1 files changed, 120 insertions, 0 deletions
diff --git a/llvm/lib/TableGen/StringToOffsetTable.cpp b/llvm/lib/TableGen/StringToOffsetTable.cpp
new file mode 100644
index 000000000000..d73b5749ad7d
--- /dev/null
+++ b/llvm/lib/TableGen/StringToOffsetTable.cpp
@@ -0,0 +1,120 @@
+//===- StringToOffsetTable.cpp - Emit a big concatenated string -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/TableGen/StringToOffsetTable.h"
+#include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/TableGen/Main.h"
+
+using namespace llvm;
+
+unsigned StringToOffsetTable::GetOrAddStringOffset(StringRef Str,
+                                                   bool appendZero) {
+  auto [II, Inserted] = StringOffset.insert({Str, size()});
+  if (Inserted) {
+    // Add the string to the aggregate if this is the first time found.
+    AggregateString.append(Str.begin(), Str.end());
+    if (appendZero)
+      AggregateString += '\0';
+  }
+
+  return II->second;
+}
+
+void StringToOffsetTable::EmitStringTableDef(raw_ostream &OS, const Twine &Name,
+                                             const Twine &Indent) const {
+  OS << formatv(R"(
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Woverlength-strings"
+#endif
+{0}static constexpr char {1}Storage[] = )",
+                Indent, Name);
+
+  // MSVC silently miscompiles string literals longer than 64k in some
+  // circumstances. The build system sets EmitLongStrLiterals to false when it
+  // detects that it is targetting MSVC. When that option is false and the
+  // string table is longer than 64k, emit it as an array of character
+  // literals.
+  bool UseChars = !EmitLongStrLiterals && AggregateString.size() > (64 * 1024);
+  OS << (UseChars ? "{\n" : "\n");
+
+  llvm::ListSeparator LineSep(UseChars ? ",\n" : "\n");
+  llvm::SmallVector<StringRef> Strings(split(AggregateString, '\0'));
+  // We should always have an empty string at the start, and because these are
+  // null terminators rather than separators, we'll have one at the end as
+  // well. Skip the end one.
+  assert(Strings.front().empty() && "Expected empty initial string!");
+  assert(Strings.back().empty() &&
+         "Expected empty string at the end due to terminators!");
+  Strings.pop_back();
+  for (StringRef Str : Strings) {
+    OS << LineSep << Indent << "  ";
+    // If we can, just emit this as a string literal to be concatenated.
+    if (!UseChars) {
+      OS << "\"";
+      OS.write_escaped(Str);
+      OS << "\\0\"";
+      continue;
+    }
+
+    llvm::ListSeparator CharSep(", ");
+    for (char C : Str) {
+      OS << CharSep << "'";
+      OS.write_escaped(StringRef(&C, 1));
+      OS << "'";
+    }
+    OS << CharSep << "'\\0'";
+  }
+  OS << LineSep << Indent << (UseChars ? "};" : "  ;");
+
+  OS << formatv(R"(
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
+
+{0}static constexpr llvm::StringTable {1} =
+{0}    {1}Storage;
+)",
+                Indent, Name);
+}
+
+void StringToOffsetTable::EmitString(raw_ostream &O) const {
+  // Escape the string.
+  SmallString<256> EscapedStr;
+  raw_svector_ostream(EscapedStr).write_escaped(AggregateString);
+
+  O << "    \"";
+  unsigned CharsPrinted = 0;
+  for (unsigned i = 0, e = EscapedStr.size(); i != e; ++i) {
+    if (CharsPrinted > 70) {
+      O << "\"\n    \"";
+      CharsPrinted = 0;
+    }
+    O << EscapedStr[i];
+    ++CharsPrinted;
+
+    // Print escape sequences all together.
+    if (EscapedStr[i] != '\\')
+      continue;
+
+    assert(i + 1 < EscapedStr.size() && "Incomplete escape sequence!");
+    if (isDigit(EscapedStr[i + 1])) {
+      assert(isDigit(EscapedStr[i + 2]) && isDigit(EscapedStr[i + 3]) &&
+             "Expected 3 digit octal escape!");
+      O << EscapedStr[++i];
+      O << EscapedStr[++i];
+      O << EscapedStr[++i];
+      CharsPrinted += 3;
+    } else {
+      O << EscapedStr[++i];
+      ++CharsPrinted;
+    }
+  }
+  O << "\"";
+}