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Merged
merged 1 commit into from
Aug 15, 2025
Merged

RuntimeLibcalls: Generate table of libcall name lengths #153210

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5 changes: 4 additions & 1 deletion llvm/include/llvm/IR/RuntimeLibcalls.h
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Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,9 @@ struct RuntimeLibcallsInfo {
static StringRef getLibcallImplName(RTLIB::LibcallImpl CallImpl) {
if (CallImpl == RTLIB::Unsupported)
return StringRef();
return RuntimeLibcallImplNameTable[RuntimeLibcallNameOffsetTable[CallImpl]];
return StringRef(RuntimeLibcallImplNameTable.getCString(
RuntimeLibcallNameOffsetTable[CallImpl]),
RuntimeLibcallNameSizeTable[CallImpl]);
}

/// Return the lowering's selection of implementation call for \p Call
Expand Down Expand Up @@ -182,6 +184,7 @@ struct RuntimeLibcallsInfo {
LLVM_ABI static const char RuntimeLibcallImplNameTableStorage[];
LLVM_ABI static const StringTable RuntimeLibcallImplNameTable;
LLVM_ABI static const uint16_t RuntimeLibcallNameOffsetTable[];
LLVM_ABI static const uint8_t RuntimeLibcallNameSizeTable[];

/// Map from a concrete LibcallImpl implementation to its RTLIB::Libcall kind.
LLVM_ABI static const RTLIB::Libcall ImplToLibcall[RTLIB::NumLibcallImpls];
Expand Down
23 changes: 18 additions & 5 deletions llvm/test/TableGen/RuntimeLibcallEmitter.td
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Expand Up @@ -137,6 +137,19 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
// CHECK-NEXT: 54, // sqrtl
// CHECK-NEXT: 54, // sqrtl
// CHECK-NEXT: };
// CHECK-EMPTY:
// CHECK-NEXT: const uint8_t RTLIB::RuntimeLibcallsInfo::RuntimeLibcallNameSizeTable[] = {
// CHECK-NEXT: 0,
// CHECK-NEXT: 9,
// CHECK-NEXT: 9,
// CHECK-NEXT: 9,
// CHECK-NEXT: 9,
// CHECK-NEXT: 5,
// CHECK-NEXT: 6,
// CHECK-NEXT: 5,
// CHECK-NEXT: 5,
// CHECK-NEXT: };
// CHECK-EMPTY:
// CHECK-NEXT: const RTLIB::Libcall llvm::RTLIB::RuntimeLibcallsInfo::ImplToLibcall[RTLIB::NumLibcallImpls] = {
// CHECK-NEXT: RTLIB::UNKNOWN_LIBCALL, // RTLIB::Unsupported
// CHECK-NEXT: RTLIB::MEMCPY, // RTLIB::___memcpy
Expand All @@ -162,11 +175,11 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
// CHECK-NEXT: }

// CHECK: iota_range<RTLIB::LibcallImpl> RTLIB::RuntimeLibcallsInfo::lookupLibcallImplNameImpl(StringRef Name) {
// CHECK: static constexpr std::pair<uint16_t, uint16_t> HashTableNameToEnum[16] = {
// CHECK: {2, 9}, // 0x000000705301b8, ___memset
// CHECK: {0, 0},
// CHECK: {6, 6}, // 0x0000001417a2af, calloc
// CHECK: {0, 0},
// CHECK: static constexpr uint16_t HashTableNameToEnum[16] = {
// CHECK: 2, // 0x000000705301b8, ___memset
// CHECK: 0,
// CHECK: 6, // 0x0000001417a2af, calloc
// CHECK: 0,
// CHECK: };

// CHECK: unsigned Idx = (hash(Name) % 8) * 2;
Expand Down
27 changes: 17 additions & 10 deletions llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp
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Expand Up @@ -459,17 +459,14 @@ void RuntimeLibcallEmitter::emitNameMatchHashTable(
OS << "iota_range<RTLIB::LibcallImpl> RTLIB::RuntimeLibcallsInfo::"
"lookupLibcallImplNameImpl(StringRef Name) {\n";

// Emit pair of RTLIB::LibcallImpl, size of the string name. It's important to
// avoid strlen on the string table entries.
OS << " static constexpr std::pair<uint16_t, uint16_t> HashTableNameToEnum["
<< Lookup.size() << "] = {\n";
// Emit RTLIB::LibcallImpl values
OS << " static constexpr uint16_t HashTableNameToEnum[" << Lookup.size()
<< "] = {\n";

for (auto [FuncName, Hash, TableVal] : Lookup) {
OS << " {" << TableVal << ", " << FuncName.size() << "},";

if (TableVal != 0) {
OS << " " << TableVal << ',';
if (TableVal != 0)
OS << " // " << format_hex(Hash, 16) << ", " << FuncName;
}

OS << '\n';
}
Expand All @@ -480,11 +477,12 @@ void RuntimeLibcallEmitter::emitNameMatchHashTable(
<< ";\n\n"
" for (int I = 0; I != "
<< Collisions << R"(; ++I) {
auto [Entry, StringSize] = HashTableNameToEnum[Idx + I];
const uint16_t Entry = HashTableNameToEnum[Idx + I];
const uint16_t StrOffset = RuntimeLibcallNameOffsetTable[Entry];
const uint8_t StrSize = RuntimeLibcallNameSizeTable[Entry];
StringRef Str(
&RTLIB::RuntimeLibcallsInfo::RuntimeLibcallImplNameTableStorage[StrOffset],
StringSize);
StrSize);
if (Str == Name)
return libcallImplNameHit(Entry, StrOffset);
}
Expand Down Expand Up @@ -520,6 +518,15 @@ const uint16_t RTLIB::RuntimeLibcallsInfo::RuntimeLibcallNameOffsetTable[] = {
}
OS << "};\n";

OS << R"(
const uint8_t RTLIB::RuntimeLibcallsInfo::RuntimeLibcallNameSizeTable[] = {
)";

OS << " 0,\n";
for (const RuntimeLibcallImpl &LibCallImpl : RuntimeLibcallImplDefList)
OS << " " << LibCallImpl.getLibcallFuncName().size() << ",\n";
OS << "};\n\n";

// Emit the reverse mapping from implementation libraries to RTLIB::Libcall
OS << "const RTLIB::Libcall llvm::RTLIB::RuntimeLibcallsInfo::"
"ImplToLibcall[RTLIB::NumLibcallImpls] = {\n"
Expand Down