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[ARM64EC] Add support for function aliases on ARM64EC #132295

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Merged
merged 1 commit into from
Mar 31, 2025
Merged

[ARM64EC] Add support for function aliases on ARM64EC #132295

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37 changes: 29 additions & 8 deletions llvm/lib/Target/AArch64/AArch64Arm64ECCallLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -627,10 +627,10 @@ Function *AArch64Arm64ECCallLowering::buildGuestExitThunk(Function *F) {
Function::Create(Arm64Ty, GlobalValue::WeakODRLinkage, 0, ThunkName, M);
GuestExit->setComdat(M->getOrInsertComdat(ThunkName));
GuestExit->setSection(".wowthk$aa");
GuestExit->setMetadata(
GuestExit->addMetadata(
"arm64ec_unmangled_name",
MDNode::get(M->getContext(),
MDString::get(M->getContext(), F->getName())));
*MDNode::get(M->getContext(),
MDString::get(M->getContext(), F->getName())));
GuestExit->setMetadata(
"arm64ec_ecmangled_name",
MDNode::get(M->getContext(),
Expand Down Expand Up @@ -803,6 +803,23 @@ bool AArch64Arm64ECCallLowering::runOnModule(Module &Mod) {
DispatchFnGlobal =
M->getOrInsertGlobal("__os_arm64x_dispatch_call", DispatchFnPtrType);

// Mangle names of function aliases and add the alias name to
// arm64ec_unmangled_name metadata to ensure a weak anti-dependency symbol is
// emitted for the alias as well. Do this early, before handling
// hybrid_patchable functions, to avoid mangling their aliases.
for (GlobalAlias &A : Mod.aliases()) {
auto F = dyn_cast_or_null<Function>(A.getAliaseeObject());
if (!F)
continue;
if (std::optional<std::string> MangledName =
getArm64ECMangledFunctionName(A.getName().str())) {
F->addMetadata("arm64ec_unmangled_name",
*MDNode::get(M->getContext(),
MDString::get(M->getContext(), A.getName())));
A.setName(MangledName.value());
}
}

DenseMap<GlobalAlias *, GlobalAlias *> FnsMap;
SetVector<GlobalAlias *> PatchableFns;

Expand Down Expand Up @@ -837,20 +854,24 @@ bool AArch64Arm64ECCallLowering::runOnModule(Module &Mod) {
// emitGlobalAlias to emit the right alias.
auto *A =
GlobalAlias::create(GlobalValue::LinkOnceODRLinkage, OrigName, &F);
auto *AM = GlobalAlias::create(GlobalValue::LinkOnceODRLinkage,
MangledName.value(), &F);
F.replaceUsesWithIf(AM,
[](Use &U) { return isa<GlobalAlias>(U.getUser()); });
F.replaceAllUsesWith(A);
F.setMetadata("arm64ec_exp_name",
MDNode::get(M->getContext(),
MDString::get(M->getContext(),
"EXP+" + MangledName.value())));
A->setAliasee(&F);
AM->setAliasee(&F);

if (F.hasDLLExportStorageClass()) {
A->setDLLStorageClass(GlobalValue::DLLExportStorageClass);
F.setDLLStorageClass(GlobalValue::DefaultStorageClass);
}

FnsMap[A] = GlobalAlias::create(GlobalValue::LinkOnceODRLinkage,
MangledName.value(), &F);
FnsMap[A] = AM;
PatchableFns.insert(A);
}
}
Expand Down Expand Up @@ -928,9 +949,9 @@ bool AArch64Arm64ECCallLowering::processFunction(
if (!F.hasLocalLinkage() || F.hasAddressTaken()) {
if (std::optional<std::string> MangledName =
getArm64ECMangledFunctionName(F.getName().str())) {
F.setMetadata("arm64ec_unmangled_name",
MDNode::get(M->getContext(),
MDString::get(M->getContext(), F.getName())));
F.addMetadata("arm64ec_unmangled_name",
*MDNode::get(M->getContext(),
MDString::get(M->getContext(), F.getName())));
if (F.hasComdat() && F.getComdat()->getName() == F.getName()) {
Comdat *MangledComdat = M->getOrInsertComdat(MangledName.value());
SmallVector<GlobalObject *> ComdatUsers =
Expand Down
26 changes: 13 additions & 13 deletions llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
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Expand Up @@ -45,6 +45,7 @@
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
Expand Down Expand Up @@ -1387,22 +1388,21 @@ void AArch64AsmPrinter::emitFunctionEntryLabel() {
return Sym;
};

if (MCSymbol *UnmangledSym =
getSymbolFromMetadata("arm64ec_unmangled_name")) {
MCSymbol *ECMangledSym = getSymbolFromMetadata("arm64ec_ecmangled_name");

if (ECMangledSym) {
// An external function, emit the alias from the unmangled symbol to
// mangled symbol name and the alias from the mangled symbol to guest
// exit thunk.
SmallVector<MDNode *> UnmangledNames;
MF->getFunction().getMetadata("arm64ec_unmangled_name", UnmangledNames);
for (MDNode *Node : UnmangledNames) {
StringRef NameStr = cast<MDString>(Node->getOperand(0))->getString();
MCSymbol *UnmangledSym = MMI->getContext().getOrCreateSymbol(NameStr);
if (std::optional<std::string> MangledName =
getArm64ECMangledFunctionName(UnmangledSym->getName())) {
MCSymbol *ECMangledSym =
MMI->getContext().getOrCreateSymbol(*MangledName);
emitFunctionAlias(UnmangledSym, ECMangledSym);
emitFunctionAlias(ECMangledSym, CurrentFnSym);
} else {
// A function implementation, emit the alias from the unmangled symbol
// to mangled symbol name.
emitFunctionAlias(UnmangledSym, CurrentFnSym);
}
}
if (MCSymbol *ECMangledSym =
getSymbolFromMetadata("arm64ec_ecmangled_name"))
emitFunctionAlias(ECMangledSym, CurrentFnSym);
}
}

Expand Down
42 changes: 42 additions & 0 deletions llvm/test/CodeGen/AArch64/arm64ec-alias.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,42 @@
; RUN: llc -mtriple arm64ec-windows-msvc -filetype asm -o - %s | FileCheck %s

define void @func() {
ret void
}

define dso_local void @patchable_func() hybrid_patchable {
ret void
}

@func_alias = alias void (), ptr @func
@func_alias2 = alias void (), ptr @func_alias
@patchable_alias = alias void (), ptr @patchable_func

; CHECK: .weak_anti_dep func_alias
; CHECK-NEXT: .set func_alias, "#func_alias"
; CHECK-NEXT: .weak_anti_dep func_alias2
; CHECK-NEXT: .set func_alias2, "#func_alias2"
; CHECK-NEXT: .weak_anti_dep func
; CHECK-NEXT: .set func, "#func"
; CHECK: .weak_anti_dep patchable_alias
; CHECK-NEXT: .set patchable_alias, "#patchable_alias"

; CHECK: .globl "#func_alias"
; CHECK-NEXT: .def "#func_alias";
; CHECK-NEXT: .scl 2;
; CHECK-NEXT: .type 32;
; CHECK-NEXT: .endef
; CHECK-NEXT: .set "#func_alias", "#func"
; CHECK-NEXT: .globl "#func_alias2"
; CHECK-NEXT: .def "#func_alias2";
; CHECK-NEXT: .scl 2;
; CHECK-NEXT: .type 32;
; CHECK-NEXT: .endef
; CHECK-NEXT: .set "#func_alias2", "#func_alias"

; CHECK: .globl "#patchable_alias"
; CHECK-NEXT: .def "#patchable_alias";
; CHECK-NEXT: .scl 2;
; CHECK-NEXT: .type 32;
; CHECK-NEXT: .endef
; CHECK-NEXT: .set "#patchable_alias", "#patchable_func"
16 changes: 8 additions & 8 deletions llvm/test/CodeGen/AArch64/dllexport.ll
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Expand Up @@ -88,10 +88,10 @@ define weak_odr dllexport void @l() {
; CHECK-GNU-EC: .ascii " -export:o,data"
; CHECK-GNU-EC: .ascii " -export:p,data"
; CHECK-GNU-EC: .ascii " -export:q,data"
; CHECK-GNU-EC: .ascii " -export:r"
; CHECK-GNU-EC: .ascii " -export:s"
; CHECK-GNU-EC: .ascii " -export:t"
; CHECK-GNU-EC: .ascii " -export:u"
; CHECK-GNU-EC: .ascii " -export:#r,EXPORTAS,r"
; CHECK-GNU-EC: .ascii " -export:#s,EXPORTAS,s"
; CHECK-GNU-EC: .ascii " -export:#t,EXPORTAS,t"
; CHECK-GNU-EC: .ascii " -export:#u,EXPORTAS,u"
; CHECK-MSVC-EC-NOT: /EXPORT:f
; CHECK-MSVC-EC-NOT: /EXPORT:#f,EXPORTAS,f
; CHECK-MSVC-EC: .ascii " /EXPORT:#g,EXPORTAS,g"
Expand All @@ -106,7 +106,7 @@ define weak_odr dllexport void @l() {
; CHECK-MSVC-EC: .ascii " /EXPORT:o,DATA"
; CHECK-MSVC-EC: .ascii " /EXPORT:p,DATA"
; CHECK-MSVC-EC: .ascii " /EXPORT:q,DATA"
; CHECK-MSVC-EC: .ascii " /EXPORT:r"
; CHECK-MSVC-EC: .ascii " /EXPORT:s"
; CHECK-MSVC-EC: .ascii " /EXPORT:t"
; CHECK-MSVC-EC: .ascii " /EXPORT:u"
; CHECK-MSVC-EC: .ascii " /EXPORT:#r,EXPORTAS,r"
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Does this work with the MSVC linker?

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Yes, it works, I rechecked to be sure. Thanks!

; CHECK-MSVC-EC: .ascii " /EXPORT:#s,EXPORTAS,s"
; CHECK-MSVC-EC: .ascii " /EXPORT:#t,EXPORTAS,t"
; CHECK-MSVC-EC: .ascii " /EXPORT:#u,EXPORTAS,u"
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