Re-land part of r354244 "[DAGCombiner] Eliminate dead stores to stack."
This part introduces the lifetime node.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354578 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/CodeGen/SelectionDAG.h b/include/llvm/CodeGen/SelectionDAG.h
index b76f731..8f14226 100644
--- a/include/llvm/CodeGen/SelectionDAG.h
+++ b/include/llvm/CodeGen/SelectionDAG.h
@@ -1016,6 +1016,12 @@
ArrayRef<SDValue> Ops, EVT MemVT,
MachineMemOperand *MMO);
+ /// Creates a LifetimeSDNode that starts (`IsStart==true`) or ends
+ /// (`IsStart==false`) the lifetime of the portion of `FrameIndex` between
+ /// offsets `Offset` and `Offset + Size`.
+ SDValue getLifetimeNode(bool IsStart, const SDLoc &dl, SDValue Chain,
+ int FrameIndex, int64_t Size, int64_t Offset = -1);
+
/// Create a MERGE_VALUES node from the given operands.
SDValue getMergeValues(ArrayRef<SDValue> Ops, const SDLoc &dl);
diff --git a/include/llvm/CodeGen/SelectionDAGNodes.h b/include/llvm/CodeGen/SelectionDAGNodes.h
index c0dd9d1..a5d494f 100644
--- a/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -1692,6 +1692,37 @@
}
};
+/// This SDNode is used for LIFETIME_START/LIFETIME_END values, which indicate
+/// the offet and size that are started/ended in the underlying FrameIndex.
+class LifetimeSDNode : public SDNode {
+ int64_t Size;
+ int64_t Offset; // -1 if offset is unknown.
+public:
+ LifetimeSDNode(unsigned Opcode, unsigned Order, const DebugLoc &dl,
+ SDVTList VTs, int64_t Size, int64_t Offset)
+ : SDNode(Opcode, Order, dl, VTs), Size(Size), Offset(Offset) {}
+
+ int64_t getFrameIndex() const {
+ return cast<FrameIndexSDNode>(getOperand(1))->getIndex();
+ }
+
+ bool hasOffset() const { return Offset >= 0; }
+ int64_t getOffset() const {
+ assert(hasOffset() && "offset is unknown");
+ return Offset;
+ }
+ int64_t getSize() const {
+ assert(hasOffset() && "offset is unknown");
+ return Size;
+ }
+
+ // Methods to support isa and dyn_cast
+ static bool classof(const SDNode *N) {
+ return N->getOpcode() == ISD::LIFETIME_START ||
+ N->getOpcode() == ISD::LIFETIME_END;
+ }
+};
+
class JumpTableSDNode : public SDNode {
friend class SelectionDAG;
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index dd28443..156f772 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -6506,6 +6506,36 @@
return SDValue(N, 0);
}
+SDValue SelectionDAG::getLifetimeNode(bool IsStart, const SDLoc &dl,
+ SDValue Chain, int FrameIndex,
+ int64_t Size, int64_t Offset) {
+ const unsigned Opcode = IsStart ? ISD::LIFETIME_START : ISD::LIFETIME_END;
+ const auto VTs = getVTList(MVT::Other);
+ SDValue Ops[2] = {
+ Chain,
+ getFrameIndex(FrameIndex,
+ getTargetLoweringInfo().getFrameIndexTy(getDataLayout()),
+ true)};
+
+ FoldingSetNodeID ID;
+ AddNodeIDNode(ID, Opcode, VTs, Ops);
+ ID.AddInteger(FrameIndex);
+ ID.AddInteger(Size);
+ ID.AddInteger(Offset);
+ 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, Offset);
+ createOperands(N, Ops);
+ CSEMap.InsertNode(N, IP);
+ InsertNode(N);
+ SDValue V(N, 0);
+ NewSDValueDbgMsg(V, "Creating new node: ", this);
+ return V;
+}
+
/// InferPointerInfo - If the specified ptr/offset is a frame index, infer a
/// MachinePointerInfo record from it. This is particularly useful because the
/// code generator has many cases where it doesn't bother passing in a
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 75f7cc0..1b75dc7 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6373,8 +6373,11 @@
if (TM.getOptLevel() == CodeGenOpt::None)
return nullptr;
+ const int64_t ObjectSize =
+ cast<ConstantInt>(I.getArgOperand(0))->getSExtValue();
+ Value *const ObjectPtr = I.getArgOperand(1);
SmallVector<Value *, 4> Allocas;
- GetUnderlyingObjects(I.getArgOperand(1), Allocas, *DL);
+ GetUnderlyingObjects(ObjectPtr, Allocas, *DL);
for (SmallVectorImpl<Value*>::iterator Object = Allocas.begin(),
E = Allocas.end(); Object != E; ++Object) {
@@ -6390,15 +6393,13 @@
if (SI == FuncInfo.StaticAllocaMap.end())
return nullptr;
- int FI = SI->second;
-
- SDValue Ops[2];
- Ops[0] = getRoot();
- Ops[1] =
- DAG.getFrameIndex(FI, TLI.getFrameIndexTy(DAG.getDataLayout()), true);
- unsigned Opcode = (IsStart ? ISD::LIFETIME_START : ISD::LIFETIME_END);
-
- Res = DAG.getNode(Opcode, sdl, MVT::Other, Ops);
+ const int FrameIndex = SI->second;
+ int64_t Offset;
+ if (GetPointerBaseWithConstantOffset(
+ ObjectPtr, Offset, DAG.getDataLayout()) != LifetimeObject)
+ Offset = -1; // Cannot determine offset from alloca to lifetime object.
+ Res = DAG.getLifetimeNode(IsStart, sdl, getRoot(), FrameIndex, ObjectSize,
+ Offset);
DAG.setRoot(Res);
}
return nullptr;
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index 490b2f9..3652863 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -709,6 +709,9 @@
<< " -> "
<< ASC->getDestAddressSpace()
<< ']';
+ } else if (const LifetimeSDNode *LN = dyn_cast<LifetimeSDNode>(this)) {
+ if (LN->hasOffset())
+ OS << "<" << LN->getOffset() << " to " << LN->getOffset() + LN->getSize() << ">";
}
if (VerboseDAGDumping) {
