https://github.com/MacDue updated
https://github.com/llvm/llvm-project/pull/149063
>From 4250bec812603b7520dc36f26d68a2c3834ad6cd Mon Sep 17 00:00:00 2001
From: Benjamin Maxwell <benjamin.maxw...@arm.com>
Date: Tue, 15 Jul 2025 11:47:39 +0000
Subject: [PATCH 1/2] [AArch64][SME] Support Windows/stack probes in
MachineSMEABIPass
On Windows or with stack probes on other targets, additional code needs
to be inserted after dynamic stack allocations to validate stack
accesses and/or ensure enough stack space has been allocated.
Rather than handle this case in the MachineSMEABIPass (like we do for
the standard case), we allocate the memory for the lazy save buffer in
SelectionDAG, which allows the existing expansions to emit the correct
code.
Note: This means in these cases, we may allocate a lazy save buffer when
there are no lazy saves present in the function (as we have to allocate
the buffer before the MachineSMEABIPass runs).
Change-Id: If89ab54c4de79f6fe5513a6b387e9e349f7bc7d1
---
.../AArch64/AArch64ExpandPseudoInsts.cpp | 1 +
.../Target/AArch64/AArch64ISelLowering.cpp | 34 ++++++++-
.../AArch64/AArch64MachineFunctionInfo.h | 10 +++
.../lib/Target/AArch64/AArch64SMEInstrInfo.td | 7 ++
llvm/lib/Target/AArch64/MachineSMEABIPass.cpp | 25 +++++--
.../CodeGen/AArch64/sme-lazy-save-windows.ll | 71 +++++++++++++++++++
.../AArch64/sme-za-lazy-save-buffer.ll | 26 ++++---
7 files changed, 160 insertions(+), 14 deletions(-)
create mode 100644 llvm/test/CodeGen/AArch64/sme-lazy-save-windows.ll
diff --git a/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
b/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
index c0d118aa3afed..b76172fd2e934 100644
--- a/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
@@ -1642,6 +1642,7 @@ bool AArch64ExpandPseudo::expandMI(MachineBasicBlock &MBB,
}
case AArch64::InOutZAUsePseudo:
case AArch64::RequiresZASavePseudo:
+ case AArch64::SMEStateAllocPseudo:
case AArch64::COALESCER_BARRIER_FPR16:
case AArch64::COALESCER_BARRIER_FPR32:
case AArch64::COALESCER_BARRIER_FPR64:
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 49135d05b689b..d586942582d8b 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -8154,7 +8154,39 @@ SDValue AArch64TargetLowering::LowerFormalArguments(
if (Subtarget->hasCustomCallingConv())
Subtarget->getRegisterInfo()->UpdateCustomCalleeSavedRegs(MF);
- if (!Subtarget->useNewSMEABILowering() || Attrs.hasAgnosticZAInterface()) {
+ if (Subtarget->useNewSMEABILowering() && !Attrs.hasAgnosticZAInterface()) {
+ if (Subtarget->isTargetWindows() || hasInlineStackProbe(MF)) {
+ SDValue Size;
+ if (Attrs.hasZAState()) {
+ SDValue SVL = DAG.getNode(AArch64ISD::RDSVL, DL, MVT::i64,
+ DAG.getConstant(1, DL, MVT::i32));
+ Size = DAG.getNode(ISD::MUL, DL, MVT::i64, SVL, SVL);
+ } else if (Attrs.hasAgnosticZAInterface()) {
+ SDValue Callee = DAG.getExternalSymbol(
+ "__arm_sme_state_size", getPointerTy(DAG.getDataLayout()));
+ auto *RetTy = EVT(MVT::i64).getTypeForEVT(*DAG.getContext());
+ TargetLowering::CallLoweringInfo CLI(DAG);
+ CLI.setDebugLoc(DL).setChain(Chain).setLibCallee(
+ CallingConv::AArch64_SME_ABI_Support_Routines_PreserveMost_From_X1,
+ RetTy, Callee, {});
+ std::tie(Size, Chain) = LowerCallTo(CLI);
+ }
+ if (Size) {
+ SDValue Buffer = DAG.getNode(
+ ISD::DYNAMIC_STACKALLOC, DL, DAG.getVTList(MVT::i64, MVT::Other),
+ {Chain, Size, DAG.getConstant(1, DL, MVT::i64)});
+ Chain = Buffer.getValue(1);
+
+ Register BufferPtr =
+ MF.getRegInfo().createVirtualRegister(&AArch64::GPR64RegClass);
+ Chain = DAG.getCopyToReg(Chain, DL, BufferPtr, Buffer);
+ Chain = DAG.getNode(AArch64ISD::SME_STATE_ALLOC, DL,
+ DAG.getVTList(MVT::Other), Chain);
+ FuncInfo->setEarlyAllocSMESaveBuffer(BufferPtr);
+ MFI.CreateVariableSizedObject(Align(16), nullptr);
+ }
+ }
+ } else {
// Old SME ABI lowering (deprecated):
// Create a 16 Byte TPIDR2 object. The dynamic buffer
// will be expanded and stored in the static object later using a
diff --git a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h
b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h
index 3f6980fe11aea..0f9654939be53 100644
--- a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h
+++ b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h
@@ -239,6 +239,10 @@ class AArch64FunctionInfo final : public
MachineFunctionInfo {
// Holds the SME function attributes (streaming mode, ZA/ZT0 state).
SMEAttrs SMEFnAttrs;
+ // Holds the TPIDR2 block if allocated early (for Windows/stack probes
+ // support).
+ Register EarlyAllocSMESaveBuffer = AArch64::NoRegister;
+
// Note: The following properties are only used for the old SME ABI lowering:
/// The frame-index for the TPIDR2 object used for lazy saves.
TPIDR2Object TPIDR2;
@@ -257,6 +261,12 @@ class AArch64FunctionInfo final : public
MachineFunctionInfo {
const DenseMap<MachineBasicBlock *, MachineBasicBlock *> &Src2DstMBB)
const override;
+ void setEarlyAllocSMESaveBuffer(Register Ptr) {
+ EarlyAllocSMESaveBuffer = Ptr;
+ }
+
+ Register getEarlyAllocSMESaveBuffer() { return EarlyAllocSMESaveBuffer; }
+
// Old SME ABI lowering state getters/setters:
Register getSMESaveBufferAddr() const { return SMESaveBufferAddr; };
void setSMESaveBufferAddr(Register Reg) { SMESaveBufferAddr = Reg; };
diff --git a/llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
b/llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
index d50dcd8ebd815..02d86a924e7d2 100644
--- a/llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
+++ b/llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
@@ -90,6 +90,8 @@ let hasSideEffects = 1 in {
def RequiresZASavePseudo : Pseudo<(outs), (ins), []>, Sched<[]>;
}
+def SMEStateAllocPseudo : Pseudo<(outs), (ins), []>, Sched<[]>;
+
def CommitZAPseudo
: Pseudo<(outs),
(ins GPR64:$tpidr2_el0, i64imm:$restore_routine, variable_ops), []>,
@@ -105,6 +107,11 @@ def AArch64_requires_za_save
[SDNPHasChain, SDNPInGlue]>;
def : Pat<(AArch64_requires_za_save), (RequiresZASavePseudo)>;
+def AArch64_sme_state_alloc
+ : SDNode<"AArch64ISD::SME_STATE_ALLOC", SDTypeProfile<0, 0,[]>,
+ [SDNPHasChain]>;
+def : Pat<(AArch64_sme_state_alloc), (SMEStateAllocPseudo)>;
+
//===----------------------------------------------------------------------===//
// Instruction naming conventions.
//===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/AArch64/MachineSMEABIPass.cpp
b/llvm/lib/Target/AArch64/MachineSMEABIPass.cpp
index 7b72344a615e2..d25749960a191 100644
--- a/llvm/lib/Target/AArch64/MachineSMEABIPass.cpp
+++ b/llvm/lib/Target/AArch64/MachineSMEABIPass.cpp
@@ -166,6 +166,7 @@ struct MachineSMEABI : public MachineFunctionPass {
SmallVector<BlockInfo> Blocks;
SmallVector<ZAState> BundleStates;
std::optional<TPIDR2State> TPIDR2Block;
+ std::optional<MachineBasicBlock::iterator> AfterSMEProloguePt;
} State;
EdgeBundles *Bundles = nullptr;
@@ -212,6 +213,13 @@ void MachineSMEABI::collectNeededZAStates(MachineFunction
&MF,
MachineBasicBlock::iterator MBBI(MI);
LiveUnits.stepBackward(MI);
LiveRegs PhysLiveRegs = GetPhysLiveRegs();
+ // The SMEStateAllocPseudo marker is added to a function if the save
+ // buffer was allocated in SelectionDAG. It marks the end of the
+ // allocation -- which is a safe point for this pass to insert any TPIDR2
+ // block setup.
+ if (MI.getOpcode() == AArch64::SMEStateAllocPseudo) {
+ State.AfterSMEProloguePt = MBBI;
+ }
auto [NeededState, InsertPt] = getInstNeededZAState(
TRI, MI, /*ZALiveAtReturn=*/SMEFnAttrs.hasSharedZAInterface());
assert((InsertPt == MBBI ||
@@ -465,23 +473,25 @@ void MachineSMEABI::emitAllocateLazySaveBuffer(
auto &Subtarget = MF.getSubtarget<AArch64Subtarget>();
const TargetInstrInfo &TII = *Subtarget.getInstrInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
+ auto *AFI = MF.getInfo<AArch64FunctionInfo>();
DebugLoc DL = getDebugLoc(MBB, MBBI);
Register SP = MRI.createVirtualRegister(&AArch64::GPR64RegClass);
Register SVL = MRI.createVirtualRegister(&AArch64::GPR64RegClass);
- Register Buffer = MRI.createVirtualRegister(&AArch64::GPR64RegClass);
+ Register Buffer = AFI->getEarlyAllocSMESaveBuffer();
// Calculate SVL.
BuildMI(MBB, MBBI, DL, TII.get(AArch64::RDSVLI_XI), SVL).addImm(1);
// 1. Allocate the lazy save buffer.
- {
+ if (Buffer == AArch64::NoRegister) {
// TODO This function grows the stack with a subtraction, which doesn't
work
// on Windows. Some refactoring to share the functionality in
// LowerWindowsDYNAMIC_STACKALLOC will be required once the Windows ABI
// supports SME
assert(!Subtarget.isTargetWindows() &&
"Lazy ZA save is not yet supported on Windows");
+ Buffer = MRI.createVirtualRegister(&AArch64::GPR64RegClass);
// Get original stack pointer.
BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::COPY),
SP).addReg(AArch64::SP);
// Allocate a lazy-save buffer object of the size given, normally SVL * SVL
@@ -632,8 +642,15 @@ bool MachineSMEABI::runOnMachineFunction(MachineFunction
&MF) {
// Allocate save buffer (if needed).
if (State.TPIDR2Block.has_value()) {
- MachineBasicBlock &EntryBlock = MF.front();
- emitAllocateLazySaveBuffer(EntryBlock, EntryBlock.getFirstNonPHI());
+ if (State.AfterSMEProloguePt) {
+ // Note: With inline stack probes the AfterSMEProloguePt may not be in
the
+ // entry block (due to the probing loop).
+ emitAllocateLazySaveBuffer(*(*State.AfterSMEProloguePt)->getParent(),
+ *State.AfterSMEProloguePt);
+ } else {
+ MachineBasicBlock &EntryBlock = MF.front();
+ emitAllocateLazySaveBuffer(EntryBlock, EntryBlock.getFirstNonPHI());
+ }
}
return true;
diff --git a/llvm/test/CodeGen/AArch64/sme-lazy-save-windows.ll
b/llvm/test/CodeGen/AArch64/sme-lazy-save-windows.ll
new file mode 100644
index 0000000000000..873b6d9244f46
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/sme-lazy-save-windows.ll
@@ -0,0 +1,71 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
UTC_ARGS: --version 5
+; RUN: llc -mtriple=aarch64-windows-msvc -aarch64-streaming-hazard-size=0
-mattr=+sve,+sme < %s | FileCheck %s
+; RUN: llc -mtriple=aarch64-windows-msvc -aarch64-streaming-hazard-size=0
-mattr=+sve,+sme -aarch64-new-sme-abi < %s | FileCheck %s
--check-prefix=CHECK-NEWLOWERING
+
+declare void @private_za_callee()
+declare void @shared_za_callee() "aarch64_inout_za"
+
+define void @test_lazy_save() nounwind "aarch64_inout_za" {
+; CHECK-LABEL: test_lazy_save:
+; CHECK: // %bb.0:
+; CHECK-NEXT: stp x30, x29, [sp, #-32]! // 16-byte Folded Spill
+; CHECK-NEXT: str x19, [sp, #16] // 8-byte Folded Spill
+; CHECK-NEXT: mov x29, sp
+; CHECK-NEXT: sub sp, sp, #16
+; CHECK-NEXT: rdsvl x8, #1
+; CHECK-NEXT: mul x9, x8, x8
+; CHECK-NEXT: lsr x15, x9, #4
+; CHECK-NEXT: bl __chkstk
+; CHECK-NEXT: sub x9, sp, x15, lsl #4
+; CHECK-NEXT: mov sp, x9
+; CHECK-NEXT: stur x9, [x29, #-16]
+; CHECK-NEXT: sub x9, x29, #16
+; CHECK-NEXT: sturh wzr, [x29, #-6]
+; CHECK-NEXT: stur wzr, [x29, #-4]
+; CHECK-NEXT: sturh w8, [x29, #-8]
+; CHECK-NEXT: msr TPIDR2_EL0, x9
+; CHECK-NEXT: bl private_za_callee
+; CHECK-NEXT: smstart za
+; CHECK-NEXT: mrs x8, TPIDR2_EL0
+; CHECK-NEXT: sub x0, x29, #16
+; CHECK-NEXT: cbnz x8, .LBB0_2
+; CHECK-NEXT: // %bb.1:
+; CHECK-NEXT: bl __arm_tpidr2_restore
+; CHECK-NEXT: .LBB0_2:
+; CHECK-NEXT: msr TPIDR2_EL0, xzr
+; CHECK-NEXT: mov sp, x29
+; CHECK-NEXT: ldr x19, [sp, #16] // 8-byte Folded Reload
+; CHECK-NEXT: ldp x30, x29, [sp], #32 // 16-byte Folded Reload
+; CHECK-NEXT: ret
+;
+; CHECK-NEWLOWERING-LABEL: test_lazy_save:
+; CHECK-NEWLOWERING: // %bb.0:
+; CHECK-NEWLOWERING-NEXT: stp x30, x29, [sp, #-32]! // 16-byte Folded Spill
+; CHECK-NEWLOWERING-NEXT: str x19, [sp, #16] // 8-byte Folded Spill
+; CHECK-NEWLOWERING-NEXT: mov x29, sp
+; CHECK-NEWLOWERING-NEXT: sub sp, sp, #16
+; CHECK-NEWLOWERING-NEXT: rdsvl x8, #1
+; CHECK-NEWLOWERING-NEXT: mul x9, x8, x8
+; CHECK-NEWLOWERING-NEXT: lsr x15, x9, #4
+; CHECK-NEWLOWERING-NEXT: bl __chkstk
+; CHECK-NEWLOWERING-NEXT: sub x9, sp, x15, lsl #4
+; CHECK-NEWLOWERING-NEXT: mov sp, x9
+; CHECK-NEWLOWERING-NEXT: sub x10, x29, #16
+; CHECK-NEWLOWERING-NEXT: stp x9, x8, [x29, #-16]
+; CHECK-NEWLOWERING-NEXT: msr TPIDR2_EL0, x10
+; CHECK-NEWLOWERING-NEXT: bl private_za_callee
+; CHECK-NEWLOWERING-NEXT: smstart za
+; CHECK-NEWLOWERING-NEXT: mrs x8, TPIDR2_EL0
+; CHECK-NEWLOWERING-NEXT: sub x0, x29, #16
+; CHECK-NEWLOWERING-NEXT: cbnz x8, .LBB0_2
+; CHECK-NEWLOWERING-NEXT: // %bb.1:
+; CHECK-NEWLOWERING-NEXT: bl __arm_tpidr2_restore
+; CHECK-NEWLOWERING-NEXT: .LBB0_2:
+; CHECK-NEWLOWERING-NEXT: msr TPIDR2_EL0, xzr
+; CHECK-NEWLOWERING-NEXT: mov sp, x29
+; CHECK-NEWLOWERING-NEXT: ldr x19, [sp, #16] // 8-byte Folded Reload
+; CHECK-NEWLOWERING-NEXT: ldp x30, x29, [sp], #32 // 16-byte Folded Reload
+; CHECK-NEWLOWERING-NEXT: ret
+ call void @private_za_callee()
+ ret void
+}
diff --git a/llvm/test/CodeGen/AArch64/sme-za-lazy-save-buffer.ll
b/llvm/test/CodeGen/AArch64/sme-za-lazy-save-buffer.ll
index a9ad6f695cf8f..1a039eeb76956 100644
--- a/llvm/test/CodeGen/AArch64/sme-za-lazy-save-buffer.ll
+++ b/llvm/test/CodeGen/AArch64/sme-za-lazy-save-buffer.ll
@@ -103,7 +103,6 @@ exit:
ret float %ret
}
-; FIXME: This is missing stack probes with -aarch64-new-sme-abi.
define float @multi_bb_stpidr2_save_required_stackprobe(i32 %a, float %b,
float %c) "aarch64_inout_za" "probe-stack"="inline-asm"
"stack-probe-size"="65536" {
; CHECK-LABEL: multi_bb_stpidr2_save_required_stackprobe:
; CHECK: // %bb.0:
@@ -165,26 +164,35 @@ define float
@multi_bb_stpidr2_save_required_stackprobe(i32 %a, float %b, float
; CHECK-NEWLOWERING-NEXT: rdsvl x8, #1
; CHECK-NEWLOWERING-NEXT: mov x9, sp
; CHECK-NEWLOWERING-NEXT: msub x9, x8, x8, x9
+; CHECK-NEWLOWERING-NEXT: .LBB2_1: // =>This Inner Loop Header: Depth=1
+; CHECK-NEWLOWERING-NEXT: sub sp, sp, #16, lsl #12 // =65536
+; CHECK-NEWLOWERING-NEXT: cmp sp, x9
+; CHECK-NEWLOWERING-NEXT: b.le .LBB2_3
+; CHECK-NEWLOWERING-NEXT: // %bb.2: // in Loop: Header=BB2_1 Depth=1
+; CHECK-NEWLOWERING-NEXT: str xzr, [sp]
+; CHECK-NEWLOWERING-NEXT: b .LBB2_1
+; CHECK-NEWLOWERING-NEXT: .LBB2_3:
; CHECK-NEWLOWERING-NEXT: mov sp, x9
+; CHECK-NEWLOWERING-NEXT: ldr xzr, [sp]
; CHECK-NEWLOWERING-NEXT: sub x10, x29, #16
; CHECK-NEWLOWERING-NEXT: stp x9, x8, [x29, #-16]
; CHECK-NEWLOWERING-NEXT: msr TPIDR2_EL0, x10
-; CHECK-NEWLOWERING-NEXT: cbz w0, .LBB2_2
-; CHECK-NEWLOWERING-NEXT: // %bb.1: // %use_b
+; CHECK-NEWLOWERING-NEXT: cbz w0, .LBB2_5
+; CHECK-NEWLOWERING-NEXT: // %bb.4: // %use_b
; CHECK-NEWLOWERING-NEXT: fmov s1, #4.00000000
; CHECK-NEWLOWERING-NEXT: fadd s0, s0, s1
-; CHECK-NEWLOWERING-NEXT: b .LBB2_3
-; CHECK-NEWLOWERING-NEXT: .LBB2_2: // %use_c
+; CHECK-NEWLOWERING-NEXT: b .LBB2_6
+; CHECK-NEWLOWERING-NEXT: .LBB2_5: // %use_c
; CHECK-NEWLOWERING-NEXT: fmov s0, s1
; CHECK-NEWLOWERING-NEXT: bl cosf
-; CHECK-NEWLOWERING-NEXT: .LBB2_3: // %exit
+; CHECK-NEWLOWERING-NEXT: .LBB2_6: // %exit
; CHECK-NEWLOWERING-NEXT: smstart za
; CHECK-NEWLOWERING-NEXT: mrs x8, TPIDR2_EL0
; CHECK-NEWLOWERING-NEXT: sub x0, x29, #16
-; CHECK-NEWLOWERING-NEXT: cbnz x8, .LBB2_5
-; CHECK-NEWLOWERING-NEXT: // %bb.4: // %exit
+; CHECK-NEWLOWERING-NEXT: cbnz x8, .LBB2_8
+; CHECK-NEWLOWERING-NEXT: // %bb.7: // %exit
; CHECK-NEWLOWERING-NEXT: bl __arm_tpidr2_restore
-; CHECK-NEWLOWERING-NEXT: .LBB2_5: // %exit
+; CHECK-NEWLOWERING-NEXT: .LBB2_8: // %exit
; CHECK-NEWLOWERING-NEXT: msr TPIDR2_EL0, xzr
; CHECK-NEWLOWERING-NEXT: mov sp, x29
; CHECK-NEWLOWERING-NEXT: ldp x29, x30, [sp], #16 // 16-byte Folded Reload
>From 4532a6ba6122458b86a29ee855acb01cb74636e1 Mon Sep 17 00:00:00 2001
From: Benjamin Maxwell <benjamin.maxw...@arm.com>
Date: Fri, 18 Jul 2025 13:29:39 +0000
Subject: [PATCH 2/2] Update comment
Change-Id: I5dca6eaca8613a33e89a5cec9cc7d2c0f9cc7fb5
---
llvm/lib/Target/AArch64/MachineSMEABIPass.cpp | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Target/AArch64/MachineSMEABIPass.cpp
b/llvm/lib/Target/AArch64/MachineSMEABIPass.cpp
index d25749960a191..46202fb9c31b1 100644
--- a/llvm/lib/Target/AArch64/MachineSMEABIPass.cpp
+++ b/llvm/lib/Target/AArch64/MachineSMEABIPass.cpp
@@ -485,10 +485,12 @@ void MachineSMEABI::emitAllocateLazySaveBuffer(
// 1. Allocate the lazy save buffer.
if (Buffer == AArch64::NoRegister) {
- // TODO This function grows the stack with a subtraction, which doesn't
work
- // on Windows. Some refactoring to share the functionality in
- // LowerWindowsDYNAMIC_STACKALLOC will be required once the Windows ABI
- // supports SME
+ // TODO: On Windows, we allocate the lazy save buffer in SelectionDAG (so
+ // Buffer != AArch64::NoRegister). This is done to reuse the existing
+ // expansions (which can insert stack checks). This works, but it means we
+ // will always allocate the lazy save buffer (even if the function contains
+ // no lazy saves). If we want to handle Windows here, we'll need to
+ // implement something similar to LowerWindowsDYNAMIC_STACKALLOC.
assert(!Subtarget.isTargetWindows() &&
"Lazy ZA save is not yet supported on Windows");
Buffer = MRI.createVirtualRegister(&AArch64::GPR64RegClass);
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