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[IntrinsicEmitter] Make AttributesMap bits adaptive #157965

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Merged
merged 1 commit into from
Sep 12, 2025
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[IntrinsicEmitter] Make AttributesMap bits adaptive #157965

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8 changes: 0 additions & 8 deletions llvm/lib/IR/Intrinsics.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -740,14 +740,6 @@ Intrinsic::ID Intrinsic::lookupIntrinsicID(StringRef Name) {
#include "llvm/IR/IntrinsicImpl.inc"
#undef GET_INTRINSIC_ATTRIBUTES

AttributeSet Intrinsic::getFnAttributes(LLVMContext &C, ID id) {
if (id == 0)
return AttributeSet();
uint16_t PackedID = IntrinsicsToAttributesMap[id - 1];
uint8_t FnAttrID = PackedID >> 8;
return getIntrinsicFnAttributeSet(C, FnAttrID);
}

Function *Intrinsic::getOrInsertDeclaration(Module *M, ID id,
ArrayRef<Type *> Tys) {
// There can never be multiple globals with the same name of different types,
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4 changes: 2 additions & 2 deletions llvm/test/TableGen/intrinsic-attrs.td
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Expand Up @@ -25,8 +25,8 @@ def int_deref_ptr_ret : Intrinsic<[llvm_ptr_ty], [], [Dereferenceable<RetIndex,
// CHECK-NEXT: });

// CHECK: static constexpr uint16_t IntrinsicsToAttributesMap[] = {
// CHECK: 0 << 8 | 0, // llvm.deref.ptr.ret
// CHECK: 1 << 8 | 1, // llvm.random.gen
// CHECK: 0 << 2 | 0, // llvm.deref.ptr.ret
// CHECK: 1 << 2 | 1, // llvm.random.gen
// CHECK: }; // IntrinsicsToAttributesMap

// CHECK: static constexpr ArgNoAttrIDPair ArgAttrIdTable[] = {
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41 changes: 27 additions & 14 deletions llvm/utils/TableGen/Basic/IntrinsicEmitter.cpp
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Expand Up @@ -629,21 +629,24 @@ static constexpr uint16_t IntrinsicsToAttributesMap[] = {)";
UniqAttributes.try_emplace(&Int, ID);
}

constexpr uint16_t NoFunctionAttrsID = 255;
if (UniqAttributes.size() > 256)
PrintFatalError("Too many unique argument attributes for table!");
// Note, ID 255 is used to indicate no function attributes.
if (UniqFnAttributes.size() > 255)
PrintFatalError("Too many unique function attributes for table!");

// Assign a 16-bit packed ID for each intrinsic. The lower 8-bits will be its
// "argument attribute ID" (index in UniqAttributes) and upper 8 bits will be
const uint8_t UniqAttributesBitSize = Log2_32_Ceil(UniqAttributes.size() + 1);
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@jurahul jurahul Sep 14, 2025 •
edited
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@elvinw-intel why is the +1 needed here? Assuming UniqAttributes.size() == 256, we should be able to use 8 bits, but it seems here it will use 9 bits.

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@elvinw-intel why is the +1 needed here? Assuming UniqAttributes.size() == 256, we should be able to use 8 bits, but it seems here it will use 9 bits.

yes that is incorrect and need to be fixed - I can add the fix in follow up or create a new draft.

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Thanks. A separate PR may be preferable to not mix two things in one.

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#158714 to adjust both bit calculations

// Note, ID `-1` is used to indicate no function attributes.
const uint8_t UniqFnAttributesBitSize =
Log2_32_Ceil(UniqFnAttributes.size() + 2);
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
// "argument attribute ID" (index in UniqAttributes) and upper bits will be
// its "function attribute ID" (index in UniqFnAttributes).
for (const CodeGenIntrinsic &Int : Ints) {
uint16_t FnAttrIndex =
hasFnAttributes(Int) ? UniqFnAttributes[&Int] : NoFunctionAttrsID;
OS << formatv("\n {} << 8 | {}, // {}", FnAttrIndex,
UniqAttributes[&Int], Int.Name);
OS << formatv("\n {} << {} | {}, // {}", FnAttrIndex,
UniqAttributesBitSize, UniqAttributes[&Int], Int.Name);
}

OS << R"(
Expand Down Expand Up @@ -749,8 +752,8 @@ AttributeList Intrinsic::getAttributes(LLVMContext &C, ID id,
return AttributeList();

uint16_t PackedID = IntrinsicsToAttributesMap[id - 1];
uint8_t FnAttrID = PackedID >> 8;
uint8_t ArgAttrID = PackedID & 0xFF;
uint16_t FnAttrID = PackedID >> ({});
uint16_t ArgAttrID = PackedID & ({});
using PairTy = std::pair<unsigned, AttributeSet>;
alignas(PairTy) char ASStorage[sizeof(PairTy) * {}];
PairTy *AS = reinterpret_cast<PairTy *>(ASStorage);
Expand All @@ -772,10 +775,20 @@ AttributeList Intrinsic::getAttributes(LLVMContext &C, ID id,
}
return AttributeList::get(C, ArrayRef(AS, NumAttrs));
}

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

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

void IntrinsicEmitter::EmitIntrinsicToBuiltinMap(
Expand Down