DWARF parsing and writing support using LLVM (#2520)

This imports LLVM code for DWARF handling. That code has the
Apache 2 license like us. It's also the same code used to
emit DWARF in the common toolchain, so it seems like a safe choice.

This adds two passes: --dwarfdump which runs the same code LLVM
runs for llvm-dwarfdump. This shows we can parse it ok, and will
be useful for debugging. And --dwarfupdate writes out the DWARF
sections (unchanged from what we read, so it just roundtrips - for
updating we need #2515).

This puts LLVM in thirdparty which is added here.

All the LLVM code is behind USE_LLVM_DWARF, which is on
by default, but off in JS for now, as it increases code size by 20%.

This current approach imports the LLVM files directly. This is not
how they are intended to be used, so it required a bunch of
local changes - more than I expected actually, for the platform-specific
stuff. For now this seems to work, so it may be good enough, but
in the long term we may want to switch to linking against libllvm.
A downside to doing that is that binaryen users would need to
have an LLVM build, and even in the waterfall builds we'd have a
problem - while we ship LLVM there anyhow, we constantly update
it, which means that binaryen would need to be on latest llvm all
the time too (which otherwise, given DWARF is quite stable, we
might not need to constantly update).

An even larger issue is that as I did this work I learned about how
DWARF works in LLVM, and while the reading code is easy to
reuse, the writing code is trickier. The main code path is heavily
integrated with the MC layer, which we don't have - we might want
to create a "fake MC layer" for that, but it sounds hard. Instead,
there is the YAML path which is used mostly for testing, and which
can convert DWARF to and from YAML and from binary. Using
the non-YAML parts there, we can convert binary DWARF to
the YAML layer's nice Info data, then convert that to binary. This
works, however, this is not the path LLVM uses normally, and it
supports only some basic DWARF sections - I had to add ranges
support, in fact. So if we need more complex things, we may end
up needing to use the MC layer approach, or consider some other
DWARF library. However, hopefully that should not affect the core
binaryen code which just calls a library for DWARF stuff.

Helps #2400

1 files changed, 388 insertions, 0 deletions

diff --git a/third_party/llvm-project/include/llvm/Support/ScopedPrinter.h b/third_party/llvm-project/include/llvm/Support/ScopedPrinter.h
new file mode 100644
index 000000000..88daedc87
--- /dev/null
+++ b/third_party/llvm-project/include/llvm/Support/ScopedPrinter.h
@@ -0,0 +1,388 @@
+//===-- ScopedPrinter.h ----------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_SCOPEDPRINTER_H
+#define LLVM_SUPPORT_SCOPEDPRINTER_H
+
+#include "llvm/ADT/APSInt.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+
+namespace llvm {
+
+template <typename T> struct EnumEntry {
+  StringRef Name;
+  // While Name suffices in most of the cases, in certain cases
+  // GNU style and LLVM style of ELFDumper do not
+  // display same string for same enum. The AltName if initialized appropriately
+  // will hold the string that GNU style emits.
+  // Example:
+  // "EM_X86_64" string on LLVM style for Elf_Ehdr->e_machine corresponds to
+  // "Advanced Micro Devices X86-64" on GNU style
+  StringRef AltName;
+  T Value;
+  EnumEntry(StringRef N, StringRef A, T V) : Name(N), AltName(A), Value(V) {}
+  EnumEntry(StringRef N, T V) : Name(N), AltName(N), Value(V) {}
+};
+
+struct HexNumber {
+  // To avoid sign-extension we have to explicitly cast to the appropriate
+  // unsigned type. The overloads are here so that every type that is implicitly
+  // convertible to an integer (including enums and endian helpers) can be used
+  // without requiring type traits or call-site changes.
+  HexNumber(char Value) : Value(static_cast<unsigned char>(Value)) {}
+  HexNumber(signed char Value) : Value(static_cast<unsigned char>(Value)) {}
+  HexNumber(signed short Value) : Value(static_cast<unsigned short>(Value)) {}
+  HexNumber(signed int Value) : Value(static_cast<unsigned int>(Value)) {}
+  HexNumber(signed long Value) : Value(static_cast<unsigned long>(Value)) {}
+  HexNumber(signed long long Value)
+      : Value(static_cast<unsigned long long>(Value)) {}
+  HexNumber(unsigned char Value) : Value(Value) {}
+  HexNumber(unsigned short Value) : Value(Value) {}
+  HexNumber(unsigned int Value) : Value(Value) {}
+  HexNumber(unsigned long Value) : Value(Value) {}
+  HexNumber(unsigned long long Value) : Value(Value) {}
+  uint64_t Value;
+};
+
+raw_ostream &operator<<(raw_ostream &OS, const HexNumber &Value);
+const std::string to_hexString(uint64_t Value, bool UpperCase = true);
+
+template <class T> const std::string to_string(const T &Value) {
+  std::string number;
+  llvm::raw_string_ostream stream(number);
+  stream << Value;
+  return stream.str();
+}
+
+class ScopedPrinter {
+public:
+  ScopedPrinter(raw_ostream &OS) : OS(OS), IndentLevel(0) {}
+
+  void flush() { OS.flush(); }
+
+  void indent(int Levels = 1) { IndentLevel += Levels; }
+
+  void unindent(int Levels = 1) {
+    IndentLevel = std::max(0, IndentLevel - Levels);
+  }
+
+  void resetIndent() { IndentLevel = 0; }
+
+  int getIndentLevel() { return IndentLevel; }
+
+  void setPrefix(StringRef P) { Prefix = P; }
+
+  void printIndent() {
+    OS << Prefix;
+    for (int i = 0; i < IndentLevel; ++i)
+      OS << "  ";
+  }
+
+  template <typename T> HexNumber hex(T Value) { return HexNumber(Value); }
+
+  template <typename T, typename TEnum>
+  void printEnum(StringRef Label, T Value,
+                 ArrayRef<EnumEntry<TEnum>> EnumValues) {
+    StringRef Name;
+    bool Found = false;
+    for (const auto &EnumItem : EnumValues) {
+      if (EnumItem.Value == Value) {
+        Name = EnumItem.Name;
+        Found = true;
+        break;
+      }
+    }
+
+    if (Found) {
+      startLine() << Label << ": " << Name << " (" << hex(Value) << ")\n";
+    } else {
+      startLine() << Label << ": " << hex(Value) << "\n";
+    }
+  }
+
+  template <typename T, typename TFlag>
+  void printFlags(StringRef Label, T Value, ArrayRef<EnumEntry<TFlag>> Flags,
+                  TFlag EnumMask1 = {}, TFlag EnumMask2 = {},
+                  TFlag EnumMask3 = {}) {
+    typedef EnumEntry<TFlag> FlagEntry;
+    typedef SmallVector<FlagEntry, 10> FlagVector;
+    FlagVector SetFlags;
+
+    for (const auto &Flag : Flags) {
+      if (Flag.Value == 0)
+        continue;
+
+      TFlag EnumMask{};
+      if (Flag.Value & EnumMask1)
+        EnumMask = EnumMask1;
+      else if (Flag.Value & EnumMask2)
+        EnumMask = EnumMask2;
+      else if (Flag.Value & EnumMask3)
+        EnumMask = EnumMask3;
+      bool IsEnum = (Flag.Value & EnumMask) != 0;
+      if ((!IsEnum && (Value & Flag.Value) == Flag.Value) ||
+          (IsEnum && (Value & EnumMask) == Flag.Value)) {
+        SetFlags.push_back(Flag);
+      }
+    }
+
+    llvm::sort(SetFlags, &flagName<TFlag>);
+
+    startLine() << Label << " [ (" << hex(Value) << ")\n";
+    for (const auto &Flag : SetFlags) {
+      startLine() << "  " << Flag.Name << " (" << hex(Flag.Value) << ")\n";
+    }
+    startLine() << "]\n";
+  }
+
+  template <typename T> void printFlags(StringRef Label, T Value) {
+    startLine() << Label << " [ (" << hex(Value) << ")\n";
+    uint64_t Flag = 1;
+    uint64_t Curr = Value;
+    while (Curr > 0) {
+      if (Curr & 1)
+        startLine() << "  " << hex(Flag) << "\n";
+      Curr >>= 1;
+      Flag <<= 1;
+    }
+    startLine() << "]\n";
+  }
+
+  void printNumber(StringRef Label, uint64_t Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  void printNumber(StringRef Label, uint32_t Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  void printNumber(StringRef Label, uint16_t Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  void printNumber(StringRef Label, uint8_t Value) {
+    startLine() << Label << ": " << unsigned(Value) << "\n";
+  }
+
+  void printNumber(StringRef Label, int64_t Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  void printNumber(StringRef Label, int32_t Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  void printNumber(StringRef Label, int16_t Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  void printNumber(StringRef Label, int8_t Value) {
+    startLine() << Label << ": " << int(Value) << "\n";
+  }
+
+  void printNumber(StringRef Label, const APSInt &Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  void printBoolean(StringRef Label, bool Value) {
+    startLine() << Label << ": " << (Value ? "Yes" : "No") << '\n';
+  }
+
+  template <typename... T> void printVersion(StringRef Label, T... Version) {
+    startLine() << Label << ": ";
+    printVersionInternal(Version...);
+    getOStream() << "\n";
+  }
+
+  template <typename T> void printList(StringRef Label, const T &List) {
+    startLine() << Label << ": [";
+    bool Comma = false;
+    for (const auto &Item : List) {
+      if (Comma)
+        OS << ", ";
+      OS << Item;
+      Comma = true;
+    }
+    OS << "]\n";
+  }
+
+  template <typename T, typename U>
+  void printList(StringRef Label, const T &List, const U &Printer) {
+    startLine() << Label << ": [";
+    bool Comma = false;
+    for (const auto &Item : List) {
+      if (Comma)
+        OS << ", ";
+      Printer(OS, Item);
+      Comma = true;
+    }
+    OS << "]\n";
+  }
+
+  template <typename T> void printHexList(StringRef Label, const T &List) {
+    startLine() << Label << ": [";
+    bool Comma = false;
+    for (const auto &Item : List) {
+      if (Comma)
+        OS << ", ";
+      OS << hex(Item);
+      Comma = true;
+    }
+    OS << "]\n";
+  }
+
+  template <typename T> void printHex(StringRef Label, T Value) {
+    startLine() << Label << ": " << hex(Value) << "\n";
+  }
+
+  template <typename T> void printHex(StringRef Label, StringRef Str, T Value) {
+    startLine() << Label << ": " << Str << " (" << hex(Value) << ")\n";
+  }
+
+  template <typename T>
+  void printSymbolOffset(StringRef Label, StringRef Symbol, T Value) {
+    startLine() << Label << ": " << Symbol << '+' << hex(Value) << '\n';
+  }
+
+  void printString(StringRef Value) { startLine() << Value << "\n"; }
+
+  void printString(StringRef Label, StringRef Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  void printString(StringRef Label, const std::string &Value) {
+    printString(Label, StringRef(Value));
+  }
+
+  void printString(StringRef Label, const char* Value) {
+    printString(Label, StringRef(Value));
+  }
+
+  template <typename T>
+  void printNumber(StringRef Label, StringRef Str, T Value) {
+    startLine() << Label << ": " << Str << " (" << Value << ")\n";
+  }
+
+  void printBinary(StringRef Label, StringRef Str, ArrayRef<uint8_t> Value) {
+    printBinaryImpl(Label, Str, Value, false);
+  }
+
+  void printBinary(StringRef Label, StringRef Str, ArrayRef<char> Value) {
+    auto V = makeArrayRef(reinterpret_cast<const uint8_t *>(Value.data()),
+                          Value.size());
+    printBinaryImpl(Label, Str, V, false);
+  }
+
+  void printBinary(StringRef Label, ArrayRef<uint8_t> Value) {
+    printBinaryImpl(Label, StringRef(), Value, false);
+  }
+
+  void printBinary(StringRef Label, ArrayRef<char> Value) {
+    auto V = makeArrayRef(reinterpret_cast<const uint8_t *>(Value.data()),
+                          Value.size());
+    printBinaryImpl(Label, StringRef(), V, false);
+  }
+
+  void printBinary(StringRef Label, StringRef Value) {
+    auto V = makeArrayRef(reinterpret_cast<const uint8_t *>(Value.data()),
+                          Value.size());
+    printBinaryImpl(Label, StringRef(), V, false);
+  }
+
+  void printBinaryBlock(StringRef Label, ArrayRef<uint8_t> Value,
+                        uint32_t StartOffset) {
+    printBinaryImpl(Label, StringRef(), Value, true, StartOffset);
+  }
+
+  void printBinaryBlock(StringRef Label, ArrayRef<uint8_t> Value) {
+    printBinaryImpl(Label, StringRef(), Value, true);
+  }
+
+  void printBinaryBlock(StringRef Label, StringRef Value) {
+    auto V = makeArrayRef(reinterpret_cast<const uint8_t *>(Value.data()),
+                          Value.size());
+    printBinaryImpl(Label, StringRef(), V, true);
+  }
+
+  template <typename T> void printObject(StringRef Label, const T &Value) {
+    startLine() << Label << ": " << Value << "\n";
+  }
+
+  raw_ostream &startLine() {
+    printIndent();
+    return OS;
+  }
+
+  raw_ostream &getOStream() { return OS; }
+
+private:
+  template <typename T> void printVersionInternal(T Value) {
+    getOStream() << Value;
+  }
+
+  template <typename S, typename T, typename... TArgs>
+  void printVersionInternal(S Value, T Value2, TArgs... Args) {
+    getOStream() << Value << ".";
+    printVersionInternal(Value2, Args...);
+  }
+
+  template <typename T>
+  static bool flagName(const EnumEntry<T> &lhs, const EnumEntry<T> &rhs) {
+    return lhs.Name < rhs.Name;
+  }
+
+  void printBinaryImpl(StringRef Label, StringRef Str, ArrayRef<uint8_t> Value,
+                       bool Block, uint32_t StartOffset = 0);
+
+  raw_ostream &OS;
+  int IndentLevel;
+  StringRef Prefix;
+};
+
+template <>
+inline void
+ScopedPrinter::printHex<support::ulittle16_t>(StringRef Label,
+                                              support::ulittle16_t Value) {
+  startLine() << Label << ": " << hex(Value) << "\n";
+}
+
+template<char Open, char Close>
+struct DelimitedScope {
+  explicit DelimitedScope(ScopedPrinter &W) : W(W) {
+    W.startLine() << Open << '\n';
+    W.indent();
+  }
+
+  DelimitedScope(ScopedPrinter &W, StringRef N) : W(W) {
+    W.startLine() << N;
+    if (!N.empty())
+      W.getOStream() << ' ';
+    W.getOStream() << Open << '\n';
+    W.indent();
+  }
+
+  ~DelimitedScope() {
+    W.unindent();
+    W.startLine() << Close << '\n';
+  }
+
+  ScopedPrinter &W;
+};
+
+using DictScope = DelimitedScope<'{', '}'>;
+using ListScope = DelimitedScope<'[', ']'>;
+
+} // namespace llvm
+
+#endif