearray7_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_bytearray7_size_m1 = external hidden global [0 x i8], !absolute_symbol !5
; CHECK-DAG: @__typeid_bytearray7_byte_array = external hidden global [0 x i8]
; X86-DAG: @__typeid_bytearray7_bit_mask = external hidden global [0 x i8], !absolute_symbol !0
; CHECK-DAG: @__typeid_allones32_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_allones32_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_allones32_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_allones32_size_m1 = external hidden global [0 x i8], !absolute_symbol !4
; CHECK-DAG: @__typeid_allones7_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_allones7_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_allones7_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_allones7_size_m1 = external hidden global [0 x i8], !absolute_symbol !5

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3 changes: 1 addition & 2 deletions llvm/unittests/Analysis/BasicAliasAnalysisTest.cpp
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Expand Up @@ -81,8 +81,7 @@ TEST_F(BasicAATest, AliasInstWithObjectOfImpreciseSize) {

Value *IncomingI32Ptr = F->arg_begin();

auto *GlobalPtr =
cast<GlobalVariable>(M.getOrInsertGlobal("some_global", B.getInt8Ty()));
auto *GlobalPtr = M.getOrInsertGlobal("some_global", B.getInt8Ty());

// Without sufficiently restricted linkage/an init, some of the object size
// checking bits get more conservative.
Expand Down
4 changes: 2 additions & 2 deletions llvm/unittests/IR/ConstantsTest.cpp
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Expand Up @@ -774,12 +774,12 @@ TEST(ConstantsTest, ComdatUserTracking) {
EXPECT_TRUE(Users.size() == 0);

Type *Ty = Type::getInt8Ty(Context);
GlobalVariable *GV1 = cast<GlobalVariable>(M.getOrInsertGlobal("gv1", Ty));
GlobalVariable *GV1 = M.getOrInsertGlobal("gv1", Ty);
GV1->setComdat(C);
EXPECT_TRUE(Users.size() == 1);
EXPECT_TRUE(Users.contains(GV1));

GlobalVariable *GV2 = cast<GlobalVariable>(M.getOrInsertGlobal("gv2", Ty));
GlobalVariable *GV2 = M.getOrInsertGlobal("gv2", Ty);
GV2->setComdat(C);
EXPECT_TRUE(Users.size() == 2);
EXPECT_TRUE(Users.contains(GV2));
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