TableGen: Use StringOffsetTable for RuntimeLibcall names

llvm/include/llvm/IR/RuntimeLibcalls.h

@@ -16,6 +16,7 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Sequence.h"
+#include "llvm/ADT/StringTable.h"
 #include "llvm/IR/CallingConv.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/Support/AtomicOrdering.h"
@@ -77,12 +78,16 @@ struct RuntimeLibcallsInfo {
   /// Get the libcall routine name for the specified libcall.
   // FIXME: This should be removed. Only LibcallImpl should have a name.
   const char *getLibcallName(RTLIB::Libcall Call) const {
-    return LibCallImplNames[LibcallImpls[Call]];
+    return getLibcallImplName(LibcallImpls[Call]);
   }
 
   /// Get the libcall routine name for the specified libcall implementation.
+  // FIXME: Change to return StringRef
   static const char *getLibcallImplName(RTLIB::LibcallImpl CallImpl) {
-    return LibCallImplNames[CallImpl];
+    if (CallImpl == RTLIB::Unsupported)
+      return nullptr;
+    return RuntimeLibcallImplNameTable[RuntimeLibcallNameOffsetTable[CallImpl]]
+        .data();
   }
 
   /// Return the lowering's selection of implementation call for \p Call
@@ -144,7 +149,9 @@ struct RuntimeLibcallsInfo {
 
   /// Names of concrete implementations of runtime calls. e.g. __ashlsi3 for
   /// SHL_I32
-  LLVM_ABI static const char *const LibCallImplNames[RTLIB::NumLibcallImpls];
+  LLVM_ABI static const char RuntimeLibcallImplNameTableStorage[];
+  LLVM_ABI static const StringTable RuntimeLibcallImplNameTable;
+  LLVM_ABI static const uint16_t RuntimeLibcallNameOffsetTable[];
 
   /// Map from a concrete LibcallImpl implementation to its RTLIB::Libcall kind.
   LLVM_ABI static const RTLIB::Libcall ImplToLibcall[RTLIB::NumLibcallImpls];

llvm/include/llvm/TableGen/StringToOffsetTable.h

@@ -23,10 +23,15 @@ namespace llvm {
 class StringToOffsetTable {
   StringMap<unsigned> StringOffset;
   std::string AggregateString;
+
+  /// If this is to be a static class member, the prefix to use (i.e. class name
+  /// plus ::)
+  const StringRef ClassPrefix;
   const bool AppendZero;
 
 public:
-  StringToOffsetTable(bool AppendZero = true) : AppendZero(AppendZero) {
+  StringToOffsetTable(bool AppendZero = true, StringRef ClassPrefix = "")
+      : ClassPrefix(ClassPrefix), AppendZero(AppendZero) {
     // Ensure we always put the empty string at offset zero. That lets empty
     // initialization also be zero initialization for offsets into the table.
     GetOrAddStringOffset("");

llvm/lib/IR/RuntimeLibcalls.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/IR/RuntimeLibcalls.h"
+#include "llvm/ADT/StringTable.h"
 
 using namespace llvm;
 using namespace RTLIB;

llvm/lib/TableGen/StringToOffsetTable.cpp

@@ -38,8 +38,8 @@ void StringToOffsetTable::EmitStringTableDef(raw_ostream &OS,
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Woverlength-strings"
 #endif
-static constexpr char {}Storage[] = )",
-                Name);
+{} constexpr char {}{}Storage[] = )",
+                ClassPrefix.empty() ? "static" : "", ClassPrefix, Name);
 
   // MSVC silently miscompiles string literals longer than 64k in some
   // circumstances. The build system sets EmitLongStrLiterals to false when it
@@ -83,10 +83,10 @@ static constexpr char {}Storage[] = )",
 #pragma GCC diagnostic pop
 #endif
 
-static constexpr llvm::StringTable
-{0} = {0}Storage;
+{1}constexpr llvm::StringTable
+{2}{0} = {0}Storage;
 )",
-                Name);
+                Name, ClassPrefix.empty() ? "static " : "", ClassPrefix);
 }
 
 void StringToOffsetTable::EmitString(raw_ostream &O) const {

llvm/test/TableGen/RuntimeLibcallEmitter.td

@@ -116,19 +116,40 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
 // CHECK-NEXT:   RTLIB::Unsupported
 // CHECK-NEXT: };
 // CHECK-EMPTY:
-// CHECK-NEXT: const char *const llvm::RTLIB::RuntimeLibcallsInfo::LibCallImplNames[RTLIB::NumLibcallImpls] = {
-// CHECK-NEXT: nullptr, // RTLIB::Unsupported
-// CHECK-NEXT: "___memcpy", // RTLIB::___memcpy
-// CHECK-NEXT: "___memset", // RTLIB::___memset
-// CHECK-NEXT: "__ashlsi3", // RTLIB::__ashlsi3
-// CHECK-NEXT: "__lshrdi3", // RTLIB::__lshrdi3
-// CHECK-NEXT: "bzero", // RTLIB::bzero
-// CHECK-NEXT: "calloc", // RTLIB::calloc
-// CHECK-NEXT: "sqrtl", // RTLIB::sqrtl_f80
-// CHECK-NEXT: "sqrtl", // RTLIB::sqrtl_f128
+// CHECK-EMPTY:
+// CHECK-NEXT: #ifdef __GNUC__
+// CHECK-NEXT: #pragma GCC diagnostic push
+// CHECK-NEXT: #pragma GCC diagnostic ignored "-Woverlength-strings"
+// CHECK-NEXT: #endif
+// CHECK-NEXT:  constexpr char RTLIB::RuntimeLibcallsInfo::RuntimeLibcallImplNameTableStorage[] =
+// CHECK-NEXT:   "\0"
+// CHECK-NEXT:   "___memcpy\0"
+// CHECK-NEXT:   "___memset\0"
+// CHECK-NEXT:   "__ashlsi3\0"
+// CHECK-NEXT:   "__lshrdi3\0"
+// CHECK-NEXT:   "bzero\0"
+// CHECK-NEXT:   "calloc\0"
+// CHECK-NEXT:   "sqrtl\0"
+// CHECK-NEXT:   ;
+// CHECK-NEXT: #ifdef __GNUC__
+// CHECK-NEXT: #pragma GCC diagnostic pop
+// CHECK-NEXT: #endif
+// CHECK-EMPTY:
+// CHECK-NEXT: constexpr llvm::StringTable
+// CHECK-NEXT: RTLIB::RuntimeLibcallsInfo::RuntimeLibcallImplNameTable = RuntimeLibcallImplNameTableStorage;
+// CHECK-EMPTY:
+// CHECK-NEXT: const uint16_t RTLIB::RuntimeLibcallsInfo::RuntimeLibcallNameOffsetTable[] = {
+// CHECK-NEXT:   0, //
+// CHECK-NEXT:   1, // ___memcpy
+// CHECK-NEXT:   11, // ___memset
+// CHECK-NEXT:   21, // __ashlsi3
+// CHECK-NEXT:   31, // __lshrdi3
+// CHECK-NEXT:   41, // bzero
+// CHECK-NEXT:   47, // calloc
+// CHECK-NEXT:   54, // sqrtl
+// CHECK-NEXT:   54, // sqrtl
 // CHECK-NEXT: };
-
-// CHECK: const RTLIB::Libcall llvm::RTLIB::RuntimeLibcallsInfo::ImplToLibcall[RTLIB::NumLibcallImpls] = {
+// CHECK-NEXT: const RTLIB::Libcall llvm::RTLIB::RuntimeLibcallsInfo::ImplToLibcall[RTLIB::NumLibcallImpls] = {
 // CHECK-NEXT: RTLIB::UNKNOWN_LIBCALL, // RTLIB::Unsupported
 // CHECK-NEXT: RTLIB::MEMCPY, // RTLIB::___memcpy
 // CHECK-NEXT: RTLIB::MEMSET, // RTLIB::___memset

llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp

@@ -8,10 +8,12 @@
 
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 #include "llvm/TableGen/SetTheory.h"
+#include "llvm/TableGen/StringToOffsetTable.h"
 #include "llvm/TableGen/TableGenBackend.h"
 
 using namespace llvm;
@@ -305,8 +307,6 @@ void RuntimeLibcallEmitter::emitGetRuntimeLibcallEnum(raw_ostream &OS) const {
 
 void RuntimeLibcallEmitter::emitGetInitRuntimeLibcallNames(
     raw_ostream &OS) const {
-  // TODO: Emit libcall names as string offset table.
-
   OS << "const RTLIB::LibcallImpl "
         "llvm::RTLIB::RuntimeLibcallsInfo::"
         "DefaultLibcallImpls[RTLIB::UNKNOWN_LIBCALL + 1] = {\n";
@@ -331,17 +331,24 @@ void RuntimeLibcallEmitter::emitGetInitRuntimeLibcallNames(
         "};\n\n";
 
   // Emit the implementation names
-  OS << "const char *const llvm::RTLIB::RuntimeLibcallsInfo::"
-        "LibCallImplNames[RTLIB::NumLibcallImpls] = {\n"
-        "  nullptr, // RTLIB::Unsupported\n";
+  StringToOffsetTable Table(/*AppendZero=*/true,
+                            "RTLIB::RuntimeLibcallsInfo::");
+
+  for (const RuntimeLibcallImpl &LibCallImpl : RuntimeLibcallImplDefList)
+    Table.GetOrAddStringOffset(LibCallImpl.getLibcallFuncName());
+
+  Table.EmitStringTableDef(OS, "RuntimeLibcallImplNameTable");
+  OS << R"(
+const uint16_t RTLIB::RuntimeLibcallsInfo::RuntimeLibcallNameOffsetTable[] = {
+)";
 
+  OS << formatv("  {}, // {}\n", Table.GetStringOffset(""),
+                ""); // Unsupported entry
   for (const RuntimeLibcallImpl &LibCallImpl : RuntimeLibcallImplDefList) {
-    OS << "  \"" << LibCallImpl.getLibcallFuncName() << "\", // ";
-    LibCallImpl.emitEnumEntry(OS);
-    OS << '\n';
+    StringRef ImplName = LibCallImpl.getLibcallFuncName();
+    OS << formatv("  {}, // {}\n", Table.GetStringOffset(ImplName), ImplName);
   }
-
-  OS << "};\n\n";
+  OS << "};\n";
 
   // Emit the reverse mapping from implementation libraries to RTLIB::Libcall
   OS << "const RTLIB::Libcall llvm::RTLIB::RuntimeLibcallsInfo::"