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, 353 insertions, 0 deletions

diff --git a/third_party/llvm-project/include/llvm/ADT/APSInt.h b/third_party/llvm-project/include/llvm/ADT/APSInt.h
new file mode 100644
index 000000000..0f991826c
--- /dev/null
+++ b/third_party/llvm-project/include/llvm/ADT/APSInt.h
@@ -0,0 +1,353 @@
+//===-- llvm/ADT/APSInt.h - Arbitrary Precision Signed Int -----*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the APSInt class, which is a simple class that
+// represents an arbitrary sized integer that knows its signedness.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_APSINT_H
+#define LLVM_ADT_APSINT_H
+
+#include "llvm/ADT/APInt.h"
+
+namespace llvm {
+
+class LLVM_NODISCARD APSInt : public APInt {
+  bool IsUnsigned;
+
+public:
+  /// Default constructor that creates an uninitialized APInt.
+  explicit APSInt() : IsUnsigned(false) {}
+
+  /// APSInt ctor - Create an APSInt with the specified width, default to
+  /// unsigned.
+  explicit APSInt(uint32_t BitWidth, bool isUnsigned = true)
+   : APInt(BitWidth, 0), IsUnsigned(isUnsigned) {}
+
+  explicit APSInt(APInt I, bool isUnsigned = true)
+   : APInt(std::move(I)), IsUnsigned(isUnsigned) {}
+
+  /// Construct an APSInt from a string representation.
+  ///
+  /// This constructor interprets the string \p Str using the radix of 10.
+  /// The interpretation stops at the end of the string. The bit width of the
+  /// constructed APSInt is determined automatically.
+  ///
+  /// \param Str the string to be interpreted.
+  explicit APSInt(StringRef Str);
+
+  /// Determine sign of this APSInt.
+  ///
+  /// \returns true if this APSInt is negative, false otherwise
+  bool isNegative() const { return isSigned() && APInt::isNegative(); }
+
+  /// Determine if this APSInt Value is non-negative (>= 0)
+  ///
+  /// \returns true if this APSInt is non-negative, false otherwise
+  bool isNonNegative() const { return !isNegative(); }
+
+  /// Determine if this APSInt Value is positive.
+  ///
+  /// This tests if the value of this APSInt is positive (> 0). Note
+  /// that 0 is not a positive value.
+  ///
+  /// \returns true if this APSInt is positive.
+  bool isStrictlyPositive() const { return isNonNegative() && !isNullValue(); }
+
+  APSInt &operator=(APInt RHS) {
+    // Retain our current sign.
+    APInt::operator=(std::move(RHS));
+    return *this;
+  }
+
+  APSInt &operator=(uint64_t RHS) {
+    // Retain our current sign.
+    APInt::operator=(RHS);
+    return *this;
+  }
+
+  // Query sign information.
+  bool isSigned() const { return !IsUnsigned; }
+  bool isUnsigned() const { return IsUnsigned; }
+  void setIsUnsigned(bool Val) { IsUnsigned = Val; }
+  void setIsSigned(bool Val) { IsUnsigned = !Val; }
+
+  /// toString - Append this APSInt to the specified SmallString.
+  void toString(SmallVectorImpl<char> &Str, unsigned Radix = 10) const {
+    APInt::toString(Str, Radix, isSigned());
+  }
+  /// toString - Converts an APInt to a std::string.  This is an inefficient
+  /// method; you should prefer passing in a SmallString instead.
+  std::string toString(unsigned Radix) const {
+    return APInt::toString(Radix, isSigned());
+  }
+  using APInt::toString;
+
+  /// Get the correctly-extended \c int64_t value.
+  int64_t getExtValue() const {
+    assert(getMinSignedBits() <= 64 && "Too many bits for int64_t");
+    return isSigned() ? getSExtValue() : getZExtValue();
+  }
+
+  APSInt trunc(uint32_t width) const {
+    return APSInt(APInt::trunc(width), IsUnsigned);
+  }
+
+  APSInt extend(uint32_t width) const {
+    if (IsUnsigned)
+      return APSInt(zext(width), IsUnsigned);
+    else
+      return APSInt(sext(width), IsUnsigned);
+  }
+
+  APSInt extOrTrunc(uint32_t width) const {
+    if (IsUnsigned)
+      return APSInt(zextOrTrunc(width), IsUnsigned);
+    else
+      return APSInt(sextOrTrunc(width), IsUnsigned);
+  }
+
+  const APSInt &operator%=(const APSInt &RHS) {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    if (IsUnsigned)
+      *this = urem(RHS);
+    else
+      *this = srem(RHS);
+    return *this;
+  }
+  const APSInt &operator/=(const APSInt &RHS) {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    if (IsUnsigned)
+      *this = udiv(RHS);
+    else
+      *this = sdiv(RHS);
+    return *this;
+  }
+  APSInt operator%(const APSInt &RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return IsUnsigned ? APSInt(urem(RHS), true) : APSInt(srem(RHS), false);
+  }
+  APSInt operator/(const APSInt &RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return IsUnsigned ? APSInt(udiv(RHS), true) : APSInt(sdiv(RHS), false);
+  }
+
+  APSInt operator>>(unsigned Amt) const {
+    return IsUnsigned ? APSInt(lshr(Amt), true) : APSInt(ashr(Amt), false);
+  }
+  APSInt& operator>>=(unsigned Amt) {
+    if (IsUnsigned)
+      lshrInPlace(Amt);
+    else
+      ashrInPlace(Amt);
+    return *this;
+  }
+
+  inline bool operator<(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return IsUnsigned ? ult(RHS) : slt(RHS);
+  }
+  inline bool operator>(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return IsUnsigned ? ugt(RHS) : sgt(RHS);
+  }
+  inline bool operator<=(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return IsUnsigned ? ule(RHS) : sle(RHS);
+  }
+  inline bool operator>=(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return IsUnsigned ? uge(RHS) : sge(RHS);
+  }
+  inline bool operator==(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return eq(RHS);
+  }
+  inline bool operator!=(const APSInt& RHS) const {
+    return !((*this) == RHS);
+  }
+
+  bool operator==(int64_t RHS) const {
+    return compareValues(*this, get(RHS)) == 0;
+  }
+  bool operator!=(int64_t RHS) const {
+    return compareValues(*this, get(RHS)) != 0;
+  }
+  bool operator<=(int64_t RHS) const {
+    return compareValues(*this, get(RHS)) <= 0;
+  }
+  bool operator>=(int64_t RHS) const {
+    return compareValues(*this, get(RHS)) >= 0;
+  }
+  bool operator<(int64_t RHS) const {
+    return compareValues(*this, get(RHS)) < 0;
+  }
+  bool operator>(int64_t RHS) const {
+    return compareValues(*this, get(RHS)) > 0;
+  }
+
+  // The remaining operators just wrap the logic of APInt, but retain the
+  // signedness information.
+
+  APSInt operator<<(unsigned Bits) const {
+    return APSInt(static_cast<const APInt&>(*this) << Bits, IsUnsigned);
+  }
+  APSInt& operator<<=(unsigned Amt) {
+    static_cast<APInt&>(*this) <<= Amt;
+    return *this;
+  }
+
+  APSInt& operator++() {
+    ++(static_cast<APInt&>(*this));
+    return *this;
+  }
+  APSInt& operator--() {
+    --(static_cast<APInt&>(*this));
+    return *this;
+  }
+  APSInt operator++(int) {
+    return APSInt(++static_cast<APInt&>(*this), IsUnsigned);
+  }
+  APSInt operator--(int) {
+    return APSInt(--static_cast<APInt&>(*this), IsUnsigned);
+  }
+  APSInt operator-() const {
+    return APSInt(-static_cast<const APInt&>(*this), IsUnsigned);
+  }
+  APSInt& operator+=(const APSInt& RHS) {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    static_cast<APInt&>(*this) += RHS;
+    return *this;
+  }
+  APSInt& operator-=(const APSInt& RHS) {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    static_cast<APInt&>(*this) -= RHS;
+    return *this;
+  }
+  APSInt& operator*=(const APSInt& RHS) {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    static_cast<APInt&>(*this) *= RHS;
+    return *this;
+  }
+  APSInt& operator&=(const APSInt& RHS) {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    static_cast<APInt&>(*this) &= RHS;
+    return *this;
+  }
+  APSInt& operator|=(const APSInt& RHS) {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    static_cast<APInt&>(*this) |= RHS;
+    return *this;
+  }
+  APSInt& operator^=(const APSInt& RHS) {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    static_cast<APInt&>(*this) ^= RHS;
+    return *this;
+  }
+
+  APSInt operator&(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return APSInt(static_cast<const APInt&>(*this) & RHS, IsUnsigned);
+  }
+
+  APSInt operator|(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return APSInt(static_cast<const APInt&>(*this) | RHS, IsUnsigned);
+  }
+
+  APSInt operator^(const APSInt &RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return APSInt(static_cast<const APInt&>(*this) ^ RHS, IsUnsigned);
+  }
+
+  APSInt operator*(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return APSInt(static_cast<const APInt&>(*this) * RHS, IsUnsigned);
+  }
+  APSInt operator+(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return APSInt(static_cast<const APInt&>(*this) + RHS, IsUnsigned);
+  }
+  APSInt operator-(const APSInt& RHS) const {
+    assert(IsUnsigned == RHS.IsUnsigned && "Signedness mismatch!");
+    return APSInt(static_cast<const APInt&>(*this) - RHS, IsUnsigned);
+  }
+  APSInt operator~() const {
+    return APSInt(~static_cast<const APInt&>(*this), IsUnsigned);
+  }
+
+  /// getMaxValue - Return the APSInt representing the maximum integer value
+  ///  with the given bit width and signedness.
+  static APSInt getMaxValue(uint32_t numBits, bool Unsigned) {
+    return APSInt(Unsigned ? APInt::getMaxValue(numBits)
+                           : APInt::getSignedMaxValue(numBits), Unsigned);
+  }
+
+  /// getMinValue - Return the APSInt representing the minimum integer value
+  ///  with the given bit width and signedness.
+  static APSInt getMinValue(uint32_t numBits, bool Unsigned) {
+    return APSInt(Unsigned ? APInt::getMinValue(numBits)
+                           : APInt::getSignedMinValue(numBits), Unsigned);
+  }
+
+  /// Determine if two APSInts have the same value, zero- or
+  /// sign-extending as needed.
+  static bool isSameValue(const APSInt &I1, const APSInt &I2) {
+    return !compareValues(I1, I2);
+  }
+
+  /// Compare underlying values of two numbers.
+  static int compareValues(const APSInt &I1, const APSInt &I2) {
+    if (I1.getBitWidth() == I2.getBitWidth() && I1.isSigned() == I2.isSigned())
+      return I1.IsUnsigned ? I1.compare(I2) : I1.compareSigned(I2);
+
+    // Check for a bit-width mismatch.
+    if (I1.getBitWidth() > I2.getBitWidth())
+      return compareValues(I1, I2.extend(I1.getBitWidth()));
+    if (I2.getBitWidth() > I1.getBitWidth())
+      return compareValues(I1.extend(I2.getBitWidth()), I2);
+
+    // We have a signedness mismatch. Check for negative values and do an
+    // unsigned compare if both are positive.
+    if (I1.isSigned()) {
+      assert(!I2.isSigned() && "Expected signed mismatch");
+      if (I1.isNegative())
+        return -1;
+    } else {
+      assert(I2.isSigned() && "Expected signed mismatch");
+      if (I2.isNegative())
+        return 1;
+    }
+
+    return I1.compare(I2);
+  }
+
+  static APSInt get(int64_t X) { return APSInt(APInt(64, X), false); }
+  static APSInt getUnsigned(uint64_t X) { return APSInt(APInt(64, X), true); }
+
+  /// Profile - Used to insert APSInt objects, or objects that contain APSInt
+  ///  objects, into FoldingSets.
+  void Profile(FoldingSetNodeID& ID) const;
+};
+
+inline bool operator==(int64_t V1, const APSInt &V2) { return V2 == V1; }
+inline bool operator!=(int64_t V1, const APSInt &V2) { return V2 != V1; }
+inline bool operator<=(int64_t V1, const APSInt &V2) { return V2 >= V1; }
+inline bool operator>=(int64_t V1, const APSInt &V2) { return V2 <= V1; }
+inline bool operator<(int64_t V1, const APSInt &V2) { return V2 > V1; }
+inline bool operator>(int64_t V1, const APSInt &V2) { return V2 < V1; }
+
+inline raw_ostream &operator<<(raw_ostream &OS, const APSInt &I) {
+  I.print(OS, I.isSigned());
+  return OS;
+}
+
+} // end namespace llvm
+
+#endif