Switch the intrinsic names to a string table

llvm/include/llvm/IR/Intrinsics.h

@@ -112,13 +112,6 @@ namespace Intrinsic {
   Function *getDeclarationIfExists(Module *M, ID id, ArrayRef<Type *> Tys,
                                    FunctionType *FT = nullptr);
 
-  /// Looks up Name in NameTable via binary search. NameTable must be sorted
-  /// and all entries must start with "llvm.".  If NameTable contains an exact
-  /// match for Name or a prefix of Name followed by a dot, its index in
-  /// NameTable is returned. Otherwise, -1 is returned.
-  int lookupLLVMIntrinsicByName(ArrayRef<const char *> NameTable,
-                                StringRef Name, StringRef Target = "");
-
   /// Map a Clang builtin name to an intrinsic ID.
   ID getIntrinsicForClangBuiltin(StringRef TargetPrefix, StringRef BuiltinName);
 

llvm/lib/IR/Intrinsics.cpp

@@ -34,16 +34,13 @@
 using namespace llvm;
 
 /// Table of string intrinsic names indexed by enum value.
-static constexpr const char *const IntrinsicNameTable[] = {
-    "not_intrinsic",
 #define GET_INTRINSIC_NAME_TABLE
 #include "llvm/IR/IntrinsicImpl.inc"
 #undef GET_INTRINSIC_NAME_TABLE
-};
 
 StringRef Intrinsic::getBaseName(ID id) {
   assert(id < num_intrinsics && "Invalid intrinsic ID!");
-  return IntrinsicNameTable[id];
+  return IntrinsicNameTable + IntrinsicNameOffsetTable[id];
 }
 
 StringRef Intrinsic::getName(ID id) {
@@ -621,9 +618,12 @@ bool Intrinsic::isTargetIntrinsic(Intrinsic::ID IID) {
   return IID > TargetInfos[0].Count;
 }
 
-int llvm::Intrinsic::lookupLLVMIntrinsicByName(ArrayRef<const char *> NameTable,
-                                               StringRef Name,
-                                               StringRef Target) {
+/// Looks up Name in NameTable via binary search. NameTable must be sorted
+/// and all entries must start with "llvm.".  If NameTable contains an exact
+/// match for Name or a prefix of Name followed by a dot, its index in
+/// NameTable is returned. Otherwise, -1 is returned.
+static int lookupLLVMIntrinsicByName(ArrayRef<unsigned> NameOffsetTable,
+                                     StringRef Name, StringRef Target = "") {
   assert(Name.starts_with("llvm.") && "Unexpected intrinsic prefix");
   assert(Name.drop_front(5).starts_with(Target) && "Unexpected target");
 
@@ -638,36 +638,53 @@ int llvm::Intrinsic::lookupLLVMIntrinsicByName(ArrayRef<const char *> NameTable,
   if (!Target.empty())
     CmpEnd += 1 + Target.size(); // skip the .target component.
 
-  const char *const *Low = NameTable.begin();
-  const char *const *High = NameTable.end();
-  const char *const *LastLow = Low;
+  const unsigned *Low = NameOffsetTable.begin();
+  const unsigned *High = NameOffsetTable.end();
+  const unsigned *LastLow = Low;
   while (CmpEnd < Name.size() && High - Low > 0) {
     size_t CmpStart = CmpEnd;
     CmpEnd = Name.find('.', CmpStart + 1);
     CmpEnd = CmpEnd == StringRef::npos ? Name.size() : CmpEnd;
-    auto Cmp = [CmpStart, CmpEnd](const char *LHS, const char *RHS) {
-      return strncmp(LHS + CmpStart, RHS + CmpStart, CmpEnd - CmpStart) < 0;
+    auto Cmp = [CmpStart, CmpEnd](auto LHS, auto RHS) {
+      // `equal_range` requires the comparison to work with either side being an
+      // offset or the value. Detect which kind each side is to set up the
+      // compared strings.
+      const char *LHSStr;
+      if constexpr (std::is_integral_v<decltype(LHS)>) {
+        LHSStr = &IntrinsicNameTable[LHS];
+      } else {
+        LHSStr = LHS;
+      }
+      const char *RHSStr;
+      if constexpr (std::is_integral_v<decltype(RHS)>) {
+        RHSStr = &IntrinsicNameTable[RHS];
+      } else {
+        RHSStr = RHS;
+      }
+      return strncmp(LHSStr + CmpStart, RHSStr + CmpStart, CmpEnd - CmpStart) <
+             0;
     };
     LastLow = Low;
     std::tie(Low, High) = std::equal_range(Low, High, Name.data(), Cmp);
   }
   if (High - Low > 0)
     LastLow = Low;
 
-  if (LastLow == NameTable.end())
+  if (LastLow == NameOffsetTable.end())
     return -1;
-  StringRef NameFound = *LastLow;
+  StringRef NameFound = &IntrinsicNameTable[*LastLow];
   if (Name == NameFound ||
       (Name.starts_with(NameFound) && Name[NameFound.size()] == '.'))
-    return LastLow - NameTable.begin();
+    return LastLow - NameOffsetTable.begin();
   return -1;
 }
 
-/// Find the segment of \c IntrinsicNameTable for intrinsics with the same
+/// Find the segment of \c IntrinsicNameOffsetTable for intrinsics with the same
 /// target as \c Name, or the generic table if \c Name is not target specific.
 ///
-/// Returns the relevant slice of \c IntrinsicNameTable and the target name.
-static std::pair<ArrayRef<const char *>, StringRef>
+/// Returns the relevant slice of \c IntrinsicNameOffsetTable and the target
+/// name.
+static std::pair<ArrayRef<unsigned>, StringRef>
 findTargetSubtable(StringRef Name) {
   assert(Name.starts_with("llvm."));
 
@@ -680,25 +697,26 @@ findTargetSubtable(StringRef Name) {
   // We've either found the target or just fall back to the generic set, which
   // is always first.
   const auto &TI = It != Targets.end() && It->Name == Target ? *It : Targets[0];
-  return {ArrayRef(&IntrinsicNameTable[1] + TI.Offset, TI.Count), TI.Name};
+  return {ArrayRef(&IntrinsicNameOffsetTable[1] + TI.Offset, TI.Count),
+          TI.Name};
 }
 
 /// This does the actual lookup of an intrinsic ID which matches the given
 /// function name.
 Intrinsic::ID Intrinsic::lookupIntrinsicID(StringRef Name) {
-  auto [NameTable, Target] = findTargetSubtable(Name);
-  int Idx = Intrinsic::lookupLLVMIntrinsicByName(NameTable, Name, Target);
+  auto [NameOffsetTable, Target] = findTargetSubtable(Name);
+  int Idx = lookupLLVMIntrinsicByName(NameOffsetTable, Name, Target);
   if (Idx == -1)
     return Intrinsic::not_intrinsic;
 
   // Intrinsic IDs correspond to the location in IntrinsicNameTable, but we have
   // an index into a sub-table.
-  int Adjust = NameTable.data() - IntrinsicNameTable;
+  int Adjust = NameOffsetTable.data() - IntrinsicNameOffsetTable;
   Intrinsic::ID ID = static_cast<Intrinsic::ID>(Idx + Adjust);
 
   // If the intrinsic is not overloaded, require an exact match. If it is
   // overloaded, require either exact or prefix match.
-  const auto MatchSize = strlen(NameTable[Idx]);
+  const auto MatchSize = strlen(&IntrinsicNameTable[NameOffsetTable[Idx]]);
   assert(Name.size() >= MatchSize && "Expected either exact or prefix match");
   bool IsExactMatch = Name.size() == MatchSize;
   return IsExactMatch || Intrinsic::isOverloaded(ID) ? ID

llvm/unittests/IR/IntrinsicsTest.cpp

@@ -63,24 +63,21 @@ class IntrinsicsTest : public ::testing::Test {
 };
 
 TEST(IntrinsicNameLookup, Basic) {
-  static constexpr const char *const NameTable[] = {
-      "llvm.foo", "llvm.foo.a", "llvm.foo.b", "llvm.foo.b.a", "llvm.foo.c",
-  };
+  using namespace Intrinsic;
+  EXPECT_EQ(Intrinsic::memcpy, lookupIntrinsicID("llvm.memcpy"));
 
-  static constexpr std::pair<const char *, int> Tests[] = {
-      {"llvm.foo", 0},     {"llvm.foo.f64", 0}, {"llvm.foo.b", 2},
-      {"llvm.foo.b.a", 3}, {"llvm.foo.c", 4},   {"llvm.foo.c.f64", 4},
-      {"llvm.bar", -1},
-  };
+  // Partial, either between dots or not the last dot are not intrinsics.
+  EXPECT_EQ(not_intrinsic, lookupIntrinsicID("llvm.mem"));
+  EXPECT_EQ(not_intrinsic, lookupIntrinsicID("llvm.gc"));
 
-  for (const auto &[Name, ExpectedIdx] : Tests) {
-    int Idx = Intrinsic::lookupLLVMIntrinsicByName(NameTable, Name);
-    EXPECT_EQ(ExpectedIdx, Idx);
-    if (!StringRef(Name).starts_with("llvm.foo"))
-      continue;
-    Idx = Intrinsic::lookupLLVMIntrinsicByName(NameTable, Name, "foo");
-    EXPECT_EQ(ExpectedIdx, Idx);
-  }
+  // Look through intrinsic names with internal dots.
+  EXPECT_EQ(memcpy_inline, lookupIntrinsicID("llvm.memcpy.inline"));
+
+  // Check that overloaded names are mapped to the underlying ID.
+  EXPECT_EQ(memcpy_inline, lookupIntrinsicID("llvm.memcpy.inline.p0.p0.i8"));
+  EXPECT_EQ(memcpy_inline, lookupIntrinsicID("llvm.memcpy.inline.p0.p0.i32"));
+  EXPECT_EQ(memcpy_inline, lookupIntrinsicID("llvm.memcpy.inline.p0.p0.i64"));
+  EXPECT_EQ(memcpy_inline, lookupIntrinsicID("llvm.memcpy.inline.p0.p0.i1024"));
 }
 
 // Tests to verify getIntrinsicForClangBuiltin.

llvm/utils/TableGen/IntrinsicEmitter.cpp

@@ -239,13 +239,37 @@ static constexpr IntrinsicTargetInfo TargetInfos[] = {
 
 void IntrinsicEmitter::EmitIntrinsicToNameTable(
     const CodeGenIntrinsicTable &Ints, raw_ostream &OS) {
+  // Built up a table of the intrinsic names.
+  constexpr StringLiteral NotIntrinsic = "not_intrinsic";
+  StringToOffsetTable Table;
+  Table.GetOrAddStringOffset(NotIntrinsic);
+  for (const auto &Int : Ints)
+    Table.GetOrAddStringOffset(Int.Name);
+
   OS << R"(// Intrinsic ID to name table.
 #ifdef GET_INTRINSIC_NAME_TABLE
 // Note that entry #0 is the invalid intrinsic!
+
+)";
+
+  Table.EmitStringLiteralDef(OS, "static constexpr char IntrinsicNameTable[]",
+                             /*Indent=*/"");
+
+  OS << R"(
+static constexpr unsigned IntrinsicNameOffsetTable[] = {
 )";
+
+  OS << formatv("  {}, // {}\n", Table.GetStringOffset(NotIntrinsic),
+                NotIntrinsic);
   for (const auto &Int : Ints)
-    OS << "  \"" << Int.Name << "\",\n";
-  OS << "#endif\n\n";
+    OS << formatv("  {}, // {}\n", Table.GetStringOffset(Int.Name), Int.Name);
+
+  OS << R"(
+}; // IntrinsicNameOffsetTable
+
+#endif
+
+)";
 }
 
 void IntrinsicEmitter::EmitIntrinsicToOverloadTable(