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[SystemZ][z/OS] Implement llvm.returnaddress for XPLINK #89440

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Merged
merged 2 commits into from
Apr 22, 2024
Merged

[SystemZ][z/OS] Implement llvm.returnaddress for XPLINK #89440

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c71fdbf
[SystemZ][z/OS] Implement llvm.returnaddress for XPLINK
redstar Apr 19, 2024
53d3385
Remove virtual keyword
redstar Apr 22, 2024
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20 changes: 12 additions & 8 deletions llvm/lib/Target/SystemZ/SystemZFrameLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -56,14 +56,17 @@ static const TargetFrameLowering::SpillSlot XPLINKSpillOffsetTable[] = {

SystemZFrameLowering::SystemZFrameLowering(StackDirection D, Align StackAl,
int LAO, Align TransAl,
bool StackReal)
: TargetFrameLowering(D, StackAl, LAO, TransAl, StackReal) {}
bool StackReal, unsigned PointerSize)
: TargetFrameLowering(D, StackAl, LAO, TransAl, StackReal),
PointerSize(PointerSize) {}

std::unique_ptr<SystemZFrameLowering>
SystemZFrameLowering::create(const SystemZSubtarget &STI) {
unsigned PtrSz =
STI.getTargetLowering()->getTargetMachine().getPointerSize(0);
if (STI.isTargetXPLINK64())
return std::make_unique<SystemZXPLINKFrameLowering>();
return std::make_unique<SystemZELFFrameLowering>();
return std::make_unique<SystemZXPLINKFrameLowering>(PtrSz);
return std::make_unique<SystemZELFFrameLowering>(PtrSz);
}

namespace {
Expand Down Expand Up @@ -272,9 +275,9 @@ void SystemZELFFrameLowering::determineCalleeSaves(MachineFunction &MF,
}
}

SystemZELFFrameLowering::SystemZELFFrameLowering()
SystemZELFFrameLowering::SystemZELFFrameLowering(unsigned PointerSize)
: SystemZFrameLowering(TargetFrameLowering::StackGrowsDown, Align(8), 0,
Align(8), /* StackRealignable */ false),
Align(8), /* StackRealignable */ false, PointerSize),
RegSpillOffsets(0) {

// Due to the SystemZ ABI, the DWARF CFA (Canonical Frame Address) is not
Expand Down Expand Up @@ -884,9 +887,10 @@ bool SystemZELFFrameLowering::usePackedStack(MachineFunction &MF) const {
return HasPackedStackAttr && CallConv;
}

SystemZXPLINKFrameLowering::SystemZXPLINKFrameLowering()
SystemZXPLINKFrameLowering::SystemZXPLINKFrameLowering(unsigned PointerSize)
: SystemZFrameLowering(TargetFrameLowering::StackGrowsDown, Align(32), 0,
Align(32), /* StackRealignable */ false),
Align(32), /* StackRealignable */ false,
PointerSize),
RegSpillOffsets(-1) {

// Create a mapping from register number to save slot offset.
Expand Down
25 changes: 22 additions & 3 deletions llvm/lib/Target/SystemZ/SystemZFrameLowering.h
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Expand Up @@ -22,7 +22,7 @@ class SystemZSubtarget;
class SystemZFrameLowering : public TargetFrameLowering {
public:
SystemZFrameLowering(StackDirection D, Align StackAl, int LAO, Align TransAl,
bool StackReal);
bool StackReal, unsigned PointerSize);

static std::unique_ptr<SystemZFrameLowering>
create(const SystemZSubtarget &STI);
Expand All @@ -45,15 +45,24 @@ class SystemZFrameLowering : public TargetFrameLowering {
// Return the offset of the backchain.
virtual unsigned getBackchainOffset(MachineFunction &MF) const = 0;

// Return the offset of the return address.
virtual int getReturnAddressOffset(MachineFunction &MF) const = 0;

// Get or create the frame index of where the old frame pointer is stored.
virtual int getOrCreateFramePointerSaveIndex(MachineFunction &MF) const = 0;

// Return the size of a pointer (in bytes).
unsigned getPointerSize() const { return PointerSize; }

private:
unsigned PointerSize;
};

class SystemZELFFrameLowering : public SystemZFrameLowering {
IndexedMap<unsigned> RegSpillOffsets;

public:
SystemZELFFrameLowering();
SystemZELFFrameLowering(unsigned PointerSize);

// Override TargetFrameLowering.
bool
Expand Down Expand Up @@ -97,6 +106,11 @@ class SystemZELFFrameLowering : public SystemZFrameLowering {
return usePackedStack(MF) ? SystemZMC::ELFCallFrameSize - 8 : 0;
}

// Return the offset of the return address.
int getReturnAddressOffset(MachineFunction &MF) const override {
return (usePackedStack(MF) ? -2 : 14) * getPointerSize();
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If this is the only place you need the pointer size, can't you just get it from MF?

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That was my first approach. The expression is a bit clumsy, and it is needed twice (here, and for XPLINK), and therefore I refactored it into a new function. Then I realized that it should be used in other place, too, for example:

But this should be a follow-up PR.

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OK, fair enough.

}

// Get or create the frame index of where the old frame pointer is stored.
int getOrCreateFramePointerSaveIndex(MachineFunction &MF) const override;
};
Expand All @@ -105,7 +119,7 @@ class SystemZXPLINKFrameLowering : public SystemZFrameLowering {
IndexedMap<unsigned> RegSpillOffsets;

public:
SystemZXPLINKFrameLowering();
SystemZXPLINKFrameLowering(unsigned PointerSize);

bool
assignCalleeSavedSpillSlots(MachineFunction &MF,
Expand Down Expand Up @@ -146,6 +160,11 @@ class SystemZXPLINKFrameLowering : public SystemZFrameLowering {
return 0;
}

// Return the offset of the return address.
int getReturnAddressOffset(MachineFunction &MF) const override {
return 3 * getPointerSize();
}

// Get or create the frame index of where the old frame pointer is stored.
int getOrCreateFramePointerSaveIndex(MachineFunction &MF) const override;
};
Expand Down
12 changes: 7 additions & 5 deletions llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
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Expand Up @@ -3816,17 +3816,19 @@ SDValue SystemZTargetLowering::lowerRETURNADDR(SDValue Op,
report_fatal_error("Unsupported stack frame traversal count");

SDValue FrameAddr = lowerFRAMEADDR(Op, DAG);
auto *TFL = Subtarget.getFrameLowering<SystemZELFFrameLowering>();
int Offset = (TFL->usePackedStack(MF) ? -2 : 14) *
getTargetMachine().getPointerSize(0);
const auto *TFL = Subtarget.getFrameLowering<SystemZFrameLowering>();
int Offset = TFL->getReturnAddressOffset(MF);
SDValue Ptr = DAG.getNode(ISD::ADD, DL, PtrVT, FrameAddr,
DAG.getConstant(Offset, DL, PtrVT));
return DAG.getLoad(PtrVT, DL, DAG.getEntryNode(), Ptr,
MachinePointerInfo());
}

// Return R14D, which has the return address. Mark it an implicit live-in.
Register LinkReg = MF.addLiveIn(SystemZ::R14D, &SystemZ::GR64BitRegClass);
// Return R14D (Elf) / R7D (XPLINK), which has the return address. Mark it an
// implicit live-in.
SystemZCallingConventionRegisters *CCR = Subtarget.getSpecialRegisters();
Register LinkReg = MF.addLiveIn(CCR->getReturnFunctionAddressRegister(),
&SystemZ::GR64BitRegClass);
return DAG.getCopyFromReg(DAG.getEntryNode(), DL, LinkReg, PtrVT);
}

Expand Down
41 changes: 41 additions & 0 deletions llvm/test/CodeGen/SystemZ/zos-ret-addr.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,41 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
; RUN: llc < %s -mtriple=s390x-ibm-zos | FileCheck %s

; The current function's return address is in the link register.
define ptr @rt0() norecurse nounwind readnone {
; CHECK-LABEL: rt0:
; CHECK: lgr 3, 7
; CHECK-NEXT: b 2(7)
entry:
%0 = tail call ptr @llvm.returnaddress(i32 0)
ret ptr %0
}

; Check the caller's return address.
define ptr @rtcaller() nounwind "backchain" {
; CHECK-LABEL: rtcaller:
; CHECK: stmg 4, 7, 2048(4)
; CHECK-NEXT: lg 1, 2048(4)
; CHECK-NEXT: lg 3, 24(1)
; CHECK-NEXT: lmg 4, 7, 2048(4)
; CHECK-NEXT: b 2(7)
entry:
%0 = tail call ptr @llvm.returnaddress(i32 1)
ret ptr %0
}

; Check the caller's caller's return address.
define ptr @rtcallercaller() nounwind "backchain" {
; CHECK-LABEL: rtcallercaller:
; CHECK: stmg 4, 7, 2048(4)
; CHECK-NEXT: lg 1, 2048(4)
; CHECK-NEXT: lg 1, 0(1)
; CHECK-NEXT: lg 3, 24(1)
; CHECK-NEXT: lmg 4, 7, 2048(4)
; CHECK-NEXT: b 2(7)
entry:
%0 = tail call ptr @llvm.returnaddress(i32 2)
ret ptr %0
}

declare ptr @llvm.returnaddress(i32) nounwind readnone