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[TargetLowering] Fix the problem of emulated-TLS implementation witho… (#101490)

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For a __thread variable x, when emulated TLS is enabled and there is an
access to x, the compiler first looks up the symbol __emutls_v.x within
the module. However, the issue arises with an alias y of x, the compiler
still tries to look up __emutls_v.y instead of __emutls_v.x. As a
result, the lookup returns a nullptr, causing the compiler to crash. The
purpose of this MR (Merge Request) is to ensure that in emulated TLS,
before checking __emutls_v.y, the compiler first identifies which global
value y is an alias of.
This commit is contained in:
cceerczw 2024-08-08 01:56:48 +08:00 committed by GitHub
parent 64510c1411
commit 6f8e8faa12
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2 changed files with 23 additions and 3 deletions
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9
llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
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@ -10245,10 +10245,13 @@ SDValue TargetLowering::LowerToTLSEmulatedModel(const GlobalAddressSDNode *GA,
ArgListTy Args;
ArgListEntry Entry;
std::string NameString = ("__emutls_v." + GA->getGlobal()->getName()).str();
Module *VariableModule = const_cast<Module*>(GA->getGlobal()->getParent());
const GlobalValue *GV =
cast<GlobalValue>(GA->getGlobal()->stripPointerCastsAndAliases());
SmallString<32> NameString("__emutls_v.");
NameString += GV->getName();
StringRef EmuTlsVarName(NameString);
GlobalVariable *EmuTlsVar = VariableModule->getNamedGlobal(EmuTlsVarName);
const GlobalVariable *EmuTlsVar =
GV->getParent()->getNamedGlobal(EmuTlsVarName);
assert(EmuTlsVar && "Cannot find EmuTlsVar ");
Entry.Node = DAG.getGlobalAddress(EmuTlsVar, dl, PtrVT);
Entry.Ty = VoidPtrType;

17
llvm/test/CodeGen/AArch64/emutls_alias.ll Normal file
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@ -0,0 +1,17 @@
; RUN: llc < %s -emulated-tls -mtriple=aarch64-linux-ohos \
; RUN: | FileCheck -check-prefix=EMUTLS_CHECK %s
%struct.__res_state = type { [5 x i8] }
@foo = dso_local thread_local global %struct.__res_state { [5 x i8] c"\01\02\03\04\05" }, align 1
@bar = hidden thread_local(initialexec) alias %struct.__res_state, ptr @foo
define dso_local i32 @main() {
%1 = alloca i32, align 4
store i32 0, ptr %1, align 4
store i8 0, ptr @bar, align 1
; EMUTLS_CHECK: adrp x0, __emutls_v.foo
; EMUTLS_CHECK-NEXT: add x0, x0, :lo12:__emutls_v.foo
ret i32 0
}