[llvm] [NFCI][TableGen] Make `Intrinsic::getAttributes` table driven (PR #152349)
Rahul Joshi via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 6 11:02:18 PDT 2025
https://github.com/jurahul created https://github.com/llvm/llvm-project/pull/152349
None
>From 6aede33b4a707c3f2705bff8cec9aead0d4f6e88 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Wed, 6 Aug 2025 08:52:07 -0700
Subject: [PATCH] [NFCI][TableGen] Make `Intrinsic::getAttributes` table driven
---
llvm/test/TableGen/intrinsic-attrs.td | 18 +-
.../utils/TableGen/Basic/IntrinsicEmitter.cpp | 176 ++++++++++++------
2 files changed, 132 insertions(+), 62 deletions(-)
diff --git a/llvm/test/TableGen/intrinsic-attrs.td b/llvm/test/TableGen/intrinsic-attrs.td
index 92a90dcafd48c..bcded0cd2e9f1 100644
--- a/llvm/test/TableGen/intrinsic-attrs.td
+++ b/llvm/test/TableGen/intrinsic-attrs.td
@@ -27,14 +27,16 @@ def int_deref_ptr_ret : Intrinsic<[llvm_ptr_ty], [], [Dereferenceable<RetIndex,
// CHECK: static constexpr uint16_t IntrinsicsToAttributesMap[] = {
// CHECK: 0 << 8 | 0, // llvm.deref.ptr.ret
// CHECK: 1 << 8 | 1, // llvm.random.gen
+// CHECK: }; // IntrinsicsToAttributesMap
+
+// CHECK: static constexpr ArgNoAttrIDPair ArgAttrIdTable[] = {
+// CHECK-NEXT: {0, 0},
+// CHECK: }; // ArgAttrIdTable
+
+// CHECK: static constexpr ArgAttributesInfo ArgAttributesInfoTable[] = {
+// CHECK-NEXT: {0, 1},
+// CHECK-NEXT: {0, 0},
+// CHECK-NEXT: }; // ArgAttributesInfoTable
// CHECK: getAttributes(LLVMContext &C, ID id,
// CHECK-NEXT: FunctionType *FT) {
-// CHECK: case 1:
-// CHECK-NEXT: HasFnAttr = true;
-// CHECK-NEXT: break;
-// CHECK-NEXT: case 0:
-// CHECK-NEXT: AS[0] = {0, getIntrinsicArgAttributeSet(C, 0, FT->getContainedType(0))};
-// CHECK-NEXT: HasFnAttr = true;
-// CHECK-NEXT: NumAttrs = 1
-// CHECK-NEXT: break;
diff --git a/llvm/utils/TableGen/Basic/IntrinsicEmitter.cpp b/llvm/utils/TableGen/Basic/IntrinsicEmitter.cpp
index 49f719453e0bb..293e64e97cc33 100644
--- a/llvm/utils/TableGen/Basic/IntrinsicEmitter.cpp
+++ b/llvm/utils/TableGen/Basic/IntrinsicEmitter.cpp
@@ -561,7 +561,8 @@ static AttributeSet getIntrinsicArgAttributeSet(LLVMContext &C, unsigned ID,
} // getIntrinsicArgAttributeSet
)";
- // Compute unique function attribute sets.
+ // Compute unique function attribute sets. Note that ID 255 will be used for
+ // intrinsics with no function attributes.
std::map<const CodeGenIntrinsic *, unsigned, FnAttributeComparator>
UniqFnAttributes;
OS << R"(
@@ -570,6 +571,8 @@ static AttributeSet getIntrinsicFnAttributeSet(LLVMContext &C, unsigned ID) {
default: llvm_unreachable("Invalid attribute set number");)";
for (const CodeGenIntrinsic &Int : Ints) {
+ if (!hasFnAttributes(Int))
+ continue;
unsigned ID = UniqFnAttributes.size();
if (!UniqFnAttributes.try_emplace(&Int, ID).second)
continue;
@@ -621,9 +624,7 @@ static AttributeSet getIntrinsicFnAttributeSet(LLVMContext &C, unsigned ID) {
static constexpr uint16_t IntrinsicsToAttributesMap[] = {)";
- // Compute the maximum number of attribute arguments and the map. For function
- // attributes, we only consider whether the intrinsics has any function
- // arguments or not.
+ // Compute unique argument attributes.
std::map<const CodeGenIntrinsic *, unsigned, AttributeComparator>
UniqAttributes;
for (const CodeGenIntrinsic &Int : Ints) {
@@ -631,86 +632,153 @@ static constexpr uint16_t IntrinsicsToAttributesMap[] = {)";
UniqAttributes.try_emplace(&Int, ID);
}
- // Emit an array of AttributeList. Most intrinsics will have at least one
- // entry, for the function itself (index ~1), which is usually nounwind.
- for (const CodeGenIntrinsic &Int : Ints) {
- uint16_t FnAttrIndex = UniqFnAttributes[&Int];
- OS << formatv("\n {} << 8 | {}, // {}", FnAttrIndex,
- UniqAttributes[&Int], Int.Name);
- }
+ 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
// its "function attribute ID" (index in UniqFnAttributes).
- if (UniqAttributes.size() > 256)
- PrintFatalError("Too many unique argument attributes for table!");
- if (UniqFnAttributes.size() > 256)
- PrintFatalError("Too many unique function attributes for table!");
+ for (const CodeGenIntrinsic &Int : Ints) {
+ uint16_t FnAttrIndex =
+ hasFnAttributes(Int) ? UniqFnAttributes[&Int] : NoFunctionAttrsID;
+ OS << formatv("\n {} << 8 | {}, // {}", FnAttrIndex,
+ UniqAttributes[&Int], Int.Name);
+ }
OS << R"(
-};
+}; // IntrinsicsToAttributesMap
+)";
+
+ // For a given intrinsic, its attributes are constructed by populating the
+ // local array `AS` below with its non-empty argument attributes followed by
+ // function attributes if any. Each argument attribute is constructed as:
+ //
+ // getIntrinsicArgAttributeSet(C, ArgAttrID, FT->getContainedType(ArgNo));
+ //
+ // Create a table that records, for each argument attributes, the set of
+ // <ArgNo, ArgAttrID> pairs that are needed to construct its argument
+ // attributes. These tables for all intrinsics will be concatenated into one
+ // large table and then for each intrinsic, we remember the Staring index and
+ // number of size of its slice of entries (i.e., number of arguments with
+ // non-empty attributes), so that we can build the attribute list for an
+ // intrinsic without using a switch-case.
+
+ // Find the max number of attributes to create the local array and create
+ // a concatenated list of <ArgNo, AttrID> pairs.
+ struct ArgNoAttrIDPair {
+ uint16_t ArgNo, ArgAttrID;
+ ArgNoAttrIDPair(uint16_t ArgNo, uint16_t ArgAttrID)
+ : ArgNo(ArgNo), ArgAttrID(ArgAttrID) {}
+ };
+
+ // For each unique ID in UniqAttributes, reacord the starting index in the
+ // flattened ArgNoAttrIDPair table, and the number of non-empty arg
+ // attributes.
+ struct ArgAttributesInfo {
+ uint16_t StartIndex;
+ uint16_t NumAttrs;
+ ArgAttributesInfo(uint16_t StartIndex, uint16_t NumAttrs)
+ : StartIndex(StartIndex), NumAttrs(NumAttrs) {}
+ };
+ SmallVector<ArgNoAttrIDPair> ArgAttrIdTable;
+ SmallVector<ArgAttributesInfo> ArgAttributesInfoTable(UniqAttributes.size(),
+ {0, 0});
-AttributeList Intrinsic::getAttributes(LLVMContext &C, ID id,
- FunctionType *FT) {)";
- // Find the max number of attributes to create the local array.
unsigned MaxNumAttrs = 0;
for (const auto [IntPtr, UniqueID] : UniqAttributes) {
const CodeGenIntrinsic &Int = *IntPtr;
- unsigned NumAttrs =
- llvm::count_if(Int.ArgumentAttributes,
- [](const auto &Attrs) { return !Attrs.empty(); });
+ unsigned NumAttrs = 0;
+ unsigned StartIndex = ArgAttrIdTable.size();
+
+ for (const auto &[ArgNo, Attrs] : enumerate(Int.ArgumentAttributes)) {
+ if (Attrs.empty())
+ continue;
+
+ uint16_t ArgAttrID = UniqArgAttributes.find(Attrs)->second;
+ ArgAttrIdTable.emplace_back((uint16_t)ArgNo, ArgAttrID);
+ ++NumAttrs;
+ }
+
+ // Record the start index and size of the list for this unique ID.
+ if (NumAttrs)
+ ArgAttributesInfoTable[UniqueID] =
+ ArgAttributesInfo(StartIndex, NumAttrs);
+
NumAttrs += hasFnAttributes(Int);
MaxNumAttrs = std::max(MaxNumAttrs, NumAttrs);
}
+ if (ArgAttrIdTable.size() >= std::numeric_limits<uint16_t>::max())
+ PrintFatalError("Size of ArgAttrIdTable exceeds supported limit");
+
+ // Emit the 2 tables (flattened ArgNo, ArgAttrID) and ArgAttrIdTableIndex
+ OS << R"(
+namespace {
+struct ArgNoAttrIDPair {
+ uint16_t ArgNo, ArgAttrID;
+};
+} // namespace
+
+static constexpr ArgNoAttrIDPair ArgAttrIdTable[] = {
+)";
+ for (const auto &[ArgNo, ArgAttrID] : ArgAttrIdTable)
+ OS << formatv(" {{{}, {}},\n", ArgNo, ArgAttrID);
+ OS << R"(}; // ArgAttrIdTable
+
+namespace {
+struct ArgAttributesInfo {
+ uint16_t StartIndex;
+ uint16_t NumAttrs;
+};
+} // namespace
+
+static constexpr ArgAttributesInfo ArgAttributesInfoTable[] = {
+)";
+ for (const auto &[StartIndex, NumAttrs] : ArgAttributesInfoTable)
+ OS << formatv(" {{{}, {}},\n", StartIndex, NumAttrs);
+ OS << "}; // ArgAttributesInfoTable\n";
+
+ // Now emit the Intrinsic::getAttributes function. This will first map
+ // from intrinsic ID -> unique arg/function attr ID (using the
+ // IntrinsicsToAttributesMap) table. Then it will use the unique arg ID to
+ // construct all the argument attributes (using the ArgAttributesInfoTable and
+ // ArgAttrIdTable) and then add on the function attributes if any.
OS << formatv(R"(
+AttributeList Intrinsic::getAttributes(LLVMContext &C, ID id,
+ FunctionType *FT) {{
if (id == 0)
return AttributeList();
uint16_t PackedID = IntrinsicsToAttributesMap[id - 1];
uint8_t FnAttrID = PackedID >> 8;
+ uint8_t ArgAttrID = PackedID & 0xFF;
std::pair<unsigned, AttributeSet> AS[{}];
- unsigned NumAttrs = 0;
- bool HasFnAttr = false;
- switch(PackedID & 0xFF) {{
- default: llvm_unreachable("Invalid attribute number");
-)",
- MaxNumAttrs);
- for (const auto [IntPtr, UniqueID] : UniqAttributes) {
- OS << formatv(" case {}:\n", UniqueID);
- const CodeGenIntrinsic &Int = *IntPtr;
-
- unsigned NumAttrs = 0;
-
- for (const auto &[AttrIdx, Attrs] : enumerate(Int.ArgumentAttributes)) {
- if (Attrs.empty())
- continue;
+ // Construct an ArrayRef for easier range checking.
+ ArrayRef<ArgAttributesInfo> ArgAttributesInfoTableAR(ArgAttributesInfoTable);
+ if (ArgAttrID >= ArgAttributesInfoTableAR.size())
+ llvm_unreachable("Invalid arguments attribute ID");
- unsigned ArgAttrID = UniqArgAttributes.find(Attrs)->second;
- OS << formatv(" AS[{}] = {{{}, getIntrinsicArgAttributeSet(C, {}, "
- "FT->getContainedType({}))};\n",
- NumAttrs++, AttrIdx, ArgAttrID, AttrIdx);
- }
-
- if (hasFnAttributes(Int))
- OS << " HasFnAttr = true;\n";
-
- if (NumAttrs)
- OS << formatv(" NumAttrs = {};\n", NumAttrs);
- OS << " break;\n";
+ auto [StartIndex, NumAttrs] = ArgAttributesInfoTableAR[ArgAttrID];
+ for (unsigned Idx = 0; Idx < NumAttrs; ++Idx) {{
+ auto [ArgNo, ArgAttrID] = ArgAttrIdTable[StartIndex + Idx];
+ AS[Idx] = {{ArgNo,
+ getIntrinsicArgAttributeSet(C, ArgAttrID, FT->getContainedType(ArgNo))};
}
-
- OS << R"( }
- if (HasFnAttr) {
- AS[NumAttrs++] = {AttributeList::FunctionIndex,
+ if (FnAttrID != {}) {
+ AS[NumAttrs++] = {{AttributeList::FunctionIndex,
getIntrinsicFnAttributeSet(C, FnAttrID)};
}
return AttributeList::get(C, ArrayRef(AS, NumAttrs));
}
#endif // GET_INTRINSIC_ATTRIBUTES
-)";
+)",
+ MaxNumAttrs, NoFunctionAttrsID);
}
void IntrinsicEmitter::EmitIntrinsicToBuiltinMap(
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