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[IR][SDAG] Remove lifetime size handling from SDAG #150944

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Merged
merged 1 commit into from
Jul 29, 2025
Merged

[IR][SDAG] Remove lifetime size handling from SDAG #150944

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14 changes: 8 additions & 6 deletions llvm/docs/LangRef.rst
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Expand Up @@ -26653,9 +26653,10 @@ object's lifetime.
Arguments:
""""""""""

The first argument is a constant integer representing the size of the
object, or -1 if it is variable sized. The second argument is a pointer
to an ``alloca`` instruction.
The first argument is a constant integer, which is ignored and will be removed
in the future.

The second argument is a pointer to an ``alloca`` instruction.

Semantics:
""""""""""
Expand Down Expand Up @@ -26693,9 +26694,10 @@ The '``llvm.lifetime.end``' intrinsic specifies the end of a
Arguments:
""""""""""

The first argument is a constant integer representing the size of the
object, or -1 if it is variable sized. The second argument is a pointer
to an ``alloca`` instruction.
The first argument is a constant integer, which is ignored and will be removed
in the future.

The second argument is a pointer to an ``alloca`` instruction.

Semantics:
""""""""""
Expand Down
5 changes: 2 additions & 3 deletions llvm/include/llvm/CodeGen/SelectionDAG.h
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Expand Up @@ -1428,10 +1428,9 @@ class SelectionDAG {
EVT MemVT, MachineMemOperand *MMO);

/// Creates a LifetimeSDNode that starts (`IsStart==true`) or ends
/// (`IsStart==false`) the lifetime of the portion of `FrameIndex` between
/// offsets `0` and `Size`.
/// (`IsStart==false`) the lifetime of the `FrameIndex`.
LLVM_ABI SDValue getLifetimeNode(bool IsStart, const SDLoc &dl, SDValue Chain,
int FrameIndex, int64_t Size);
int FrameIndex);

/// Creates a PseudoProbeSDNode with function GUID `Guid` and
/// the index of the block `Index` it is probing, as well as the attributes
Expand Down
10 changes: 3 additions & 7 deletions llvm/include/llvm/CodeGen/SelectionDAGNodes.h
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Expand Up @@ -1999,23 +1999,19 @@ class FrameIndexSDNode : public SDNode {
}
};

/// This SDNode is used for LIFETIME_START/LIFETIME_END values, which indicate
/// the offet and size that are started/ended in the underlying FrameIndex.
/// This SDNode is used for LIFETIME_START/LIFETIME_END values.
class LifetimeSDNode : public SDNode {
friend class SelectionDAG;
int64_t Size;

LifetimeSDNode(unsigned Opcode, unsigned Order, const DebugLoc &dl,
SDVTList VTs, int64_t Size)
: SDNode(Opcode, Order, dl, VTs), Size(Size) {}
SDVTList VTs)
: SDNode(Opcode, Order, dl, VTs) {}

public:
int64_t getFrameIndex() const {
return cast<FrameIndexSDNode>(getOperand(1))->getIndex();
}

int64_t getSize() const { return Size; }

// Methods to support isa and dyn_cast
static bool classof(const SDNode *N) {
return N->getOpcode() == ISD::LIFETIME_START ||
Expand Down
15 changes: 10 additions & 5 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Expand Up @@ -35,6 +35,7 @@
#include "llvm/CodeGen/ByteProvider.h"
#include "llvm/CodeGen/DAGCombine.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/SDPatternMatch.h"
Expand Down Expand Up @@ -22778,8 +22779,10 @@ SDValue DAGCombiner::visitLIFETIME_END(SDNode *N) {
const BaseIndexOffset StoreBase = BaseIndexOffset::match(ST, DAG);
// If we store purely within object bounds just before its lifetime ends,
// we can remove the store.
if (LifetimeEndBase.contains(DAG, LifetimeEnd->getSize() * 8, StoreBase,
StoreSize.getFixedValue() * 8)) {
MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
if (LifetimeEndBase.contains(
DAG, MFI.getObjectSize(LifetimeEnd->getFrameIndex()) * 8,
StoreBase, StoreSize.getFixedValue() * 8)) {
LLVM_DEBUG(dbgs() << "\nRemoving store:"; StoreBase.dump();
dbgs() << "\nwithin LIFETIME_END of : ";
LifetimeEndBase.dump(); dbgs() << "\n");
Expand Down Expand Up @@ -29415,7 +29418,7 @@ bool DAGCombiner::mayAlias(SDNode *Op0, SDNode *Op1) const {
MachineMemOperand *MMO;
};

auto getCharacteristics = [](SDNode *N) -> MemUseCharacteristics {
auto getCharacteristics = [this](SDNode *N) -> MemUseCharacteristics {
if (const auto *LSN = dyn_cast<LSBaseSDNode>(N)) {
int64_t Offset = 0;
if (auto *C = dyn_cast<ConstantSDNode>(LSN->getOffset()))
Expand All @@ -29428,13 +29431,15 @@ bool DAGCombiner::mayAlias(SDNode *Op0, SDNode *Op1) const {
LSN->getBasePtr(), Offset /*base offset*/,
LocationSize::precise(Size), LSN->getMemOperand()};
}
if (const auto *LN = cast<LifetimeSDNode>(N))
if (const auto *LN = cast<LifetimeSDNode>(N)) {
MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
return {false /*isVolatile*/,
/*isAtomic*/ false,
LN->getOperand(1),
0,
LocationSize::precise(LN->getSize()),
LocationSize::precise(MFI.getObjectSize(LN->getFrameIndex())),
(MachineMemOperand *)nullptr};
}
// Default.
return {false /*isvolatile*/,
/*isAtomic*/ false,
Expand Down
12 changes: 3 additions & 9 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Expand Up @@ -784,10 +784,6 @@ static void AddNodeIDCustom(FoldingSetNodeID &ID, const SDNode *N) {
case ISD::TargetFrameIndex:
ID.AddInteger(cast<FrameIndexSDNode>(N)->getIndex());
break;
case ISD::LIFETIME_START:
case ISD::LIFETIME_END:
ID.AddInteger(cast<LifetimeSDNode>(N)->getSize());
break;
case ISD::PSEUDO_PROBE:
ID.AddInteger(cast<PseudoProbeSDNode>(N)->getGuid());
ID.AddInteger(cast<PseudoProbeSDNode>(N)->getIndex());
Expand Down Expand Up @@ -9360,8 +9356,7 @@ SDValue SelectionDAG::getMemIntrinsicNode(unsigned Opcode, const SDLoc &dl,
}

SDValue SelectionDAG::getLifetimeNode(bool IsStart, const SDLoc &dl,
SDValue Chain, int FrameIndex,
int64_t Size) {
SDValue Chain, int FrameIndex) {
const unsigned Opcode = IsStart ? ISD::LIFETIME_START : ISD::LIFETIME_END;
const auto VTs = getVTList(MVT::Other);
SDValue Ops[2] = {
Expand All @@ -9373,13 +9368,12 @@ SDValue SelectionDAG::getLifetimeNode(bool IsStart, const SDLoc &dl,
FoldingSetNodeID ID;
AddNodeIDNode(ID, Opcode, VTs, Ops);
ID.AddInteger(FrameIndex);
ID.AddInteger(Size);
void *IP = nullptr;
if (SDNode *E = FindNodeOrInsertPos(ID, dl, IP))
return SDValue(E, 0);

LifetimeSDNode *N = newSDNode<LifetimeSDNode>(Opcode, dl.getIROrder(),
dl.getDebugLoc(), VTs, Size);
LifetimeSDNode *N =
newSDNode<LifetimeSDNode>(Opcode, dl.getIROrder(), dl.getDebugLoc(), VTs);
createOperands(N, Ops);
CSEMap.InsertNode(N, IP);
InsertNode(N);
Expand Down
4 changes: 1 addition & 3 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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Expand Up @@ -7594,8 +7594,6 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
if (TM.getOptLevel() == CodeGenOptLevel::None)
return;

const int64_t ObjectSize =
cast<ConstantInt>(I.getArgOperand(0))->getSExtValue();
const AllocaInst *LifetimeObject = cast<AllocaInst>(I.getArgOperand(1));

// First check that the Alloca is static, otherwise it won't have a
Expand All @@ -7605,7 +7603,7 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
return;

const int FrameIndex = SI->second;
Res = DAG.getLifetimeNode(IsStart, sdl, getRoot(), FrameIndex, ObjectSize);
Res = DAG.getLifetimeNode(IsStart, sdl, getRoot(), FrameIndex);
DAG.setRoot(Res);
return;
}
Expand Down
2 changes: 0 additions & 2 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
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Expand Up @@ -946,8 +946,6 @@ void SDNode::print_details(raw_ostream &OS, const SelectionDAG *G) const {
<< " -> "
<< ASC->getDestAddressSpace()
<< ']';
} else if (const LifetimeSDNode *LN = dyn_cast<LifetimeSDNode>(this)) {
OS << "<0 to " << LN->getSize() << ">";
} else if (const auto *AA = dyn_cast<AssertAlignSDNode>(this)) {
OS << '<' << AA->getAlign().value() << '>';
}
Expand Down
15 changes: 4 additions & 11 deletions llvm/test/CodeGen/X86/swap.ll
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Expand Up @@ -113,21 +113,17 @@ define dso_local void @onealloc_readback_1(ptr nocapture %a, ptr nocapture %b) l
;
; AA-LABEL: onealloc_readback_1:
; AA: # %bb.0: # %entry
; AA-NEXT: vmovups (%rdi), %xmm0
; AA-NEXT: vmovaps %xmm0, -{{[0-9]+}}(%rsp)
; AA-NEXT: vmovups (%rsi), %xmm0
; AA-NEXT: vmovups %xmm0, (%rdi)
; AA-NEXT: retq
entry:
%alloc = alloca [16 x i8], i8 2, align 1
%part1 = getelementptr inbounds [16 x i8], ptr %alloc, i64 1, i64 0
call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %part1)
call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %alloc)
call void @llvm.lifetime.start.p0(i64 32, ptr nonnull %alloc)
call void @llvm.memcpy.p0.p0.i64(ptr nonnull align 1 %part1, ptr align 1 %a, i64 16, i1 false)
call void @llvm.memcpy.p0.p0.i64(ptr nonnull align 1 %alloc, ptr align 1 %b, i64 16, i1 false)
call void @llvm.lifetime.end.p0(i64 16, ptr nonnull %part1)
tail call void @llvm.memcpy.p0.p0.i64(ptr nonnull align 1 %a, ptr align 1 %alloc, i64 16, i1 false)
call void @llvm.lifetime.end.p0(i64 16, ptr nonnull %alloc)
call void @llvm.lifetime.end.p0(i64 32, ptr nonnull %alloc)
ret void
}

Expand All @@ -144,19 +140,16 @@ define dso_local void @onealloc_readback_2(ptr nocapture %a, ptr nocapture %b) l
; AA-LABEL: onealloc_readback_2:
; AA: # %bb.0: # %entry
; AA-NEXT: vmovups (%rsi), %xmm0
; AA-NEXT: vmovaps %xmm0, -{{[0-9]+}}(%rsp)
; AA-NEXT: vmovups %xmm0, (%rdi)
; AA-NEXT: retq
entry:
%alloc = alloca [16 x i8], i8 2, align 1
%part2 = getelementptr inbounds [16 x i8], ptr %alloc, i64 1, i64 0
call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %alloc)
call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %part2)
call void @llvm.lifetime.start.p0(i64 32, ptr nonnull %alloc)
call void @llvm.memcpy.p0.p0.i64(ptr nonnull align 1 %alloc, ptr align 1 %a, i64 16, i1 false)
call void @llvm.memcpy.p0.p0.i64(ptr nonnull align 1 %part2, ptr align 1 %b, i64 16, i1 false)
call void @llvm.lifetime.end.p0(i64 16, ptr nonnull %alloc)
tail call void @llvm.memcpy.p0.p0.i64(ptr nonnull align 1 %a, ptr align 1 %part2, i64 16, i1 false)
call void @llvm.lifetime.end.p0(i64 16, ptr nonnull %part2)
call void @llvm.lifetime.end.p0(i64 32, ptr nonnull %alloc)
ret void
}

Expand Down
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