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[LLVM][SelectionDAG] Ensure Constant[FP]SDnode only store references to scalar Constant{Int,FP}. #111005

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Merged
merged 2 commits into from
Oct 15, 2024
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[LLVM][SelectionDAG] Ensure Constant[FP]SDnode only store references to scalar Constant{Int,FP}. #111005

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[LLVM][SelectionDAG] Ensure Constant[FP]SDnode only store references …
paulwalker-arm Oct 1, 2024
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paulwalker-arm Oct 10, 2024
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5 changes: 4 additions & 1 deletion llvm/include/llvm/CodeGen/SelectionDAGNodes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1678,6 +1678,7 @@ class ConstantSDNode : public SDNode {
: SDNode(isTarget ? ISD::TargetConstant : ISD::Constant, 0, DebugLoc(),
VTs),
Value(val) {
assert(!isa<VectorType>(val->getType()) && "Unexpected vector type!");
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@david-arm david-arm Oct 10, 2024

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This is just a thought, but is it worth tying these asserts down even further, i.e.

assert(val->getType()->isIntegerTy() && "Unexpected type!");

and similarly for the FP node? At the moment, these nodes still won't assert for any other unusual types.

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@paulwalker-arm paulwalker-arm Oct 10, 2024

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That's handled as part of ConstantInt construction and thus here we can safely assume val has a valid type for its class.

ConstantSDNodeBits.IsOpaque = isOpaque;
}

Expand Down Expand Up @@ -1730,7 +1731,9 @@ class ConstantFPSDNode : public SDNode {
ConstantFPSDNode(bool isTarget, const ConstantFP *val, SDVTList VTs)
: SDNode(isTarget ? ISD::TargetConstantFP : ISD::ConstantFP, 0,
DebugLoc(), VTs),
Value(val) {}
Value(val) {
assert(!isa<VectorType>(val->getType()) && "Unexpected vector type!");
}

public:
const APFloat& getValueAPF() const { return Value->getValueAPF(); }
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15 changes: 13 additions & 2 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Expand Up @@ -1656,6 +1656,11 @@ SDValue SelectionDAG::getConstant(const ConstantInt &Val, const SDLoc &DL,
EVT EltVT = VT.getScalarType();
const ConstantInt *Elt = &Val;

// Vector splats are explicit within the DAG, with ConstantSDNode holding the
// to be splatted scalar ConstantInt.
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@david-arm david-arm Oct 10, 2024

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nit: to-be-splatted?

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@paulwalker-arm paulwalker-arm Oct 10, 2024

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Done.

if (isa<VectorType>(Elt->getType()))
Elt = ConstantInt::get(*getContext(), Elt->getValue());

// In some cases the vector type is legal but the element type is illegal and
// needs to be promoted, for example v8i8 on ARM. In this case, promote the
// inserted value (the type does not need to match the vector element type).
Expand Down Expand Up @@ -1809,6 +1814,12 @@ SDValue SelectionDAG::getConstantFP(const ConstantFP &V, const SDLoc &DL,
assert(VT.isFloatingPoint() && "Cannot create integer FP constant!");

EVT EltVT = VT.getScalarType();
const ConstantFP *Elt = &V;

// Vector splats are explicit within the DAG, with ConstantFPSDNode holding
// the to be splatted scalar ConstantFP.
if (isa<VectorType>(Elt->getType()))
Elt = ConstantFP::get(*getContext(), Elt->getValue());

// Do the map lookup using the actual bit pattern for the floating point
// value, so that we don't have problems with 0.0 comparing equal to -0.0, and
Expand All @@ -1817,15 +1828,15 @@ SDValue SelectionDAG::getConstantFP(const ConstantFP &V, const SDLoc &DL,
SDVTList VTs = getVTList(EltVT);
FoldingSetNodeID ID;
AddNodeIDNode(ID, Opc, VTs, {});
ID.AddPointer(&V);
ID.AddPointer(Elt);
void *IP = nullptr;
SDNode *N = nullptr;
if ((N = FindNodeOrInsertPos(ID, DL, IP)))
if (!VT.isVector())
return SDValue(N, 0);

if (!N) {
N = newSDNode<ConstantFPSDNode>(isTarget, &V, VTs);
N = newSDNode<ConstantFPSDNode>(isTarget, Elt, VTs);
CSEMap.InsertNode(N, IP);
InsertNode(N);
}
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1 change: 1 addition & 0 deletions llvm/test/CodeGen/AArch64/sve-fp-immediates-merging.ll
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@@ -1,5 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s | FileCheck %s
; RUN: llc -use-constant-fp-for-scalable-splat < %s | FileCheck %s

target triple = "aarch64-unknown-linux-gnu"

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1 change: 1 addition & 0 deletions llvm/test/CodeGen/AArch64/sve-int-imm.ll
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@@ -1,4 +1,5 @@
; RUN: llc -mtriple=aarch64-linux-gnu -mattr=+sve < %s | FileCheck %s
; RUN: llc -mtriple=aarch64-linux-gnu -mattr=+sve -use-constant-int-for-scalable-splat < %s | FileCheck %s

;
; SVE Arith Vector Immediate Unpredicated CodeGen
Expand Down