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[IntrinsicEmitter] Make AttributesMap PackedID type-adaptive #158383

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Sep 19, 2025
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[IntrinsicEmitter] Make AttributesMap PackedID type-adaptive #158383

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2 changes: 1 addition & 1 deletion llvm/test/TableGen/intrinsic-attrs.td
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ def int_deref_ptr_ret : Intrinsic<[llvm_ptr_ty], [], [Dereferenceable<RetIndex,
// CHECK-NEXT: Attribute::get(C, Attribute::NoUnwind),
// CHECK-NEXT: });

// CHECK: static constexpr uint16_t IntrinsicsToAttributesMap[] = {
// CHECK: static constexpr uint8_t IntrinsicsToAttributesMap[] = {
// CHECK: 0 << 1 | 0, // llvm.deref.ptr.ret
// CHECK: 1 << 1 | 1, // llvm.random.gen
// CHECK: }; // IntrinsicsToAttributesMap
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55 changes: 33 additions & 22 deletions llvm/utils/TableGen/Basic/IntrinsicEmitter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -617,9 +617,7 @@ static AttributeSet getIntrinsicFnAttributeSet(LLVMContext &C, unsigned ID) {
}
OS << R"(
}
} // getIntrinsicFnAttributeSet

static constexpr uint16_t IntrinsicsToAttributesMap[] = {)";
} // getIntrinsicFnAttributeSet)";

// Compute unique argument attributes.
std::map<const CodeGenIntrinsic *, unsigned, AttributeComparator>
Expand All @@ -630,20 +628,29 @@ static constexpr uint16_t IntrinsicsToAttributesMap[] = {)";
}

const uint8_t UniqAttributesBitSize = Log2_32_Ceil(UniqAttributes.size());
// Note, ID `-1` is used to indicate no function attributes.
// Note, max value is used to indicate no function attributes.
const uint8_t UniqFnAttributesBitSize =
Log2_32_Ceil(UniqFnAttributes.size() + 1);
const uint16_t NoFunctionAttrsID =
maskTrailingOnes<uint16_t>(UniqFnAttributesBitSize);
if (UniqAttributesBitSize + UniqFnAttributesBitSize > 16)
PrintFatalError(
"More than 16 bits are used for IntrinsicsToAttributesMap's entry!");

// Assign a 16-bit packed ID for each intrinsic. The lower bits will be its
const uint32_t NoFunctionAttrsID =
maskTrailingOnes<uint32_t>(UniqFnAttributesBitSize);
uint8_t AttributesMapDataBitSize =
PowerOf2Ceil(UniqAttributesBitSize + UniqFnAttributesBitSize);
if (AttributesMapDataBitSize < 8)
AttributesMapDataBitSize = 8;
else if (AttributesMapDataBitSize > 64)
PrintFatalError("Packed ID of IntrinsicsToAttributesMap exceeds 64b!");
else if (AttributesMapDataBitSize > 16)
PrintWarning("Packed ID of IntrinsicsToAttributesMap exceeds 16b, "
"this may cause performance drop (pr106809), "
"please consider redesigning intrinsic sets!");

// Assign a packed ID for each intrinsic. The lower bits will be its
// "argument attribute ID" (index in UniqAttributes) and upper bits will be
// its "function attribute ID" (index in UniqFnAttributes).
OS << formatv("\nstatic constexpr uint{}_t IntrinsicsToAttributesMap[] = {{",
AttributesMapDataBitSize);
for (const CodeGenIntrinsic &Int : Ints) {
uint16_t FnAttrIndex =
uint32_t FnAttrIndex =
hasFnAttributes(Int) ? UniqFnAttributes[&Int] : NoFunctionAttrsID;
OS << formatv("\n {} << {} | {}, // {}", FnAttrIndex,
UniqAttributesBitSize, UniqAttributes[&Int], Int.Name);
Expand Down Expand Up @@ -746,14 +753,21 @@ static constexpr ArgAttributesInfo ArgAttributesInfoTable[] = {{
// construct all the argument attributes (using the ArgAttributesInfoTable and
// ArgAttrIdTable) and then add on the function attributes if any.
OS << formatv(R"(

template <typename IDTy>
inline std::pair<uint32_t, uint32_t> unpackID(const IDTy PackedID) {{
constexpr uint8_t UniqAttributesBitSize = {};
const uint32_t FnAttrID = PackedID >> UniqAttributesBitSize;
const uint32_t ArgAttrID = PackedID &
maskTrailingOnes<uint32_t>(UniqAttributesBitSize);
return {{FnAttrID, ArgAttrID};
}

AttributeList Intrinsic::getAttributes(LLVMContext &C, ID id,
FunctionType *FT) {{
if (id == 0)
return AttributeList();

uint16_t PackedID = IntrinsicsToAttributesMap[id - 1];
uint16_t FnAttrID = PackedID >> ({});
uint16_t ArgAttrID = PackedID & ({});
auto [FnAttrID, ArgAttrID] = unpackID(IntrinsicsToAttributesMap[id - 1]);
using PairTy = std::pair<unsigned, AttributeSet>;
alignas(PairTy) char ASStorage[sizeof(PairTy) * {}];
PairTy *AS = reinterpret_cast<PairTy *>(ASStorage);
Expand All @@ -776,19 +790,16 @@ AttributeList Intrinsic::getAttributes(LLVMContext &C, ID id,
return AttributeList::get(C, ArrayRef(AS, NumAttrs));
}

AttributeSet Intrinsic::getFnAttributes(LLVMContext &C, ID id) {
AttributeSet Intrinsic::getFnAttributes(LLVMContext &C, ID id) {{
if (id == 0)
return AttributeSet();
uint16_t PackedID = IntrinsicsToAttributesMap[id - 1];
uint16_t FnAttrID = PackedID >> ({});
auto [FnAttrID, _] = unpackID(IntrinsicsToAttributesMap[id - 1]);
return getIntrinsicFnAttributeSet(C, FnAttrID);
}
#endif // GET_INTRINSIC_ATTRIBUTES

)",
UniqAttributesBitSize,
maskTrailingOnes<uint16_t>(UniqAttributesBitSize), MaxNumAttrs,
NoFunctionAttrsID, UniqAttributesBitSize);
UniqAttributesBitSize, MaxNumAttrs, NoFunctionAttrsID);
}

void IntrinsicEmitter::EmitIntrinsicToBuiltinMap(
Expand Down