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[IR] Allow uses of llvm.global_ctors and llvm.global_dtors #96477

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[IR] Allow uses of llvm.global_ctors and llvm.global_dtors #96477

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2 changes: 0 additions & 2 deletions llvm/lib/IR/Verifier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -850,8 +850,6 @@ void Verifier::visitGlobalVariable(const GlobalVariable &GV) {
GV.getName() == "llvm.global_dtors")) {
Check(!GV.hasInitializer() || GV.hasAppendingLinkage(),
"invalid linkage for intrinsic global variable", &GV);
Check(GV.materialized_use_empty(),
"invalid uses of intrinsic global variable", &GV);

// Don't worry about emitting an error for it not being an array,
// visitGlobalValue will complain on appending non-array.
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14 changes: 10 additions & 4 deletions llvm/lib/Transforms/Utils/ModuleUtils.cpp
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Expand Up @@ -35,15 +35,15 @@ static void appendToGlobalArray(StringRef ArrayName, Module &M, Function *F,
// to the list.
SmallVector<Constant *, 16> CurrentCtors;
StructType *EltTy;
if (GlobalVariable *GVCtor = M.getNamedGlobal(ArrayName)) {
GlobalVariable *GVCtor = M.getNamedGlobal(ArrayName);
if (GVCtor) {
EltTy = cast<StructType>(GVCtor->getValueType()->getArrayElementType());
if (Constant *Init = GVCtor->getInitializer()) {
unsigned n = Init->getNumOperands();
CurrentCtors.reserve(n + 1);
for (unsigned i = 0; i != n; ++i)
CurrentCtors.push_back(cast<Constant>(Init->getOperand(i)));
}
GVCtor->eraseFromParent();
} else {
EltTy = StructType::get(IRB.getInt32Ty(),
PointerType::get(FnTy, F->getAddressSpace()),
Expand All @@ -67,8 +67,14 @@ static void appendToGlobalArray(StringRef ArrayName, Module &M, Function *F,

// Create the new global variable and replace all uses of
// the old global variable with the new one.
(void)new GlobalVariable(M, NewInit->getType(), false,
GlobalValue::AppendingLinkage, NewInit, ArrayName);
auto *NewGVCtor =
new GlobalVariable(M, NewInit->getType(), false,
GlobalValue::AppendingLinkage, NewInit, ArrayName);
if (GVCtor) {
NewGVCtor->takeName(GVCtor);
GVCtor->replaceAllUsesWith(NewGVCtor);
GVCtor->eraseFromParent();
}
}

void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority, Constant *Data) {
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9 changes: 9 additions & 0 deletions llvm/test/CodeGen/Generic/global-ctors-dtors-uses.ll
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@@ -0,0 +1,9 @@
;; Run opt with asan to trigger `appendToGlobalArray` call which should update uses of `llvm.global_ctors`
; RUN: opt -passes=asan -S %s -o - | FileCheck %s
; CHECK: @llvm.global_ctors = appending global [2 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 65535, ptr ptrauth (ptr @foo, i32 0, i64 55764, ptr getelementptr inbounds ([1 x { i32, ptr, ptr }], ptr @llvm.global_ctors, i32 0, i32 0, i32 1)), ptr null }, { i32, ptr, ptr } { i32 1, ptr @asan.module_ctor, ptr @asan.module_ctor }]

@llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 65535, ptr ptrauth (ptr @foo, i32 0, i64 55764, ptr getelementptr inbounds ([1 x { i32, ptr, ptr }], ptr @llvm.global_ctors, i32 0, i32 0, i32 1)), ptr null }]

define void @foo() {
ret void
}
16 changes: 0 additions & 16 deletions llvm/test/Verifier/global-ctors-dtors-uses.ll
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2 changes: 1 addition & 1 deletion llvm/test/tools/llvm-reduce/remove-ifunc-program-addrspace.ll
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Expand Up @@ -16,7 +16,7 @@ define void @existing_ctor() addrspace(1) {
; CHECK-FINAL: [[TABLE:@[0-9]+]] = internal addrspace(2) global [6 x ptr addrspace(1)] poison, align 8

; CHECK-FINAL: @llvm.global_ctors = appending addrspace(2) global [2 x { i32, ptr addrspace(1), ptr }] [{ i32, ptr addrspace(1), ptr } { i32 0, ptr addrspace(1) @existing_ctor, ptr null }, { i32, ptr addrspace(1), ptr } { i32 10, ptr addrspace(1) [[TABLE_CTOR:@[0-9]+]], ptr null }]
@llvm.global_ctors = appending global [1 x { i32, ptr addrspace(1), ptr }] [{ i32, ptr addrspace(1), ptr } { i32 0, ptr addrspace(1) @existing_ctor, ptr null }]
@llvm.global_ctors = appending addrspace(2) global [1 x { i32, ptr addrspace(1), ptr }] [{ i32, ptr addrspace(1), ptr } { i32 0, ptr addrspace(1) @existing_ctor, ptr null }]
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You can't just adjust the test to avoid an assert, you have to fix the assert




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